One of these patients was in the microscope only arm (1/20 moreover = 5%). Four of these patients were in the endoscope only arm (4/31 = 11%), and none of the patients in the EA-MVD group were BNI class IV or V (0/7 = 0%). This was not a statistically different difference between the three groups (MVD, EA-MVD, and E-MVD), using the Kruskal Wallis test (P = 0.5018); see Table 1. Of the five patients with HFS, all five had an excellent outcome with complete resolution of their hemifacial spasm. The two patients with geniculate neuralgia did not experience significant benefit and were classified as BNI class IV at last followup. The patient with glossopharyngeal neuralgia had complete relief of pain. The conventionally treated patient who had previous cyber knife surgery did not respond to MVD.

Three of the 8 E-MVD patients who had previous gamma knife surgery or MVD did report 100 percent resolution of pain. Three of the 4 EA-MVD patients who were previously treated procedurally also reported complete resolution of their symptoms. Complications were unusual overall. In the TGN cohort, there was one wound infection (MVD), one temporary facial palsy (MVD), which required temporary gold weight but returned to normal by 9 months, and one CSF otorrhea, which required lumbar drainage for five days but sealed on its own (E-MVD). The total complication rate was 3/62 = 4.8% complication rate. None of the complications appear to have been directly related to endoscopic technique. In the hemifacial spasm cohort, there was one temporary facial palsy, which improved at six months to HB grade I (EA-MVD).

This was in a patient with very severe hemifacial spasm and significant tonus, who had received prior Botox therapy. In the three patients with glossopharyngeal and geniculate neuralgia, no complications were identified. Patients who required reoperation generally did well. The one patient in the conventional MVD group who was previously explored (no Teflon was found intraoperatively) had complete resolution of symptoms (BNI 1) following MVD. One patient in the EA-MVD who had a previous MVD without success also saw complete resolution of his symptoms. Three of the 6 patients with previous MVD who underwent E-MVD had a BNI score of 1 at followup. These data are supported by previous findings in which reoperation is both safe and frequently effective for either persistent or recurrent facial pain [3].

We performed a simple stepwise forward logistic regression analysis using the primary outcome measure of a BNI class score of three or better. We included the following variables: gender, presence of vein, artery, use of endoscope, and neurolysis. Surprisingly, the strongest predictor of success was the performance of a neurolytic procedure, although the overall P value of the model only AV-951 approached statistical significance at P = 0.0593 (STATA 10). This finding forced us to look at the results in patients undergoing neurolysis.