Cerebral Haemodynamics and Orthostatic Response to Upright Posture in Acute Ischaemic Stroke (CHORUS)

Stroke is the leading cause of adult disability and mortality in Australia. The majority of strokes are ischaemic in nature and occur when a blood vessel to the brain is occluded, usually by a clot.

Cerebral blood flow in acute ischaemic stroke is highly dynamic, and factors that either impair or promote cerebral blood flow during the acute phase may directly affect the infarct size and associated clinical deficit. Lowering the head of the bed in the early hours of stroke may theoretically assist flow to the ischaemic tissue. Conversely, there is growing support for early mobilisation after stroke with the potential to reduce cerebral blood flow and decrease infarct size. Currently there is no consensus and no clinical guidelines on the safety of early upright posture when caring for acute stroke patients.

Against a backdrop of a number of large, international clinical trials that studied the effects of early activity (AVERT) or bed rest for 24 hours (HeadPoST) to improve recovery, further evaluation of the extent and clinical relevance of orthostatic changes (upright posture inclusive) in cerebral blood flow in acute ischaemic stroke using transcranial Doppler ultrasound was warranted.

The CHORUS study (Frontiers in Neurology 2024) investigated the effects of head positioning (participants moved from lying flat in bed to upright sitting and standing) in acute ischaemic stroke within 48h post stroke onset on cerebral blood flow velocities using transcranial doppler ultrasound. The study results were affected by the COVID-19 pandemic, which unfortunately limited the study sample size. Still, a total of 42 participants with acute ischaemic stroke and 22 healthy controls were recruited.

The study showed that moving to more upright positions within 2 days post stroke reduced cerebral blood flow velocities in the affected hemisphere, however these changes were not significantly different for stroke participants (anterior and posterior circulation strokes combined) with or without occlusive disease, nor in controls. The decrease in cerebral blood flow velocities in participants with anterior circulation stroke with occlusive disease differed significantly from those without occlusive disease.

Although the sample size was limited, we expect the study protocol and preliminary data to inform the development of larger trials in the field.