Surgical Management of Hemifacial Spasm Associated with Chiari I Malformation: Analysis of 28 Cases

OBJECTIVE: Hemifacial spasm (HFS) associated with Chiari I malformation (CIM) is rare. This study aimed to analyze the frequency of HFS associated with CIM in our department and further to investigate the clinical characteristics, treatment strategies, and outcomes of these cases. METHODS: Twenty-eight of 831 patients with HFS who fulfilled the criteria for CIM were analyzed retrospectively. In this series, microvascular decompression (MVD) was performed in 23 patients (82.1%). The remaining 5 patients (17.9%) with obvious symptoms attributable to CIM were treated only with foramen magnum decompression. The mean follow-up period was 41 +/- 21.7 months. RESULTS: The frequency of HFS associated with CIM was 3.4%. There were 19 women (67.9%) and 9 men (32.1%) with a mean age of 36.4 +/- 7.5 years. The most common symptoms were headache, paraesthesias, and muscular weakness with the exception of typical HFS. Seventeen patients (73.9%) experienced immediate postoperative spasm relief, and 21 patients (91.3%) were spasm relief at discharge after MVD. However, 3 patients (14.3%) experienced delayed recurrence of HFS after successful MVD in the follow-up. After foramen magnum decompression, 3 of 5 patients experienced complete relief of the spasm, and 4 patients showed improvement in the CIM-related symptoms. CONCLUSIONS: The results suggest that MVD can still be an effective treatment for HFS when it coexists with CIM. Furthermore, posterior fossa crowdedness may be a common risk factor for the 2 diseases, and foramen magnum decompression should be considered as the primary procedure in patients with HFS and symptomatic CIM.