Progressive myopathy in hyperkalemic periodic paralysis
W. G. Bradley, R. Taylor, D. R. Rice, I. Hausmanowa-Petruzewicz, L. S. Adelman, M. Jenkison, H. Jedrzejowska, H. Drac and W. W. Pendlebury
Department of Neurology, University of Vermont School of Medicine, Medical Center Hospital, Burlington 05405.
A progressive degenerative myopathy has been well described in hypokalemic
periodic paralysis but is not as widely recognized in hyperkalemic periodic
paralysis. We studied four families with the latter disease in which some
members developed a progressive myopathy. Episodes of paralysis were
prolonged, lasting for months in some cases, and in one case paralysis was
sufficiently severe to require ventilatory support. The progressive
myopathy tended to develop at a time when attacks of paralysis were
decreasing in frequency. Muscle biopsy specimens showed variability in
fiber size, internal nuclei, and fibers with vacuoles. Electron microscopy
showed myofibrillary degeneration and tubular aggregates. An abnormal
biopsy specimen was more common in older patients. Our experience suggests
that a progressive myopathy is as common in hyperkalemic periodic paralysis
as it is in the hypokalemic disorder.
