General Information II: Epidemiology, Natural History & Etiology

Epidemiology (“How common is it, and how is its distribution?”)

1. The incidence of trigeminal neuralgia (“How common is it?”) is about 40/million population/year.
2. Trigeminal neuralgia is more common in the female sex (F:M 1.7:1).
3. Over 80% of trigeminal neuralgia patients are older than 50 years of age at the                           time of onset.
4. 5-8% of trigeminal neuralgia patients have a brain mass (i.e. brain tumor or cyst) causing direct compression on the trigeminal nerve.
5. 2-9% of trigeminal neuralgia patients have multiple sclerosis (MS).
6. 2-4% of MS patients have trigeminal neuralgia.

Natural History

1. 25% of patients experience spontaneous resolution after the initial episode(s), and experience trigeminal neuralgia recurrence months to years later.
2. Approximately 50% of trigeminal neuralgia patients initially managed medically will eventually require surgical intervention due to:
   1. Failed medical therapy
      1. Ineffective medical therapy
      2. Significant side-effects
   2. Personal choice

Etiology (“What causes trigeminal neuralgia?”)

For patients other than those with MS or brain lesions found to be causing trigeminal neuralgia, the “vascular compression theory” is the popular one explaining the cause of trigeminal neuralgia in the majority of patients.  Aging leads to mild brain sagging as well as blood vessel elongation, hardening and dilatation, all of which lead to the nearby blood vessel(s) coming into direct contact with the trigeminal nerve.  This “vascular compression” on the trigeminal nerve leads to certain changes (“demyelination”) within the nerve, ultimately resulting in “short-circuiting” among nerve fibers, which in turn causes the trigeminal neuralgia’s typical electrical shock-like pain.