Ectopic discharge in injured nerves: comparison of trigeminal and somatic afferents.

Using the teased fiber recording method, we have compared pathophysiological properties of afferent axons injured in the infraorbital nerve (ION) vs the sciatic nerve in rats. Both myelinated and unmyelinated axons ending in ION neuromas produced much less ongoing discharge than those ending in sciatic nerve neuromas. Similarly, mechanosensitivity and acute injury discharge in ION neuromas were minimal. These differences may be related to the different spectrum of neuropathic symptomatology associated with nerve injury in the trigeminal vs the segmental innervation fields.