Peripheral nerve morphometry in myotonic dystrophy.

Biopsy specimens of muscle and cutaneous branches of the common peroneal nerve from four patients with myotonic dystrophy (MD) were evaluated by morphometric techniques and compared to age-matched control nerves. Myelinated fiber densities were normal in the superficial and deep peroneal nerves of patients with MD. Internode length and frequency of abnormal fibers was not significantly different in MD and control nerves, nor were the number of myelin lamellae, number of neurofilaments per unit area, or number of microtubules per unit area to axis cylinder area. There was no evidence of morphologic abnormality of peripheral nerve in MD.