Hemilingual spasm treated with microvascular decompression of the posterior inferior cerebellar artery: illustrative case.

backgroundHemilingual spasm (HLS) is an extremely rare condition that induces persistent paroxysms of unilateral tongue spasms with associated speech impairment and pain. Although neurovascular compression has been implicated in its pathogenesis, case accumulation to date has been very limited, with even fewer instances of successful therapy via microvascular decompression (MVD) described. The authors report the second case of HLS treated with MVD and the first such treatment for HLS attributable to posterior inferior cerebellar artery (PICA) compression of the hypoglossal nerve rootlets. OBSERVATIONS: A 62-year-old woman presented with approximately 15 years of severe, persistent, and painful right tongue spasms and fasciculations. Numerous medical, psychiatric, and interventional treatments had failed to provide relief. MRI revealed likely neurovascular compromise of the right hypoglossal rootlets by the ipsilateral PICA, and MVD was recommended. Intraoperative electromyography (EMG) demonstrated pretreatment pulsatile myotonic discharges, which resolved completely after decompression. The patient recovered very well and, as of the 3-month postoperative follow-up, had complete resolution of painful spasms and approximately 70% reduction in the frequency of nonpainful fasciculations. LESSONS: MVD is a safe and effective treatment for patients with medically refractory HLS. Intraoperative EMG provides valuable insight into successful decompression; however, further investigation is required to validate this finding. https://thejns.org/doi/10.3171/CASE24869.