[From Morvan's disease to potassium channelopathies].

The term Morvan's disease, first coined in 1890, is still in use, although the generic term neuromyotonia--which is not exempt from criticism--has largely superseded it. Symptoms and signs are variable, ranging from benign painful fasciculations, pseudomyotonic cases, rigid forms, cases in which central nervous system features are also present (with, in addition to nerve hyperexcitability, agitation, confusion, delirium, insomnia, hyperhidrosis and tachycardia). A distal peripheral motor nerve is the origin of nerve hyperexcitability. There is growing evidence that autoimmunity is involved in the pathogenesis of many cases. Antibodies to voltage-gated potassium channels are detected in the serum of many patients with peripheral nerve hyperexcitability. Other cases are probably genetic. Inherited disorders are related to episodic dominant ataxia type 1, with the same mutation of a gene coding for potassium channel subunit Kv 1-1. Many inappropriate or non specific names are used to refer to peripheral nerve hyperexcitability. Isaacs syndrome, voltage-gated potassium channelopathy, or Morvan's syndrome are suggested.