Abstract
The authors reviewed 23 cases of angiographically occult cerebrovascular malformations (AOCVM's) operated on in our institute during the past 13 years and investigated their clinicopathological characteristics. There were 18 arteriovenous malformations (AVM's) and 5 cavernous angiomas (CA's). Ages of patients ranged from 7 to 69 years (mean, 45 years). There were 8 men and 15 women. Fourteen of the 18 AVM cases presented intraparenchymatous hemorrhage: 11 in the cerebral hemisphere, 2 in the cerebellum and 1 in the medulla. In the remaining 4 cases, epilepsy was the initial symptom. Angiographically occult AVM's constituted 24.8% of all AVM's (73 cases) operated on during the same period. All 5 CA's presented with intraparenchymatous hemorrhage: 4 in the cerebral hemisphere and 1 in the cerebellum. Among the causes of intraparenchymatous hemorrhage, AOCVM constituted about 19% of the 80 cases with lobar intracerebral hemorrhage and 20% of the 15 cases with cerebellar hemorrhage operated on during the same period. Five of the 19 AOCVM cases presenting with intraparenchymatous hemorrhage had previous bleeding episodes. In all 4 cases presenting with epilepsy, hemosiderin deposits indicating the presence of old hemorrhage were found histologically. In one case with AVM, hemorrhage recurred 3 year after the initial operation. Histological examination of the specimen taken at the first operation showed only cavernous vessels whereas examination of the specimen removed at the second operation using a serial sectioning technique revealed it to be an AVM.
In conclusion: 1) All patients who are strongly suspected of harboring AOCVM's on CT and/or MRI should be treated surgically so as to prevent recurrent hemorrhages and to confirm the pathology. 2) In cases of intraparenchymatous hemorrhage, the hematoma wall should be searched thoroughly using a surgical microscope to find any vascular nodule [6]. 3) Incomplete removal of an AOCVM might cause recurrent hemorrhage. 4) The removed tissues should be examined histologically using the serial sectioning technique [11] to obtain a precise pathological diagnosis.
The operative technique using a surgical microscope to find a bleeding cause in cases of intraparenchymatous hemorrhage is described and the operative indication for lobar intracerebral hemorrhage is discussed.
