Researcher Receives $350 K to Study Genetic Cause of Trigeminal Neuralgia

Dr. Scott Diehl

RSDM researcher Dr. Scott Diehl has received a second grant of $350,000 to explore a possible genetic basis for Trigeminal Neuralgia (TN), a rare orofacial pain condition.

The funding, awarded by the Facial Pain Research Foundation, supports Diehl and a team of collaborators from Oregon Health and Science University and the University of Toronto, who are studying whether the origins of the disease, which affects one in 10,000 people, could be genetic. The most recent round of funding allows Diehl, who specializes in genetic research, to continue work he began in 2015 with an earlier grant from the foundation.

TN affects the trigeminal nerve, which spans from below the jaw to above the eye and leads to episodes of debilitating pain. The onset of Trigeminal Neuralgia is often sudden and random, beginning with an episode of severe pain that reoccurs. “One day something just happens to trigger the episode. The nerve will just start firing uncontrollably and they’ll experience one to two minutes of severe facial pain where they feel like they’ve been hit with a baseball bat,’’ says Diehl, a professor in the Department of Oral Biology. Sometimes, the short periods of excruciating pain will be triggered by a light touch to the patient’s face or a mundane activity, like tooth brushing. Other times, there’s no catalyst.

“People live in terror of what’s going to trigger another episode. They might go hours or days before it happens again,’’ said Diehl.

Until recently, TN was mostly attributed to neurovascular compression – when a blood vessel wraps around the nerve and compresses it, eventually causing damage, said Diehl. While this can be surgically repaired, not all incidents of TN are caused by compression and surgery is not always effective, according to Diehl. In other cases, pain is managed through anti-seizure medications, which can have side effects and lose efficacy over time.

Recent research suggests, however, that at least some cases of TN might be hereditary. “We find that with seven to ten percent of patients there’s a family history,’’ he said. Diehl and his collaborators, Dr. Kim Burchiel of the Department of Neurosurgery at Oregon Health & Science University and Dr. Ze’ev Seltzer, an emeritus Professor of Physiology at the University of Toronto, are working with samples from more than 1,000 TN patients.

Diehl is especially interested in testing samples from younger patients, who often don’t have neurovascular compression and are believed to be more likely to carry genes that cause TN to develop. Diehl’s hope is that discovery of genetic mutations that cause TN will allow researchers to develop new cures or more effective treatments. “It’s possible that novel targets discovered from genetic studies of TN could lead to better ways of treating other, more common types of chronic pain caused by nerve damage for which we have no effective therapies, and as a result contribute to the opioid crisis in our country today,’’ said Diehl.