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Updated: Aug 10, 2026
Microvascular Decompression: Salient Surgical Principles and Technical Nuances
Published on: July 5, 2011
Electrophysiological monitoring of trigeminal nerve sensory root using sensory-masseter response for microvascular
Weichao Jiang1, Yin Kang1, Huijuan Wan2
1Department of Neurosurgery and Department of Neuroscience, Fujian Key Laboratory of Brain Tumors Diagnosis and Precision Treatment, Xiamen Key Laboratory of Brain Center, Xiamen Neurosurgical Quality Control Center, School of Medicine, the First Affiliated Hospital of Xiamen University, Xiamen University, Xiamen, Fujian, China.
Purpose:
Trigeminal neuralgia (TN), a debilitating condition, is commonly treated with microvascular decompression (MVD). However, effective intraoperative neurophysiological monitoring remains challenging. This study introduces a novel electrophysiological technique using sensory-masseter response (SMR) to monitor trigeminal nerve compression during MVD.
Methods:
A total of 34 patients with TN underwent MVD. A concentric neurostimulator was employed to systematically deliver microcurrent stimulation to various intracranial segments of the trigeminal sensory root. We specifically probed the segment distal to the suspected neurovascular conflict (NVC) site, the actual compression point itself, and the segment central to the NVC site. Stimulation was performed at equivalent anatomical levels on both the compressed and non-compressed sides for comparison. Simultaneously, compound muscle action potentials (CMAPs) were recorded from the masseter muscle. These recorded potentials were defined as the SMR. The spatial correlation between SMR positivity and NVC was analyzed to assess its clinical utility.
Results:
SMR was successfully recorded in 28 out of 34 patients (82.4%). Among these 28 SMR-positive cases, NVC was identified at the stimulation site in 24 cases, with 19 showing visible vascular indentation. The mean SMR latency was 3.30 ± 0.36 ms. The stimulation threshold required to elicit SMR was significantly lower at the NVC site (median 0.3 mA, IQR 0.2-0.4 mA) compared to the distal segment of the NVC side (p < 0.001), the non-compressed side (p < 0.001), and the central segment of the NVC side (p = 0.012). A strong association was observed between NVC and SMR positivity (p < 0.001). These findings suggest that SMR positivity correlates with NVC sites.
Conclusion:
This study introduces a novel electrophysiological technique SMR for localizing NVC during microvascular decompression for trigeminal neuralgia. SMR is likely mediated by focal demyelination and sensory-motor anastomoses. Although SMR demonstrates potential in assisting intraoperative localization during MVD, its clinical value requires further validation.
