後硬膜動脈がPICAの側副路となった椎骨解離性動脈瘤の自然閉塞の1例

Spontaneous Occlusion of PICA-involved Dissecting Aneurysm with Development of a Collateral Channel from the Posterior Meningeal Artery

Ⅰ．はじめに

　非出血発症の椎骨動脈解離は，一般に予後がよいために保存的治療が第一選択となる．瘤様拡張部が認められた場合は，より慎重な経過観察が必要で，瘤様拡張部の増大時には出血予防のための手術治療が考慮される．今回われわれは，疼痛発症の後下小脳動脈（PICA）involved typeの椎骨解離性動脈瘤が，後硬膜動脈を側副路としてPICAが温存され，自然閉塞した稀な経時的変化を経験したので，文献的考察を加えて報告する．

　A 53-year-old man suffered severe headache, which continued for three days. No abnormality was shown on CT scan, and a dissecting aneurysm of the right vertebral artery was suspected on MRI. Cerebral angiography revealed a dissection aneurysm of the right vertebral artery involved with the posterior inferior cerebellar artery (PICA) as pearl and string sign. The patient was conservatively managed under careful blood pressure control, and was followed by serial MRI. He presented with Wallenberg syndrome three weeks later. Second angiography revealed the occlusion of the PICA-involved dissecting aneurysm and the lateral medullary segment of the PICA supplied by a newly arising vessel from the right posterior meningeal artery (PMA). For the conservative treatment of a vertebral dissection aneurysm involved with PICA presenting with only pain, observation of the course by MRI was effective, and the PMA could develop as the collateral channel to the PICA territory.