The facial pain syndrome known as trigeminal neuralgia was described more than 300 years ago 1).
Typical trigeminal neuralgia caused by microvascular compression of the trigeminal nerve root in the posterior fossa may become transformed over time into atypical trigeminal neuralgia, if left untreated. This transformation involves change in the character of pain and development of sensory impairment. Two representative cases are presented to support this theory.
If the theory of progressive change in character of pain and degree of sensory impairment in the course of otherwise typical trigeminal neuralgia is correct, trigeminal neuralgia, atypical neuralgia, and trigeminal neuropathic pain may represent different degrees of injury to the trigeminal nerve, therefore comprising a continuous spectrum rather than discrete diagnoses 2).
Slavin KV. Commentary: Development and Evaluation of a Preoperative Trigeminal Neuralgia Scoring System to Predict Long-Term Outcome Following Microvascular Decompression. Neurosurgery. 2019 Dec 9. pii: nyz540. doi: 10.1093/neuros/nyz540. [Epub ahead of print] PubMed PMID: 31813971.