Intraoperative microneurography in patients with classic trigeminal neuralgia

The aim. To present the fi rst results of intraoperative microneurography of the trigeminal root in patients with classic trigeminal neuralgia and  to  assess the  relationship between recorded electrical activity and pain regression or persistence after microvascular decompression.
Materials and methods. The study included 13 patients with classic trigeminal neuralgia who underwent microvascular decompression (MVD) and 4 patients with posterior cranial fossa tumors (control group). Patients were divided into three groups: Group 1 – MVD with tactile stimulation (n = 9); Group 2 – MVD without stimulation (n = 4); Group 3 – control group with tactile stimulation (n = 4). Electrical activity of the nerve root was recorded before and after decompression. Pain assessment was performed using the Visual Analog Scale and the BNI scale.
Results. In all patients of Group 1, deep tactile stimulation evoked electrical activity of the trigeminal root before surgery, whereas superfi cial stimulation was not accompanied by recordable activity. After MVD, a signifi cant reduction in electrical activity was observed in 67 % of cases (6 out of 9), which correlated with pain regression. In  three patients with persistent pain (Group  1), electrical activity was  also recorded after surgery. In Group 2, no spontaneous ectopic activity was detected. In the control group, no electrical activity characteristic of classic trigeminal neuralgia was found. The signal-to-background amplitude ratio in patients with persistent pain after surgery was signifi cantly greater than 1 compared to the pain regression group (p = 0.003).
Conclusion. Intraoperative microneurography allows the  detection of  pathological electrical activity of the trigeminal root in patients with classic trigeminal neuralgia, which correlates with the presence of pain and its regression after surgical intervention. The proposed parameter – the ratio of electrical activity amplitude to  background – may  be considered a  potential criterion for  the  eff ectiveness of decompression, but requires further study in an expanded cohort.

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