Characteristics of cerebral hemodynamics in patients with chronic brain ischemia

Abstract

Background. Literature sources report conflicting results regarding the severity of clinical symptoms of hydrocephalus (HC) and their association with cerebral arterial blood flow (CABF); most studies do not show a direct relationship, while some suggest a link between clinical severity and progressive decrease in CABF. The study of hemodynamic changes in the brain of patients with chronic brain ischemia (CBI), elucidation of their relationship with cognitive impairments helps to improve diagnostic approaches and optimize the prognosis of the disease. The purpose of this study is to investigate the state of cerebral hemodynamics and to establish its relationship with changes in cognitive functions in patients with CBI and HC. Materials and Methods. A comprehensive examination of 110 patients with CBI and HC was performed. The localization of the HC and results of Montreal Cognitive Test (MoCA scale) were taken into account. Computed tomography of the brain was performed with subsequent determination of morphometric parameters and indices. The state of cerebral blood flow and structural changes of blood vessels were studied using transcranial color-coded duplex ultrasonography (TCCS) of intracranial vessels and extracranial divisions. Microsoft Excel 2011 and Statistica were used for statistical processing of the results. Results. It was found that there was a significantly larger diameter of both common carotid arteries (CCA), thickness of complex intima\media (CIM), maximum systolic velocity (Vs), velocity at the end of the diastolic cycle (Vd), as well as peripheral resistance (IR) in left CCA (p <0,05) in patients with CBI and HC compared with patients with CBI without HC. Significantly larger diameter of left internal carotid artery (ICA), Vs, Vd and IR was revealed; Vs and Vd in the right ICA; Vd in the extracranial devision of vertebral artery (VA) in patients with HC. A significant relationship was found between the following blood flow parameters and the values of the MoCA scale: Vs MCA/MoCA (r = 0,45, p <0,05), Vs ACA/MoCA (r = 0,38, p <0.05), ICA diameter/MoCA (r = -0,51, p <0,05). It was found that the diameter of CCA and the thickness of CIM were significantly larger in patients with CBI with internal HC in comparison with patients with CBI with external HC (p <0,01). Vs and Vd in patients with internal hydrocephalus were significantly lower, and IR was significantly higher compared with patients with external hydrocephalus (p <0,01). The diameter of ICA and IR in patients with CBI with internal HC was significantly higher, and Vs was significantly lower compared with patients with CBI and external HC (p <0,01). Significantly different values were found in Vs and IR meanings in middle cerebral artery (MCA) and Vs in anterior cerebral artery (ACA) in patients with CBI with internal HC compared with patients with CBI with external HC.

Conclusions. Functional parameters of blood flow and structural changes of cerebral arteries in patients with CBI with concomitant hydrocephalus differed significantly from those in patients without hydrocephalus and depended on the type and severity of hydrocephalus. ICA occlusion, ICA stenosis >50%, and intracranial venous stasis were significantly more common in patients with severe and moderate HC compared with those with mild HC. A weak relationship was found between the structure of carotid arteries and blood flow in intracranial arteries in patients with CBI and HC. There was a significant relationship between blood flow indices and the values of the MoCA scale, which indicated the effect of changes in the vessels of the anterior circular basin on the cognitive functions and the lack of such connection with blood flow indices in vertebrobasilar basin.