S66 Pathophysiological implications and current evidence for the treatment of trigeminal neuralgia

Abstract

Aim Appreciate how current understanding of the pathophysiology of trigeminal neuralgia has impacted on treatments. The ignition theory puts forward the hypothesis that some form of trauma to the trigeminal nerve at any level results in abnormal firing of neurons which result in episodic pain. It is likely that patients with trigeminal neuralgia have some form of abnormality of their sodium channels. Currently the most effective medications are sodium channel blockers whereas other drugs such as opioids whose mode of action is different are not effective. Current drugs act centrally and so result in significant side effects especially cognitive ones which often result in cessation of the medication. The episodic nature of the disorder also means patients can stop their medication for weeks or months and have no pain attacks. However if pain is poorly controlled or quality of life is significantly affected then surgical options can be utilised. It is postulated that pressure from a significant artery in the root entry zone leads to demyelination and consequently allows for ectopic impulses to be generated. Separating the vessel from the trigeminal nerve can lead to complete resolution of pain in 70% of cases for ten years. However some of the impulses may be generated at the Gasserian ganglion level and so destructive procedures at that level result in pain relief for an average of five years. These do however result in sensory changes.