Cerebral Autoregulation and Brain Networks in Occlusive Processes of the Internal Carotid Artery

Abstract

Patients with unilateral occlusive processes of the internal carotid artery (ICA) show subtle cognitive deficits. Decline in cerebral autoregulation and in functional and structural integrity of brain networks have previously been reported in the affected hemisphere (AH). However, the association between cerebral autoregulation, brain networks, and cognition remains to be elucidated. Fourteen neurologically asymptomatic patients (65 ± 11 years) with either ICA occlusion or high-grade ICA stenosis and 11 age-matched healthy controls (HC) (67 ± 6 years) received neuropsychologic testing, transcranial Doppler sonography to assess cerebral autoregulation using vasomotor reactivity (VMR), and magnetic resonance imaging to probe white matter microstructure and resting-state functional connectivity (RSFC). Patients performed worse on memory and executive tasks when compared with controls. Vasomotor reactivity, white matter microstructure, and RSFC were lower in the AH of the patients when compared with the unaffected hemisphere and with controls. Lower VMR of the AH was associated with several ipsilateral clusters of lower white matter microstructure and lower bilateral RSFC in patients. No correlations were found between VMR and cognitive scores. In sum, impaired cerebral autoregulation was associated with reduced structural and functional connectivity in cerebral networks, indicating possible mechanisms by which severe unilateral occlusive processes of the ICA lead to cognitive decline.

Functional and structural cortical characteristics after restricted focal motor cortical infarction evaluated at chronic stage – Indications from a preliminary study

“…Previously, carotid artery stenosis has been shown to affect DWI-weighted MRI and MTs (Avirame et al, 2015;List et al, 2014). In the present study, two patients were observed with hemodynamically relevant carotid artery stenosis (Table 1).…”

Connectometry evaluation in patients undergoing carotid endarterectomy: an exploratory study

“…A similar approach was adopted by Chang TY et al [14], comparing patients with unilateral ICA stenosis (³ 60%) and HCs using a battery of neuropsychological tests, resting state fcMR and perfusion MR. Network analysis revealed that in the patients' group the hemispheres ipsilateral to the ICA stenosis was impaired in "degree" and "global efficiency". Avirame K et al [15] In this analysis, we investigated if there were short-term brain local connectivity changes after CEA, and if they were accompanied or not by changes in cognitive performances measured by MMSE. The group connectometry analysis revealed that patients who underwent CEA showed statistically significant (p-FDR = 0.0106667) short term local connectivity changes in corpus callosum and cerebellum.…”

“…Some of the studies above mentioned analyzed differences in brain connectivity comparing patients with ICA stenosis and normal healthy controls [13][14][15][16], others investigated on brain connectivity before and after CAS [17,18], and another one compared changes following CAS or aggressive medical therapy [19]. Another study by Schaaf et al [20] evidenced increased BOLD signal immediately after CEA probably due to the higher intracranial blood flow.…”

Dissociation among hemodynamic measures in asymptomatic high grade carotid artery stenosis

“…Our pCASL measurement specifically assesses cortical blood flow(35). Although CASL depends for its calculation on “arterial transit time”(36, 37) -- a variable related mathematically to MFV -- its final output of cortical blood flow is influenced by distinct physiological variables such as cortical blood volume,(16) collateral patterns,(38) cortical network connectivity,(39) and local neurotransmitter effects(40, 41). Impaired cortical flow may thus have functional implications for the cortex that are distinct from the non-specific reduced flow velocity identified by TCD.…”