Asymmetric calf hypertrophy of neurogenic origin

A 47-year-old male presented with painful swelling of the right calf. His medical history was negative, except for a herniation of disc LIV-V 5 years before. Physical examination revealed unilateral calf hypertrophy with moderate weakness of plantarflexion, mild paresis of dorsiflexion. Electromyography showed a peripheral neurogenic lesion in the right anterior tibial muscle, but normal findings were obtained from the unaffected quadriceps muscle. Histological examination of the right gastrocnemic muscle showed neurogenic changes with typical targetoid fibers, but no pathological changes were present in the quadriceps muscle. Chronic asymmetric spinal muscular atrophy is an infrequent neuromuscular disease and because of asymmetric appearance, it might be difficult to distinguish from other, acquired neurogenic muscle diseases such as radiculopathy caused by intervertebral disc herniation. Our case confirms that muscular hypertrophy can follow partial denervation in humans.