Impaired cerebral autoregulation and neurovascular coupling in middle cerebral artery stroke: Influence of severity?

Abstract

We aimed to assess cerebral autoregulation (CA) and neurovascular coupling (NVC) in stroke patients of differing severity comparing responses to healthy controls and explore the association between CA and NVC with functional outcome. Patients admitted with middle cerebral artery (MCA) stroke and healthy controls were recruited. Stroke severity was defined by the National Institutes of Health Stroke Scale (NIHSS) scores: ≤4 mild, 5-15 moderate and ≥16 severe. Transcranial Doppler ultrasound and Finometer recorded MCA cerebral blood flow velocity (CBFv) and blood pressure, respectively, over 5 min baseline and 1 min passive movement of the elbow to calculate the autoregulation index (ARI) and CBFv amplitude responses to movement. All participants were followed up for three months. A total of 87 participants enrolled in the study, including 15 mild, 27 moderate and 13 severe stroke patients, and 32 control subjects. ARI was lower in the affected hemisphere (AH) of moderate and severe stroke groups. Decreased NVC was seen bilaterally in all stroke groups. CA and NVC correlated with stroke severity and functional outcome. CBFv regulation is significantly impaired in acute stroke, and further compromised with increasing stroke severity. Preserved CA and NVC in the acute period were associated with improved three-month functional outcome.

Cerebral hemodynamics in stroke thrombolysis (CHiST) study

“…This is in agreement with the recent study carried out by Salinet et al who assessed more than 50 ischemic stroke patients up to 31 hours post symptom onset. It was reported that patients with mild (median NIHSS = 2) and moderate (median NIHSS = 9) stroke severity, there was no significant differences between AH and NAH CBV [41]. AIS patients in the present study had an admission mean NIHSS of 8.2, and this may therefore explain the lack of significant differences between AH and NAH CBV.…”

Middle cerebral artery velocity dynamic response profile during exercise is attenuated following multiple ischemic strokes: a case report

“…Second, acute exercise causes neural activation in areas such as the primary sensorimotor cortex and results in increased blood flow to these regions (Orgogozo and Larsen, ; Ogoh and Ainslie, ), which is mediated by neurovascular coupling (Venkat et al ). Ischemic stroke damages the neurovascular unit resulting in neurovascular uncoupling (Salinet et al ), a situation in which vasodilatory mediators produced by active neurons fail to result in arteriolar vasodilation (Cai et al ). Thus, the reduced Amp and increased TD observed could partially result from neurovascular unit damage (directly related to the stroke), which fails to couple blood flow to local neuronal activity.…”

Pathophysiological and clinical considerations in the perioperative care of patients with a previous ischaemic stroke: a multidisciplinary narrative review

“…However, it is well known that CA is impaired for at least a month after stroke. 97,135 The aetiology of perioperative stroke in patients with no history of stroke is predominantly embolic or thrombotic, with little contribution demonstrated by watershed ischaemia, at least in cardiac surgery. 136,137 Given the findings of Wesselink and colleagues 133 that although not associated with increased stroke risk, intraoperative hypotension is associated with increased perioperative mortality, risk of myocardial infarction, and acute kidney injury, and given that patients after stroke have impaired cerebral autoregulatory function for at least a month after a stroke, we recommend intraoperative blood pressure should be maintained as close as practical to the patient's preoperative, awake blood pressure, and should not be allowed to decrease below a MAP of 80 mm Hg based on the point at which cumulative risk begins to accrue in non-stroke patients.…”