MR imaging of idiopathic trigeminal neuralgia: correlation with non-surgical therapy.

Magnetic resonance (MR) findings in patients with idiopathic trigeminal neuralgia were evaluated and correlated with the effectiveness of non-surgical treatments. Thirty-four patients with idiopathic trigeminal neuralgia (ITN) were examined using T1- and T2-weighted spin-echo (SE) pulse sequence techniques to evaluate their trigeminal root-entry zones and the vessels contacted prior to non-surgical treatment (retrogasserian glycerol injection, peripheral nerve block, or only oral analgesics). Vascular contact at the proximal portion of the preganglionic segment (PGS) of the trigeminal nerve and deformity of the PGS on the affected side were observed in 97% and 47% of the patients, respectively. Non-surgical treatments were curative in 12 (67%) but failed in two (11%) of the 18 patients without deformed PGS. However, among 16 patients with deformed PGS, they were curative in only six (37.5%) and failed in four (25%). Results of this study suggest that MR imaging could be useful in the clinical assessment of trigeminal neuralgia prior to instituting non-surgical treatment.