No abstract

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.

Platelet activating factor (PAF) content and PAF-acetylhydrolase (PAFAH) activity were measured in the plasma and haematoma of 34 chronic subdural haematoma (CSH) patients. The plasma PAF level in patients with CSH was higher than that in healthy controls. Although there was no correlation between the plasma PAF levels and the interval between the onset of symptoms and the day of sampling, namely, the interval after bleeding, the haematoma PAF level gradually decreased according to the interval after the onset of symptoms. There was no difference between plasma PAFAH activity in patients with CSH and that in healthy controls, and haematoma enzyme activity gradually increased correlated with the interval between the onset of symptoms and surgery. In addition, the localization of PAF in haematoma capsules was histochemically determined. PAF was solely localized to the peri-sinusoidal vessels in the outer membrane of haematoma capsules. Based on these biochemical and histochemical studies, we speculated that PAF may play a role in the development of chronic subdural haematomas.

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Dynamic computed tomography (CT) is an established method for the evaluation of perfusion in acute ischemic stroke, but is not frequently used to assess infratentorial ischemia. Eleven patients with vertebrobasilar ischemia underwent dynamic CT on admission and/or during the followup period. The time of appearance (TA) and time to peak (TTP) were mapped and differences in TA (DTA) and TTP (DTTP) between the bilateral middle cerebral artery and posterior cerebral artery (PCA) territories were calculated. Conventional angiography and brain imaging including CT and magnetic resonance imag ing were also performed. The TA and TTP maps obtained within 48 hours after onset exhibited time delay in eight of nine patients in the bilateral PCA territories. DTA and DTTP were greater in patients with stenosis or occlusion of the bilateral vertebral arteries or the basilar artery, and in patients without collateral circulation via the posterior communicating arteries than in control subjects. Furthermore, TA and TTP normalized dramatically in patients with recanalization of the arteries. DTA and DTTP were also normalized. DTA and DTTP were negatively correlated with the time from onset to examina tion. Dynamic CT can provide important information in patients with vertebrobasilar ischemic stroke, and may allow the diagnosis of acute ischemia and monitoring of the course.