October 31, 2010

Understanding Medical Exams: USMLE 1, 2 and 3

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The United States Medical Licensing Examination® (USMLE®) is a three-step examination for medical licensure in the United States and is sponsored by the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners® (NBME®). Physicians with an M.D. degree are required to pass this examination before being permitted to practice medicine in the United States.

October 30, 2010

PLAB Question 25

No comments:
The incubation period for the onset of rubeola is approximately:

a) less than 10 minutes
b) 1-2 hours
c) 3-6 hours
d) 12-24 hours
e) 2-4 days
f) one to three weeks
g) one to three months
h) 6-12 months
i) 2-5 years
j) over 10 years

The correct answer is F

rubeola -> measles; the incubation period is generally 8 to 12 days from exposure to onset of symptoms; the average interval from exposure to appearance of the rash is 14 days.

In family studies, the average interval between appearance of rash in the source case and subsequent cases is 14 days, with a range of 7 to 18 days.

PLAB Question 24

No comments:
A 38 year old male with Down's syndrome develops shortness of breath and diffuse epistaxis. On examination he is found to have generalised large lymph nodes and hepatosplenomegaly. There are diffuse petechiae and ecchymoses, on his skin.

A Romanovsky-stained smear of his bone marrow is most likely to demonstrate:

a) target cells
b) melanocytes
c) lymphoblasts with clumped chromatin
d) transitional epithelial cells
e) mast cell infiltration
f) neutropenia
g) Burr cells
h) squamous epithelial cells
i) anti-nuclear antibodies
j) clumps of neutrophils

The correct answer is C

Acute leukemias are commoner in Down's syndrome. Experienced morphologists can reproducibly classify about 70% of acute leukemias as either ALL or AML by the blast appearance on Romanovsky-stained smears based on nuclear and cytoplasmic features.

The most important morphologic characteristic in identifying blasts is the nuclear chromatin pattern.

The chromatin in lymphoblasts is more clumped and irregularly distributed. The presence of nucleoli varies. Nucleoli may be indistinct or appear prominent because of chromatin condensation along the nucleolar and nuclear membranes.

PLAB Question 23

No comments:
A 34 year old complains of fatigue and weight gain. On examination she is found to have dry skin and a bitemporal hemianopia.

The cause of her weight gain is most likely to be:

a) Pickwickian syndrome
b) Cushing's syndrome
c) affective disorder
d) Sjogren's syndrome
e) Laurence-Moon-Bardet-Biedl Syndrome
f) fibromyalgia
g) Stein-Leventhal Syndrome
h) secondary hypothyroidism
i) hypothalamic disorder
j) Carpenter's syndrome

The correct answer is H

Secondary hypothyroidism should be suspected when, in the setting of overt hypothyroidism, the TSH level is inappropriately low.

Concurrent amenorrhea, galactorrhea, postural hypotension, or visual field cut also suggests pituitary-hypothalamic pathology. Imaging of the sellar region is indicated.

Computed tomography (CT) scan is best for detection of small lesions within the sella; magnetic resonance imaging (MRI) is best for imaging the suprasellar region. TRH stimulation is sometimes used to confirm secondary hypothyroidism, but the test often fails to distinguish among secondary causes.

PLAB Question 22

No comments:
Consider these values - MCV: Decreased; Serum ferritin: Decreased; Total iron binding capacity: Increased; Serum iron: Decreased; Marrow iron: Absent

a) Thalassaemia trait
b) Hypoparathyroidism
c) Hereditary sideroblastic anaemia
d) Protein energy malnutrition
e) Chronic renal failure
f) Anaemia of chronic disease
g) Acute blood loss
h) Iron deficiency anaemia
i) Oral contraceptives
j) Megaloblastic anaemia

The correct answer is H

Iron deficiency anaemia or IDA is recognized from the combination of abnormal iron-supply studies and microcytic, hypochromic red blood cell morphology. The [serum iron] SI falls to very low levels [<4 mol/L (<30 g/dL)], while the total iron binding capacity [TIBC] increases. The ferritin level is always less than 15 g/L.

Once the patient's hemoglobin level falls below 100 to 110 g/L (10 to 11 g/dL), poorly hemoglobinized cells begin to enter the circulation.

When the anaemia is only of moderate severity, the cells tend to be microcytic but not hypochromic. At lower hemoglobin levels, both microcytosis and hypochromia become more pronounced.

Furthermore, red blood cell production becomes increasingly ineffective, resulting in greater degrees of aniso- and poikilocytosis. With very severe iron-deficiency anaemia , cigar- or pencil-shaped red blood cells may be observed.

As a rule, target cells are not seen with iron deficiency. When present, they suggest a globin chain production defect, i.e. one of the thalassemias. They may also be seen in the presence of liver disease.

The more common diagnostic problem is the potential confusion between iron deficiency and an inflammatory block in iron delivery from the reticuloendothelial system to the erythroid progenitors [the anaemia of chronic disease or AoCD]. However, while both the SI and TIBC decline in patients with AoCD, the TIBC is increased in iron deficiency anaemia while the SI is decreased. However, serum ferritin is increased in AoCD where it is decreased in iron deficiency anaemia and if a marrow aspiration is performed, AoCD will show normal to increased iron stores together with a hypoproliferative marrow morphology. Moreover, in anaemia of chronic disease [AoCD] patients typically show a low SI, low TIBC, a normal to high serum ferritin level.

PLAB Question 21

No comments:
A young man develops nonfluent, effortful speech with dysarthria. he is able to undertsand speech. He fails to repeat the sentence "no ifs, ands or buts about it". A CT scan is normal.

The investigation of choice at this stage would be:

a) skull x-ray
b) non-contrast CT scan brain
c) contrast CT scan brain
d) contrast enhanced MRI of the optic nerves
e) four vessel cerebral angiogram
f) single vessel cerebral angiogram
g) MR cerebral Angiography
h) mri with emphasis on the frontal lobe
i) mri of the pituitary gland
j) mri with emphasis on the temporal lobe

The correct answer is J

The clinical features are suggestive of what is known as Broca's aphasia. It is also known as expressive aphasia. It is characterized by nonfluent, effortful speech with dysarthria.

Comprehension is usually good. It is Typically caused by frontal lobe lesions. Typical tasks on examination that they fail is to repeat the sentence "no ifs, ands or buts about it".

These patients may only have (for example), a single word left in their vocabulary. Aphemia means mute but writes fluently.

October 27, 2010

PLAB Question 20

No comments:
A 60 year old patient presents with three days onset of severe abdominal pain radiating to the back. On physical examination, a pulsatile mass in the periumbilical region is found. The patient is hemodynamically stable.

The next most appropriate step would be:

a) serum glucose
b) oral cholecystogram
c) liver biopsy
d) intravenous urogram
e) endoscopy
f) CT scan of the abdomen
g) blood culture
h) serum alcohol level
i) serum amylase
j) ultrasound of the abdomen

The correct answer is F

When patients have the classic triad of pain, hypotension, and a pulsatile abdominal mass, the diagnosis of ruptured Abdominal Aortic Aneurysm(AAA)is straightforward and is usually made rapidly. However, many patients do not present classically, and misdiagnosis of ruptured AAAs, which leads to a delay in definitive surgical therapy, is very common.

Patients who are misdiagnosed are usually hemodynamically stable on presentation but are at risk for sudden and catastrophic deterioration.

Because patients with ruptured AAAs usually have abdominal, back, or flank pain, with or without hypotension, common misdiagnoses are other disease processes causing these symptoms.

The sudden onset of pain often leads to the clinical suspicion of renal colic. Abdominal pain and tenderness may suggest pancreatitis, intestinal ischemia, or other intraabdominal disorders. The diagnosis of musculoskeletal back pain is especially dangerous because such patients are often discharged from the Emergency Department.

PLAB Question 19

No comments:
Consider the following values - MCV: Decreased; Serum ferritin: Increased; Total iron binding capacity: Normal; Serum iron: Increased; Marrow iron: Present.

The most likely diagnosis is:

a) Thalassaemia trait
b) Hypoparathyroidism
c) Hereditary sideroblastic anaemia
d) Protein energy malnutrition
e) Chronic renal failure
f) Anaemia of chronic disease
g) Acute blood loss
h) Iron deficiency anaemia
i) Oral contraceptives
j) Megaloblastic anaemia

The correct answer is C

Patients with a defect in mitochondrial function resulting in a sideroblastic anaemia can also present with a microcytic, hypochromic anaemia.

Hereditary sideroblastic anaemia is a rare condition that presents in childhood either as an X-linked or autosomally inherited condition. Red blood cell morphology is typically dimorphic, and measurements of iron supply make the distinction from iron deficiency quite easy.

Patients who develop an acquired ringed sideroblastic anaemia typically exhibit excessive iron accumulation, even to the point of tissue iron overload. Their red blood cell morphology can be quite variable, while marrow morphology demonstrates the pathognomonic finding of ringed sideroblasts.

PLAB Question 18

No comments:
A young woman develops mild hypertension that first develops during pregnancy.

Which of the treatment strategies below is the most preferred first-line therapy for her:

a) immediate delivery
b) intravenous Hydralazine
c) alpha-blocker
d) Labetolol
e) change current treatment immediately
f) diuretic
g) Methyldopa
h) calcium antagonist
i) angiotensin-converting enzyme inhibitors
j) angiotensin II receptor antagonist

The correct answer is G

Methyldopa is preferred as first-line therapy by many clinicians when hypertension develops during pregnancy. If it is not well tolerated, alternatives are available.

Use of a diuretic, a mainstay of hypertension management, is considered controversial in pregnant patients but the primary concern is theoretical. Diuretics can be used if warranted. Experience with calcium antagonists is limited.

PLAB Question 17

No comments:

Match the following mechanism or pattern with the appropriate disease:

Progressive degeneration of anterior horn cells resulting in progressive muscle weakness, wasting and fasciculations

PLAB Question 16

No comments:
A 25 year old man has a three day history of shivering, general malaise and productive cough. The x-ray shows right lower lobe consolidation.

What is the most likely pathogen?

a) Mycobacterium avium complex
b) Coxiella burnetii
c) Escherichia coli (Gram -ve)
d) Haemophilus influenzae
e) Legionella pneumophila
f) Strep pneumococcus
g) Mycobacterium tuberculosis
h) Mycoplasma pneumoniae
i) Pneumocystis carinii
j) Staphylococcus aureus

The correct answer is F

Pneumococcal pneumonia most commonly presents as a segmental or lobar alveolar consolidation.
Pleural effusion can be found in 20-60% of cases. Cavitation is very uncommon with pneumococcal infection.

October 25, 2010

USMLE 1 Question 20

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Sputum sample was collected from a 60 yr old man suffering from a purulent cough and fever. The man was later found to have lobar pneumonia. The sputum was subjected to a gram staining technique. Gram positive, capsulated, flame shaped diplococci were seen when the stained smear was examined under the microscope. Sputum culture on blood agar revealed dome shape centrally umblicated colonies with evidence of alpha hemolysis.

The organism causing the infection is likely to be

a) Staphylococcus aureus
b) Klebsiella pneumoniae
c) Streptococcus pneumoniae
d) Corynebacterium diptheriae
e) Mycoplasma pneumoniae

The correct answer is C

Streptococcus pneumoniae is a gram-positive flame shaped organism and is seen characteristically as diplococci (i.e. is in pairs) and capsulated. The organism grows on blood agar to form dome shaped centrally umblicated colonies and produces alpha hemolysis of the RBCs.

Staphylococcus aureus is not the correct answer since it is typically seen in clusters under the microscope when gram stained and also its colonies are raised and not dome shaped. It produces beta hemolysis on blood agar rather than alpha hemolysis.

Klebsiella pneumoniae is also unlikely since it is a gram negative rather than gram positive organism. It will be seen under the microscope as rods rather then cocci.

Corynebacterium diphtheriae only causes an upper respiratory tract infection. It does not cause pneumonia so it cannot be brought up in the sputum.

Mycoplasma pneumoniae can cause a pneumonia but is incorrect since it does not take up gram stain and also it does not grow on blood agar.

USMLE 1 Question 19

No comments:
A growing number of human diseases have been discovered to be caused by inherited mutations in genes encoding channels.

What inherited ion-channel diseases affects the chloride channel?

a) Liddle's syndrome
b) cystic fibrosis
c) hemoglobin M disease
d) Becker's muscular dystrophy
e) X-linked hereditary nephritis

The correct answer is B

The gene responsible for Cystic fibrosis encodes a membrane-associated protein called the cystic fibrosis transmembrane regulator.

The most common gene mutation, F508, leads to absence of a phenylalanine residue at position 508 on the CFTR protein which is a part of a cAMP-regulated Cl channel and appears to regulate Cl and Na transport across epithelial membranes.

Heterozygotes may show subtle abnormalities of epithelial transport but are clinically normal.

USMLE 1 Question 18

No comments:
What specific part of the eye is mainly responsible for acute vision ?

a) zonnule of Zinn
b) limbus
c) optic disc
d) macula
e) fovea

The correct answer is E

The fovea lies slightly below and to one side of the optic disk. It is found in the centre of a shallow depression or pit (the macula).

Only cones are present at the fovea, which is an area approximately 0.2 mm in diameter: all other parts of the retina including blood vessels are pushed aside.

The cones here have individual connections with the bipolar and ganglion cells, hence the fovea gives us our most sensitive and acute vision.

USMLE 1 Question 17

No comments:
A 40yr old man visiting a coastal area had sea food for dinner consisting of oyster and shrimps. Next morning he developed severe abdominal pain, diarrhea, vomiting and fever.

The stools were blood stained. The man did not require any rehydration therapy and was treated with ciprofloxacillin and recovered in about 2 days.

These clinical features are typical of infection by

a) Vibrio cholerae
b) Vibrio parahaemolyticus
c) Vibrio vulnificus
d) Salmonella typhi
e) Rota virus

The correct answer is B

Vibrio parahaemolyticus is an important cause of gastroenteritis and food poisoning world wide. The gastroenteritis due to this organism is specifically and characteristically associated with the intake of sea food especially shrimps and oysters.

It causes an acute diarrheal disease within 24hrs of ingestion of the infected food. The patient develops severe abdominal pain, diarrhea, vomiting and fever. The stools in a severe infection maybe blood stained. The disease is more or less self limiting and is cured within 1-3 days.

Vibrio cholerae is incorrect since it causes a very severe gastroenteritis which has characteristically rice water stools and not blood stained stools. Also it has no association with consumption of sea food. The patient is severely dehydrated and if not rehydrated can die within hours.

Vibrio vulnificus also causes an infection after consumption of sea food but it is not the correct answer since it does not typically cause any gastrointestinal manifestations. The organism is absorbed quickly and causes a fatal septicemia.

Salmonella typhi does not typically cause an acute diarrheal disease. It does not manifest within 24hrs and has an incubation period of 7-14 days. Also it is a systemic infection and does not cause any gastrointestinal manifestations.

Rota virus causes mild diarrhea, usually in infants and children. It rarely infects adults. Also the diarrhea is very mild associated with little or no abdominal pain and rarely fever. It has no definite association with sea food

USMLE 1 Question 16

No comments:
A 60yr old farmer presents with a chronic cough and progressive dyspnea for the last 6yrs. The chest x-ray revealed a reticulonodular infiltrate associated with honey-combing of the lung.

Pulmonary function studies show a restrictive pattern with loss of lung volumes, impaired diffusion capacity, decreased compliance, and an exercise-induced hypoxemia. Serum studies demonstrate precipitating antibodies against extracts of moldy hay.

The causative organism in this case is likely to be:

a) Aspergillus
b) Thermophillic actinomycetes
c) Pencillium casei
d) Bacillus subtillis
e) Bacillus anthracis

The correct answer is B

The pulmonary function tests are suggestive of a restrictive lung disease. The chest X-ray consisitng of reticulonodular infiltrates and honey combing of the lung also point towards a restrictive lung disease most likely interstitial pneumonitis.

The presence of precipitating antibodies against extracts of moldy hay and the man's occupation clinches the diagnosis as that of a Farmer's Lung.

Farmer's lung is a rare kind of occupational disease seen in farmers due to exposure to dusts generated from harvested, humid warm hay that permits the rapid proliferation of spores of thermophillic actinomycetes.

It is a type of hypersensitivity pneumonitis in which interstitial lung involvement occurs. The disease has an insidious course over years associated with chronic cough and progressive dyspnea. End stage lung disease is characterized by a fibrotic lung with reticulonodular infiltrates and honey combing of the lung.

Aspergillus is responsible for a variety of occupational and other interstitial lung diseases with prolonged symptoms but it is not the causative agent of farmer's lung.

Pencillium casei is responsible for cheese washer's lung. Bacillus subtillis is responsible for detergent worker's disease. Bacillus anthracis is responsible for pulmonary anthrax which is a very acute disease resulting in death within days if not treated. It also causes parenchymal pneumonia rather than interstitial lung involvement.

October 24, 2010

ABCs of CPR Rearranged to "CAB" - 2010 AHA guidelines

October 20, 2010 — Chest compressions should be the first step in addressing cardiac arrest. Therefore, the American Heart Association (AHA) now recommends that the A-B-Cs (Airway-Breathing-Compressions) of cardiorespiratory resuscitation (CPR) be changed to C-A-B (Compressions-Airway-Breathing).

The changes were documented in the 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care, published in the November 2 supplemental issue of Circulation: Journal of the American Heart Association, and represent an update to previous guidelines issued in 2005.

"The 2010 AHA Guidelines for CPR and ECC [Emergency Cardiovascular Care] are based on the most current and comprehensive review of resuscitation literature ever published," note the authors in the executive summary. The new research includes information from "356 resuscitation experts from 29 countries who reviewed, analyzed, evaluated, debated, and discussed research and hypotheses through in-person meetings, teleconferences, and online sessions ('webinars') during the 36-month period before the 2010 Consensus Conference."

According to the AHA, chest compressions should be started immediately on anyone who is unresponsive and is not breathing normally. Oxygen will be present in the lungs and bloodstream within the first few minutes, so initiating chest compressions first will facilitate distribution of that oxygen into the brain and heart sooner; starting with "A" rather than "C" adds another 30 critical seconds.

"For more than 40 years, CPR training has emphasized the ABCs of CPR, which instructed people to open a victim's airway by tilting their head back, pinching the nose and breathing into the victim's mouth, and only then giving chest compressions," noted Michael R. Sayre, MD, coauthor and chairman of the AHA's Emergency Cardiovascular Care Committee, in an AHA written release. "This approach was causing significant delays in starting chest compressions, which are essential for keeping oxygen-rich blood circulating through the body," he added.

The new guidelines also recommend that during CPR, rescuers increase the speed of chest compressions to a rate of at least 100 times a minute. In addition, compressions should be made more deeply into the chest, to a depth of at least 2 inches in adults and children and 1.5 inches in infants.

Persons performing CPR should also avoid leaning on the chest so that it can return to its starting position, and compression should be continued as long as possible without the use of excessive ventilation.

9-1-1 centers are now directed to deliver instructions assertively so that chest compressions can be started when cardiac arrest is suspected.

The new guidelines also recommend more strongly that dispatchers instruct untrained lay rescuers to provide Hands-Only CPR (chest compression only) for adults who are unresponsive, with no breathing or no normal breathing.

Other Key Recommendations

Other key recommendations for healthcare professionals performing CPR include the following:
  • Effective teamwork techniques should be learned and practiced regularly.
  • Quantitative waveform capnography, used to measure carbon dioxide output, should be used to confirm intubation and monitor CPR quality.
  • Therapeutic hypothermia should be part of an overall interdisciplinary system of care after resuscitation from cardiac arrest.
  • Atropine is no longer recommended for routine use in managing and treating pulseless electrical activity or asystole.
Pediatric advanced life support guidelines emphasize organizing care around 2-minute periods of continuous CPR. The new guidelines also discuss resuscitation of infants and children with various congenital heart diseases and pulmonary hypertension.

Circulation. 2010;122[suppl 3]:S640-S656.

USMLE 2 Question 20

No comments:
A 30 year old man presents with bilateral eye pain. He is thought to have conjunctivitis and is given antibiotic eye drops but the pain persists and recurs with blurriness, redness and photophobia. A slit lamp examination reveals tiny floating particles in the anterior chamber between the cornea iris and tiny dots on the back layer of the cornea. The pupil appeared stuck to the lens behind

a) Ankylosing spondylitis
b) Reactive arthritis
c) Psoriatic arthropathy
d) Pyrophosphate arthropathy
e) Haemochromatosis

The correct answer is A

The eye is made of 3 coats. The middle coat is called the uvea. It consists of the iris in the front, the ciliary body a little further back (pars plicata + pars plana,) and the choroid at the back behind the retina.

Uveitis is a broad term referring to inflammation of any of the components of the uvea.

THE SLIT LAMP MICROSCOPE: (1) In the anterior chamber between the cornea and iris - CELLS which are tiny floating particles, and FLARE which is a visible beam of light. (2) On the back layer of the cornea, tiny dots called Keratic Precipitates (KP's) which are adherent inflammatory cells. (3) The pupil can get stuck to the lens behind causing adhesions called POSTERIOR SYNECHIAE.

This patient's recurrent anterior uveitis represents an HLA-B27-associated primary spondyloarthropathy. His systemic signs and symptoms could be due to HLA-B27-associated, non-specific disease processes (undifferentiated or unclassifiable spondyloarthropathy). Or, they may not be related to the HLA-B27 antigen at all.

There is a strong relationship between acute anterior uveitis and HLA-B27. Studies show that more than 50 percent of cases of acute anterior uveitis are associated with the HLA-B27 antigen.

USMLE 2 Question 19

No comments:
A 13 year old female has swollen cervical lymph nodes and is febrile. Her blood culture is positive for staphylococcus aureus. She shows other signs of being septic. The intern attending her tells her associate that the patient's WBC count is 15,000 cc/mm with a shift to the left.

What does she mean by a 'shift to the left?'

a) increased number of white blood cells in the peripheral blood
b) decreased number of white blood cells in the peripheral blood
c) hypersegmented granulocytes present in the peripheral blood
d) increased number of immature white blood cells in the peripheral blood
e) increased number of immature red blood cells in the peripheral blood

The correct answer is D

A shift to the left refers to an increase number of immature white blood cells in the peripheral smear. Typically, the immature white blood cells are being released prematurely by the bone marrow in order to combat some sort of infection.

An increased number of white blood cells in the peripheral blood (choice a) is called a leukocytosis. A decreased number of white blood cells in the peripheral blood (choice b) is called a leukopenia. Hypersegmented granulocytes present in the peripheral blood (choice c) is a shift to the right. An increased number of immature red blood cells in the peripheral blood (choice e) is a reticulocytosis.

USMLE 2 Question 18

No comments:
While working with a missions organisation in Africa a doctor is asked to see a 28 year old male with fresh bleeding per rectum. The man gives a history of increasing fever, headache and constipation. On inspection he is noted to have a relatively slow pulse rate and pinkish spots are seen on his abdomen.

The most likely diagnosis is

a) Lyme disease
b) brucellosis
c) typhoid fever
d) listeriosis
e) psittacosis

The correct answer is C

Typhoid fever is a disease largely of developing countries where sanitary conditions are insufficient to stop its spread.

Typhoid fever is a protracted disease that is associated with bacteremia, fever, and chills during the first week; widespread reticuloendothelial involvement with rash, abdominal pain, and prostration in the second week; and ulceration of Peyer patches with intestinal bleeding and shock during the third week.

Typhoid fever may lead to an erosion of the blood vessels in Peyer's patches that without appropriate treatment may result in gross blood in the feces in 10 to 20% of the patients.

Severe intestinal hemorrhage may complicate approximately 2% of the cases late in the course of untreated typhoid fever. Such intestinal bleeding may precede perforation, another complication of typhoid fever.

USMLE 2 Question 17

No comments:
A 50 year old woman visits a general practitioner because of a feeling of breathlessness (dyspnoea), especially on climbing the stairs to her house. She has never smoked in her life. On examination, the physician finds a central cyanosis, and the following is a photo of her hands.

On auscultation of her lungs, crepitations are heard bilaterally over the lower zones posteriorly,and there is increased tactile vocal fremitus. A chest X-ray is requested.

The most likely finding on this Chest X-Ray is

a) consolidation
b) pneumothorax
c) pleural effusion
d) coin lesion
e) emphysema

The correct answer is A

In this case the woman was diagnosed as having fibrosing alveolitis. Fibrosing alveolitis is a group of diseases of the lower respiratory tract that leads to the loss of the functional alveolar units and a limit in the transfer of oxygen from air to blood.

There is widespread inflammation and deposition of scar tissue within the lung tissue.

Gross clubbing of the fingers & toes occurs in fibrosing alveolitis. Smoking increases the risk. People over 40 years old are affected more frequently. The incidence is 1 out of 1000 people.

The cause is unknown. Currently, researchers believe that it may result from either an autoimmune disorder, a condition in which the body's immune system attacks its own tissues, or the after-effects of an infection, most likely a virus. A series of events takes place in which the inflammation occurs in the lungs and, eventually, the fibrosis processes, become uncontrollable.

Increased vocal fremitus is due to scarred, consolidated lung. Vocal fremitus decreased when the bronchi are obstructed and it is totally absent, when the lung is seperated from the chest wall by pleural effusion or pneumothorax.

USMLE 2 Question 16

No comments:
26 year old female experiences chest pain. She also complains of paplitations. An ECHO is done and shows that she has mitral valve prolapse. Her physical findings are classic for mitral valve prolapse.

Which of the following is associated with mitral valve prolapse:

a) large v wave in the jugular pulse
b) diastolic rumbling murmur
c) increased pulse pressure
d) large a wave in the jugular pulse
e) mid systolic click with a systolic murmur

The correct answer is E

A mid systolick click with a systolic murmur is heard with mitral valve proplapse. Mitral valve prolapse is also called 'click murmur syndrome'.

A large v wave in the jugular pulse (choice a) is seen with tricuspid insufficiency. A diastolic rumbling murmur (choice b) is heard with mitral stenosis, not with mitral valve proplapse. The pulse pressure is the difference between systolic and diastolic pressure. An increased pulse pressure (choice c) is seen with aortic regurgitation. A large a wave in the jugular pulse (choice d) is seen with tricuspid stenosis.

October 20, 2010

USMLE 2 Question 15

No comments:
An 8-year-old boy regularly experiences moderately severe sneezing spells and watery eyes in May and June, September and October, and occasionally during January through March. Immediate skin test show a positive reaction to Alternaria, Cladosporium, house dust and grass and ragweed pollens.

The most appropriate treatment would include:

a) Antigen avoidance
b) immunotherapy against the known offending antigen
c) Antihistamine-decongestant preparation
d) Topical adrenergic agonist
e) oral adrenergic agonist

The correct answer is C

Antihistamine-decongestant preparations remain the initial drug of choice for allergic rhinitis.

Nasal cromolyn sodium, which in some cases is as effective as an antihistamine-decongestant in treating seasonal allergic rhinitis, could have been recomended for the 8-year-old boy with seasonal symptoms.

Administration to nasal cromolyn sodium, however, requires the patient to carry a nasal pump and administer the treatment approximately four times daily prior to expected antigen exposure, making it inconvenient for some patients.

Patients who cannot tolerate oral medications may respond to cromolyn sodium, however. It is sometimes effective for perennial allergic rhinitis, but is more often used to alleviate acute seasional symptoms.

USMLE 2 Question 14

No comments:
A 54 year old man presents with a symmetrical distal arthopathy. On examination he has finger clubbing and a symmetrical arthropathy. Radiography demonstrates visible periosteal newbone formation over the diaphyses of his metacarpals and phalanges.

These features are a recognised complication of:

a) juvenile rheumatoid arthritis
b) scleroderma
c) epidermolysis bullosa
d) bronchial carcinoma
e) infectious mononucleosis

The correct answer is D

Hypertrophic pulmonary arthropathy is often diagnosed radiologically, when a patient presents with a symmetrical distal arthopathy. It is characterised by finger clubbing and a vaguely symmetrical arthropathy, with visible periosteal newbone formation over the diaphyses, but usually not extending to the bone end. There may be hyperaemia.

The condition is thought to be a form of autonomic neuropathy, although the exact mechanism is not fully understood. The more pronouced that a uniform periosteal reaction appears then the greater likelihood of the patient's having survived long enough to generate it.

In adults, intrathoracic sepsis and carcinoma of the bronchus are the most frequent underlying conditions. Congenital heart disease has an association with HPOA. This and bowel disorders such as Crohn's disease, are more probable in the young as causes of peripheral periosteal reactions.

USMLE 2 Question 13

No comments:

Which of the following medications have the highest risk of producing this arrythmia when the patient is also taking amiodarone?

a) Flecainide
b) Phenytoin
c) Propafenone
d) Chloroquine
e) Lidocaine

The correct answer is E

Common clinical features in drug-induced torsade de pointes include hypokalemia and cycle-length prolongation just prior to initiation of the arrhythmia.

Among these agents sotalol, which is a class III agent, has the highest risk of producing torsades, which is a polymorphic, pause-dependent ventricular tachycardia causing syncope and sudden cardiac death.

USMLE 2 Question 12

No comments:
A patient with systemic amyloidosis becomes progressively jaundiced over three months. On examination he is found to have hepato-splenomegaly, a markedly raised serum alkaline phosphatase.

This patient is most likely to have amyloidosis involvement in the

a) anterior pararenal space
b) space of Disse
c) vestibule space
d) epidural space
e) sub-arachnoid space

The correct answer is B

The peri-sinuisodal space in the livers are known as spaces of Disse and serve as a major site of amyloid involvement. Hepatocytes are separated from the sinusoids by this plasma-filled space.

In the liver, as in other organs, amyloidosis gives rise to amorphous, hyaline extracellular deposits in the walls of arteries and arterioles, with lesser involvement of portal or hepatic veins.

Hepatic involvement is common in patients with systemic amyloidosis. Localized disease in the liver is rare but has been reported. Features of hepatic amyloidosis include hepatomegaly and increased serum alkaline phosphatase, each of which are found in 60% of patients with biopsy-proven liver involvement; clinical liver disease, however, is rarely encountered.

A small number of patients with hepatic amyloidosis develop severe intrahepatic cholestasis with jaundice. This syndrome portends a poor prognosis, although death results from extrahepatic (primarily renal)disease.

Liver biopsy is not required to confirm hepatic involvement in patients with known systemic amyloidosis. If the diagnosis is uncertain, liver biopsy may be useful and can be performed safely if clotting parameters are normal and any history of a bleeding disorder is excluded.

October 18, 2010

USMLE 2 Question 11

No comments:
An 18 year old male works in a company where lunches are often catered. One day, the water at the company facility is not working, but they manage to have the lunch anyway. Two weeks later, he becomes sick. He develops anorexia, nausea, malaise and jaundice. During the course of the next four weeks, seven people who shared in the lunch become ill with similar symptoms. After a few weeks, each of the seven people completely recovers and they replace their caterer.

What is a likely diagnosis?

a) primary biliary cirrhosis
b) hepatitis B
c) hepatocellular carcinoma
d) Laennec's cirrhosis
e) hepatitis A

The correct answer is E

With no water working, but a catered lunch proceeding anyway, there was probably rampant poor sanitation present.

Hepatitis A is transmitted by the fecal oral route and is readily transmitted by poor sanitation. Hepatitis A can occur in epidemics, as in this scenario. The incubation period is two to six weeks, which was the time frame the employees developed symptoms. The symptoms include anorexia, nausea, malaise and jaundice.

Primary biliary cirrhosis tends to occur in women aged 40-60 and does not occur in clusters of people over a brief time frame.

The incubation period for hepatitis A is much shorter than for hepatitis B. Hepatitis A has an incubation period of 2-6 weeks, as seen in this scenario. Hepatitis B has an incubation period of 4 weeks to 6 month, which is not the time frame presented in this scenario.

Hepatocellular carcinoma is associated with long-standing liver disease, such as cirrhosis or hepatitis B or C, which is not the case here. Laennec's cirrhosis is associated with heavy alcohol use over many years.

October 17, 2010

USMLE 1 Question 15

No comments:
A 70 year old known hypertensive man presents to the general practitioner complaining of sudden onset of a drooping right eyelid and slurred speech. Examination revealed the tongue deviated to the right.

A Horner's syndrome on the right was diagnosed. Further examination showed a loss of pain sensation of the left side.The physician also noted a poor visual acuity from both eyes.

Which area of the brain is involved in ischaemia?

a) spinal cord at the level of C2
b) dorsolateral medulla
c) anterior pons
d) right side of midbrain
e) left side of midbrain

The correct answer is B

This patient's clinical condition suggests ischemia of the dorsolateral medulla.

Involvement of the ninth and tenth cranial nerve nuclei result in ipsilateral tongue deviation to the right and ipsilateral palatal weakness, respectively.

Involvement of the central sympathetic pathway results in an ipsilateral Horner's syndrome. Damage to the lateral spinothalamic tract results in contralateral loss of pain and temperature sensation.

The poor visual acuity in this case was irrelevant and an incidental finding- this was corrected with reading glasses.

USMLE 1 Question 14

No comments:
The aqueous humour of the eye may be divided into an anterior chamber and a posterior chamber.

What mostly tends to seperate these chambers?

a) lens
b) cornea
c) iris
d) limbus
e) ciliary processes

The correct answer is C

The iris is an annular membrane dividing the aqueous humour into the anterior chamber, nearer the cornea, and the posterior chamber, towards the lens.

The inner portion of the iris, the pupillary zone, is separated from the ciliary zone by the zig-zagging collarette.

The colour of eyes is determined by the amount of pigment in the iris. With no pigment the eyes appear blue; with increasing amounts of pigment the colour tends towards grey, brown and black.

USMLE 1 Question 13

No comments:
What suspensory ligaments connect the outer edge of the lens of the eye with the ciliary processes?

a) zonnules of Zinn
b) zonnules of Schlemm
c) cruciate ligaments
d) ligaments of Treitz
e) ciliary ligaments

The correct answer is A

Also known as the suspensory ligament, the Zonnules of Zinn comprise a network of collagen fibres which connect the outer edge of the lens with the ciliary processes.

In this hammock of fine fibres lies the lens.

To the right is the margin of the vitreous humour, to the left is the posterior chamber, which lies between the zonnules and the iris. Below in the ciliary processes lie cells which are excreting aqueous humour, which flows to the pupil.

USMLE 1 Question 12

No comments:
A physician is explaining to his student that the process of hearing requires that amplified mechanical energy is transmitted from the middle ear to the cochlea. He claims that the process of amplification is necessary in order to amplify weak vibrations in the air before reaching the inner ear.

Which of the following factors has the greatest amplifying influence on sound?

a) the ratio of the size of the oval window to the size of the eardrum
b) the shape of the middle ear
c) the bone lever system
d) the pressure gradient between middle ear and the nasopharynx
e) the physician is wrong, amplification does not occur within the middle ear

The correct answer is A

The amplified mechanical energy transmitted from the middle ear to the cochlea is transferred into hydraulic pressure. This hydraulic pressure creates movement to the cochlear duct and to the organ of Corti (the seat of hearing). The oval window is the interface between middle and inner ear. The stirrup passes on the vibrations to the oval window, a small thin membrane covering an opening in the bony case of the cochlea.

The size of the window (15-30 times smaller than the eardrum), produces critical amplification needed to match the vibrations in the air and the fluid in the cochlea. The sound is amplified at the window another 15 to 30 times.

Amplification from outer to inner ear.

There are three distinct areas where the incoming sound vibrations are amplified on the way to the inner ear. The reason for this is to magnify weak vibrations in air so that they can establish pressure waves in liquid.

The shape of the ear canal may increase pressure times 10.

The stirrup, anvil, and hammer bones of the middle ear may nearly triple the pressure.

The arrangement between the eardrum and oval window provide up to another 30 times magnification.

The results in amplification is 800 times before the sound wave sets the liquid of the inner ear into motion.

USMLE 1 Question 11

No comments:
When our eyes attempt to focus on a close object what action is typically required?

a) increase in the tension of the lens capsule
b) the lens becomes less convex
c) the sympathetic system is stimulated
d) the zonnules of zinn contract
e) the ciliary muscles contract

The correct answer is E

The smooth muscle of the ciliary body consists of both radial and circular fibres. When we wish to focus on some close object we must increase the power of our optics. This process is called accommodation.

The out of focus retinal image triggers the parasympathetic system which contracts the ciliary muscle. The muscle moves forward and inwards; consequently the zonnules of zinn relax, decreasing the tension in the lens capsule which becomes more convex, increasing the lens' power.

This is an important junction where the iris and the sclera meet. Close by is the circular canal of Schlemm, which runs around the eye just below the limbus. Aqueous humour is exuded from secretory cells just below the pigment epithelium in the cauliflower-like ciliary processes. The aqueous humour drains through the Zonnules of Zinn to the posterior chamber and through the pupil to the anterior chamber. The fibrous Zonnules of Zinn, which support the lens, are attached to the valleys between the ciliary processes.

PLAB Question 15

No comments:
MCV: Decreased Serum ferritin: Increased Total iron binding capacity: Normal Serum iron: Increased Marrow iron: Present

a) Thalassaemia trait
b) Hypoparathyroidism
c) Hereditary sideroblastic anaemia
d) Protein energy malnutrition
e) Chronic renal failure
f) Anaemia of chronic disease
g) Acute blood loss
h) Iron deficiency anaemia
i) Oral contraceptives
j) Megaloblastic anaemia

The correct answer is C

Patients with a defect in mitochondrial function resulting in a sideroblastic anaemia can also present with a microcytic, hypochromic anaemia. Hereditary sideroblastic anaemia is a rare condition that presents in childhood either as an X-linked or autosomally inherited condition.

Red blood cell morphology is typically dimorphic, and measurements of iron supply make the distinction from iron deficiency quite easy. Table (click and then see below).

Patients who develop an acquired ringed sideroblastic anaemia typically exhibit excessive iron accumulation, even to the point of tissue iron overload. Their red blood cell morphology can be quite variable, while marrow morphology demonstrates the pathognomonic finding of ringed sideroblasts

PLAB Question 14

No comments:
A malignant tumor of the retina is known to affect children under the age of 5.

What is the classical appearance of the pupil at presentation in such a child?

a) constricted pupils
b) dilated pupils
c) irregular pupils
d) argyll robertson pupil
e) hutchinson pupil
f) holmes-adie (myotonic ) pupil
g) Marcus-Gunn pupil
h) sluggish pupil
i) white pupil
j) tonic pupil

The correct answer is I

The cause of most cases of retinoblastoma has recently been determined to be the absence of a tumor suppresser gene.

Retinoblastoma and other associated malignancies tend to run in families. One or both eyes may be affected. A visible whiteness in the pupil may be present. Blindness can occur in the affected eye, and the eyes may appear crossed.

The tumor can spread to the eye socket, and to the brain, by means of the optic nerve.

The risk factors other than a family history are not known. This is a rare tumor.

PLAB Question 13

No comments:
An elderly woman with known congestive heart failure presents with severe dyspnea at rest.

The most appropriate treatment at this stage would be

a) hydrochlorothiazide
b) captopril
c) A loop diuretic
d) warfarin
e) calcium supplements
f) vitamin K
g) verapamil
h) beta blockers
i) digitalis
j) amiloride

The correct answer is C

If it is judged reasonable to attempt outpatient management of such patients, a loop diuretic such as furosemide or ethacrynic acid is necessary. Small doses of loop diuretics may also benefit patients with mild to moderate failure that cannot be adequately controlled by thiazides.

Patients with more severe CHF, manifested by dyspnea at rest, orthopnea, or paroxysmal nocturnal dyspnea, represent the other end of the spectrum.

Caution is warranted when treating a patient for the first time with a loop diuretic, because a marked diuresis may be evoked, even from a small dose. If a thiazide had been used previously, it should be stopped rather than continued in conjunction with the loop diuretic, because the two agents are very potent when used together.

The combination of a thiazide and loop diuretic is indicated in cases of failure refractory to large doses of the loop diuretic alone. The maximal effect of a loop diuretic can be achieved by using a large single daily dose, rather than smaller doses spread throughout the day.

PLAB Question 12

No comments:
An 80 year old develops bilaterally symmetric hearing loss which is gradual in onset. On examination he is found to have a predominantly high frequency loss.

A likely diagnosis is:

a) Meniere's disease
b) Presbycusis
c) Multiple sclerosis
d) Aminoglycosides
e) Acoustic neuroma
f) Chronic otitis media
g) Lyme disease
h) Alport's syndrome
i) Usher's syndrome
j) bacterial labyrinthitis

The correct answer is B

Presbycusis is hearing loss associated with aging and is the most common cause of diminished hearing in the elderly.

There are four types of presbycusis, distinguished according to the correlated pathologic changes in the cochlea. Hair cell loss and cochlear neuron degeneration are the most widely recognized changes.

The hearing loss is bilaterally symmetric and gradual in onset. The majority of cases begin with a loss of the high frequencies with slow progression. Eventually, middle- and low-frequency sounds also become difficult to perceive

PLAB Question 11

No comments:
A young man develops acute hepatitis B. Four months after his presentation he asks for a test that would predict the likelihood of developing long term disease.

Which agent would be most helpful in estimating the likelihood of developing chronic active hepatitis in this patient?

a) recombinant hepatitis B vaccine
b) hepatitis C virus
c) Hepatitis B surface antigen
d) hepatitis C vaccine
e) hepatitis D
f) hepatitis B immune globulin (HBIG)
g) hepatitis B virus DNA
h) hepatitis B e antigen
i) hepatitis A
j) atopic dermatitis

The correct answer is H

Hepatitis B e antigen (HBeAg) is a product of the gene that codes for the nucleocapsid core; its presence signifies the presence of a state of high virus replication. As such, patients with HBeAg have a high level of circulating virions, high infectivity, and substantial liver injury.

HBeAg becomes detectable in all patients early during acute hepatitis B, and, therefore, there is no clinical utility to the test during early acute hepatitis B; however, if circulating HBeAg persists beyond the first 3 months of acute hepatitis, the likelihood of chronic infection is increased.

Testing for HBeAg is more important during chronic infection, for the presence of HBeAg denotes a more highly replicative chronic infection, associated with increased infectivity (eg, 20-25% infectivity of a needlestick) and liver injury (eg, chronic active hepatitis).

When anti-HBe can be detected in the absence of HBeAg during chronic infection, the patient can be classified as having a less replicative infection, with limited infectivity (eg, 0.1% infectivity of a needlestick) and liver injury (chronic carrier).

Hepatitis B virus DNA (HBV DNA) is a more quantitative marker of HBV replication, and is helpful in following patients with chronic disease and in monitoring the success of antiviral therapy

October 15, 2010

Risk of thigh fractures with bone drugs - FDA

No comments:
WASHINGTON (Reuters) - Osteoporosis drugs used by millions of women to prevent bones from breaking may increase the chances for an unusual type of thigh fracture, U.S. health officials warned on Wednesday.

The drugs known as bisphosphonates include Merck & Co Inc's Fosamax, Roche Holding AG's Boniva, Novartis AG's Reclast and Warner Chilcott Plc's Actonel.

The action could drive patients to Amgen Inc's just-launched rival medicine, Prolia, a different type of osteoporosis drug that is the company's most important future growth driver.

Food and Drug Administration officials said all bisphosphonates used for osteoporosis will carry a new warning about rare but serious fractures of the thigh bone, even though it remains unclear if the medicines caused the fractures.

The agency advised doctors to consider if patients on therapy for more than five years still need the drugs.

The new warning "should not cause patients taking bisphosphonates to be fearful of their medicine," said Dr. Sandra Kweder, deputy director of the FDA's new drugs office.

The drugs "are an important mainstay of osteoporosis management" and "have prevented innumerable fractures in their years of use," Kweder told reporters on a conference call.

More than 5 million U.S. patients filled prescriptions for bisphosphonates in 2009, the FDA said.

Concern about thigh fractures may lead patients to seek alternatives such as Amgen's Prolia, Bernstein & Co analyst Geoff Porges said. A positive impact on Prolia could been seen as early as the fourth quarter, he said.

"Today's label change is likely to raise the level of concern among patients about the safety of bisphosphonates significantly," Porges said in a research note.

Osteoporosis is a progressive bone-thinning condition most common in women after menopause. Actonel and Reclast are injectable. The other drugs are taken orally.

The most common fractures seen with osteoporosis typically occur in the hip, wrist or spine. They can cause pain and require hospitalization or surgery.

A study of hospital discharge data showed hip fractures dropped to 428 from 598 per 100,000 people in the 10 years after approval of the first bisphosphonate in 1996, FDA officials said. No treatment eliminates fracture risk completely.

Thigh fractures also can occur from osteoporosis, but the ones reported in recent years were unusual because they often appeared after little or no trauma and were seen in younger patients, the FDA's Kweder said. In most cases, patients felt a dull, aching pain in the thigh or groin months before a complete fracture.

People with those symptoms should contact a doctor to try and prevent the fracture, FDA officials said. The agency is requiring consumer-friendly guides to be dispensed with bisphosphonates to explain possible risks.

The unusual fractures appeared to account for less than 1 percent of all hip and femur fractures, the FDA said.

Dr. Felicia Cosman, clinical director of the National Osteoporosis Foundation, said there was little evidence bisphosphonates help after five to seven years and that may be the time when thigh fracture rates increase.

"If the safety profile is changing and the efficacy is not clear, then many people should consider having an interruption in continuous use of the drug" after that time, she said.

Merck said Fosamax had not been associated with any increased fracture risk in clinical studies of more than 28,000 patients. Still, the company voluntarily added information about the unusual thigh fractures to the drug's prescribing instructions in July 2009.

Fosamax also is sold as a cheaper generic under the name alendronate.

Roche unit Genentech said it would work with the FDA to provide information to doctors and patients "to make informed decisions."

Merck shares gained 1.4 percent on Wednesday to close at $37.16, while Novartis shares rose 0.4 percent to $59.45, both on the New York Stock Exchange. Warner Chilcott shares rose 4 cents to $25.00 on Nasdaq.


October 14, 2010

3 Healthy Habits That Reduces Risk of Breast Cancer

No comments:
Exercise, healthy weight, moderate alcohol benefit even women with a family history, experts say

TUESDAY, Oct. 12 (HealthDay News) -- Women who maintain certain "breast-healthy" habits can lower their risk of breast cancer, even if a close relative has had the disease, a new study finds.

Engaging in regular physical activity, maintaining a healthy weight and drinking alcohol in moderation, if at all, was shown in a large study to help protect against breast cancer in postmenopausal women, the researchers said.

"Whether or not you have a family history, the risk of breast cancer was lower for women engaged in these three sets of behavior compared to women who were not," said study leader Dr. Robert Gramling, associate professor of family medicine at the University of Rochester Medical Center in New York.

The study was published online Oct. 12 in the journal Breast Cancer Research.

Gramling wanted to look at the effects of lifestyle habits on breast cancer risk because he suspects some women with a family history may believe their risk is out of their control.

He analyzed data on U.S. women aged 50 to 79 from the Women's Health Initiative study starting in 1993. During 5.4 years of follow-up, 1,997 women were diagnosed with invasive breast cancer.

Gramling excluded women with a personal history of breast cancer or with a family history of early-onset cancer (diagnosed before age 45), then observed the impact of the healthy habits.

Excluding those with an early-onset family history makes sense, because a stronger genetic (versus environmental) component is thought to play a role in early-onset, experts say.

Following all three habits reduced the risk of breast cancer for women with and without a late-onset family history. "For women who had a family history and adhered to all these behaviors, about six of every 1,000 women got breast cancer over a year's time," he said.

In comparison, about seven of every 1,000 women developed breast cancer each year if they had a late-onset family history and followed none of the behaviors.

Among women without a family history who followed all three habits, about 3.5 of every 1,000 were diagnosed with breast cancer annually, compared to about 4.6 per 1,000 per year for those without a family history who followed none of the habits.

For his study, Gramling considered regular physical activity to be 20 minutes of heart-rate raising exercise at least five times a week. Moderate alcohol intake was defined as fewer than seven drinks a week. A healthy body weight was defined in the standard way, having a body mass index, or BMI, of 18.5 to under 25.

Gramling hopes his research will reverse the thinking of women whose mother or sister had breast cancer who sometimes believe they are doomed to develop the disease, too.

The findings echo what other experts have known, said Dr. Susan Gapstur, vice president of the epidemiology research program at the American Cancer Society, who reviewed the study findings.

"The results of this study show that both women with a family history [late-onset] and without will benefit from maintaining a healthy weight and exercising, and consuming lower amounts of alcohol, limiting their alcohol consumption," she said.

The American Cancer Society guidelines for reducing breast cancer risk include limiting alcohol to no more than a drink a day, maintaining a healthy weight and engaging in 45 to 60 minutes of "intentional physical activity" five or more days a week.

The risk reduction effects found in the Gramling study may actually increase if women follow the more intense exercise guidelines of the ACS, Gapstur said.

More information

To learn more about breast cancer risk factors, visit the American Cancer Society.

SOURCES: Robert Gramling, M.D., D.Sc., associate professor, family medicine and community and preventive medicine, University of Rochester Medical Center, Rochester, N.Y.; Susan Gapstur, Ph.D., vice president, epidemiology research program, American Cancer Society, Atlanta; Oct. 12, 2010, Breast Cancer Research, online

October 13, 2010

PLAB Question 10

No comments:
An insulin dependendent diabetic uses an insulin pump to control his blood sugar levels. He is obsessed with strict control of his blood sugar level and makes sure his blood sugar level never exceeds the normal level. He now presents with a seizure without any prior warning.

This complication of diabetes is best described as:

a) keto acidosis
b) Nonketotic Hyperosmolarity
c) autonomic neuropathy
d) Hypoglycaemia unawareness
e) peripheral neuropathy
f) infection
g) Amytrophy
h) Focal nerve palsy
i) retinopathy
j) nephropathy

The correct answer is D

Whilst most patients with diabetes are aware of the symptoms of a hypoglycaemic reaction, there are some in whom the first sign may be a seizure or unconsciousness. It would appear that in these patients there is little adrenaline secreted in response to the falling blood glucose and the body's ability to raise the blood glucose level is impaired.

Hypoglycaemia unawareness occurs more frequently in those attempting very tight control of their diabetes especially if on an insulin pump (frequent episodes of hypoglycaemia leads to a blunting of the counter-regulatory hormonal responses due to low blood glucose).

Patients who have this problem are at particular risk of developing severe hypoglycaemic reactions and their doctors must take this into account in setting somewhat higher target levels of blood glucose control. Increased blood glucose monitoring is helpful in reducing the number of hypoglycaemic episodes in these patients, especially when unaccustomed or special activities are undertaken.

Hypoglycaemia unawareness may be brought on by frequent, undiagnosed, hypoglycaemic events which leads to autonomic failure. Scrupulous prevention of these hypoglycaemic events may restore the hypoglycaemic awareness.

Further, it is important to be aware that undiagnosed hypoglycaemic events often occur during the night.

PLAB Question 9

No comments:
A 14-year-old boy scout complains of exercise-induced sharp chest pain at the left lower sternal border that diminishes with resting and does not awaken him. He has never had anything like this before. Palpation along the sternal edge replicates the symptoms.

The most likely diagnosis is:

a) mitral insufficiency
b) aortic stenosis
c) pericarditis
d) tricuspid incompetence
e) costochondritic pain
f) hiatus hernia
g) perciardial tamponade
h) reflux esophagitis
i) aortic insufficiency
j) pleuritis

The correct answer is E

To diagnose costochondritic pain one may palpate the fingers up the ribs alongside the sternum or compress or lift the rib cage. This would elicit chest wall pain. Chest wall problems and GI causes account for over 90% of the chest pain Primary Care Physicians see.

PLAB Question 8

No comments:
Aniridia is associated with

a) sickle cell anemia
b) Alport's syndrome
c) ureteric lithiasis
d) Goodpasture's syndrome
e) Systemic lupus erythematosus
f) Henoch-Schonlein purpura
g) Postinfectious glomerulonephritis
h) hemolytic-uremic syndrome
i) Wilm's tumour
j) IgA nephropathy

The correct answer is I

The syndromes associated with Wilms tumor are marked by the presence of aniridia, partial or complete hemihypertrophy, and genitourinary abnormalities, such as hypospadias and cryptorchidism.

PLAB Question 7

No comments:
A primigravida has a single episode of vaginal bleeding in her third trimester. All investigations are normal and at term she goes on to have an uneventful normal vaginal delivery of a healthy infant.

Placental examination post-delivery demonstrates a normal sized placenta with a dark-red mass lesion on the fetal surface.

The likely diagnosis is:

a) placental migration
b) uterine myoma
c) Uterine rupture
d) choriocarcinoma
e) chorangioma
f) Vasa previa
g) subplacental abruptio placenta
h) subchorionic abruptio placenta
i) placenta accreta
j) placenta previa

The correct answer is E

This appearance is most typical of a benign neoplasm composed of small vascular channels--essentially a form of hemangioma known as a chorangioma (chorioangioma, placental angioma). These are focal fleshy, dark-red areas on the placenta. These benign hemangiomas occur in 1 percent of placentas.

While small chorioangiomas are usually of no clinical significance, large chorioangiomas are associated with fetal anemia, thrombocytopenia, hydrops, hydramnios, intrauterine growth retardation, prematurity and stillbirth.

The neoplasm's gross appearance can be variable, with a tan to yellow to white to red to brown appearance depending upon vascularity, fibrosis, and hemosiderin deposition. Most chorangiomas are small and of no clinical significance.

USMLE 2 Question 10

No comments:

Identify the lesion depicted above:

a) acute extradural hematoma
b) sub-acute acute extradural hematoma
c) acute subarachnoid hematoma
d) subacute subdural hematoma
e) acute subdural hematoma

The correct answer is D

Subdural hematomas which become symptomatic between 3 days and 3 weeks after initial injury are considered subacute.

Compared to the normal brain parenchyma, subacute subdural hematomas appear isodense to low density. These collections may be subtle, especially if they are bilateral.

Medial displacement of the gray-white matter interface is an important finding to identify.

USMLE 2 Question 9

No comments:
A 70 year old man presents to his general practitioner complaining of dull and boring pain which radiates to the back. He has found that the pain intensifies by lying down and tends to be relieved by crouching forward. On questioning he admits to smoking 25 cigarettes daily,and to losing 12 pounds(5 kg) over the last 2 months.

On examination he is found to be cachexic, he was afebrile, and appears jaundiced. Abdominal palpation reveals a mass in the upper abdomen under the right costal margin.

The most likely cause for this man's jaundice is

a) a malignant lesion of the head of the pancreas
b) stones in the common bile duct
c) hepatocellular carcinoma
d) hepatitis B
e) gall bladder carcinoma

The correct answer is B

Pancreatic cancer is the 4th most common cancer causing death in the U.S. The disease is more common in men especially those between 60 and 70 years. The cause is unknown, but the incidence is greater in smokers. In fact Cigarette smoking is one of the greatest risk factors for the development of cancer of the pancreas.

Rapid spread. Most of the carcinomas of the pancreas are advanced by the time they cause symptoms. Pain in the back and upper abdomen occurs when a pancreatic tumor presses against the nerves in those areas. The disease is not only common, but it is also extremely difficult to treat.

The most commonly occurring cancers of the pancreas tend to grow rapidly. More than 90 percent of them arise in the ductal cells, which transport digestive enzymes to the duodenum. Two- thirds of ductal cell tumors grow in the head of the pancreas; the other third develop in the gland's body and tail.

A large firm liver eventually develops due to seeding

USMLE 2 Question 8

No comments:
You are asked to ensure that all your hemodialysis staff have appropriate prophylaxis against hepatitis B. One of the workers is not immunised.

Which agent would offer most appropriate prophylaxis?

a) recombinant hepatitis B vaccine
b) hepatitis B e antigen
c) Hepatitis B surface antigen
d) hepatitis C vaccine
e) hepatitis B immune globulin (HBIG)

The correct answer is A

Active immunization has become possible with the advent of hepatitis B vaccine. The original vaccine was prepared from the plasma of hepatitis B carriers. Although this vaccine underwent multistep inactivation that destroyed the infectivity of all known viruses (including HIV), concerns over the origin of the vaccine from high-risk persons limited its acceptance.

In 1987, a recombinant vaccine became available, derived from recombinant yeast into which the gene for surface antigen had been inserted. Such vaccines have replaced plasma-derived vaccines.

USMLE 2 Question 7

No comments:
A 35 year old with no history of a rheumatoid disorder presents with mild photophobia and sectoral hyperemia. Topical neosynephrine is administered but the engorged vessels do not blanch.

a) orbital pseudotumor
b) uveitis
c) episcleritis
d) scleritis
e) conjunctivitis

The correct answer is C

Episcleritis-an inflammatory condition of the episclera. Usually sectoral and self limiting. The eye is often tender and mildly photophobic.

2.5% neosynephrine topically can be used diagnostically: the conjunctival vessels blanch but the episcleral vessels remain engorged in episcleritis as opposed to conjunctivitis where most vessels blanch.

Sectoral hyperemia, is distinguished from conjunctivitis by radially oriented vessels that do not move with the conjunctiva. Episcleritis is self-limited, although topical non-steroidal anti-inflammatory medications such as flurbiprofen or diclofenac may hasten resolution. In contradistinction to scleritis, episcleritis is not usually related to systemic rheumatoid disease.

USMLE 1 Question 10

No comments:
Salmonella bacteria are more resistant than Streptococci to penicillin G.

Which of the following factors is most closely associated with this difference?

a) cytoplasmic membrane
b) cytoplasm
c) plasmids
d) peptidoglycan
e) outer membrane

The correct answer is E

Gram-negative bacteria are inherently resistant to penicillin because their vulnerable cell wall is protected by an outer membrane that prevents permeation of the penicillin molecule.

In gram-negative bacteria, the cell envelope is composed of the outer membrane, peptidoglycan and the cytoplasmic membrane. The outer membrane acts as a sieve to restrict the entry of molecules into the gram-negative cell.

Although bacterial cells have only one main chromosome, they may have other pieces of genetic material. These smaller pieces of DNA are known as plasmids and are defined as extrachromosomal pieces of DNA which are capable of autonomous (or regulated) replication.

Some plasmids code for proteins that degrade antibiotics but this is not the most correct answer in this case.

USMLE 1 Question 9

No comments:
A carpenter gets a splinter of wood embedded in his finger pulp.

What is the first line of defense against this foreign body?

a) Macrophages
b) Neutrophils
c) B-lymphocytes
d) T-Lymphocytes
e) Monocytes

The correct answer is B

Neutrophils, which are also known as polymorphonuclear leukocytes (PMN), represent 50 to 60% of the total circulating leukocytes and constitute the "first line of defence" against infectious agents or "nonself" substances that penetrate the body's physical barriers.

Once an inflammatory response is initiated, neutrophils are the first cells to be recruited to sites of infection or injury.

USMLE 1 Question 8

No comments:
A 70 year old known hypertensive man presents to the general practitioner complaining of sudden onset of a drooping right eyelid and slurred speech. Examination revealed the tongue deviated to the right. A Horner's syndrome on the right was diagnosed.

Further examination showed a loss of pain sensation of the left side. The physician also noted a poor visual acuity from both eyes.

Which area of the brain is involved in ischaemia?

a) spinal cord at the level of C2
b) dorsolateral medulla
c) anterior pons
d) right side of midbrain
e) left side of midbrain

The correct answer is A

This patient's clinical condition suggests ischemia of the dorsolateral medulla.

Involvement of the ninth and tenth cranial nerve nuclei result in ipsilateral tongue deviation to the right and ipsilateral palatal weakness, respectively.

Involvement of the central sympathetic pathway results in an ipsilateral Horner's syndrome.

Damage to the lateral spinothalamic tract results in contralateral loss of pain and temperature sensation.

The poor visual acuity in this case was irrelevant and an incidental finding- this was corrected with reading glasses

USMLE 1 Question 7

No comments:
A 35 year old man has a three day history of a productive cough. His x-ray shows evidence of bilateral consolidation. A sputum culture grows a gram positive organism that is lysed by ethyl hydrocupriene (Optochin).

These features are characteristic of

a) Streptococcus pneumoniae
b) Bacteroides fragilis
c) Coxiella burnetii
d) Escherichia coli
e) Haemophilus influenzae

The correct answer is A

The optochin test is a presumptive test that is used to identify strains of Streptococcus pneumoniae.

Optochin (ethyl hydrocupreine) disks are placed on inoculated blood agar plates. Because S. pneumoniae is not optochin resistant, a zone of inhibition will develop around the disk where the bacteria have been lysed. This zone is typically 14mm from the disk or greater.

Streptococcus pneumoniae is a gram-positive coccus that in clinical specimens often appears in pairs with tapered ends (lancet shaped), although it grows in short chains on nutrient broth media. It is a relatively fastidious facultative anaerobe and requires increased carbon dioxide for optimum recovery from clinical specimens.

Susceptibility to ethyl hydrocupriene hydrochloride (Optochin) distinguishes pneumococci from other streptococci in the clinical microbiology laboratory.

October 05, 2010

PLAB Question 6

No comments:
Gonorrhea typically causes:

a) Lymphogranuloma Venereum
b) Testicular Torsion
c) Hydrocele
d) Epididymitis
e) seminoma
f) mature teratoma
g) varicocele
h) lymphoma
i) orchitis
j) Spermatocele

The correct answer is D


Gonorrhea and tuberculosis almost always infect the epididymis before testis.

PLAB Question 5

No comments:
A 35 year old farmer develops a carbuncle-like painless ulcer on his hands. The ulcer has pustules and a black, necrotic central scab and is surrounded by extensive soft tissue swelling.

This is suggestive of:

a) behcet's disease
b) dermetitis herpetiformis
c) psoriasis
d) anthrax
e) chickenpox
f) smallpox
g) candidiasis
h) gonococcal septicemia
i) acne rosacea
j) syphilis

The correct answer is D


Infection with anthrax is usually seen in people who have come in contact with animal products, especially those who live in the countryside (eg, 'Woolsorter's disease' which is pulmonary anthrax).

Typically there is a typical painless lesion (ulcer) at site of infection with a black, necrotic (dying tissue) eschar (scab). Local swelling is prominent.

USMLE 2 Question 6

No comments:
In a patient with Wolff Parkinson White syndrome, the most characteristic finding on an ECG is:

a) ST segment elevation
b) inversion of lead I
c) Q wave measuring 50% of QRS height
d) delta waves
e) ST segment depression


The correct answer is D


In WPW pre-ecxitation syndrome findings on the ECG include delta wave (initial slurring) of the QRS complex and short PR interval.

The combination of PR interval <0.12 sec, a delta wave at the beginning of the QRS complex, and a rapid, regular tachyarrhythmia has been termed the Wolff-Parkinson-White (WPW) syndrome.

The PR interval is short because the descending electrical impulse bypasses the normal AV nodal conduction delay. The delta wave is produced by slow intramyocardial conduction that results when the impulse, instead of being delivered to the ventricular myocardium via the normal conduction system, is delivered directly into the ventricular myocardium via an abnormal or anomalous bundle.

The QRS duration is prolonged because it begins too early.

USMLE 2 Question 5

No comments:
A 34 year old HIV positive patient develops a new-onset of confusion. A CT scan of the brain reveals multiple enhancing lesions.

The most likely diagnosis is:

a) HIV encephalitis
b) cryptococcus
c) PML
d) lymphoma
e) toxoplasmosis

The correct answer is E


The main differential diagnosis of focal brain lesions in HIV-infected patients is between CNS lymphoma and toxoplasmic encephalitis.

In T gondii-seropositive, HIV-infected patients with CD4 T-cell counts <100/┬ÁL, who are not receiving anti-T gondii prophylaxis, the presence of multiple enhancing lesions is strongly suggestive of toxoplasmic encephalitis.

In patients on prophylaxis, or those with a single brain lesion, the differential diagnosis includes CNS lymphoma, fungal abscess, mycobacterial or cytomegaloviral disease, or Kaposi sarcoma in addition to toxoplasmic encephalitis.

The absence of anti-T gondii IgG in serum strongly argues against the diagnosis of toxoplasmic encephalitis.

USMLE 1 Question 6

No comments:
A 52 year old woman notices a lump in her subcutaneous tissue in her arm. The lesion is removed. She is very relieved to learn that the lesion is benign.

Which of the following characteristics in the histology of this lesion would tend to point towards a benign neoplasm rather than a malignant one?

a) infiltration of the surrounding tissues
b) metastasis
c) prominent mitotic figures
d) anaplasia
e) well defined encapsulation

The correct answer is E


A well defined, well demarcated lesion is more characteristic of a benign neoplasm than an malignant neoplasm. Infiltration of the surrounding tissues (choice a) is seen with malignant lesions.

Metastasis (choice b) occurs with malignant neoplasms. Prominent mitotic figures (choice c) are seen with a malignancy. Anaplasia (choice d) refers to the characteristic of malignant cells to be poorly differentiated or resemble immature forms.

USMLE 1 Question 5

No comments:
A 25 year old body builder presents to his physician with a swelling in the groin.He has never been to see a doctor before. On examination,the patient is afebrile, the mass is 3cm x 3cm. It can be reduced on gentle palpation. When asked to cough,an impulse is felt by the physician and a mass appears inferomedial to the external ring in the inguinal region.

The most likely diagnosis is

a) enlarged lymph node
b) ectopic testes
c) indirect inguinal hernia
d) saphena varix
e) direct inguinal hernia

The correct answer is E


Heavy lifting is more likely to result in a DIRECT hernia. Direct inguinal hernias are secondary to a developed weakness of the transversalis fascia in the floor of Hesselbach's triangle.

The sac is usually composed of a single layer, the peritoneum. It passes through or around the conjoint tendon to reach the superficial inguinal ring; thus it does not pass through the deep inguinal ring.

Some have suggested that these hernias are related to heriditary or acquired defects in collagen synthesis or turnover. Hernia and saphena varix can give a cough impulse, however the incidence of hernia is higher.

October 04, 2010

USMLE 2 Question 4

No comments:
A twelve year old girl develops a change in mental status with psychosis over a 24 day period. On examination she is found to be febrile and appears restlessness. She has a CT scan which is normal. She is admitted but deteriorates over the next 24 hours and passes away in the intensive care unit.

An autopsy reveals severe edema, hemorrhages and necrosis confined primarily to the temporal lobes. Histology reveals intranuclear inclusion bodies.

A likely diagnosis is

a) herpes encephalitis
b) child abuse
c) meningitis
d) cerebral glioma
e) infectious mononucleosis

The correct answer is A

Clinically, herpes encephalitis is characterized by rapid onset of fever, chills, restlessness, and signs of increased intracranial pressure. The mortality rate of herpes encephalitis is at least 25%.

The characteristic gross appearance of herpes encephalitis include edema, hemorrhages and necrosis confined primarily to the temporal lobes. The degree of edema is evidenced by the medial displacement of the uncal gyri. The involvement may be bilateral or may be unilateral.

In the acute stages, microscopic examination reveals vascular destruction with infiltrates of neutrophils and lymphocytes as shown on this slide. In the later stages, glial proliferation becomes the prominent feature.

The histological feature which characterizes herpes simplex encephalitis is the finding of eosinophilic intranuclear inclusion bodies (Cawdry type A). The inclusions may be seen in neurons, astrocytes, and oligodendroglia. At the ultrastructural level, the nuclear inclusions of herpes simplex are found to contain viral particles with a characteristic bull's eye appearance.

Herpes simplex, a DNA virus, is carried by a majority of the human population. The virus is harbored in the trigeminal ganglia, and produces lesions in the oral mucosa when activated by stress. Herpes simplex encephalitis arises sporadically and does not necessarily occur in people with a history of oral lesions.

USMLE 2 Question 3

No comments:
A strong association with Rheumatoid arthritis is a feature of

a) orbital pseudotumor
b) uveitis
c) episcleritis
d) scleritis
e) conjunctivitis

The correct answer is D

Scleritis,often associated with rheumatoid arthritis and other immune disorders, is a potentially destructive inflammation of the collagen in the deep episcleral vessels and the sclera. The eye is sometimes painful. Fortunately, scleritis is rare.

An experienced observer is required to make the diagnosis.

Scleritis coexists with a serious systemic disease in almost one-half of cases; frequently the underlying problem is a connective tissue disorder. Rheumatoid arthritis occurs almost one-third of the time, in patients suffering from scleritis.

Other connective tissue diseases seen with scleritis include: Systemic lupus erythematosus (SLE), Polyarteritis nodosa, Ankylosing spondylitis, Wegener's granulomatosis, Relapsing polychondritis, Sarcoidosis.

USMLE 1 Question 4

No comments:
A dental surgeon carries out a block of the inferior alveolar nerve by infiltrating local anaesthetic at the mandibular foramen.

Which clinical feature may result from this procedure?

a) Numbness of the lower lip on the injected side
b) Ineffective block for the incisor teeth
c) Numbness of the side of the tongue
d) Inability of the patient to clench his jaws
e) Transient weakness of the facial muscles on the injected side

The correct answer is A

The inferior alveolar nerve, a branch of the mandibular division of the trigeminal nerve (V), traverses the inferior alveolar, or dental, canal of the mandible to supply all the teeth of that hemimandible; all the teeth on that side are therefore anaesthetised.

The mental branch of the nerve emerges through the mental foramen to supply the lower lip, which becomes numb in a successfully performed block. The muscles of the tongue, of mastication and of facial expression are not affected.

USMLE 1 Question 3

No comments:
A man came to the emergency room after a road traffic accident. He had swelling, pain and shortening of the left arm. On examination the man was found to have a fracture of the mid shaft of the humerus. On further examination the man was found to have a wrist drop, finger drop and thumb drop on the left side.

The cause for this is:

a) injury to the radial nerve
b) injury to the ulnar nerve
c) injury to the median nerve
d) injury to the axillary nerve
e) none of the above

The correct answer is A

Radial nerve during its course along the arm passes through the radial groove present in the mid shaft area of the humerus. The nerve is commonly damaged due to a mid shaft fracture of the humerus.

The radial nerve is responsible for supplying the extensor muscles of the wrist, fingers and the thumb.

The damage to the nerve causes paralysis of the extensor muscles in the forearm. This results in unopposed action of the flexor muscles causing a wrist, finger and thumb drop.

The ulnar nerve is never injured in a fracture of the mid- shaft of the humerus. The injury to the ulnar nerve results in the paralysis of the flexor carpii ulnaris and medial half of the flexor digitorum profundus. The paralysis of these muscles causes flattening of the medial border of the forearm and claw hand deformity of the hand. It does not cause a wrist, thumb or finger drop.

Median nerve injury does not occur with the fracture of mid shaft of the humerus. Also the median nerve supplies the flexors of the wrist therefore injury to the nerve causes flexion weakness at the wrist and not a 'drop' deformity.

Axillary nerve is a short nerve which does not reach up to the level of mid shaft of humerus, thus cannot be injured in its fracture. Also it does not supply any muscles in the forearm therefore its injury does not cause a wrist, finger or thumb drop.

PLAB Question 4

No comments:
A 28-year-old woman sought medical attention for amenorrhea of two years' duration. Normal menarche had occurred at age 13, followed by regular menstrual cycles. At age 25, she had noticed a diminution in the frequency of menses, and at age 26, menses had ceased. Around that time she also had noticed a milky discharge from both breasts. A visual field test reveals bitemporal hemianopsia. Family history is unremarkable.

The investigation of choice at this stage would be

a) skull x-ray
b) non-contrast CT scan brain
c) contrast CT scan brain
d) contrast enhanced MRI of the optic nerves
e) four vessel cerebral angiogram
f) single vessel cerebral angiogram
g) MR cerebral Angiography
h) mri with emphasis on the frontal lobe
i) mri of the pituitary gland
j) mri with emphasis on the temporal lobe

The correct answer is I

The most important positive finding in the history is the development of milky discharge from the breasts, concurrent with secondary amenorrhea. On the basis of the history, one can make a presumptive diagnosis of amenorrhea and galactorrhea from hyperprolactinemia.

Causes of hyperprolactinemia that must be considered include a prolactin-secreting pituitary tumor (although the negative family history reduces the likelihood of MEN type I); a functional disorder in the hypothalamus that has blocked the release of dopamine, which inhibits the pituitary's production of prolactin; and rare disorders such as ectopic production of prolactin by a tumor (e.g., lung or kidney carcinoma). Primary hypothyroidism is another consideration, since it is also a cause of hyperprolactinemia.

Skull films and CT-scans have been replaced by MRI for imaging of the pituitary fossa and sella turcica. These may still be used in centers without an MRI.

The results of the eye examination in this patient are very important because a pituitary macroadenoma--that is, an adenoma larger than 1 cm--that extends above the level of the sella turcica may impinge on the optic chiasm and cause a bitemporal hemianopsia or impinge on the optic nerves and cause blind spots. Upward enlargement can involve hypothalamic tissue and the brain stem, as well as the optic chiasm. The classic finding of chiasmatic involvement is bitemporal hemianopsia.

An additional finding of a junctional scotoma (a central scotoma in one eye with reduced visual acuity and an upper temporal field defect in the opposite eye) combines with bitemporal hemianopsia to account for up to 96% of all visual defects.

Hypothalamic damage can result in hypotension, disturbed thermoregulation, and cardiac dysrhythmias. Brain stem compression causing altered levels of consciousness and changes in muscle tone, respiratory and pupillary reactions, and unusual signs such as hiccoughs and retraction nystagmus.