Prä- und postoperative trigeminus-evozierte potenziale bei idiopathischer trigeminusneuralgie und mikrovaskulärer dekompression

Introduction: Evoked potentials after superficial stimulation of the trigeminal nerve branches and contralateral recording over the postcentral facial area were performed in 20 patients with idiopathic trigeminal neuralgia. The aim of this study was to detect if there are changes in the trigeminal evoked potentials (TEP) in these patients and if microvascular decompression of the trigeminal nerve in the parapontine angle alters the potentials. Methods: The TEP were divided in two groups according to the recording time. Potentials in the first ten milliseconds (ms) after stimulus were called short-latency potentials and those after ten ms to hundred ms long-latency potentials. Results: In the first ten ms the potentials N1, P2, N3, P5, N6, P8 and N9 could be recorded. N13, P20, N27, P31, N37, P44, N55, P65 and N90 could be identified as long-latency potentials. In the preoperative recordings a significant difference concerning the latency of the potentials N3 and P5 could be found in the involved nerve branches (p<0.01). Postoperatively, after surgical neurovascular decompression of the trigeminal nerve root entry zone, the latency of these potentials was normalized. No significant differences were detected in the recordings of the long-latency potentials and the latencies are comparable with those stated in the literature. Conclusion: The short-latency potentials of the involved nerve branches in patients with idiopathic trigeminal neuralgia show significant differences. Normalisation of these potentials can help to explain the theory of neurovascular compression and decompression.