Trigeminal neuralgia (TN), a facial pain disorder caused by irritation of the trigeminal nerve, is known to occur in many people with multiple sclerosis (MS). A new study published in Acta Neurologica Scandinavica has delved further into the relationship between these two conditions, and the results suggest an association between TN and the presence of demyelinating lesions in the vicinity of the trigeminal ganglia.

“We wanted to understand whether TN is a syndrome appearing in the late stage of MS, when MS is generally characterized by slowly progressing degeneration of the brain, or whether it could be the first episode of MS, thus linked more closely to episodes of systemically driven neuroinflammation,” explains corresponding author Sini Laakso.

Credit: Viktoriya Kabanova/Alamy Stock Vector

The new study included 2,575 patients with MS from the Finnish MS register and 2,008 patients with TN who were identified from a hospital administrative database. From the total cohort, 55 individuals had both MS and TN, and the incidence of TN was found to be 15-fold higher among patients with MS than in the general neurological outpatient population.

Laakso and colleagues obtained head MRI scans from 41 of the patients who had both MS and TN. In 26 (63%) of these individuals, demyelinating lesions were found in close proximity to the trigeminal ganglia. Most of the patients with MS who developed TN had relapsing–remitting MS, in which inflammation and demyelination are the predominant pathogenetic mechanisms.

the incidence of TN was … 15-fold higher among patients with MS than in the general neurological outpatient population

“Together, these findings suggest that there is a strong association between TN and MS, and that if an acute demyelinating lesion is identified close to the trigeminal nucleus, the onset of TN should be considered a relapse of MS,” comments Laakso. “A prospective study is now needed to investigate the presence of acute demyelinating lesions at the time of onset of TN.”