Clinical and Neurophysiological Correlates of Cognitive Disorders in Patients with Carotid Atherosclerosis

INTRODUCTION: Cognitive disorders often do not come to the fore in the interpretation of clinical manifestations in hemodynamically significant stenoses of brachiocephalic arteries. In this regard, the objectification of cognitive disorders based on a battery of tests, as well as of their neurophysiological correlates, is an important task of both angiology and neurology. Endogenous evoked potential P300 is a frequently used neurophysiological phenomenon characterizing the psychophysiological functions of perception, attention, and thinking. AIM: To study the dynamics of cognitive functions and their neurophysiological correlates in patients with hemodynamically significant carotid artery stenosis before and after carotid endarterectomy. MATERIALS AND METHODS: An open prospective study included 60 patients divided to two groups. Group A included 30 ‘symptomatic' patients with a hemodynamically significant lesion (stenosis) of the internal carotid artery and a history of acute cerebrovascular accident. Group B included 30 ‘asymptomatic patients' without a history of cerebrovascular events. Within the study, before surgery for carotid stenosis and 6 months after, the following parameters were assessed: cognitive status (according to the MMSE, FAB, MoCA, NIHSS scales), and also clinical and neurophysiological correlates of cognitive functions (P300 evoked potential). RESULTS: In the group of patients with neurological disorders (group A), a reliably greater number of errors (p = 0.048), as well as a decrease in the amplitude (p = 0.006) and increase in latency (p = 0.022) of P2 component of P300 cognitive evoked potential were determined. Based on the parameters of P300 event-related potential, a logit regression model was created that permitted to classify patients to the above-mentioned groups. The cluster analysis of dynamics of cognitive functions was additionally performed before and after surgery. In cluster 1, there were 45% of symptomatic patients, 55% of asymptomatic ones, in cluster 2 — 58% and 32%, respectively, no reliable differences were found (chi-square 0.58; p = 0.445). Cluster 1 was characterized by initially higher level of test performance with some increase in this parameter after surgery; Cluster 2 was characterized by a lower level of these parameters, with the greatest differences found in frontal assessment battery (FAB) characteristics. Reliable differences in the level of P300 were found only after surgery: the greatest differences were recorded in the amplitude of P2, P3, N2 components. CONCLUSION: The factor of cognitive impairment is a separate phenomenon, not closely related to focal neurological syndrome in patients with carotid atherosclerosis. An objective neurophysiological criterion for cognitive impairment in these patients is the endogenous evoked potential P300. With this, the greatest differences between the neurophysiological correlates of cognitive disorders are determined 6 months after the operation for carotid stenosis.