• Masahide Matsuda, Hiroyoshi Akutsu, Tetsuya Yamamoto, Eiichi Ishikawa, and Akira Matsumura.
• Department of Neurosurgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan. Electronic address: m-matsuda@md.tsukuba.ac.jp.
• World Neurosurg. 2016 May 1; 89: 729.e11-3.

BackgroundHemifacial spasm (HFS) caused by a contralateral tumor is extremely rare, and all previously reported cases involved tumors at the cerebellopontine angle. We provide the first report to our knowledge of HFS caused by a contralateral foramen magnum meningioma, which improved after tumor removal without microvascular decompression.Case DescriptionAn 80-year-old woman presented with HFS caused by a contralateral foramen magnum meningioma. She had a 3-year history of gradual worsening of right-sided HFS. Magnetic resonance imaging showed a homogeneous gadolinium-enhancing tumor occupying the left ventrolateral portion of the foramen magnum. The loop of the right anterior inferior cerebellar artery extended into the right pontomedullary junction, compressing the root exit zone (REZ) of the right facial nerve. After tumor removal, with no attempt of confirmation of vascular compression of the right facial nerve REZ, facial spasm gradually decreased and eventually almost disappeared. Postoperative magnetic resonance imaging revealed that the loop of anterior inferior cerebellar artery had shifted away from the right facial nerve REZ. Dorsal shift of the anterior inferior cerebellar artery loop toward the facial nerve REZ along with dorsal shift of the vertebral and basilar arteries secondary to the huge contralateral mass located in the ventrolateral portion of the foramen magnum was suggested to represent the main cause of facial spasm.ConclusionsAlthough an extremely rare condition, facial spasm can develop as a result of contralateral tumors in locations other than the cerebellopontine angle.Copyright © 2016 Elsevier Inc. All rights reserved.

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