MR Imaging and IVIR Angiography in Patients with Hemifacial Spasm

ABSTRACT

PURPOSE: To determine the usefulness of MR imaging and MR angiography (MRA) in the evaluation of patients with hemifacial spasm. MATERIAL AND METHODS: One hundred and twenty-five patients with hemifacial spasm were included in this study. Axial T1-, T2-weighted images, proton density image (3mm thickness, 256 x 192) and 3-D TOF MRA were performed. Relation between facial nerve and adjacent arterial structures was carefully evaluated, which was correlated with surgical findings. RESULTS: MRA identified the presen(~e of offending vessels at the root exit zone of facial nerve and its origin in 117 patients(52 PICA, 50 AICA, 6 vertebral artery, 9 dual vessels). There were 4 false negatives and 4 false positives. Vascular groove at the root exit zone was identified in 52 cases, but there was no positive correlation between severity and duration of symptoms. The presence of ipsilateral or contralateral distal loop formation of vertebral artery were noted in 63 patients. In addition, 4 cases of neoplastic and vascular lesions were also demonstrated on MR imaging. CONCLUSION: Combination of MR imaging and MRA is an useful screening modality in the presurgical evaluation of hemifacial spasm, which can demonstrate the offending vessels as well as other pathologic lesions.