Familial myoedema, muscular hypertrophy and stiffness.

A father and son with muscular hypertrophy, stiffness and myoedema are described. The local swelling after tapping the muscle was not accompanied by electrical activity. Histological and histochemical studies of muscle biopsy showed no abnormalities. Electron-microscopy showed multiple vacuoles to be due to T-tubule dilatation. Further studies are necessary to determine the significance of this finding in the pathogenesis of muscle sensitivity to mechanical irritation in this rare syndrome.