Nerve atrophy and a small cerebellopontine angle cistern in patients with trigeminal neuralgia

Abstract

Object The aim of this study was to provide information to help confirm the diagnosis of trigeminal neuralgia (TN) using MR imaging. Methods The authors evaluated atrophy of the trigeminal nerve, the cross-sectional area of the cerebellopontine angle (CPA) cistern, and the length of the cisternal segment of the trigeminal nerve on the affected side in 26 consecutive patients with TN who were treated using Gamma Knife surgery. Results The mean volume of the trigeminal nerve on the affected side was significantly smaller than the mean volume of the trigeminal nerve on the unaffected side (p < 0.001). Nerve atrophy was present in 25 patients (96.2%) on the affected side and in 1 patient on the unaffected side. The mean cross-sectional area of the CPA cistern on the affected side (188.5 mm2) was significantly smaller than the mean volume on the unaffected side (232.8 mm2) in 25 of the 26 patients (p = 0.001). The mean length of the cisternal segment of the trigeminal nerve on the affected side (7.9 mm) was significantly shorter than the mean length on the unaffected side (9.6 mm) in 25 of the 26 patients (p = 0.001). Conclusions Among the patients with TN, there was a statistically significant difference in the MR imaging findings of the affected side compared with the unaffected side of the trigeminal nerve. Atrophy of the trigeminal nerve and a small CPA cistern in patients with TN provides additional markers for the diagnosis of TN and helps confirm the diagnosis based on clinical examination.