Improved Outcome of Microvascular Decompression for Hemifacial Spasm by Advanced Preoperative Imaging and Intraoperative EMG Monitoring of Lateral Spread

Objective: MVD for hemifacial spasm still presents a challenge regarding postoperative outcome. Insufficient improvement in a great proportion of patients undergoing MVD for hemifacial spasm is a limitation for this treatment. The effect of a combination of preoperative imaging and intraoperative monitoring of lateral spread on the outcome is presented. Methods: From 1991 to 2004 a consecutive series of 33 patients with MVD for hemifacial spasm is analyzed retrospectively. Surgical technique consisted of a standard MVD in all cases. In 15 versus 18 cases lateral spread was monitored during surgery. Prior to surgery, depending on the available MRI technique, 17 patients received routine T₁- and T₂-weighted MRI, 16 received high resolution MRI with 3D-visualization. The immediate postoperative and the long-term outcomes were analyzed depending on the preoperatively and intraoperatively applied imaging and monitoring technique. Results: Patients without intraoperative monitoring had an immediate success rate of 11 (18) and 13 (18) on long term. 13 out of 15 patients with monitoring of lateral spread had an immediate postoperative relief of spasm. In the long term the success rate was 14 (15). Correlated the outcome to the applied technology of imaging and image processing we found only 9 (16) immediate relief and 11 (16) long-term improvements in the group of patients with routine T₁- and T₂-weighted MRT and without monitoring of lateral spread. The combination of monitoring of lateral spread and advanced imaging resulted in an immediate relief in 13 out of 14 cases and long-term improvement in 13 (14) as well. Conclusions: The positive effect of developing and introducing new technologies on the outcome of MVD for hemifacial spasm is demonstrated. The combination of preoperative advanced imaging technology and intraoperative monitoring of lateral spread can ensure favorable results by guiding the surgeon to the definite site of pathology.