Head Positioning in Acute Stroke

P atients with acute ischemic stroke (AIS) depend on cere-bral blood flow (CBF) to maintain perfusion of the at-risk penumbral tissue, 1,2 which is critically dependent on arterial blood pressure when cerebral autoregulation is affected.3 Thus, the simple process of positioning an AIS patient lying flat or head down is appealing in that it allows gravitational force to enhance blood flow in the collateral and leptomeningeal circulation.4,5 However, as most of the evidence pertaining to the effects of head positioning have been derived from studies with small, nonrandomized, and nonblinded assessment of physiological parameters in subjects, 4,5 these data are prone to considerable bias and, not unexpectedly, has resulted in guidelines differing, or making no specific recommendation, as to the optimal head position for patients with acute stroke.Japanese guidelines, for example, recommend that patients with suspected acute stroke be placed head down to improve CBF in the prehospital phase, 6 while other guidelines recommend the head-up position in the hospital to reduce intracranial pressure and risk of aspiration pneumonia.[7][8][9] Consequently, there is considerable variability in clinical protocols and views among physicians about head positioning in acute stroke.10 In this review, we examine the current evidence on head positioning, and discuss the first large-scale randomized evaluation, the HeadPoST (Head Position in Acute Stroke Trial), 11 which attempted to resolve such uncertainty by quantifying the balance of potential benefits and harms of lying-flat versus sitting-up, head positioning on clinical outcomes in patients with acute stroke. MethodologyWe undertook a review of published systematic reviews, meta-analysis, and randomized clinical trials on the effects of head positioning in acute stroke.We used the following search terms: cerebrovascular disease, stroke, cerebral infarction, intracerebral hemorrhage (ICH), head position, head posture, body position, systematic reviews, randomized clinical trials, and modified Rankin Scale (mRS).We searched PUBMED and OVID-MEDLINE for articles published from January 2013 to July 2018.We also included articles if they were prospective cohort-based in their assessment of the effects of head positioning in acute stroke that reported measurements of CBF, blood pressure, oxygenation, and functional outcome.In particular, studies were included that reported effects of head positioning by measurement of mean CBF velocities using transcranial Doppler in AIS patients that allowed quantification in the meta-analysis.