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.

The rural Prehospital Acute Stroke Triage (PAST) trial protocol: a controlled trial for rapid facilitated transport of rural acute stroke patients to a regional stroke centre.

RATIONALE: Access to intravenous thrombolysis for acute ischaemic stroke is limited worldwide, particularly in regional and rural areas including in Australia. We are testing the effectiveness of a new rural Prehospital Acute Stroke Triage protocol that includes prehospital assessment and rapid transport of patients from a rural catchment to the major stroke centre in Newcastle, NSW, Australia. The local district hospitals within the rural catchment do not have the capability or infrastructure to deliver acute stroke thrombolysis. The trial has relevance to stroke clinicians, health service managers and planners responsible for rural populations. AIMS: To implement a system of rapid prehospital assessment and facilitated transport that will significantly increase stroke thrombolysis rates to 10% of ischaemic stroke cases in the rural catchment. Validate an eight-point modified National Institutes of Health Stroke Scale for use by paramedics in the prehospital setting to assess patients' potential eligibility for stroke thrombolysis. DESIGN: The joint project between the John Hunter Hospital Acute Stroke Team and the Ambulance Service of NSW will use a prospective cohort with an historical control group. Tools and protocols have been developed and education undertaken for ambulance field and operations centre personnel. These include a cut-down eight-item National Institutes of Health Stroke Scale (Hunter NIHSS-8) score to be used in the field by paramedics and a transport decision matrix to expedite transport for a suspected stroke patient (road or road plus air transport). OUTCOMES: The primary outcome measure will be the rate of intravenous tissue plasminogen activator delivery for those who suffer an ischaemic stroke following protocol implementation, in comparison with historical rates over a corresponding period prior to implementation, for residents within the catchment. Sixty cases are required in the postimplementation time epoch to demonstrate a statistically significant absolute increase in thrombolysis rates for ischaemic strokes from <1% to 10%, (power of 80%, α error of 0.05). The major secondary outcome will be inter-rater reliability of the Hunter NIHSS-8.

Improving access to acute stroke therapies: a controlled trial of organised pre-hospital and emergency care.

OBJECTIVE: To assess the effectiveness of the PAST (Pre-hospital Acute Stroke Triage) protocol in reducing pre-hospital and emergency department (ED) delays to patients receiving organised acute stroke care, thereby increasing access to thrombolytic therapy. DESIGN: Prospective cohort study using historical controls. SETTING: Hunter Region of New South Wales, September 2005 to March 2006 (pre-intervention) and September 2006 to March 2007 (post-intervention). PARTICIPANTS: Consecutive patients presenting with acute stroke to a regional, tertiary referral hospital. INTERVENTION: PAST protocol, comprising a pre-hospital stroke assessment tool for ambulance officers, an ambulance protocol for hospital bypass for potentially thrombolysis-eligible patients, and pre-hospital notification of the acute stroke team. MAIN OUTCOME MEASURES: Proportion of patients who received intravenous tissue plasminogen activator (tPA), process of care time points (symptom onset to ED arrival, ED arrival to tPA treatment, and ED transit time), and clinical outcomes of patients treated with tPA. RESULTS: The proportion of ischaemic stroke patients treated with tPA increased from 4.7% (pre-intervention) to 21.4% (post-intervention) (P < 0.001). Time point outcomes also improved, with a reduction in median times from symptom onset to ED arrival from 150 to 90.5 min (P = 0.004) and from ED arrival to stroke unit admission from 361 to 232.5 minutes (P < 0.001). Of those treated with tPA, 43% had minimal or no disability at 3 months. CONCLUSIONS: Organised pre-hospital and ED acute stroke care increases patient access to tPA treatment, which is proven to reduce stroke-related disability.