Sex differences in stroke reperfusion therapy in Aotearoa (New Zealand)

BACKGROUND AND AIMS

Stroke is a leading cause of death in Aotearoa (New Zealand), and stroke reperfusion therapy is a key intervention. Sex differences in stroke care have previously been asserted internationally. This study assessed potential differences in stroke reperfusion rates and quality metrics by sex in Aotearoa (New Zealand).

METHODS

This study used data from three overlapping sources. The National Stroke Reperfusion Register provided 4-year reperfusion data from 2018 to 2021 on all patients treated with reperfusion therapy (intravenous thrombolysis and thrombectomy), including time delays, treatment rates, mortality and complications. Linkage to Ministry of Health administrative and REGIONS Care study data provided an opportunity to control for confounders and explore potential mechanisms. T-test and Wilcoxon rank-sum analyses were used for continuous variables, while the chi-squared test and logistic regression were used for comparing dichotomous variables.

RESULTS

Fewer women presented with ischaemic stroke (12 186 vs 13 120) and were 4.2 years older than men (median (interquartile range (IQR)) 79 (68-86) vs 73 (63-82) years). Women were overall less likely to receive reperfusion therapy (13.9% (1704) vs 15.8% (2084), P < 0.001) with an adjusted odds ratio of 0.83 (0.77-0.90), P < 0.001. The adjusted odds ratio for thrombolysis was lower for women (0.82 (0.76-0.89), P < 0.001), but lower rates of thrombectomy fell just short of statistical significance ((0.89 (0.79-1.00), P = 0.05). There were no significant differences in complications, delays or documented reasons for non-thrombolysis.

CONCLUSIONS

Women were less likely to receive thrombolysis, even after adjusting for age and stroke severity. We found no definitive explanation for this disparity.

Abstract WP69: Days Alive And Out Of Hospital As A Measure Of Stroke Outcome In Patients Receiving Hyperacute Stroke Intervention

Background: Patient outcome after stroke is frequently assessed with the modified Rankin Scale score (mRS), which is a 7-level ordinal scale from 0 - no disability, to 6- dead that is usually obtained by in-person or telephone interviews. The mRS can be prone to bias and can have significant inter-rater variability. Days alive and out of hospital at 90 days (DAOH-90) is an objective, readily available outcome measure that accounts for survival, time spent in hospital or rehabilitation settings, re-admission, and institutionalization. We aimed to assess the criterion, construct and face validity of DAOH.

Methods: Consecutive ischemic stroke patients treated with thrombolysis or endovascular thrombectomy were used in this analysis. DAOH-90 was calculated from the national minimum dataset, an administrative nationwide database. mRS at 90 days was assessed with in-person or telephone interviews. Simple descriptive statistics were applied (median [IQR]). The ability of DAOH-90 to distinguish between the commonly applied cut-points of mRS-90 was assessed using the area under the receiver operating curve (AUROC). The associations of DAOH-90 with commonly used stroke prognostic variables were assessed with Spearman’s correlation.

Results: 1067 ischemic stroke patients (481 male, median age 69 [58-78], median NIHSS 16 [11-20] were included in this study. Overall, median DAOH-90 was 68 [25-82] and median mRS-90 was 2 [1-4]. There was a strong association between mRS-90 and DAOH-90 (Spearman's rho correlation 0.79, p<0.001). AUROC (95% CI) for predicting mRS>0, mRS>1, mRS>2 were 0.85 (0.83-0.88), AUC 0.88 (0.86-0.90), AUC 0.90 (0.88-0.92) respectively. DAOH-90 was significantly correlated with age (spearman rho -0.37, p=0.002), admission NIHSS (spearman rho -0.37, p<0.001), Alberta stroke programme early CT score (spearman rho 0.23, p<0.001), and admission blood glucose concentration (spearman rho -0.24, p<0.001).

Conclusion: DAOH is statistically valid outcome measure in ischemic stroke that strongly relates to mRS at 90 days. DAOH is an objective, patient-centric outcome measure that can be determined from large datasets and therefore its place in stroke research warrants further study.

Abstract WMP4: Bridging Thrombolysis In Stroke Patients With Low Aspects Prior To Endovascular Thrombectomy

Background: In stroke patients with large vessel occlusion and extensive early ischemic change, the role of bridging thrombolysis prior to endovascular thrombectomy (EVT) is still to be determined.

Aim: To examine the impact of ischemic change on the efficacy and safety of bridging thrombolysis in patients treated with EVT.

Methods: Consecutive anterior circulation EVT patients from a prospectively collected registry were included in this retrospective analysis. Alberta stroke programme early CT scores (ASPECTS) were evaluated from initial non-contrast CT scan with lower score indicating larger areas of early ischemic change. Outcome measures included symptomatic intracranial hemorrhage and functional independence (modified Rankin scale score 0-2) at day 90. Multivariable logistic regression models with interaction terms between ASPECTS and bridging thrombolysis were created. ASPECTS was treated as numeric variable in the primary analysis and trichotomized (ASPECTS ≤5, 6-8, 9-10) in a sensitivity analysis.

Results: 872 EVT patients (384 female, mean ± SD age of 67 ± 15, baseline NIHSS 16 [IQR 11-20], median ASPECTS 8 [range 2-10]) were included. 436 (50%) received bridging intravenous thrombolysis with alteplase. There was no significant main effect of ASPECTS on sICH (main effect OR 0.73 95%CI 0.45-1.21, p=0.24) and no modifying effect of thrombolysis (interaction p=0.65). With decreasing numeric ASPECTS, the probability of functional independence reduced (main effect OR 1.34 95%CI 1.20-1.49, p<0.001), and this the reduction was steeper in those without bridging thrombolysis (interaction p=0.035). The interaction was not significant when ASPECTS was split into the 3 categories (p=0.28).

Conclusion: In anterior circulation patients treated with EVT, bridging thrombolysis was associated with a higher probability of functional independence in those with more extensive early ischemia as determined by ASPECTS. These results suggest patients with large ischemic cores may still benefit from bridging thrombolysis, but this will need to be evaluated in further studies.

Abstract 79: Direct Bypass To Endovascular Capable Stroke Center Compared To Secondary Transfer From Primary Stroke Centers

Introduction: All stroke care in our metropolitan region is provided by three primary stroke centers (PSCs) and a central endovascular thrombectomy capable stroke center (EVT-SC). There is a hybrid organizational structure with all potential large vessel occlusion (LVO) patients taken to the nearest stroke center during office-hours, and directly bypassed to the EVT-SC after-hours.

Aim: To compare process times and EVT outcomes in PSC locality patients who were transferred to the EVT-SC by these two methods.

Methods: Between August 2017 and February 2021, consecutive anterior LVO patients transferred via road with EVT initiation within 6 hours were included. Patients were grouped into method of presentation: 1) PSC locality patients directly bypassed to EVT-SC (‘EVT-SC direct’); 2) PSC locality patients taken to local PSC with subsequent transfer to EVT-SC (‘PSC-transfer’); 3) patients normally resident in the EVT-SC locality (‘EVT-SC local’). The primary outcome was 3-month functional independence (modified Rankin Scale score 0-2). Secondary outcomes included symptomatic intracranial hemorrhage, and mortality at 7-days and at 3-months.

Results: 343 patients (142 women; mean±SD age 66.5±16.0 years) were included. There were 91 (26.5%) EVT-SC direct, 168 (49.0%) PSC-transfer, and 84 (24.5%) EVT-SC local patients. For EVT-SC direct patients, the median (interquartile range) distance travelled was 13 (10-18) miles. EVT-SC direct patients were younger (mean±SD age 63.8±15.1 years versus 68.5±15.0 years; P =0.02), had shorter LKN-to-thrombolysis (120 vs 147 minutes, P =0.004) and LKN-to-puncture times (190 vs 230 minutes, P< 0.001), compared to the PSC-transfer patients. With multivariable logistic regression analysis, at 3-months EVT-SC direct patients were more likely to be functionally independent (OR=2.04, [95% CI, 1.12-3.73]; P =0.02), and less likely to be dead (OR=0.33, [95% CI, 0.12-0.91]; P =0.03). For every 100 patients directly bypassed to EVT-SC, there were 14 additional patients functionally independent and 9 less deaths at 3-months.

Conclusion: The results of this study suggest where the distance is less than 20 miles, direct bypass to EVT-SC is associated with better process times and outcomes.

Abstract WP168: Anticoagulation Therapy In Endovascular Thrombectomy Patients With Large Vessel Occlusion Due To Cardioembolism

Introduction: In ischemic stroke patients, cardioembolism, predominantly due to atrial fibrillation (AF), is a leading preventable cause of large vessel occlusion (LVO). Despite proven efficacy, inadequate oral anticoagulant (OAC) therapy continues to be a major problem in patients with AF, mechanical heart valves and other potential sources of emboli.

Aim: To determine rates of cardioembolic LVO, the adequacy of OAC, and the association of OACs with clinical outcomes in LVO patients treated with endovascular thrombectomy (EVT).

Methods: Trial of Org 10172 in Acute Stroke Treatment classification was used to determine stroke etiology in consecutive patients treated with EVT. Pre-stroke indication for OAC and the adequacy of anticoagulation were determined for patients with cardioembolic LVO. The primary outcome was 3-month functional independence (modified Rankin Scale score 0-2). Secondary outcomes included early neurological recovery (reduction in National Institutes of Health Stroke Scale score ≥8 points, or score of 0-1 at 24-hours), symptomatic intracranial hemorrhage, and 3-month mortality and modified Rankin Scale score.

Results: Between January 2015 and December 2020, 784 patients were treated with EVT. There were 416 patients (213 men; mean±SD age 67.1±15.9) with cardioembolic LVO, including 221 (53.1%) prevalent AF, 99 (23.8%) incident AF, 48 (11.5%) mechanical heart valve, 10 (2.4%) cardiomyopathy-related LVO, 10 (2.4%) left ventricular thrombus-related LVO and 11 (2.6%) patent foramen ovale-related LVO patients. There was adequate anticoagulation in 8 (16.7%) mechanical heart valve patients. Of the 191 prevalent AF patients with pre-stroke indications for OAC, 59 (30.9%) patients had adequate anticoagulation, and were less likely to have internal carotid artery occlusion (6.8% versus 18.9%, P =0.03) and more likely to achieve functional independence (OR=1.97 [95% CI 1.01-3.83]; P =0.04) than those with inadequate anticoagulation.

Conclusion: Over half of EVT treated patients had cardioembolic LVO. Only one-third of patients with an indication for OAC at the time of LVO were adequately anticoagulated. This suggests that up to one in five patients with LVO requiring EVT may have been prevented with adequate anticoagulation.

Abstract TP236: Brain And Infarct Temperature Changes With Active Conductive Head Cooling: A Magnetic Resonance Spectroscopy Imaging Study

Background and Purpose: Active conductive head cooling (HC) is a simple and non-invasive intervention that may potentially slow infarct growth in patients with stroke. Using magnetic resonance spectroscopy imaging (MRSI), we investigated the effect of HC on brain and systemic temperatures.

Methods: A cooling cap (WElkins Temperature Regulation System, 2nd Gen) was used to administer HC for 80 minutes to healthy volunteers and patients at least 6 months following a large vessel occlusion stroke. Serial MRSI scans were obtained before and during HC. Brain temperature was estimated using the Metabolite Imaging and Data Analysis System software package, which allows voxel-level temperature calculations using the chemical shift difference between metabolite (N-acetylaspartate, creatine, choline) and water resonances. Rectal temperature, the 11-point Numerical Pain Rating Scale score, heart rate, and blood pressure were measured. The primary outcome was the mean difference in brain temperature before and after HC.

Results: Eleven participants (6 healthy volunteers, and 5 post-stroke) had a total of 66 MRSI scans performed over 80±5 minutes of HC. An average absolute temperature of -1.3±0.5°C was delivered via the cooling cap to the scalp of the participants. Following HC, significant reductions in brain temperature (ΔT = -0.9±0.7°C, P =0.002), and to a lesser extent, rectal temperature (ΔT = -0.3±0.1°C, P =0.03) were observed. Linear regression analysis of all 66 MRSI scans showed a brain temperature-by-time gradient of -0.53°C per hour ( P =0.001). In the stroke patients, the temperature-by-time gradient within the infarct was -0.60°C per hour ( P =0.01). HC was well-tolerated, heart rate and blood pressure remained stable, the median (IQR) Numerical Pain Rating Scale score was 2.5 (1-3) at 80 minutes, and none developed shivering.

Conclusions: HC was well-tolerated and resulted in potentially clinically meaningful reductions in brain and infarct temperature, with only slight reduction in systemic temperature. Future research should investigate the feasibility of HC as a potential neuroprotective strategy in patients being considered for acute stroke therapies such as mechanical thrombectomy.

Abstract P486: Mechanical Embolectomy Using a Novel Telescopic System Featuring a Specialized Delivery and 0.088” Aspiration Catheter for the Treatment of Acute Ischemic Stroke: Preliminary Results of the SUMMIT NZ Trial

Background: The treatment approach of aspiration rather than use of a stent retriever as first-line therapy is increasingly regarded as standard of care for acute ischemic stroke. Continued technological advances include the ongoing development of aspiration embolectomy catheters that are larger in bore, guided by delivery catheters that are more maneuverable through the tortuous neurovasculature.

Methods: SUMMIT NZ (ACTRN12619000890134p) was designed as a prospective, single-arm, open label clinical trial at two sites in New Zealand. Eligible participants were patients presenting with acute ischemic stroke from either anterior or posterior circulation large-vessel occlusion within 24 hours of onset, a National Institutes of Health Stroke Scale Score ≥ 6 and a pre-stroke modified Rankin Score of ≤ 2. A novel tapered tip delivery catheter was specifically designed to deliver 0.070” and 0.088” aspiration catheters telescoped through a specialized 8F 90 cm introducer sheath (Route 92 Medical, Inc. San Mateo, CA). The primary effectiveness endpoint was arterial revascularization as measured by a modified Thrombosis in Cerebrovascular Infarction (mTICI) score of 2b or greater at the end of angiography after all endovascular treatments as adjudicated by an independent core laboratory. The primary safety endpoints were device-related peri-procedural complications such as dissection or perforation, symptomatic Intracranial Cerebral Hemorrhage (SICH) at 24 hours and embolization to a previously uninvolved territory.

Results: From September 27, 2019 to June 23, 2020, 18 subjects (mean age 69.5, NIHSSS 15.2, time last known well 6.2 hours) were enrolled with a diagnosis of acute ischemic stroke. Acute occlusion was located in the middle cerebral artery (78%, 14/18) and internal carotid artery (22%, 4/18). Successful revascularization was achieved in 94% (17/18) of subjects. No serious adverse device effects have been reported.

Conclusions: Preliminary findings suggest that aspiration first mechanical embolectomy using a novel telescoping system including an 0.088” inner diameter aspiration catheter achieves a high rate of arterial revascularization with an acceptable safety profile. A full report on enrollment and results are to be presented.

Dynamic CTA-Derived Perfusion Maps Predict Final Infarct Volume: The Simple Perfusion Reconstruction Algorithm

BACKGROUND AND PURPOSE

Infarct core volume measurement using CTP (CT perfusion) is a mainstay paradigm for stroke treatment decision-making. Yet, there are several downfalls with cine CTP technology that can be overcome by adopting the simple perfusion reconstruction algorithm (SPIRAL) derived from multiphase CTA. We compare SPIRAL with CTP parameters for the prediction of 24-hour infarction.

MATERIALS AND METHODS

Seventy-two patients had admission NCCT, multiphase CTA, CTP, and 24-hour DWI. All patients had successful/quality reperfusion. Patient-level and cohort-level receiver operator characteristic curves were generated to determine accuracy. A 10-fold cross-validation was performed on the cohort-level data. Infarct core volume was compared for SPIRAL, CTP-time-to-maximum, and final DWI by Bland-Altman analysis.

RESULTS

When we compared the accuracy in patients with early and late reperfusion for cortical GM and WM, there was no significant difference at the patient level (0.83 versus 0.84, respectively), cohort level (0.82 versus 0.81, respectively), or the cross-validation (0.77 versus 0.74, respectively). In the patient-level receiver operating characteristic analysis, the SPIRAL map had a slightly higher, though nonsignificant (P < .05), average receiver operating characteristic area under the curve (cortical GM/WM, r = 0.82; basal ganglia  = 0.79, respectively) than both the CTP-time-to-maximum (cortical GM/WM = 0.82; basal ganglia = 0.78, respectively) and CTP-CBF (cortical GM/WM = 0.74; basal ganglia = 0.78, respectively) parameter maps. The same relationship was observed at the cohort level. The Bland-Altman plot limits of agreement for SPIRAL and time-to-maximum infarct volume were similar compared with 24-hour DWI.

CONCLUSIONS

We have shown that perfusion maps generated from a temporally sampled helical CTA are an accurate surrogate for infarct core.

Abstract 100: Reperfusion Improves Clinical Outcome Across the 4.5-9h and Wake-Up Stroke Time Continuum in EXTEND and EPITHET

Introduction: Intravenous alteplase reduces disability after ischemic stroke in patients 4.5-9h after onset and with wake-up onset stroke who have favorable perfusion imaging. We examined the benefit of reperfusion in reducing disability, including by onset to randomization time strata in the EXTEND and EPITHET randomized trials.

Methods: Patients were randomized to alteplase or placebo after perfusion mismatch imaging. Reperfusion was defined as >90% reduction in Tmax>6s lesion volume at 24h. Ordinal logistic regression adjusted for baseline age and NIHSS was used to analyze functional improvement in day 90 modified Rankin scale overall, including a reperfusion*time to randomization interaction term, and in the 4.5-6h, 6-9h and wake-up time strata. Symptomatic hemorrhage was defined as large parenchymal hematoma with ≥4 point NIHSS increase (SITS).

Results: Reperfusion was assessable in 270/294 (92%) patients, 68/133 (51%) alteplase and 38/137 (28%) placebo reperfused (p<0.001). Median age 76 (IQR 66-81) in reperfused vs 74 (IQR 64.5-81) in non-reperfused, median baseline NIHSS 10 (IQR 7-15) in reperfused vs 12 (IQR 8-17.5) in non-reperfused. Overall, reperfusion was associated with common odds ratio 7.7 (95%CI 4.6-12.8, p<0.0001) in ordinal “shift” analysis. There was no heterogeneity in the beneficial effect of reperfusion effect by time to randomization (p=0.63). Reperfusion was associated with significantly improved functional outcome in each of the 4.5-6h, 6-9h and wake-up time strata (figure). Symptomatic hemorrhage, assessed in all 294 patients, occurred in 3/51 (5.9%) 4.5-6h, 2/28 (7.1%) 6-9h, 4/73 (5.5%) wake-up stroke in the alteplase-treated patients (van Elteren p=0.66).

Conclusions: Strong benefits of reperfusion in all time strata without differential risk in symptomatic hemorrhage support the durable treatment effect of alteplase in perfusion mismatch-selected patients throughout the 4.5-9h and wake-up stroke time window.

Abstract 69: The Influence of Motor Cortex Inhibition on Upper Limb Recovery: A Multimodal Study

Background: After stroke, there may be abnormalities in gamma-aminobutyric acid (GABA)-mediated inhibitory function within primary motor cortex (M1), which may have implications for residual motor impairment and the potential for functional improvements at the chronic stage. The present study examined primary motor cortex (M1) inhibition in patients over the first 12 weeks after stroke, and in a cohort of age-similar healthy controls.

Methods: Excitatory/inhibitory (E/I) balance was assessed from glutamate/glutamine (Glx) and gamma aminobutyric acid (GABA) concentrations from magnetic resonance spectroscopy (MRS) at 2 and 6 weeks after stroke. Threshold tracking paired-pulse transcranial magnetic stimulation (TMS) was used to assess motor cortex inhibition at 2, 6, and 12 weeks after stroke. Upper limb impairment and function were assessed with Fugl-Meyer Upper Extremity Scale and Action Research Arm Test at 2, 6, 12 and 26 weeks after stroke.

Results: By 12 weeks, patients with a functionally intact corticospinal pathway as evident by the presence of MEPs in paretic upper-limb exhibited a proportional recovery such that upper limb impairment resolved by ~70% of the maximum possible (proportional recovery), whereas patients without MEPs had relatively poorer and more variable outcomes. Spectroscopy results indicated that there was an E/I in Glx:GABA ratio in both hemispheres compared to age-similar controls. Long-latency intracortical inhibition measures from TMS indicated an elevated GABA B -receptor mediated inhibition in both hemispheres during the spontaneous recovery period after stroke compared to controls. Patients with higher tonic inhibition in ipsilesional M1 tend to have a longer recovery period.

Conclusion: The ability to modulate tonic inhibition levels early after stroke may have implications for upper limb recovery during the spontaneous recovery period.

Time for a Time Window Extension: Insights from Late Presenters in the ESCAPE Trial

BACKGROUND AND PURPOSE

The safety and efficacy of endovascular therapy for large-artery stroke in the extended time window is not yet well-established. We performed a subgroup analysis on subjects enrolled within an extended time window in the Endovascular Treatment for Small Core and Proximal Occlusion Ischemic Stroke (ESCAPE) trial.

MATERIALS AND METHODS

Fifty-nine of 315 subjects (33 in the intervention group and 26 in the control group) were randomized in the ESCAPE trial between 5.5 and 12 hours after last seen healthy (likely to have groin puncture administered 6 hours after that). Treatment effect sizes for all relevant outcomes (90-day mRS shift, mRS 0-2, mRS 0-1, and 24-hour NIHSS scores and intracerebral hemorrhage) were reported using unadjusted and adjusted analyses.

RESULTS

There was no evidence of treatment heterogeneity between subjects in the early and late windows. Treatment effect favoring intervention was seen across all clinical outcomes in the extended time window (absolute risk difference of 19.3% for mRS 0-2 at 90 days). There were more asymptomatic intracerebral hemorrhage events within the intervention arm (48.5% versus 11.5%, P = .004) but no difference in symptomatic intracerebral hemorrhage.

CONCLUSIONS

Patients with an extended time window could potentially benefit from endovascular treatment. Ongoing randomized controlled trials using imaging to identify late presenters with favorable brain physiology will help cement the paradigm of using time windows to select the population for acute imaging and imaging to select individual patients for therapy.

Tenecteplase versus alteplase before endovascular thrombectomy (EXTEND-IA TNK): A multicenter, randomized, controlled study

Background and hypothesis Intravenous thrombolysis with alteplase remains standard care prior to thrombectomy for eligible patients within 4.5 h of ischemic stroke onset. However, alteplase only succeeds in reperfusing large vessel arterial occlusion prior to thrombectomy in a minority of patients. We hypothesized that tenecteplase is non-inferior to alteplase in achieving reperfusion at initial angiogram, when administered within 4.5 h of ischemic stroke onset, in patients planned to undergo endovascular therapy. Study design EXTEND-IA TNK is an investigator-initiated, phase II, multicenter, prospective, randomized, open-label, blinded-endpoint non-inferiority study. Eligibility requires a diagnosis of ischemic stroke within 4.5 h of stroke onset, pre-stroke modified Rankin Scale≤3 (no upper age limit), large vessel occlusion (internal carotid, basilar, or middle cerebral artery) on multimodal computed tomography and absence of contraindications to intravenous thrombolysis. Patients are randomized to either IV alteplase (0.9 mg/kg, max 90 mg) or tenecteplase (0.25 mg/kg, max 25 mg) prior to thrombectomy. Study outcomes The primary outcome measure is reperfusion on the initial catheter angiogram, assessed as modified treatment in cerebral infarction 2 b/3 or the absence of retrievable thrombus. Secondary outcomes include modified Rankin Scale at day 90 and favorable clinical response (reduction in National Institutes of Health Stroke Scale by ≥8 points or reaching 0-1) at day 3. Safety outcomes are death and symptomatic intracerebral hemorrhage. Trial registration ClinicalTrials.gov NCT02388061.

Abstract 112: Predicting REcovery Potential of Upper Limb Function After Stroke to Increase Rehabilitation Efficiency

Introduction: The PREP algorithm combines clinical assessment [Shoulder Abduction Finger Extension (SAFE) score], transcranial magnetic stimulation (TMS) and diffusion-tensor imaging to predict potential for upper limb recovery following stroke. Patients’ recovery potential is predicted to be Complete, Notable, Limited or None.

Hypothesis: The PREP algorithm may be used in a ‘real world’ clinical setting to set individual rehabilitation goals.

Methods: This study recruited 194 patients with upper limb weakness within 3 days of stroke. Assessments were made at baseline and 12 weeks by assessors blinded to PREP algorithm prediction. The initial benchmarking phase recruited 85 patients and PREP algorithm information was not shared with clinical teams or patients. The results were used to refine the algorithm and guide implementation in three ways. First, patients with a SAFE score > 7, predicted to have Complete upper limb recovery, were given a self-directed therapy program. Second, patients with a SAFE score of 5-7 could be given a Notable recovery prognosis, without requiring TMS. Third, 19% of patients exceeded their predicted upper limb recovery, so this possibility was conveyed to patients and clinical teams. The implementation phase recruited 109 patients, and PREP algorithm predictions were shared with patients and clinical teams.

Results: Interim analyses (n = 135) find that the PREP algorithm correctly predicted upper limb function at 12 weeks for 85% of patients. Implementation of the algorithm decreased length of stay by 7 days (95%CI 2 - 15 days, p < 0.05) and increased the proportion of patients discharged home from the acute stroke unit from 28% to 49% (p < 0.01). Implementation also decreased upper limb therapy dose (p < 0.01), yet patient outcomes were similar between the two phases. Primary endpoint analysis will be complete in November 2015.

Conclusions: Making predictions about the potential for recovery of upper limb function, and setting individual rehabilitation goals accordingly, may increase the efficiency of post-stroke rehabilitation.

Abstract 147: Cannabis, Ischemic Stroke and Transient Ischemic Attack: A Case Control Study

Background: Cannabis is the most widely used illicit drug of abuse. A temporal relationship between cannabis use and stroke has been reported in case series and population based studies. To date this relationship has not been confirmed. We performed a case-controlled study on the recent use of cannabis in younger stroke patients.

Methods: Consecutive ischemic stroke/TIA patients aged 18-55 years had urine screens for cannabis. A control cohort of age, sex and ethnicity matched hospital patients were screened for cannabis using anonymized urine samples obtained for other indications and which would otherwise be discarded. The study was performed with the approval of the regional Ethics Committee.

Results: One hundred and sixty of 218 (73%) ischemic stroke/TIA patients had urine drug screens [100 men, 60 women; mean (SD) age 44.8 (8.7) years], of whom 150 (94%) had ischemic stroke and 10 (6%) had TIA. Fifty-eight patients did not have drug screens, mainly because they were admitted outside office hours or had been discharged early (primarily TIA patients). All of the patients approached to provide a urine sample agreed to do so. Twenty-five (15.6%) patients had positive cannabis drug screens, and these patients were more likely to be male (84% versus 59%, χ 2 p=0.016) and tobacco smokers (88% versus 28%, χ 2 p<0.001). There were no differences in age, stroke mechanism or most vascular risk factors between those with and without positive cannabis tests. Control urine samples were obtained from 160 patients matched for age (t-test, p=0.979), sex (χ 2 p=0.492) and ethnicity (χ 2 p=0.910). Thirteen (8.1%) control participants tested positive for cannabis. In a logistic regression analysis adjusted for age, sex and ethnicity, cannabis use was associated with increased risk of ischemic stroke and TIA (odds ratio 2.30, 95% confidence intervals 1.07-4.95).

Conclusions: This study provides the strongest evidence to date of an association between cannabis and stroke, with ischemic stroke and TIA patients twice as to have recently used cannabis likely as control participants. Cannabis is generally perceived as having few serious adverse effects. This study suggests that this may not be the case and that the association between cannabis and stroke warrants further investigation.

The spectrum captured: a methodological approach to studying incidence and outcomes of traumatic brain injury on a population level

OBJECTIVE

Drawing on the experience of conducting the Brain Injury Incidence and Outcomes New Zealand in the Community study, this article aims to identify the issues arising from the implementation of proposed guidelines for population-based studies of incidence and outcomes in traumatic brain injury (TBI).

STUDY DESIGN AND SETTING

All new cases of TBI (all ages and severities) were ascertained over a 1-year period, using overlapping prospective and retrospective sources of case ascertainment in New Zealand. All eligible TBI cases were invited to participate in a comprehensive assessment at baseline and at 1-month follow-up.

RESULTS

Our experience to date has revealed the feasibility of case ascertainment methods. Consultation with community health services and professionals resulted in feasible referral pathways to support the identification of TBI cases. 'Hot pursuit' methods of recruitment were essential to ensure complete case ascertainment for this population with few additional cases of TBI identified through cross-checks.

CONCLUSION

This review of proposed guidelines in relation to practical study methodology provides a framework for future comparable population-based epidemiological studies of TBI incidence and outcomes in developed countries.

Permanent genetic resources added to Molecular Ecology Resources Database 1 October 2010-30 November 2010

This article documents the addition of 277 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Ascochyta rabiei, Cambarellus chapalanus, Chionodraco hamatus, Coptis omeiensis, Cynoscion nebulosus, Daphnia magna, Gerbillus nigeriae, Isurus oxyrinchus, Lates calcarifer, Metacarcinus magister, Oplegnathus fasciatus, Pachycondyla verenae, Phaethon lepturus, Pimelodus grosskopfii, Rotylenchulus reniformis, Scomberomorus niphonius, Sepia esculenta, Terapon jarbua, Teratosphaeria cryptica and Thunnus obesus. These loci were cross-tested on the following species: Austropotamobius italicus, Cambarellus montezumae, Cambarellus puer, Cambarellus shufeldtii, Cambarellus texanus, Chionodraco myersi, Chionodraco rastrospinosus, Coptis chinensis, Coptis chinensis var. brevisepala, Coptis deltoidea, Coptis teeta, Orconectes virilis, Pacifastacus leniusculus, Pimelodus bochii, Procambarus clarkii, Pseudopimelodus bufonius, Rhamdia quelen, Sepia andreana, Sepiella maindroni, Thunnus alalunga, Thunnus albacares, Thunnus maccoyii, Thunnus orientalis, Thunnus thynnus and Thunnus tonggol.

Ischemic diffusion lesion reversal is uncommon and rarely alters perfusion-diffusion mismatch

OBJECTIVE

The use of diffusion-weighted imaging (DWI) to define irreversibly damaged infarct core is challenged by data suggesting potential partial reversal of DWI abnormalities. However, previous studies have not considered infarct involution. We investigated the prevalence of DWI lesion reversal in the EPITHET Trial.

METHODS

EPITHET randomized patients 3-6 hours from onset of acute ischemic stroke to tissue plasminogen activator (tPA) or placebo. Pretreatment DWI and day 90 T2-weighted images were coregistered. Apparent reversal of the acute ischemic lesion was defined as DWI lesion not incorporated into the final infarct. Voxels of CSF at follow-up were subtracted from regions of apparent DWI lesion reversal to adjust for infarct atrophy. All cases were visually cross-checked to exclude volume loss and coregistration inaccuracies.

RESULTS

In 60 patients, apparent reversal involved a median 46% of the baseline DWI lesion (median volume 4.9 mL, interquartile range 2.6-9.5 mL) and was associated with less severe baseline hypoperfusion (p < 0.001). Apparent reversal was increased by reperfusion, regardless of the severity of baseline hypoperfusion (p = 0.02). However, the median volume of apparent reversal was reduced by 45% when CSF voxels were subtracted (2.7 mL, interquartile range 1.6-6.2 mL, p < 0.001). Perfusion-diffusion mismatch classification only rarely altered after adjusting the baseline DWI volume for apparent reversal. Visual comparison of acute DWI to subacute DWI or day 90 T2 identified minor regions of true DWI lesion reversal in only 6 of 93 patients.

CONCLUSIONS

True DWI lesion reversal is uncommon in ischemic stroke patients. The volume of apparent lesion reversal is small and would rarely affect treatment decisions based on perfusion-diffusion mismatch.

Time to treatment with intravenous alteplase and outcome in stroke: an updated pooled analysis of ECASS, ATLANTIS, NINDS, and EPITHET trials

BACKGROUND

Early administration of intravenous recombinant tissue plasminogen activator (rt-PA) after ischaemic stroke improves outcome. Previous analysis of combined data from individual patients suggested potential benefit beyond 3 h from stroke onset. We re-examined the effect of time to treatment with intravenous rt-PA (alteplase) on therapeutic benefit and clinical risk by adding recent trial data to the analysis.

METHODS

We added data from ECASS III (821 patients) and EPITHET (100 patients) to a pool of common data elements from six other trials of alteplase for acute stroke (2775 patients). We used multivariate logistic regression to assess the relation of stroke onset to start of treatment (OTT) with treatment on favourable 3-month outcome (defined as modified Rankin score 0-1), mortality, and occurrence and outcome of clinically relevant parenchymal haemorrhage. The presence of an arterial occlusion was inferred from the patient's symptoms and absence of haemorrhage or other causes of ischaemic stroke. Vascular imaging was not a requirement in the trials. All patients with confirmed OTT within 360 min were included in the analysis.

FINDINGS

Treatment was started within 360 min of stroke onset in 3670 patients randomly allocated to alteplase (n=1850) or to placebo (n=1820). Odds of a favourable 3-month outcome increased as OTT decreased (p=0.0269) and no benefit of alteplase treatment was seen after around 270 min. Adjusted odds of a favourable 3-month outcome were 2.55 (95% CI 1.44-4.52) for 0-90 min, 1.64 (1.12-2.40) for 91-180 min, 1.34 (1.06-1.68) for 181-270 min, and 1.22 (0.92-1.61) for 271-360 min in favour of the alteplase group. Large parenchymal haemorrhage was seen in 96 (5.2%) of 1850 patients assigned to alteplase and 18 (1.0%) of 1820 controls, with no clear relation to OTT (p=0.4140). Adjusted odds of mortality increased with OTT (p=0.0444) and were 0.78 (0.41-1.48) for 0-90 min, 1.13 (0.70-1.82) for 91-180 min, 1.22 (0.87-1.71) for 181-270 min, and 1.49 (1.00-2.21) for 271-360 min.

INTERPRETATION

Patients with ischaemic stroke selected by clinical symptoms and CT benefit from intravenous alteplase when treated up to 4.5 h. To increase benefit to a maximum, every effort should be taken to shorten delay in initiation of treatment. Beyond 4.5 h, risk might outweigh benefit.

FUNDING

None.

Magnetic resonance molecular imaging of post-stroke neuroinflammation with a P-selectin targeted iron oxide nanoparticle

We have developed a magnetic resonance molecular imaging method using a novel iron-oxide contrast agent targeted towards P-selectin - MNP-PBP (magnetic nanoparticle-P-selectin binding peptide) - to image endothelial activation following cerebral ischemia/reperfusion. MNP-PBP consists of approximately 1000 PBP ligands (primary sequence: GSIQPRPQIHNDGDFEEIPEEYLQ GGSSLVSVLDLEPLDAAWL) conjugated to a 50 nm diameter aminated dextran iron oxide particle. In vitro P- and E-selectin binding was assessed by competition ELISA. Transient focal cerebral ischemia was induced in male C57/BL 6 mice followed by contrast injection (MNP-PBP; MNP-NH2; Feridex; MNP-PBP-FITC) at 24 h after reperfusion and T(2) magnetic resonance imaging at 9.4 T was performed. Infarction and microvasculature accumulation of contrast agent was assessed in coronal brain sections. MNP-PBP attenuated antibody binding to P-selectin by 34.8 +/- 1.7%. P-selectin was preferentially increased in the infarct hemisphere and MNP-PBP-FITC accumulation in the infarct hemisphere microvasculature was observed. Compared with the nontargeted iron oxide agents MNP-NH2 and Feridex, MNP-PBP showed a significantly greater T(2) effect within the infarction. MR imaging of P-selectin expression with a targeted iron oxide nanoparticle contrast agent may reveal early endothelial activation in stroke and other neuroinflammatory states.

Medication compliance in ischaemic stroke patients

AIM

This study aimed to assess the degree of patient compliance with medications prescribed at hospital discharge following ischaemic stroke, and concordance between self-reported medication use and general practitioner (GP) records.

METHODS

The Auckland City Hospital Stroke database was used to identify consecutive patients with ischaemic stroke over a three-month period. Participants were contacted and invited to participate in a telephone questionnaire that asked about current medications. GPs were also asked to list the medications their patients were taking.

RESULTS

Fifty-one patients were approached to participate of whom 48 consented to be interviewed at 6 weeks and 47 at 6 months. At 6 weeks, 36 of 38 (95%) were compliant with aspirin, 12 of 13 (92%) dipyridamole, 8 of 9 (88%) warfarin, 36 of 41 (88%) statins, 33 of 38 (87%) antihypertensive medications, and 7 of 7 (100%) diabetes medications. At 6 months, 97% were compliant with aspirin, 100% dipyridamole, 100% warfarin, 94% statins, 91% antihypertensive medications, and 100% diabetes medications. Natural or herbal remedy use was reported by 10 of 48 (21%) at 6 weeks and 11 of 47 (23%) at 6 months. Blister packs were used by 8 of 48 (17%) at 6 weeks and 5 of 47 (11%) at 6 months.

CONCLUSION

Adherence to secondary stroke prevention medication was between 87% and 100% at 6 weeks with similar findings at 6 months after discharge. We speculate that these high compliance rates may be due to one-on-one stroke nurse counselling and the use of stroke information packs, which include information about the importance of adherence to secondary prevention medication.

Baseline diabetic status and admission blood glucose were poor prognostic factors in the EPITHET trial

BACKGROUND

Previous data have suggested that diabetes and hyperglycemia predict poor outcome following stroke. We studied the prognostic impact of diabetes and admission blood glucose in the Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET).

METHODS

EPITHET was a prospective randomized placebo-controlled trial of intravenous tissue plasminogen activator (tPA) in the 3- to 6-hour time window. A preexisting diagnosis of diabetes was noted and baseline serum glucose was measured.

RESULTS

Intravenous tPA attenuated infarct growth in non-diabetics, but not in diabetics (p = 0.029). In the tPA treatment group, admission blood glucose was higher among patients with poor functional outcome (p = 0.002).

CONCLUSIONS

Diabetes and hyperglycemia attenuate the effects of tPA on infarct evolution. Future thrombolytic trials should consider randomizing patients by subgroups based on diabetic status and serum glucose levels.

Quantified T1 as an adjunct to apparent diffusion coefficient for early infarct detection: a high-field magnetic resonance study in a rat stroke model

BACKGROUND

Thrombolytic treatment for acute stroke has focused attention on accurate identification of injured vs. salvageable brain tissue, particularly if reperfusion occurs. However, our knowledge of differences in acute magnetic resonance imaging changes between transient and permanent ischemia and how they reflect permanently damaged tissue remain incomplete.

AIMS AND/OR HYPOTHESIS

Magnetic resonance imaging characteristics vary widely following ischemia and, at acute times, T1, T2 or apparent diffusion coefficient quantification may differentiate viable tissue from that destined to infarct.

METHODS

High-resolution magnetic resonance imaging was performed at 9.4 T following permanent or transient (90 min) middle cerebral artery occlusion in spontaneously hypertensive male rats or Wistar rats. Within 30 min, quantified maps of the apparent diffusion coefficient, T1, and T2 were performed and measures determined for sequences in the infarct and compared with that in the contralateral region. Lesion area for each magnetic resonance imaging sequence (T1, T2, apparent diffusion coefficient, and perfusion maps) was delineated for different time points using quantitative threshold measures and compared with final histological damage.

RESULTS

Early extensive changes in T1 following both transient and permanent middle cerebral artery occlusion provided a sensitive early indicator of the final infarct area. Following reperfusion, small but measurable early T2 changes indicative of early development of vasogenic edema occurred in the transient but not permanent groups. In transient middle cerebral artery occlusion, at 70 min apparent diffusion coefficient decreased (P<0.001) and then pseudonormalized at 150 min. In permanent middle cerebral artery occlusion, apparent diffusion coefficient declined over time. Lesion area detected using T1 maps exceeded that with T2 and apparent diffusion coefficient at 70 and 150 min in both groups (P<0.001).

CONCLUSIONS

The results indicate that, independent of reperfusion, quantified T1 is superior for detecting early ischemic changes that are not necessarily detected with T2 or apparent diffusion coefficient.

Kir6.2-containing ATP-sensitive potassium channels protect cortical neurons from ischemic/anoxic injury in vitro and in vivo

ATP-sensitive potassium (K(ATP)) channels are weak inward rectifiers that appear to play an important role in protecting neurons against ischemic damage. Cerebral stroke is a major health issue, and vulnerability to stroke damage is regional within the brain. Thus, we set out to determine whether K(ATP) channels protect cortical neurons against ischemic insults. Experiments were performed using Kir6.2(-/-) K(ATP) channel knockout and Kir6.2(+/+) wildtype mice. We compared results obtained in Kir6.2(-/-) and wildtype mice to evaluate the protective role of K(ATP) channels against focal ischemia in vivo, and, using cortical slices, against anoxic stress in vitro. Immunohistochemistry confirmed the presence of K(ATP) channels in the cortex of wildtype, but not Kir6.2(-/-), mice. Results from in vivo and in vitro experimental models indicate that Kir6.2-containing K(ATP) channels in the cortex provide protection from neuronal death. Briefly, in vivo focal ischemia (15 min) induced severe neurological deficits and large cortical infarcts in Kir6.2(-/-) mice, but not in wildtype mice. Imaging analyses of cortical slices exposed briefly to oxygen and glucose deprivation (OGD) revealed a substantial number of damaged cells (propidium iodide-labeled) in the Kir6.2(-/-) OGD group, but few degenerating neurons in the wildtype OGD group, or in the wildtype and Kir6.2(-/-) control groups. Slices from the three control groups had far more surviving cells (anti-NeuN antibody-labeled) than slices from the Kir6.2(-/-) OGD group. These findings suggest that stimulation of endogenous cortical K(ATP) channels may provide a useful strategy for limiting the damage that results from cerebral ischemic stroke.

Ethnic differences in syringomyelia in New Zealand

OBJECTIVE

To determine the prevalence of syringomyelia in a defined population in New Zealand and measure the prevalence of syringomyelia in the three main ethnic groups (Maori, Pacific people and Caucasians/others) living in this region.

METHODS

A retrospective study of all confirmed cases of syringomyelia diagnosed in residents of northern New Zealand from 1961 to 2003.

RESULTS

In all, syringomyelia was diagnosed in 137 patients. The mean age at onset of symptoms was 27.5 years and mean age at diagnosis was 32.6 years. The incidence of new cases increased from 0.76/100,000 a year between 1962 and 1971 to 4.70/100,000 a year by 1992-2001. The prevalence of syringomyelia in 2003 was 8.2/100,000 people: 5.4/100,000 in Caucasians or others, 15.4/100,000 in Maori and 18.4/100,000 in Pacific people (chi2 = 37.0, p<0.0001). Syringomyelia was more often associated with an isolated Chiari I malformation in Pacific people (84.4%) as compared with 42.9% of Maori and 38.2% of Caucasians or others (chi2 = 62.3, p<0.0001).

CONCLUSION

The prevalence of syringomyelia is higher in northern New Zealand than in studies carried out before the advent of magnetic resonance imaging. The prevalence is particularly high in Maori and Pacific people. The cause of the ethnic differences in the prevalence of syringomyelia identified in this study is unexplained and warrants further investigation.

Insular cortical ischaemia does not independently predict acute hypertension or hyperglycaemia within 3 h of onset

OBJECTIVES

To test the hypothesis that insular cortical ischaemia is associated with acute hypertension and hyperglycaemia.

METHODS

From the Canadian Activase for Stroke Effectiveness Study, which included only patients treated with thrombolysis hyperacutely (ie, within 3 h of onset of stroke), 966 patients were identified with ischaemia affecting (n = 685), or sparing (n = 281), the insular cortex. Demographic and clinical data, pretreatment indices of blood pressure, blood glucose, atrial fibrillation, and clinical imaging and outcome measures were compared between the two groups. Multivariable linear regression was used to assess predictors of systolic blood pressure and glucose levels before thrombolysis.

RESULTS

Pretreatment hypertension (p = 0.009), but not hyperglycaemia (p = 0.32), was predicted by insular ischaemia in univariable linear regression analyses. After adjusting for other factors, however, insular cortical ischaemia was not found to be an independent predictor for acute hypertension or hyperglycaemia.

CONCLUSIONS

Raised blood pressure or serum glucose levels in hyperacute (<3 h) cerebral ischaemia is not independently predicted by insular involvement. Several hours are required for sympathetic manifestations of insular ischaemia to evolve.

Changing attitudes to the management of ischaemic stroke between 1997 and 2004: a survey of New Zealand physicians

AIM

In 1997, a survey of New Zealand physicians' opinions on the management of stroke was carried out. Since then, there have been a number of advances in stroke therapy. We have repeated the 1997 survey to assess changes in physicians' opinions on stroke management.

METHODS

A questionnaire was sent to 293 physicians responsible for patients admitted with acute stroke to hospitals throughout New Zealand. It included questions on the management of acute stroke and secondary prevention and was based on the 1997 questionnaire.

RESULTS

Responses were received from 211 physicians of whom 174 (82%) managed patients with an acute stroke. The number of respondents who thought that stroke units were efficacious has increased (57% in 1997 to 89%, P < 0.001). The use of aspirin acutely (P < 0.001) and intravenous tissue plasminogen activator (P = 0.006) has also increased. In 2004, antihypertensive therapy for secondary stroke prevention would be commenced if the blood pressure was 150/90 by 98% of respondents and 140/90 by 70% of respondents. In 2004, a statin would be commenced if the total cholesterol level was 4.0 mmol/L by 56% of respondents and 5.0 mmol/L by 91% of respondents.

CONCLUSIONS

This survey has shown important changes in the management of ischaemic stroke over the past 7 years.

Refining the perfusion-diffusion mismatch hypothesis

BACKGROUND AND PURPOSE

The Echoplanar Imaging Thrombolysis Evaluation Trial (EPITHET) tests the hypothesis that perfusion-weighted imaging (PWI)-diffusion-weighted imaging (DWI) mismatch predicts the response to thrombolysis. There is no accepted standardized definition of PWI-DWI mismatch. We compared common mismatch definitions in the initial 40 EPITHET patients.

METHODS

Raw perfusion images were used to generate maps of time to peak (TTP), mean transit time (MTT), time to peak of the impulse response (Tmax) and first moment transit time (FMT). DWI, apparent diffusion coefficient (ADC), and PWI volumes were measured with planimetric and thresholding techniques. Correlations between mismatch volume (PWIvol-DWIvol) and DWI expansion (T2(Day 90-vol)-DWI(Acute-vol)) were also assessed.

RESULTS

Mean age was 68+/-11, time to MRI 4.5+/-0.7 hours, and median National Institutes of Health Stroke Scale (NIHSS) score 11 (range 4 to 23). Tmax and MTT hypoperfusion volumes were significantly lower than those calculated with TTP and FMT maps (P<0.001). Mismatch > or =20% was observed in 89% (Tmax) to 92% (TTP/FMT/MTT) of patients. Application of a +4s (relative to the contralateral hemisphere) PWI threshold reduced the frequency of positive mismatch volumes (TTP 73%/FMT 68%/Tmax 54%/MTT 43%). Mismatch was not significantly different when assessed with ADC maps. Mismatch volume, calculated with all parameters and thresholds, was not significantly correlated with DWI expansion. In contrast, reperfusion was correlated inversely with infarct growth (R=-0.51; P=0.009).

CONCLUSIONS

Deconvolution and application of PWI thresholds provide more conservative estimates of tissue at risk and decrease the frequency of mismatch accordingly. The precise definition may not be critical; however, because reperfusion alters tissue fate irrespective of mismatch.

Intra-arterial thrombolysis for retinal artery occlusion: the Calgary experience

INTRODUCTION

Retinal artery occlusion represents a medical emergency with poor prognosis for visual recovery. Spontaneous improvement is estimated to occur in less than 15% of central retinal artery occlusion (CRAO) cases and conventional treatments have provided only limited benefit. Intra-arterial thrombolysis has been reported as a potentially efficacious and safe treatment.

METHODS

We performed a retrospective chart review of all retinal artery occlusion cases treated with intra-arterial recombinant tissue-type plasminogen activator (rtPA) from January 1998 to May 2004. Patients received Goldmann perimetry visual field testing at a variable interval following the procedure (2 days-2.5 years). Visual acuity (VA) was re-assessed in May 2004.

RESULTS

Eight cases (59-77 years) were treated for CRAO, 6-18 hours post-onset with intra-arterial rtPA (10-20 mg over 15-60 minutes); one case of branch occlusion (BRAO) was treated with 30 mg rtPA over 75 minutes, 12 hours post-onset. Among the six patients with CRAO assessed in clinic, three experienced improvement in VA by two or more gradations (Snellen lines); three improved by one gradation. However, none achieved a final VA better than 20/300. The case of branch occlusion improved to a VA of 20/20. All patients had residual monocular field defects.

CONCLUSIONS

Our findings reveal a limited benefit for intra-arterial tPA compared to the rate of spontaneous improvement and conventional forms of therapy for retinal artery occlusion.

Imaging of the brain in acute ischaemic stroke: comparison of computed tomography and magnetic resonance diffusion-weighted imaging

BACKGROUND AND OBJECTIVES

Controversy exists about the optimal imaging technique in acute stroke. It was hypothesised that CT is comparable with DWI, when both are read systematically using quantitative scoring.

METHODS

Ischaemic stroke patients who had CT within six hours and DWI within seven hours of onset were included. Five readers used a quantitative scoring system (ASPECTS) to read the baseline (b) and follow up CT and DWI. Use of MRI in acute stroke was also assessed in patients treated with tissue plasminogen activator (tPA) by prospectively recording reasons for exclusion. Patients were followed clinically at three months.

RESULTS

bDWI and bCT were available for 100 consecutive patients (admission median NIHSS = 9). The mean bDWI and bCT ASPECTS were positively related (p<0.001). The level of interrater agreement ranged from good to excellent across all modalities and time periods. Bland-Altman plots showed more variability between bCT and bDWI than at 24 hours. The difference between bCT and bDWI was < or =2 ASPECTS points. Of bCT scans with ASPECTS 8-10, 81% had DWI ASPECTS 8-10. Patients with bCT ASPECTS of 8-10 were 1.9 times more likely to have a favourable outcome at 90 days than those with a score of 0-7 (95% CI 1.1 to 3.1, p = 0.002). The relative likelihood of favourable outcome with a bDWI ASPECTS 8-10 was 1.4 (95% CI 1.0 to 1.9, p = 0.10). Of patients receiving tPA 45% had contraindications to urgent MRI.

CONCLUSION

The differences between CT and DWI in visualising early infarction are small when using ASPECTS. CT is faster and more accessible than MRI, and therefore is the better neuroimaging modality for the treatment of acute stroke.

The probability of middle cerebral artery MRA flow signal abnormality with quantified CT ischaemic change: targets for future therapeutic studies

OBJECTIVES

In this study we define the probability of vascular abnormality in the middle cerebral artery (MCA) territory according to the extent of ischaemic change seen using computed tomography (CT). We assessed the sensitivity and specificity of the hyperdense middle cerebral artery (HMCA) and the "dot" sign using magnetic resonance angiography (MRA).

METHODS

Patients presenting with ischaemic stroke had a CT scan (<6 h) prior to MRI (<7 h). A quantitative CT scoring system (ASPECTS) was applied to CT and diffusion weighted images (DWI) at baseline and follow up (24 h) by five independent observers. The presence of HMCA and the MCA "dot" sign was also evaluated. An expert reader assessed the 3D time of flight (TOF) MRA in the anterior circulation for areas of decreased vascular signal in the MCA territory, with an absent signal taken to represent severely reduced or absent flow.

RESULTS

A total of 100 consecutive patients had baseline CT and MR scans. The median NIHSS was 9. The median CT ASPECTS was 8 and equalled the median DWI ASPECTS. There were a total of 10 HMCA and 19 MCA "dot" signs, with four patients having both HMCA and "dot" signs. A total of 47 MRA flow signal abnormalities were observed in the anterior circulation.

CONCLUSIONS

In the absence of accessible neurovascular imaging, the extent of CT ischaemia (ASPECTS) is a strong predictor of vascular occlusion. The CT hyperdense artery signs have a high positive predictive value but low negative predictive value.

The Rise and Fall of NMDA Antagonists for Ischemic Stroke

It has long been accepted that high concentrations of glutamate can destroy neurons, and this is the basis of the theory of excitotoxicity during brain injury such as stroke. Glutamate N-methyl-D-aspartate (NMDA) receptor antagonists such as Selfotel, Aptiganel, Gavestinel and others failed to show neuroprotective efficacy in human clinical trials or produced intolerable central nervous system adverse effects. The failure of these agents has been attributed to poor studies in animal models and to poorly designed clinical trials. We also speculate that NMDA receptor antagonism may have hindered endogenous mechanisms for neuronal survival and neuroregeneration. It remains to be proven in human stroke whether NMDA receptor antagonism can be neuroprotective.

Hemi-orolingual angioedema and ACE inhibition after alteplase treatment of stroke

One hundred seventy-six consecutive patients treated with IV tissue plasminogen activator (tPA) for acute ischemic stroke were examined prospectively, and orolingual angioedema was found in nine (5.1%; 95% CI 2.3 to 9.5). The reaction was typically mild, transient, and contralateral to the ischemic hemisphere. Risk of angioedema was associated with angiotensin-converting enzyme inhibitors (relative risk [RR] 13.6; 95% CI 3.0 to 62.7) and signs on initial CT of ischemia in the insular and frontal cortex (RR 9.1; 95% CI 1.4 to 30.0).

Use of the Alberta Stroke Program Early CT Score (ASPECTS) for assessing CT scans in patients with acute stroke

BACKGROUND AND PURPOSE

Clinicians are insecure reading CT scans by using the one-third rule for acute middle cerebral artery stroke (1/3 MCA rule) before treating patients with recombinant tissue plasminogen activator. The 1/3 MCA rule is a poorly defined volumetric estimate of the size of cerebral infarction of the MCA. A 10-point quantitative topographic CT scan score, the Alberta Stroke Program Early CT Score (ASPECTS), is described and illustrated. A sharp increase in dependence and death occurs with an ASPECTS of 7 or less. We describe how to use ASPECTS and why it works with CT scans obtained on all commonly used axial baselines. We also describe interobserver reliability among clinicians from different specialties and with different experience in reading CT scans in the context of acute stroke.

METHODS

The six physicians who developed ASPECTS answered a questionnaire on precisely how they interpret and use ASPECTS. The ASPECTS areas as interpreted by these physicians were compared with one another and with standards in the literature. kappa statistics were used to assess the interobserver reliability of ASPECTS versus the 1/3 MCA rule.

RESULTS

The exact methods of interpretation varied among the six individual observers, with either a 3:3 or 4:2 split on the specific questions. The overall interobserver agreement was good compared with that of the 1/3 MCA rule. Normal anatomic vascular and interobserver variations explain why ASPECTS can be applied with different CT axial baselines.

CONCLUSION

ASPECTS is a systematic, robust, and practical method that can be applied to different axial baselines. Clinician agreement is superior to that of the 1/3 MCA rule.

The value of apparent diffusion coefficient maps in early cerebral ischemia

BACKGROUND AND PURPOSE

Prediction of the regions of the ischemic penumbra that are likely to progress to infarction is of great clinical interest. Whether lowered apparent diffusion coefficient (ADC) values were present in the ischemic penumbra of patients presenting with acute ischemic stroke and were specific to regions of the penumbra that proceeded to infarction was investigated.

METHODS

Nineteen patients with hemispheric stroke of less than 6 hours' onset and with acute scans showing a perfusion lesion greater than a diffusion lesion (ischemic penumbra) were studied. Scans also were performed subacutely (days 3 to 5) and at outcome (day 90). The outcome scan was used to identify regions of the penumbra that proceeded to infarction.

RESULTS

The ADC ratios were significantly reduced (P <.00001) in regions of the penumbra that progressed to infarction on the outcome scan compared with those that remained normal. In regions that showed transition to infarction, the mean ADC ratios were typically 0.75 to 0.90.

CONCLUSION

Intermediate ADC values are present in the ischemic penumbra and are indicative of tissue at risk of infarction.

Perfusion magnetic resonance imaging maps in hyperacute stroke: relative cerebral blood flow most accurately identifies tissue destined to infarct

BACKGROUND AND PURPOSE

In ischemic stroke, perfusion-weighted imaging (PWI) and diffusion-weighted imaging (DWI) provide important pathophysiological information. A PWI>DWI mismatch pattern suggests the presence of salvageable tissue. However, improved methods for distinguishing PWI>DWI mismatch tissue that is critically hypoperfused from benign oligemia are required.

METHODS

We investigated the usefulness of maps of relative cerebral blood flow (rCBF), volume (rCBV), and mean transit time (rMTT) to predict transition to infarction in hyperacute (<6 hours) stroke patients with PWI>DWI mismatch patterns. Semiquantitative color-thresholded analysis was used to measure hypoperfusion volumes, including increasing color signal intensity thresholds of rMTT delay, which were compared with infarct expansion, outcome infarct size, and clinical status.

RESULTS

Acute rCBF lesion volume had the strongest correlation with final infarct size (r=0.91, P<0.001) and clinical outcome (r=0.67, P<0.01). There was a trend for acute rCBF>DWI mismatch volume to overestimate infarct expansion between the acute and outcome study (P=0.06). Infarct expansion was underestimated by acute rCBV>DWI mismatch (P<0.001). When rMTT lesions included tissue with moderately prolonged transit times (mean delay 4.3 seconds, signal intensity values 50% to 70%), infarct expansion was overestimated. In contrast, when rMTT lesions were restricted to more severely prolonged transit times (mean delay 6.1 seconds, signal intensity >70%), these regions progressed to infarction in all except 1 patient, but infarct expansion was underestimated (P<0.001).

CONCLUSIONS

The acute rCBF lesion most accurately identified tissue in the PWI>DWI mismatch region at risk of infarction. Color-thresholded PWI maps show potential for use in an acute clinical setting to prospectively predict tissue outcome.

A three-item scale for the early prediction of stroke recovery

BACKGROUND

Accurate assessment of prognosis in the first hours of stroke is desirable for best patient management. We aimed to assess whether the extent of ischaemic brain injury on magnetic reasonance diffusion-weighted imaging (MR DWI) could provide additional prognostic information to clinical factors.

METHODS

In a three-phase study we studied 66 patients from a North American teaching hospital who had: MR DWI within 36 h of stroke onset; the National Institutes of Health Stroke Scale (NIHSS) score measured at the time of scanning; and the Barthel Index measured no later than 3 months after stroke. We used logistic regression to derive a predictive model for good recovery. This logistic regression model was applied to an independent series of 63 patients from an Australian teaching hospital, and we then developed a three-item scale for the early prediction of stroke recovery.

FINDINGS

Combined measurements of the NIHSS score (p=0.01), time in hours from stroke onset to MR DWI (p=0.02), and the volume of ischaemic brain tissue on MR DWI (p=0.04) gave the best prediction of stroke recovery. The model was externally validated on the Australian sample with 0.77 sensitivity and 0.88 specificity. Three likelihood levels for stroke recovery-low (0-2), medium (3-4), and high (5-7)-were identified on the three-item scale.

INTERPRETATION

The combination of clinical and MR DWI factors provided better prediction of stroke recovery than any factor alone, shortly after admission to hospital. This information was incorporated into a three-item scale for clinical use.

Prediction of the final infarct volume within 6 h of stroke using single photon emission computed tomography with technetium-99m hexamethylpropylene amine oxime

BACKGROUND

A simple method to predict the final infarct volume within 6 h of onset of hemispheric ischemic stroke based on the measurement of cerebral blood flow (CBF) using single photon emission computed tomography (SPECT) with techneticum-99m hexamethylpropylene amine oxime ((99m)Tc-HMPAO) was investigated in a clinical model involving patients without definite early reperfusion or clinical recovery.

METHODS

A group of 16 patients (group 1) was used to establish the methodology, which was then validated in a second group of 14 patients (group 2). The final infarct volume was defined using computed tomography (CT) performed at least 7 days after stroke. The relative CBF threshold value, expressed as a percentage of the mean contralateral hemispheric value, which most closely estimated the final infarct size on coregistered CT was established for each patient.

RESULTS

The mean threshold CBF value for group 1 was 63.7%. When this value was used to predict infarct size in group 2, a close correlation was observed between the actual and the estimated sizes (r = 0.973, p < 0.0001). This value was not time dependent.

CONCLUSIONS

If no significant early reperfusion or clinical recovery occurs, a CBF threshold value of 63.7% on (99m)Tc-HMPAO SPECT performed within 6 h of stroke onset will reliably predict the final infarct size.