Congenital Myasthenic Syndrome - A Report Of Nineteen Cases

Abstract

Congenital myasthenic syndrome (CMS) is a rare disorder of the neuromuscular junction. We report here 19 patients, 7 sporadic and 12 from 6 families, with the age at diagnosis ranging between 1.5 years to 26 years (Mean-15yrs). There were 7 males and 12 females. All patients had ophthalmoplegia. Bulbar and limb muscle weakness with preserved reflexes was observed in 12 patients, All except tow presented with fluctuating opthalmoplegia, one each for cosmetic appearance and one for fatigue, Three patients had prognathism. All patients had normal ECG and serum creatine kinase levels. Acetylcholine receptor (AchR) antibodies were absent in all. Electrophysiological workup showed a decremental response to repetitive nerve stimulation at low rates (LRS) in all, Electrophysiological workup showed a decremental response to repetitive response to single stimulus. Needle EMG was normal. All patients had good response to parenteral neostigmine which was confirmed electrophysiologically. Second degree consanguinity was observed in 4 sporadic and 4 familial cases. Spontaneous remission was reported in none. This group of cases conforming to the class of CMS are noteworthy, because of high number, paucity of dysmorphic features, relatively benign course and response to anti cholinesterase drugs, Recognition of this entity from autoimmune myasthenia gravis by seronegativity and onset at birth or childhood is important as immunotherapy and thymectomy ineffective in CMS.