Regressive Vacuolar Myopathy in Steatorrhea

A case of steatorrhea with marked hypokalemia and quadriparesia with muscle spasms is presented. Efferent nerve conduction velocity was normal. Amplitude of evoked muscle potentials, abnormally low at the onset, was normal after 21 days. Decreased amplitude and duration of muscle action potentials evoked by repetitive nerve stimulation suggested impaired neuromuscular transmission at the onset. Muscle biopsy revealed a low mean diameter of fibers (38.1 μ ±9.8μ), hydropic and vacuolar changes in about 25% of fibers, rod-shaped bodies, floccular degeneration, and myophagia. Vacuolar myopathy was no longer visible in a second biopsy on the 38th day after partial correction of body electrolytes and clinical recovery. This myopathy was compared to the muscle changes occurring in familial periodic paralysis and in other dyskalemic states. The metabolic study suggests that vacuolation and electromyographic changes were related to increased sodium content of muscle fibers. Key Words.— Collateral ramification; hypokalemia; rod structures; steatorrhea; tetany; vacuolar myopathy.