Studies of traumatic neuralgias in the maxillofacial region: surgical pathology and neural mechanisms.

Microsurgical exploration of injured trigeminal nerves in patients with neuralgia revealed four variations of traumatic neuroma, associated foreign objects, and a sprouting of nerve collaterals from adjacent uninjured nerve. A comprehensive theory of traumatic trigeminal pain is proposed based on three sites of pathosis: peripheral neuroma, somatic and autonomic collateralization, and central deafferentation pathoses. Anesthesia dolorosa is related in this model to amputation neuromas and central pathosis. Sympathetic mediated pain is attributed to autonomic C-fiber units in peripheral injured zones. Hyperalgesia is attributed to mechanosensitive A-fiber units in the nerves being linked to corresponding irritable central nervous system neurons. Hyperpathia is explained on the basis of ephaptic transmission between adjacent fibers in neuromas.