Muscle pathology correlates with permanent weakness in hypokalemic periodic paralysis: a case report.

We present a morphological follow-up in a case of familial hypokalemic periodic paralysis with progressive weakness. At age 12 years muscle biopsy revealed mild vacuolar changes. Seventeen years later, after the patient had developed permanent weakness, light and electron microscopy disclosed tubular aggregates in about 15% of the fibers and medium-grade myopathic alterations. We describe correlation of muscle pathology with permanent weakness in hypokalemic periodic paralysis.