title: Postoperative oblique sagittal MR imaging of microvascular decompression for hemifacial spasm.
abstract: Pre-operative and postoperative oblique sagittal gradient-echo magnetic resonance (MR) imaging was used to evaluate micro-vascular decompression of the facial nerves in 26 patients with hemifacial spasm. The pre-operative MR images were divided into two groups as follows: 22 images in Group I, clear imaging of a high-intensity line and/or spot at the root exit zone (REZ) of the facial nerve; and 4 in Group II, and unreliable image around the REZ. Surgery found that the causative vessel was the vertebral artery (VA) in 9 cases and the anterior inferior cerebellar artery (AICA) or the posterior inferior cerebellar artery (PICA) in 13 cases in Group I, and the AICA or the PICA in the 4 cases in Group II. Postoperative MR imaging showed clear decompression as the high-intensity line and/or spot completely separated from the REZ by a low- and/or iso- intensity area in 9 cases of VA compression repositioned to the petrous dura matter, in 11 cases of PICA or AICA compression treated by shredded Teflon pledgets in Group I and in 3 cases in Group II. Postoperative MR imaging showed an incomplete separation of any high-intensity line and/or spot in the REZ in 2 cases of PICA or AICA compression in Group I and in one in Group II. The outcome was excellent in 22 of 23 cases with clear decompression, and in 1 of 3 cases of unclear decompression. Hemifacial spasm persisted in 3 cases. Oblique sagittal gradient-echo MR imaging is a useful method for postoperative follow-up which can demonstrate changes around the REZ of the facial nerve if hemifacial spasm recurs.
authors.affiliation: Department of Neurosurgery, Yamanashi Medical University, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nagaseki
authors.forename: T
authors.initials: T
authors.lastname: Horikoshi
authors.forename: T
authors.initials: T
authors.lastname: Omata
authors.forename: T
authors.initials: T
authors.lastname: Ueno
authors.forename: Y
authors.initials: Y
authors.lastname: Ohhashi
authors.forename: H
authors.initials: H
authors.lastname: Nukui
authors.forename: R
authors.initials: R
authors.lastname: Tsuji
mesh_terms: D001158:Arteries / Q000473:pathology; D002531:Cerebellum / Q000098:blood supply; D019299:Decompression, Surgical; D005069:Evaluation Studies as Topic; D005154:Facial Nerve / Q000098:blood supply*; D005260:Female; D019569:Hemifacial Spasm / Q000175:diagnosis / Q000601:surgery*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000592:standards*; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D011184:Postoperative Period; D014656:Vascular Surgical Procedures; D014711:Vertebral Artery / Q000473:pathology