Hemifacial spasm caused by intra-axial brainstem cavernous angioma with venous angiomas.

Hemifacial spasms (HFS) are usually caused by vascular compression on the extra-axial facial nerve. In this case, we concluded that an intra-axial brainstem cavernous angioma with a venous angioma diagnosed by MRI must have been responsible for HFS, because no other possible causes were found during intraoperative observations.