3,4-Diaminopyridine may improve myasthenia gravis with MuSK antibodies

Myasthenia gravis (MG) with antibodies to the muscle-specific tyrosine kinase receptor (MuSK) is characterized by prominent cranial and bulbar weakness. The disease course is often severe and some patients develop permanent, disabling symptoms despite long-term immunosuppression.1 In patients with MuSK MG, the administration of acetylcholinesterase inhibitors (AChE-I) is poorly effective and often associated with clinical and electrophysiologic signs of cholinergic hypersensitivity.2 3,4-Diaminopyridine (3,4-DAP) improves neuromuscular transmission (NMT) by increasing quantal release. We report the case of an adult patient with MuSK MG who was responsive to and tolerant of 3,4-DAP.