Lower Motor and Primary Sensory Neuron Diseases With Peroneal Muscular Atrophy

TLDR

Inherited hypertrophic neuropathies often present with early peroneal muscle weakness, symmetric neurogenic atrophy, markedly reduced peripheral nerve conduction velocities, and Schwann cell or myelin abnormalities. The study examines neuronal degeneration cases characterized by prominent peroneal muscle weakness and atrophy. The authors propose selective degeneration of anterior horn and dorsal root ganglion cells, or possibly a metabolic neuronal disorder affecting nerve terminals, as underlying mechanisms. Nerve conduction studies were normal or mildly reduced, and biopsies revealed no segmental demyelination or nerve hypertrophy.

Abstract

THE companion paper¹on this topic considered the inherited hypertrophic neuropathies in which peroneal muscle weakness and atrophy is prominent. In those disorders, a symmetric neurogenic weakness and atrophy is an early and prominent feature, conduction velocities of peripheral nerves are markedly reduced, and histologic studies reveal abnormalities of Schwann cells and of myelinization. This paper considers cases of neuronal degeneration in which peroneal muscle weakness and atrophy is prominent. In this group of cases, conduction velocities of nerves are either normal or slightly low and nerve biopsies show no evidence of segmental demyelinization or hypertrophy of nerve. In some of these cases there is probably selective degeneration of anterior horn and dorsal root ganglion cells with degeneration of axons; in other cases the site of degeneration of the neuron is less well understood—a metabolic disorder of the neuron may be the cause of degeneration of nerve terminals