[Cerebellopontile angle epidermoid presenting as hemifacial spasm].

A rare case of CP angle epidermoid presenting as hemifacial spasm was reported. The patient was a 48-year-old woman with left hemifacial spasm of 4 years duration. Preoperative CT films showed some low density area in the left CP angle, however, this finding was thought to be within normal variation. The diagnosis of CP angle epidermoid was made at the time of craniectomy aimed for microvascular decompression. The epidermoid was extending from the lower cranial nerves up to the midbrain level and successfully removed with the same craniectomy opening. Postoperative follow up during 16 months period disclosed complete disappearance of hemifacial spasm and no other neurological deficit. So far, the authors have experienced 425 cases of microvascular decompression for hemifacial spasm and there was only 1 case in whom a CP angle epidermoid was found (0.24%). A review of the literature revealed that hemifacial spasm due to CP angle epidermoid was very rare (1.2%). It was also reported that if there is CP angle epidermoid, hemifacial spasm may appear in the incidence of 7.7-10%. A possibility of CP angle epidermoid should be kept in mind when performing microvascular decompression for hemifacial spasm particularly in younger patients.