Trigeminal Neuralgia and the Use of Z-L Response as a Predictor of MVD Efficacy - Single Center Experience.

BACKGROUND

Microvascular decompression (MVD) is a surgical modality indicated in patients with pharmacoresistant classical trigeminal neuralgia. We report a single-center experience from the Department of Neurosurgery, University Hospital Olomouc, Czech Republic. During MVD, several intraoperative electrophysiological modalities may assist the surgeon; the so-called Z-L response (ZLR) has been proposed as an additional tool for confirming the offending vessel and the adequacy of decompression.

METHODS

We retrospectively evaluated a cohort of 54 patients operated on between 2021-2025, where the Z-L response technique was not used in a group of 34 patients operated on between 2021-2023, while it was used in a group of 20 patients operated on between 2024-2025.

RESULTS

The most common offending vessel was the superior cerebellar artery (25/34, 74% vs. 14/20, 70%), followed by the petrosal vein (3/34, 9% vs. 4/20, 20%), the anterior inferior cerebellar artery (6/34, 18% vs. 1/20, 5%), and the basilar artery (0/34, 0% vs. 1/20, 5%). Neuralgic pain most frequently affected the second branch of the trigeminal nerve (74%, 40/54); the third branch was affected in 50% (27/54) and the first branch in 26% (14/54). The median preoperative BNI score was 5 in the pre-ZLR group and 4.5 in the ZLR group. Median operative time was shorter in the ZLR group (80 vs. 110 min) and median length of hospitalization was 5 vs. 6 days. One postoperative abducens nerve palsy on the operated side occurred in the pre-ZLR group; no complications occurred in the ZLR group.

CONCLUSION

We observed an encouraging early trend after introducing Z-L response monitoring into our MVD workflow, with shorter operative time and favorable short-term postoperative BNI in the ZLR group. These findings should be interpreted with caution, however, because of the retrospective design, historical control group, small sample size, and substantially shorter follow-up in the ZLR group; they should not be generalized beyond our single-center experience. We plan to continue applying and refining this technique in our practice and to reassess its role once longer follow-up is available.