Normalization of reduced functional connectivity after revascularization of asymptomatic carotid stenosis

J Cereb Blood Flow Metab. 2020 Sep;40(9):1838-1848. doi: 10.1177/0271678X19874338. Epub 2019 Sep 11.

Abstract

Internal carotid artery stenosis is a risk factor for ischemic stroke. Even in the absence of visible structural brain changes, patients with asymptomatic stenosis are prone to cognitive impairment. On a neuronal level, it was suggested that stenosis may lead to disturbed functional brain connectivity. If so, carotid revascularization should have an effect on hypothesized brain network disturbances. We studied functional connectivity in a motor network by resting-state electroencephalography in 12 patients with high grade asymptomatic carotid stenosis before and after interventional or surgical revascularization as compared to 23 controls. In patients with stenosis, functional connectivity of neural oscillations was significantly decreased prior and improved returning to normal connectivity after revascularization. In a subgroup of patients, also studied by contrast perfusion magnetic resonance imaging, reduced connectivity was associated with decreased regional brain perfusion reflected by increased mean transit time in the middle cerebral artery borderzone. Cognitive testing revealed only minor differences between patients and controls. In summary, we identified oscillatory connectivity changes in patients with asymptomatic carotid stenosis correlating with regional hypoperfusion, which both normalized after revascularization. Hence, electrophysiological changes might be a reversible precursor preceding macroscopic structural brain damage and behavioral impairment in patients with asymptomatic carotid stenosis.

Keywords: Asymptomatic carotid artery stenosis; EEG; carotid revascularization; functional connectivity; perfusion MRI.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Carotid Stenosis / psychology
  • Carotid Stenosis / surgery*
  • Cerebral Revascularization / methods*
  • Cerebrovascular Circulation
  • Cognitive Dysfunction / etiology
  • Cognitive Dysfunction / psychology
  • Electroencephalography
  • Female
  • Humans
  • Magnetic Resonance Angiography
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Middle Cerebral Artery / physiology
  • Neural Pathways / physiology*
  • Neuropsychological Tests
  • Recovery of Function