Findings of global study could aid stroke patient prognosis

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Measuring the brain’s ability to control its own blood flow using a bedside test could allow clinicians to give stroke patients and their families a clearer idea of how well they’ll go on to recover.

This is the finding of a study carried out by researchers at the National Institute for Health and Care Research (NIHR) Leicester Biomedical Research Centre published in Stroke earlier this month.

In the largest study of its kind to investigate dynamic cerebral autoregulation, researchers compared results from 384 adults who had suffered ischemic stroke.

Dr Lucy Beishon from the Department of Cardiovascular Sciences at the University of Leicester, which forms part of the NIHR Leicester BRC, led the study.

She explained: “Dynamic cerebral autoregulation is a continuous, active process through which the brain maintains appropriate blood flow to its tissue through the regulation of its blood vessels.

“During an ischemic stroke a blood clot blocks the flow of blood to the brain. These blood clots typically form in areas where the arteries have been narrowed or blocked over time by fatty deposits, or a clot originates in the heart and is pumped out to the brain. This impacts on the brain’s ability to regulate its blood flow.

“We wanted to investigate the association between dynamic cerebral autoregulation and how well patients go on to recover following ischemic stroke.”

Data from 384 adults from 11 different stroke studies around the world including the UK, Portugal, Brazil, Switzerland, China, Taiwan, and Canada were compared.

Transfer function analysis (which quantifies the extent to which fluctuations in blood pressure are buffered by the brain’s blood vessels thus transmitted to cerebral blood velocity), was used to quantify dynamic cerebral autoregulation.

Data were grouped into four time points after stroke: at under 24 hours, between 24 and 72 hours, between 4 and 7 days, and at 3 months. The modified Rankin scale (mRS) had been used to assess each patient’s functional outcome at 3 months.

Dr Beishon said: “When studying and comparing the measures in these patients, and their subsequent recovery from stroke, we found that measurements of dynamic cerebral autoregulation in the early phase of stroke predicted how well they had recovered three months later.

“As dynamic cerebral autoregulation can be measured through ultrasound scans of the brain (a non-invasive procedure which can be done at the bedside) taking this measurement could allow clinicians to give patients and their families a clearer prognosis in the early stages following ischemic stroke.

“Understanding dynamic cerebral autoregulation could also guide clinical practice in the acute stage, particularly given recent advancements in acute reperfusion therapies.”

Dr Jatinder Minhas, Clinical Associate Professor of Stroke Medicine and NIHR Leicester BRC Stroke Sub-theme lead, said: “Dr Beishon has led this multicentre study over the last five years, meticulously amalgamating and analysing complex haemodynamic data provided by world-leading cerebral haemodynamic centres.

“There is tremendous potential for clinical impact based on the deeper mechanistic understanding this study provides and we are delighted this has been recognised through publication in Stroke.”