Focal myositis associated with S-1 radiculopathy: report of two cases.

[focal myositis]

Two cases are described of pseudotumoral calf hypertrophy after laminectomy for a compressive S-1 radiculopathy . The serum creatine kinase (CK ) level was normal or mildly elevated . T 2 -weighted magnetic resonance imaging (MRI ) showed calf enlargement , with an increased signal of the medial head of the gastrocnemius muscle . Electromyography revealed fibrillation potentials and positive sharp waves , but no complex repetitive discharges in the affected gastrocnemius muscle , with motor unit potentials having mixed neurogenic and myopathic features . Muscle biopsy revealed a focal myositis associated with some features of denervation . A brief course of corticosteroids was followed by remission clinically and improvement in the MRI findings .