On the natural history of trigeminal neuralgia

OBJECTIVE: Trigeminal neuralgia is usually considered a separate entity fro m atypical trigeminal neuralgia. The exact relationship among these two and several other syndromes of facial pain remains unknown. There is no long-t erm prospective study of the natural history of trigeminal neuralgia nor an y explanation for the existence of different, albeit somewhat similar, faci al pain syndromes. DESCRIPTION OF CONCEPT: On the basis of our clinical experience, we propose a theory that may explain different facial pain syndromes as sequential st ages of the same disease process. Typical trigeminal neuralgia caused by mi crovascular compression of the trigeminal nerve root in the posterior fossa may become transformed over time into atypical trigeminal neuralgia, if le ft untreated. This transformation involves change in the character of pain and development of sensory impairment. Two representative cases are present ed to support this theory. CONCLUSION: If the theory of progressive change in character of pain and de gree of sensory impairment in the course of otherwise typical trigeminal ne uralgia is correct, trigeminal neuralgia, atypical neuralgia, and trigemina l neuropathic pain may represent different degrees of injury to the trigemi nal nerve, therefore comprising a continuous spectrum rather than discrete diagnoses.