A new management strategy for Hemimasticatory spasm.

Background: Hemimasticatory spasm (HMS) is an uncommon movement disorder of the trigeminal motor rootlet characterized by unilateral, involuntary, and paroxysmal contractions of the muscles of mastication. The mechanisms for HMS are still unclear, and an efficient treatment strategy still needs to be developed. This study aims to investigate the clinical features and surgical treatment of HMS.

Methods: 12 patients with HMS were included in our study. The patient data regarding clinical characteristics, neuroimaging presentations, intraoperative findings and treatment outcomes were analyzed retrospectively. Highly selective trigeminal motor root rhizotomy (HSTR) combined with microvascular compression was performed in 9 cases with neurovascular conflict, while 3 patients without vascular compression underwent HSTR only.

Results: Intraoperative findings showed that there is one patient with 6 branches of the trigeminal motor roots, 3 patients with 2 trigeminal motor roots, and the remaining patients have 3-4 trigeminal motor roots. Seven patients had 2 motor branches severed, 3 patients had 1 motor branch severed, and 2 patients each had 3 motor branches severed. 9 patients recovered uneventfully and showed no signs of spasms, and the remaining 2 patients experienced complete disappearance of symptoms within 3 months after surgery. One patient relived immediately postoperatively but recurred 2 years later.

Conclusion: The surgical procedures of HSTR can significantly alleviate the clinical symptoms of patients with masseter spasms without bringing serious complications to patients.