骨化生を伴う脳動静脈奇形（脳石症）の1例

A Case of Angiographically Occult Arteriovenous Malformation with Metaplasia (So-called Brain Stone)

I．はじめに

　脳石症（brain stone）は1913年Schüller^15）により頭蓋内の異常骨様石灰化をHirnsteinとして初記載されたが，以後その報告例は散見されるにすぎない．今回著者らは脳動静脈奇形（cerebral ar-terio-venous malformation：AVM）が原因疾患と思われる脳石症の1例を経験したので，文献的考察を加えて報告する．

The patient was a 69-year-old female. Right hemiparesis occurred on April 25, 1996, and then was re-lieved a day later. Because headache (dull pain in the left) persisted subsequently, she consulted our de-partment on April 26. Head CT showed, without enhancement effect, osseous high density on the surface of the left frontal area. MRI showed high intensity on T1 and low intensity on T2 with flow-void like find-ings. Cerebral angiography showed a pooling of contrast medium in the same region. ¹²³Ⅰ-IMP-SPECT re-vealed reduced cerebral blood flow in the left frontal and parietal lobes just under the same region. On June 11, the patient underwent surgery during which a tumor with arachnoid hypertrophy was extracted en block. Histopathologically, there were abnormal blood vessels with elastic fibers, expanding to an ossi-fied site, and AVM accompanying ossification was thus diagnosed. Postoperative ¹²³Ⅰ-IMP-SPECT showed improved cerebral blood flow in the left frontal and parietal lobes. The patient was discharged on June 22. The TIA pathologic condition, a symptom of its onset, was considered attributable to cerebral blood flow steal due to AVM.