In this paper, a case of huge ruptured cerebellar AVM, which was totally removed by fractionated operations, is reported. A woman developed SAH at 18 years of age. Cerebral angiography showed a huge high-flow AVM occupying approximately the whole left cerebellar hemisphere, which received blood from the left SCA, AICA. and PICA. A round aneurysmal nodule was seen at the tectal segment of the left SCA. The patient became asymptomatic except for a marked bruit at the left occipital region, and was discharged without receiving any surgical procedure. At 19 years of age she developed dysarthria and double vision, and at 20 years left hemifacial spasm and hearing difficulty. At 25 years of age she was examined when she was two month pregnant. Positive neurological findings were left cranial nerve signs from the third to the eighth, left limb ataxia and trunkal ataxia. At the late stage of pregnancy she developed papilledema, and was placed under strict medical care. She gave birth to a healthy baby by caesarian section with no increase in neurological deficits. A CT scan demonstrated obstructive hydrocephalus, which was thought to be due to aqueductal stenosis caused by the mass effect of the AVM. After ventriculo-peritoneal shunt an operation for obliteration of the SCA aneurysm was carried out through the occipital transtentorial approach. The vascular lump was, however, not a true arterial aneurysm, but an enlarged portion of a arteriovenous shunt receiving several branches of the SCA. The vascular lump, which continued to the inside of the midbrain, was obliterated and removed. The vascular lump was considered to be the arteriovenous varix defined by Drake.
After discharge she was able to work as a housewife. However, one year after surgery she developed hemorrhage from the AVM, and was admitted again. After the acute stage of the SAH, partial removal of the AVM, especially of the lateral portion receiving blood from the left AICA, was carried out by left suboccipital craniectomy. After surgery cerebral angiography showed a remnant of the AVM supplied by the left SCA and PICA. The AVM was no longer of high flow. She was able to turn to her housework.
One and half years after the partial AVM removal she developed SAH again and was admitted with pontine and cerebellar signs. By reopening the previous suboccipital craniectomy the remnant of the AVM was totally removed. Thus the main part of the left cerebellar hemisphere, including the deep cerebellar nuclei, was lost. Postoperatively she could hardly walk by herself. At present, two years after the final surgery, she can walk with a stick without assistance, but can not yet return to her home life. Cerebral angiography and CT scan demonstrated total disappearance of the AVM. With a sacrifice of important cerebellar functions the holohemispheric cerebellar AVM was totally managed. Management of not easily accessible AVMs of the posterior fossa is discussed and a review of the literature on this subject is made.