Studies in familial periodic paralysis

This is a report on a study of a family with familial periodic paralysis in an attempt to clarify the underlying pathogenesis of the disorder. It was found in this particular family that no marked cationic ingress into muscle fibers could be demonstrated. Large dilatations containing granules of material staining with a positive periodic Schiff reaction were demonstrated with the paralysis. That such cisterns contained also water was confirmed. Intracellular recordings demonstrated no hyperpolarization of the membrane potential. During paralysis no propagated impulse could be recorded from intracellular electrodes by indirect or direct stimulation of the muscle fiber. This was indirectly confirmed by the presence of large quiescent areas in the electromyograph. Direct measurement of aldosterone excretion showed no increase of this hormone preceding or during the paralysis. Injection of aldosterone did not precipitate paralysis. No change in blood volume was noted during paralysis. Pitressin would not precipitate an attack. Thus aldosterone seems unlikely to be an etiological agent in this disorder. The action of thyroidal and thyrotropic hormones in the familial form of this disorder appears to be opposite to that described in the sporadic form. Electron microscopic studies suggest that fluid is accumulated in the endoplasmic reticulum and that there is a characteristic change in the mitochrondria during the paralysis. Such changes are reversible. Limited studies in carbohydrate metabolism with these patients suggest an abnormality in which intermediaty metabolites in the formation of glycogen may be responsible for the intracellular shift of water into the fiber to maintain osmotic, electric, and Donnan's equilibriums. Enzymatic studies of muscle homogenates would be the next logical study. In these patients as in others reported, paralysis may be precipitated in the presence of normal serum potassium values.