Neurophysiological study in slow-channel congenital myasthenic syndrome: case report
Lorenzoni, P.José.; Kay, Cáudia.Suely.Kamoi.; Arruda, W.Oleschko.; Scola, R.Herminia.; Werneck, L.César.
Arquivos de Neuro-Psiquiatria 64(2a): 318-321
2006
ISSN/ISBN: 0004-282X PMID: 16791378 Document Number: 597553
The slow-channel syndrome is one of the congenital myasthenic syndromes attributed to inherited kinetic disorders of the ion channel of the acetylcholine receptor of the neuromuscular junction. This is a case report of 25-years-old man with progressive ptosis and limitation of ocular movements since infancy, presented a 6-years history of worse of the external ophthalmoparesis and muscular weakness in the shoulders and hands. The motor nerve conduction studies after a supramaximal single stimulus disclosed a double compound muscle action potential (CMAP) that disappeared after a voluntary contraction of 30 seconds. Repetitive stimulation of facial and spinal accessory nerves showed a CMAP decrement greater than 10% with disappeared of the second potential. The patient received fluoxetine with mild improvement of muscular weakness, but persisted with: ptosis, limitation of ocular movements and repetitive CMAP in the motor nerve conduction study. The characteristic of disease are discussed.