Analysing Correlation Between the Facial Nerve Notch at the Root Exit Zone and Long-term Effect in Patients with Hemifacial Spasm After Microvascular Decompression: A Prospective Study

Background: Microvascular decompression (MVD) has become widely accepted for hemifacial spasm (HFS). The significance of facial nerve notch (FNN) for the outcome after MVD is still unknown. Objective: To investigate the correlative analysis between the FNN at the root exit zone (REZ) and the curative effect of MVD for HFS. Method: A prospective study was performed, which included 232 patients with Cohen score ≥2 who had undergone MVD. The patients were divided into two groups: the group with facial nerve notch (FNN) and the group without FNN, according to whether there is FNN caused by the offending vessels during the MVD operation. All the patients were followed up for 24 months. Results: The group with FNN caused by offending vessels at the REZ area was confirmed in 119 patients, of which 117 patients were immediately cured and two patients received partial relief on the 1 st day of postoperation. The group without FNN at the REZ area was confirmed in 113 patients, of which 43 patients were immediately completely cured while 70 patients were not immediately completely cured after MVD operation. After 24 months of follow-up, 119 patients with FNN were all completely cured, 71 patients without FNN were completely cured, and 42 patients without FNN were not completely cured. Multivariate logistic regression analysis shows that compared with without FNN group, the FNN group had statistical significance for the clinical results both on the-1 st -day ( P < 0.01) and 2 years of follow-up ( P < 0.05) after MVD operation. Conclusions: FNN is an important reference factor to evaluate both the short-term and long-term curative effect of microvascular decompression for hemifacial spasm. The postoperative effect of patients with FNN is much better than that of patients without FNN.