Vertically Crowded Small Posterior Fossa Is a Possible Cause of Trigeminal Neuralgia in Young Adults: Operative...

The pathophysiology of trigeminal neuralgia (TN) in young adults was investigated to reveal the specific anatomic features and operative nuances of microvascular decompression (MVD) in young adult patients.

A total of 107 MVDs for TN were performed from February 2020 to May 2025, including 76 cases of Type 1 classical TN with offending vessels confirmed during MVD surgery. Onset age was younger than 40 years in 13 patients (young adult group; 33.5 ± 7.1 years) and 40 years or older in 63 patients (elderly adult group; 61.6 ± 11.1 years). Morphometric measurements of the posterior fossa structures were performed with computed tomography and magnetic resonance imaging. The demographic data and the morphometric data were compared between the 2 groups. The trans-horizontal fissure approach was added during MVD in all young adult patients.

Demographic data and surgical results were not significantly different between the 2 groups. Involvement of the vein and trigeminocerebellar artery as the offending vessel was significantly higher in the young adult group (P < .01, P < .05). The posterior fossa anteroposterior distance, height, and volume were significantly smaller in the young adult group (P < .05, P < .001, P < .001). The trigeminal nerve length and cerebellopontine cistern width were significantly shorter in the young adult group (P < .001). Multivariable analysis showed that posterior fossa height was significantly associated with younger age onset of TN (P < .05). All young patients showed complete cure of TN after the MVD without recurrence.

Vertically crowded small posterior fossa leading to artery and/or vein contact with the trigeminal nerve is the possible cause of TN in young adult patients. MVD with opening of the horizontal fissure to widen the narrow operative field ensures good surgical outcomes for young adult patients.