[Cerebral venous hemodynamics in chronic disorders of cerebral circulation].

The aim of the work was to assess extra- and intracranial venous hemodynamics in patients with circulatory disorder-induced encephalopathy (DE). Altogether 114 DE patients were examined. There were 46 women and 68 men aged 43 to 78 years (mean age 59.6+/-12.5 years). As dependent on the clinical manifestations the patients were distributed into groups: stage 1 DE was present in 36 patients, stage 2 DE in 47>> and stage 3 DE was identified in 31 patients. 82.78% of the examined had arterial hypertension (AH), the mean standing of which accounted for 9.7+/-7.2 years. The control group accrued 36 practically normal persons aged 36 to 62 years (mean age 47.6+/-11.3 years). All the patients were provided standard neurologic examination, magnetic resonance tomography (MRT) of the brain with venography of the brachiocephalic veins and venous sinuses of the brain, Color Doppler Imaging of the extracranial vessels, and transcranial Doppler. The patients complained primarily of headache, dizziness, instability and staggering on walking, memory and work fitness decrease, and irritability. Atherosclerotic plaques which were primarily homogeneous (types IV and V according to the classification by Geroulakos et al., 1993) were identified in the carotid arteries in 76 (62%) patients. In 48 (42%) patients, stenoses were bilateral. Hemodynamically significant (>50%) stenoses were present in 42 (34%) persons. In most cases, the patients showed dilatation of the jugular veins and a mean reduction of the flow intensity to 14+/-8.1 cm/s as compared to the control group (20.6+/-11.3 cm/s). The tendency toward flow intensity lowering associated with its phasic nature disorder was particularly well-defined in patients with stage 3 DE and a long-term history of AH. On examination of the parameters of cerebral venous circulation the patients with stage 1 DE tended to the rise of the linear flow velocity (LFV) in the basal veins of Rozenthal and in the direct sinus. However, no significant changes in the PI parameters were recorded. In the patient group with stages 2 and 3 DE, there was an appreciable rise of the LFV in the deep veins in the presence of a remarkable PI lowering (the flow velocity in the vein of Rozenthal 21.8+/-7.2 cm/s in stage 2 DE, and 24.4+/-7.2 cm/s in stage 1 DE). In 87 (79%) cases, MRT revealed the signs of diffuse ischemic lesion of the brain. Fifty-five (48%) patients were diagnosed to have leukoarayos whereas in 48 (42%) cases, there were identified multiple lacunar infarctions, primarily of the deep cerebral segments. Ten (8%) patients demonstrated type 1 Arnold-Chiari abnormalities -- hypoplasia of the large cerebral cistern and 4 patients had porto-cerebellar atrophy (megacysterna magna). Analysis of the MRV revealed, in the majority of cases (in 67 or 59%), developmental abnormality of the drainage system of the brain. Thus, 42 (37%) patients were diagnosed to have hypoplasia of one of the transverse sinuses (of the right one in 23 cases and of the left one in 19 cases); 17 (15%) persons had aplasia of the transverse sinus. Eight patients showed hypoplasia of the sigmoid sinuses (of the right one in 5 cases and of the left one in 3 cases). In all the cases of developmental abnormalities of the venous sinuses, there was a compensatory dilatation of the contralateral sinus and in some cases, there were visualized the upper and lower sinuses, the identification of which in health is difficult. So, atherosclerosis of AH-induced lesion of the brachiocephalic arteries interferes with the action of the physiological "arteriovenous pump" thereby provoking venous congestion. Progression of the process is associated with depletion of the compensatory adaptive potentialities of the collateral venous outflow which (especially in concomitant developmental abnormality in the region of the posterior cranial fossa and venous sinuses) favours aggravation of venous circulatory distress, the rise of the CSF pulse pressure and the emergence of benign intracranial hypertension and hydrocephalus followed by cerebral atrophy.