The angio-architectural and histological changes of small cerebral blood vessels in experimental hydrocephalus were studied to assess the changes of the vascular bed in the cerebral mantle. Change of the microvasculature assessed from microcorrosion casts by scanning electron microscopy (SEM) and the histological changes shown by light and electron microscopy were compared before and after shunting for hydrocephalus. The changes of the rCBF were also evaluated by the hydrogen clearance method. In hydrocephalus, a reduction in the number and caliber of the capillaries was noted in both the white and gray matter in the SEM study, but the capillaries were preserved and changes were mild and nonspecific in the electron microscopic examination. Shunting resulted in the reversal of all these changes to normal along with recovery of the rCBF, which had decreased in hydrocephalus. These observations suggest that changes of the vascular bed participate in the alteration of cerebral mantle width in the hydrocephalic process, and that the changes of the microvasculature result not only from damage to the capillaries themselves but also from changes of the perivascular structures.

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The angioarchitecture of microcorrosion casts in 12 hydrocephalic rats and 5 normal control rats was investigated by using scanning electron microscopy to observe the changes of the vascular bed in the cerebral mantle in hydrocephalus. Reduction in the number and caliber of the capillaries in the white matter was the most remarkable change in the hydrocephalic rats. This change increased in proportion to the severity of hydrocephalus. A similar change was observed in the basal ganglia. The change in the cortical capillaries was mild, but the cortical ‘palisade’ pattern had disappeared in some cases. Three-dimensional consideration of the angioarchitecture by using microvascular casts compared with microangiographic technique in rat hydrocephalus was discussed.

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We report three cases of arteriovenous malformation (AVM) of the medial temporal lobe and the surgical approaches used. The AVM was fed by the anterior choroidal artery (AChA) in two cases (Cases 1 and 2) and by the posterior cerebral artery in one (Case 3). The trans-Sylvian approach was first used for cerebrospinal fluid aspiration to retract the brain in all cases, and for confirming the feeding arteries to prevent premature bleeding from the AVM in Cases 1 and 2. In Case 1, a corticotomy was then made in the fusiform gyrus via the subtemporal approach to avoid the development of speech disturbance and visual field defects, while in Cases 2 and 3, a cortical incision was made in the middle temporal gyrus because visual field defects were preoperatively present. Cases 1 and 2 achieved good recoveries, but Case 3 suffered postoperative speech disturbance and died of rebleeding from a recurrent AVM fed by the AChA 22 months after the operation. This AVM was not demonstrated on the postoperative angiograms. We emphasize the usefulness of the combination of trans-Sylvian and subtemporal approaches for this lesion, because the feeding arteries are easily identified and retraction of the temporal lobe is alleviated. A corticotomy in the fusiform gyrus is also recommended to avoid the development of not only visual field defects but also aphasia.