Progressive Weakness In A Middle-Aged Woman

DOCTORS ZONE: QUESTION & ANSWER

A 55 year old woman complains to her general practitioner of a progressive difficulty of holding objects with her left hand. She also admitted to swallowing difficulties over the past 6 months. Examination demonstrates widespread lower motor neuron involvement. The most appropriate diagnostic test is:

Please choose one:
a). Serum complement levels
b). Muscle biopsy
c). Radiograph of the wrist
d). Antinuclear antibody titre
e). Electromyography






ANSWER

The correct answer is E


Explanation

This is a case of Motor Neurone Disease.

In adults, the finding of widespread lower motor neuron signs is virtually diagnostic of motor neuron disease, especially if Babinski signs or clonus appear. Even if these definite upper motor neuron signs are lacking the diagnosis is similarly secure if inappropriately active tendon reflexes or Hoffmann signs are found in arms with weak, wasted, and twitching muscles.

There is no pathognomonic laboratory abnormality, but the clinical diagnosis should be confirmed by electromyographic (EMG ) evidence of active denervation in at least three limbs.

Nerve conduction velocities should be normal or nearly so; conduction block is rare in patients with frank upper motor neuron signs. CSF protein content is increased above 50 mg/dl in about 30% of patients and above 75 mg/dl in about 10%; the higher values seem more likely to occur in the presence of monoclonal gammopathy or lymphoma.

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