Predicting the therapeutic effect of carbamazepine in trigeminal neuralgia by analysis of neurovascular compression utilizing magnetic resonance cisternography.

The aim of this study was to determine whether the evaluation of neurovascular compression (NVC) using new criteria on magnetic resonance (MR) cisternography improves the prediction of the curative effects of carbamazepine (CBZ) in trigeminal neuralgia (TN). In this study, a new analysis of NVC using MR cisternography was performed retrospectively for 280 patients with clinical signs and symptoms suggesting TN. The new analysis examined whether the site of the NVC was less than 3mm from the edge of the exit point and within the first third of the root entry zone on MR cisternography. Prediction of the curative effects of CBZ using the new evaluation of distance to the NVC improved on the predictive ability of the previous method of calculating the NVC volume (Mantel–Haenszel coefficient, P<0.01). In particular, initial treatment with CBZ 100mg/day for 2 weeks appeared more effective for patients with NVC volumes of ≤5mm3 plus a distance to the NVC of ≤3mm, than for those with NVC volumes >5mm3. The evaluation of NVC on MR cisternography using this new approach appears to be more useful than the previous method for predicting the initial treatment response in patients with TN.