Common Trunk Anomalies Associated with Hemifacial Spasm

반얼굴연축과 관련된 공통줄기기형

Background: The compression of 7th cranial nerve by arteries is one of the various causes of hemifacial spasm (HFS). A few previous studies were revealed the relation between the compression of 7th cranial nerve and common trunk anomaly. We evaluated the common trunk anomalies in patients with HFS using MRI and MRA. Methods: From January 2001 to December 2005, 41 consecutive patients (9 men, mean age $54.5{\pm}12.6$) with HFS underwent MRI and MRA. T2 axial images and time-of-flight angiographies were reviewed for identification of the compression at root exit zone by two neuroradiologists and one neurologist. Results: Thirty-seven patients showed neurovascular compression on the lesion side. Twenty patients of them were shown the compression of 7th cranial nerve by anterior inferior cerebellar artery (AICA), and seventeen patients of them were shown the compression by posterior inferior cerebellar artery (PICA). Twenty-four patients of the thirty-seven patients had common trunk anomaly. In control, twelve of twenty-one subjects had common trunk anomaly, that the frequencies of common trunk anomaly of two groups were 58.8% in HFS and 57.1% in controls. In the twenty-four patients with common trunk anomaly, eighteen patients had dominant-AICA, and six patients had dominant-PICA. The rate of nerve compression by common trunk anomaly in the HFS with unilateral common trunk, dominant-AICA was 76.5% and dominant-PICA was 100%. Conclusions: This study also revealed that AICA was most common compressive artery. There was no difference between the HFS groups and control groups in frequency of common trunk anomaly. Thus, we could not demonstrate the relationship between common trunk anomaly and HFS.