Gain-of-function mutation Met136Val in SCN8A may not be a common cause of trigeminal neuralgia

Trigeminal neuralgia

Trigeminal neuralgia (TN) is a facial pain disorder characterized by intense and paroxysmal pain that profoundly affects quality of life and presents complex challenges in diagnosis and treatment. TN can be categorized as classical, secondary and idiopathic. Epidemiological studies show variable incidence rates and an increased prevalence in women and in the elderly, with familial cases suggesting genetic factors. The pathophysiology of TN is multifactorial and involves genetic predisposition, anatomical changes, and neurophysiological factors, leading to hyperexcitable neuronal states, central sensitization and widespread neural plasticity changes. Neurovascular compression of the trigeminal root, which undergoes major morphological changes, and focal demyelination of primary trigeminal afferents are key aetiological factors in TN. Structural and functional brain imaging studies in patients with TN demonstrated abnormalities in brain regions responsible for pain modulation and emotional processing of pain. Treatment of TN involves a multifaceted approach that considers patient-specific factors, including the type of TN, with initial pharmacotherapy followed by surgical options if necessary. First-line pharmacological treatments include carbamazepine and oxcarbazepine. Surgical interventions, including microvascular decompression and percutaneous neuroablative procedures, can be considered at an early stage if pharmacotherapy is not sufficient for pain control or has intolerable adverse effects or contraindications.

Classical trigeminal neuralgia is associated with gephyrin and sodium voltage-gated channel alpha subunit 8

Trigeminal neuralgia is highly debilitating, and its etiology is still undefined. The goal of this work was to define associations between well-characterized trigeminal neuralgia cases and common genetic variants in the population. two hundred and fifty-seven individuals diagnosed with classical trigeminal neuralgia were compared to 865 individuals without classical trigeminal neuralgia and with an assessment for lower or higher pain threshold based on the amount of anesthetic required for routine dental treatment. Genotypes of 24 variants marking genes in the VGSC (voltage-gated sodium channels) or GABA (gamma-aminobutyric acid) pathways were obtained using TaqMan chemistry end end-point analysis. Chi-square was used for all comparisons with an alpha of 0.002. An association between classical trigeminal neuralgia and individuals requiring less or more anesthetic for routine dental treatments showed associations with SCN8A rs1601012 and GPHN rs723432 (p = 0.0009 and p = 0.0002, respectively). In conclusion, classical trigeminal neuralgia is associated with SCN8A and GPHN and markers rs1601012 rs723432 may be useful to determine individual risks for the condition.

Gain-of-function mutation Met136Val in SCN8A may not be a common cause of trigeminal neuralgia

Background

The Met136Val mutation in SCN8A was described in a case of trigeminal neuralgia but no frequency among affected individuals was provided.

Methods

Direct sequencing of 123 individuals diagnosed with classic trigeminal neuralgia was performed aimed to detect the Met136Val change.

Results

No cases of classical trigeminal neuralgia studied had the Met136Val mutation in SCN8A.

Conclusion

Met136Val mutation in SCN8A is not a frequent cause of classical trigeminal neuralgia.