Trigeminal neuralgia. Current concepts regarding etiology and pathogenesis
G. H. Fromm, C. F. Terrence and J. C. Maroon
There has long been a controversy over the cause of trigeminal neuralgia.
Most clinical data favor a peripheral cause. However, most of the
experimental data tend to favor a central mechanism. Drugs that are
effective in the treatment of trigeminal neuralgia facilitate segmental
inhibition in the trigeminal nucleus, as well as depressing excitatory
transmission. The most plausible hypothesis to reconcile all of these
observations is that trigeminal neuralgia has a peripheral cause and a
central pathogenesis. Chronic irritation of the trigeminal nerve apparently
leads to both a failure of segmental inhibition in the trigeminal nucleus,
and ectopic action potentials in the trigeminal nerve. This combination of
increased firing and impaired efficiency of inhibitory mechanisms leads to
paroxysmal discharges in the trigeminal nucleus, which are perceived as
attacks of trigeminal neuralgia when they involve nociceptive
trigeminothalamic-relay neurons.
