Prognosis research of delayed facial palsy after microvascular decompression for hemifacial spasm

Although microvascular decompression (MVD) surgery has been widely accepted as an effective treatment for hemifacial spasm (HFS), delayed facial palsy (DFP) is not an unusual complication, but it has only been sporadically described in the literature. The purpose of this study was to examine the probability of occurrence, the risk/predisposing factors, and the prognosis and timing of DFP. A prospective cohort study was conducted that included patients diagnosed with HFS and treated by MVD at our institution. All patients were followed up at the outpatient department or by telephone from December 2009 to December 2014. Categorical variables were analyzed using the Pearson's Chi-square test or Fisher's exact test. Continuous variables were compared using the independent Student's t test. The Spearman rank test was used to determine the correlation between the time of onset and the duration of DFP. The risk/predisposing factors were analyzed by the logistic regression method. We enrolled 248 patients who were treated by MVD for HFS. During the follow-up period, 16 patients (6.5 %) developed DFP. Fifteen of those patients had a complete recovery, and in one patient the facial palsy did not resolve. The average onset time was 10.2 days (range, 2-30 days) after surgery, and the mean duration of DFP after MVD, with exclusion of the permanent facial palsy patient, was 59.7 days (range, 7-220 days). The time of onset was correlated with the duration of DFP after MVD (p = 0.036). Furthermore, hypertension contributed to DFP (odds ratio [OR] 4.226, 95 % confidence interval [CI] 1.089-16.401, p = 0.037). Although the degree of facial palsy was variable, most patients experienced a complete recovery without requiring any special treatment. DFP may be a self-healing disease that resolves spontaneously without any treatment. The time of onset was correlated with the duration of DFP; i.e., an earlier development of DFP corresponded with a shorter duration, whereas a later development of DFP corresponded with a longer duration. Our results also suggest that hypertension contributes to DFP.