(1)
Department of Neurology, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
(2)
MRC Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
Keywords
Lambert Eaton myasthenic syndromePost-tetanic potentiationHistory
A 64 year old man had been aware of a dry mouth and mild limitation of his exercise capacity for 3 months. He was admitted to intensive care with increasing confusion and unsteadiness. His condition had deteriorated because of progressive respiratory insufficiency and he eventually required intubation and ventilation. A tracheostomy was undertaken.
Examination
When sedation was reduced, examination showed mild facial and bulbar weakness, severe fatigable proximal limb and diaphragm weakness. The reflexes were reduced but enhanced after tonic contraction of the muscles.
Investigations
Routine blood tests were normal. Acetyl-choline receptor antibodies were negative. Voltage gated calcium channel antibodies were positive.
CT scan showed hilar and mediastinal lymphadenopathy with pulmonary consolidation, most marked at the left base.
Neurophysiology
Sensory studies were normal but the compound muscle action potential amplitudes were small. Repetitive stimulation at 3 Hz elicited a further reduction in amplitude. However maximal exercise elicited an increase in CMAP amplitude of over 100 %.
Sputum cytology showed severe dysplasia but no definite malignancy.
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