A variety of paramyotonia congenita.

Paramyotonia congenita was first described by Eulenberg (1886). It is a rare, hereditary disorder of muscle in which severe loss of power is induced by degrees of cooling which are insufficient to affect normal muscle. Myotonia also appears on cooling. However, the paralysis produced by cooling distinguishes paramyotonia from Thomsen's disease. The weakness and myotonia can easily be produced under controlled conditions so that the disease lends itself to investigation. In spite of this fact, few observations have been made and nothing is known about the fundamental defect. The present case of a man aged 51 years is of particular interest because of certain additional features, and a personal and family history of generalized attacks of weakness such as occur in familial periodic paralysis. The case history is presented in full and is followed by some observations on the induction and relief of paralysis and myotonia.