Neurogenic true hypertrophy of one calf and atrophy of the other.

Unilateral calf hypertrophy has been described in association with a variety of conditions. Bilateral neurogenic leg weakness with muscle wasting on one side and true hypertrophy on the other, however, has rarely been described. We report a 37-year-old heroin and alcohol abuser with a three-year history of weakness of the left leg and progressive enlargement of the right calf. Computed tomography of the right calf confirmed the presence of true hypertrophy. Electromyography showed denervation in the muscles of both legs. Nerve conduction studies were indicative of peripheral neuropathy. Biopsy of the gastrocnemius muscles revealed the presence of neurogenic atrophy on both sides, with marked hypertrophy and splitting of individual muscle fibers on the right. To our knowledge, this is only the second recorded case showing both muscle atrophy and muscle hypertrophy in response to denervation.