Muscle hypertrophy after partial denervation: a human case.

While undergoing long-term physiotherapy, a 41 year old woman with a chronic S1 radiculopathy developed progressive, painless enlargement of the weak calf. Gastrocnemius muscle biopsy disclosed changes of partial denervation and reinnervation, with small groups of type I and type II atrophic muscle fibres and abundant hypertrophic fibres of both types but mostly type II. It is postulated that, in addition to comprensatory work-induced type II muscle fibre hypertrophy, there was an element of (type I) stretched-induced hypertrophy of denervated fibres, a condition well recognised experimentally but not documented in man.