Metabolic studies on a case of paroxysmal myotonia with periodic paralysis

Abstract

This report describes a 25-yr-old man with paroxysmal attacks of myotonia and periodic paralysis. Clinical features of the disease coincide with those of paramyotonia. The myotonia was confirmed by electromyogram. Levels of serum potassium, sodium, phosphorus, immunoreactive insulin, and blood sugar, determined during free intervals and during spontaneous attacks of myotonia and of paralysis, were within normal range. During sodium treatment of a myotonic attack, the patient went directly from myotonia to flaccid paralysis. Potassium administration precipitated attacks of myotonia, and these attacks were obviously prevented by the restriction of dietary potassium and the administration of acetazolamide. Conversely, attacks of flaccid paralysis were readily induced by sodium injection, glucose injection, and carbohydrate feeding. It seems, therefore, that normokalemic periodic paralysis in this case is pathophysiologically identical with hypokalemic periodic paralysis. From these observations, it might be acceptable to relate paramyotonia to hypokalemic periodic paralysis. Clinical manifestations and the results of metabolic studies of the present patient might support the supposition that there is a basic defect underlying both myotonia and muscle paralysis.