Root exit zoneより遠位部で神経圧迫を認めた片側顔面痙攣の2例

Hemifacial Spasm due to Vascular Compression of the Distal Portion of Root Exit Zone of the Facial Nerve : Report of Two Cases

Ⅰ．は じ め に

　片側顔面痙攣は顔面神経に対する血管の直接的圧迫により発症する症候とされ，根本的治療として微小血管減圧術が行われる．顔面神経に対する圧迫はroot exit zone（REZ）に観察されるのが一般的である．今回われわれは，REZより遠位部で神経圧迫を認めた稀な片側顔面痙攣の2症例を経験したので，若干の文献的考察を加え報告する．

It has been generally assumed that only vascular contact at the root exit zone (REZ) of the facial nerve can cause hemifacial spasm. We treated two cases of hemifacial spasm in which compression of the distal site of the REZ of the facial nerve produced symptoms. The microvascular decompression for the patients showed excellent results. Extreme care must be taken not to stretch the internal auditory artery during surgical manipulation. The ABR monitoring is useful to prevent the postoperative hearing loss.

　It must be kept in mind that the compression of distal portions of the facial nerve may be responsible for hemifacial spasm in cases in which neurovascular compression at the REZ is not confirmed intraoperatively.