MR angiographyにより経時的評価を行った両側椎骨動脈解離の1例

Bilateral Vertebral Artery Dissection and Its Chronological Changes Detected by MR Angiography : A Case Report

　要旨　片側の解離が先行した虚血発症の頭蓋内両側椎骨動脈解離の1治療例を報告した。症例は42歳男性。1カ月前から後頭部痛を自覚し，8日前に頭部MR angiography（MRA）にて右椎骨動脈の狭窄を指摘されていたが，めまい・耳鳴にて当院に救急搬送された。頭部MRIと脳血管撮影にて，左小脳と右視床に梗塞を伴う両側椎骨動脈解離と診断した。頭部MRAにて経時的に経過観察を行いながら保存的治療を行い，2カ月後の頭部MRAでは両側椎骨動脈狭窄の改善を認めた。両側椎骨動脈解離の急性期の変化を画像診断で経時的に評価することにより，両側椎骨動脈解離の成因について考察し得た。虚血発症の椎骨動脈解離の保存的治療による予後は一般に良好とされているが，その病態進行に関しては未だ不明な点も多い。急性期の頻回の画像診断による評価法として非侵襲的なMRAは非常に有用と思われた。

　A case of intracranial bilateral vertebral artery （VA） dissection presenting with ischemic symptoms which following unilateral dissection is presented. A 42-year-old male with an occipital headache was pointed out right vertebral artery stenosis with magnetic resonance （MR） angiography 8 day before admission. He admitted to our hospital complaining of severe vertigo and tinnitus. MR images and cerebral angiograms revealed bilateral VA dissection with infarcts in light lower surface of cerebellum perfused by posterior inferior cerebellar artery and right hypothalamus. Conservative therapy was adopted and serial MR angiography was performed. His symptoms were improved gradually and MR angiograms obtained 2 months later revealed improvement of bilateral VA stenosis.

　It is generally accepted that VA dissection presenting ischemic symptoms has good outcome by conservative therapy only. However, its pathological process of progression is still unknown. Based on the serial MR findings, we discuss the mechanisms of bilateral VA dissection. In this case, we consider that unilateral VA dissection extended to contralateral vertebral artery through the vertebrobasilar junction. Frequent MR angiography in acute phase could be of great use for monitoring the progression of dissection.

（Received : January 13, 2004）