Spasmodic torticollis due to neurovascular compression of the spinal accessory nerve by the anteroinferior cerebellar artery: Case report

OBJECTIVE AND IMPORTANCE Spasmodic torticollis is a neuromuscular disorder characterized by uncontrollable clonic and intermittently tonic spasm of the neck muscles. We report a case of spasmodic torticollis attributable to neurovascular compression of the right XIth cranial nerve by the right anteroinferior cerebellar artery (AICA). CLINICAL PRESENTATION A 72-year-old man with a 2-year history of right spasmodic torticollis underwent magnetic resonance imaging, which demonstrated compression of the right XIth cranial nerve by an abnormal descending loop of the right AICA. INTERVENTION The patient underwent microvascular decompression surgery. During surgery, it was confirmed that an abnormal loop of the right AICA was compressing the right accessory nerve. Compression was released by the interposition of muscle between the artery and the nerve. CONCLUSION The patient's postoperative course was uneventful, and his symptoms were fully relieved at the 2-year follow-up examination. This is the first reported case of spasmodic torticollis attributable to compression by the AICA; usually, the blood vessels involved are the vertebral artery and the posteroinferior cerebellar artery.