Carcinomatous neuropathy. An ultrastructural study of ten cases.

Superficial peroneal nerve biopsies were studied from 10 patients with carcinomatous neuropathy. There were 6 patients with the sensorimotor form and 4 patients with the sensory form. In both forms of neuropathy, histometric studies showed a variable loss of myelinated fibers which was generally most severe in the sensory form. In most of the cases of the sensorimotor form, ultrastructural studies showed segmental demyelination with onion bulb formation and regeneration of myelinated fibers. In the sensory form, there was no segmental demyelination, the regeneration of myelinated fibers was minimal and all the cases showed a loss of unmyelinated fibers. In sensory neuropathy, the histometric and ultrastructural changes reflect the massive acute destruction of ganglion cells in the dorsal root ganglia. In sensorimotor neuropathy, the alterations indicate a slowly progressive degenerating process in which both axonal degeneration and segmental demyelination occurred.