Congenital endplate acetylcholinesterase deficiency responsive to ephedrine

Congenital myasthenic syndromes (CMS) are heterogeneous disorders. In each disorder, the safety margin of neuromuscular transmissions is compromised by one or more specific mechanisms. In each CMS, the synaptic response to acetylcholine is either increased or decreased; accordingly, pharmacotherapy aims to decrease or augment the synaptic response. This approach, however, fails in end plate (EP) acetylcholinesterase (AChE) deficiency. 1 We describe two patients with EP AChE deficiency who responded dramatically to ephedrine.