Debbie Quain

HOBOE (Head-of-Bed Optimization of Elevation) Study: Association of Higher Angle With Reduced Cerebral Blood Flow Velocity in Acute Ischemic Stroke

Background Cerebral autoregulation can be impaired after ischemic stroke, with potential adverse effects on cerebral blood flow during early rehabilitation. Objective The objective of this study was to assess changes in cerebral blood flow velocity with orthostatic variation at 24 hours after stroke. Design This investigation was an observational study comparing mean flow velocities (MFVs) at 30, 15, and 0 degrees of elevation of the head of the bed (HOB). Methods Eight participants underwent bilateral middle cerebral artery (MCA) transcranial Doppler monitoring during orthostatic variation at 24 hours after ischemic stroke. Computed tomography angiography separated participants into recanalized (artery completely reopened) and incompletely recanalized groups. Friedman tests were used to determine MFVs at the various HOB angles. Mann-Whitney U tests were used to compare the change in MFV (from 30° to 0°) between groups and between hemispheres within groups. Results For stroke-affected MCAs in the incompletely recanalized group, MFVs differed at the various HOB angles (30°: median MFV=51.5 cm/s, interquartile range [IQR]=33.0 to 103.8; 15°: median MFV=55.5 cm/s, IQR=34.0 to 117.5; 0°: median MFV=85.0 cm/s, IQR=58.8 to 127.0); there were no significant differences for other MCAs. For stroke-affected MCAs in the incompletely recanalized group, MFVs increased with a change in the HOB angle from 30 degrees to 0 degrees by a median of 26.0 cm/s (IQR=21.3 to 35.3); there were no significant changes in the recanalized group (−3.5 cm/s, IQR=−12.3 to 0.8). The changes in MFV with a change in the HOB angle from 30 degrees to 0 degrees differed between hemispheres in the incompletely recanalized group but not in the recanalized group. Limitations Generalizability was limited by sample size. Conclusions The incompletely recanalized group showed changes in MFVs at various HOB angles, suggesting that cerebral blood flow in this group may be sensitive to orthostatic variation, whereas the recanalized group maintained stable blood flow velocities.

Absolute cardiovascular risk and GP decision making in TIA and minor stroke

BACKGROUND Transient ischaemic attacks (TIA) and minor strokes (TIAMS) have the same pathophysiological mechanism as stroke and carry a high risk of recurrent ischaemic events. Diagnosis of TIAMS can be challenging and often occurs in general practice. Absolute cardiovascular risk (ACVR) is recommended as the basis for vascular risk management. Consideration of cardiovascular risk in TIAMS diagnosis has been recommended but its utility is not established. OBJECTIVES Firstly, to document the ACVR of patients with incident TIAMS and with TIAMS-mimics. Secondly, to evaluate the utility of ACVR calculation in informing the initial diagnosis of TIAMS. METHODS The International comparison of Systems of care and patient outcomes in minor Stroke and TIA (InSiST) study is an inception cohort study of patients of 17 Australian general practices presenting as possible TIAMS. An expert panel determines whether participants have had TIAMS or TIAMS-mimics. ACVR was calculated at baseline for each participating patient. In this cross-sectional baseline analysis, ACVR of TIAMS and TIAMS-mimics were compared univariately and, also, when adjusted for age and sex. The diagnostic utility of ACVR was evaluated via receiver operating characteristic (ROC) curves. RESULTS Of 179 participants, 87 were adjudicated as TIAMS. The presence of motor and speech symptoms and body mass index were associated with a diagnosis of TIAMS. ACVR was associated with TIAMS diagnosis on univariate analysis, but not when age- and sex-adjusted. ACVR did not significantly improve area under ROC curves beyond that of age and sex. CONCLUSION In patients presenting with transient or minor neurological symptoms, calculation of ACVR did not improve diagnostic accuracy for TIAMS beyond that of age and sex.

The Influence of Anterior Cerebral Artery Flow Diversion Measured by Transcranial Doppler on Acute Infarct Volume and Clinical Outcome in Anterior Circulation Stroke

Introduction Anterior cerebral artery flow diversion, measured by transcranial Doppler ultrasound, is correlated with leptomeningeal collateral flow on digital subtraction angiography in the setting of middle cerebral artery occlusion. We aimed to assess the influence of flow diversion as a marker of leptomeningeal collateralization on infarct size and penumbral volume. Methods We assessed consecutive patients presenting within six-hours of ischaemic stroke. Anterior cerebral artery flow diversion, defined as ipsilateral mean velocity of at least 30% greater than the contralateral artery, was used as the Doppler index of leptomeningeal collateralization. Multivariable regression analysis was performed to assess the impact of anterior cerebral artery flow diversion, controlling for other important clinical variables. Leptomeningeal collateralization was also graded on computed tomography angiography. Infarct core and penumbral volumes were defined using computed tomography perfusion thresholds of cerebral blood volume and mean transit time. Infarct volume, reperfusion, and vessel status were measured at 24 h using magnetic resonance techniques. Results Fifty-three patients qualified for analysis. Anterior cerebral artery flow diversion was associated with good collateral flow on computed tomography angiography (P < 0·001) and was an independent predictor of admission infarct core volume (P < 0·001), and 24 h infarct volume (P < 0·001). The likelihood of a favourable outcome (modified Rankin Score 0–2) was higher (odds ratio = 27·5, P < 0·001) in those with flow diversion. Conclusions Anterior cerebral artery flow diversion indicates effective leptomeningeal collateralization as measured by computed tomography angiography, and independently predicts acute infarct size and 90-day clinical outcome. Flow diversion appears to provide penumbral perfusion, offering some protection against infarct expansion. Acute bedside transcranial Doppler assessment of flow diversion aids prognostication and therapeutic decision making in anterior circulation stroke.