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Classically Described, Paradoxically Underrecognized: A Case of Proximal Weakness, Hyporeflexia/Areflexia, and
Ario Mirian1, Amit Kumar Sharma, Michael W Nicolle
1From the Western University, Clinical Neurological Sciences, London, Ontario, Canada.
Abstract:
We present a case of chronic, progressive proximal weakness with dysautonomia and hyporeflexia/areflexia ultimately diagnosed with Lambert-Eaton myasthenic syndrome. An approach to neuroanatomical localization is discussed leading to the appropriate selection of electrodiagnostic studies. The electrophysiologic triad of Lambert-Eaton myasthenic syndrome is demonstrated with diffusely reduced motor amplitudes, decrement with low-frequency repetitive nerve stimulation, and increment of motor amplitudes after maximum voluntary contraction. Subsequent serologic testing for P/Q-type voltage-gated calcium channel antibodies are markedly elevated. We highlight the clinical features and pitfalls of examining a patient with Lambert-Eaton myasthenic syndrome when suspecting this challenging diagnosis. The neurophysiological underpinning of the electrodiagnostic results is explained, and the diagnostic utility of single-fiber electromyography is briefly discussed.
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