***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background and Purpose — Intravenous thrombolysis is an approved treatment for anterior ( ACS ) and posterior ( PCS ) circulation stroke . However , no r and omized controlled trial has investigated safety and efficacy of intravenous thrombolysis according to stroke territory , although PCS is assumed to differ from ACS in many ways . We aim ed to compare the safety and clinical outcome of intravenous thrombolysis applied to patients with PCS and ACS . Methods — Prospect ively collected data of 883 consecutive patients with acute ischemic stroke ( 788 ACS , 95 PCS ) treated with intravenous thrombolysis in 3 Swiss stroke centers were analyzed . Presenting characteristics , symptomatic intracranial hemorrhage , mortality , and favorable outcome ( modified Rankin scale 0 or 1 ) at 3 months were compared between patients with PCS and ACS . Results — As compared with patients with ACS , those with PCS were younger ( mean age , 63 versus 67 years , P=0.012 ) and had a lower mean baseline National Institutes of Health Stroke Scale score ( 9 versus 12 , P<0.001 ) . Patients with PCS less often had symptomatic intracranial hemorrhage ( 0 % versus 5 % , P=0.026 ) and had more often a favorable outcome ( 66 % versus 47 % , P<0.001 ) . Mortality was similar in the 2 groups ( PCS , 9 % ; ACS , 13 % ; P=0.243 ) . After multivariable adjustment , PCS was an independent predictor of lower symptomatic intracranial hemorrhage frequency ( P=0.001 ) , whereas stroke territory was not associated either with favorable outcome ( P=0.177 ) or with mortality ( P=0.251 ) . Conclusions — Our study suggests that PCS is associated with a lower risk of symptomatic intracranial hemorrhage after intravenous thrombolysis as compared with ACS , whereas favorable outcome and mortality were similar in the 2 stroke territories Background and Purpose — Early reperfusion is a predictor of good outcome in acute ischemic stroke . We investigated whether middle cerebral artery ( MCA ) occlusions have a better clinical outcome and proportion of recanalization compared with internal carotid artery ( ICA ) occlusion after st and ard treatment with intravenous ( IV ) tissue plasminogen activator ( tPA ) . Patients — In a retrospective analysis of our prospect i ve stroke data base between January 7 , 1998 , and January 30 , 2002 , we identified 36 consecutive patients who were treated with IV tPA within 3 hours after symptom onset of a stroke in the distribution of a documented ICA or MCA occlusion . The National Institutes of Health Stroke Scale ( NIHSS ) score was recorded before tPA , at 24 hours , 3 days , and 3 months after stroke . Three-month outcome was recorded by modified Rankin scale . Magnetic resonance angiography or computed tomographic angiography was obtained before tPA . The presence of recanalization was assessed by transcranial Doppler and /or magnetic resonance angiography within 3 days after stroke onset . Results — Nineteen patients had MCA occlusion , and 17 had ICA-plus-MCA occlusion before tPA .  Although there was no difference in age and NIHSS at day 0 between the 2 groups , the MCA group had a lower day 3 NIHSS score compared with the ICA group ( P = 0.006 ) in an ANCOVA . In addition , patients who had a MCA occlusion had lower day 1 and 3 NIHSS scores compared with the ICA group ( P = 0.04 and P = 0.03 , respectively ; Wilcoxon rank sum ) . Similarly , NIHSS was significantly lower in patients who recanalized on days 1 and 3 ( P = 0.004 and P = 0.003 respectively , Wilcoxon rank sum ) . When we adjusted for NIHSS score at day 0 in an ANCOVA , the adjusted mean was lower in the group that recanalized compared with the group that did not recanalize ( P < 0.001 ) . There was a significant difference between the proportion of recanalization in the MCA group ( 15 of 17 recanalized , 88 % ) at 3 days after tPA compared with that of the ICA group ( 5 of 16 recanalized , 31%;P = 0.001 , Fisher exact test ) . The 3-month modified Rankin scale was not different between the 2 groups . Conclusions — Despite comparable age and NIHSS scores before IV tPA , MCA occlusions have lower day 1 and 3 NIHSS scores and higher proportion of recanalization compared with ICA occlusions . A combined IV/intra-arterial or mechanical thrombolysis may be needed to achieve early recanalization in ICA occlusions Background and Purpose — Thrombolytic therapy is licensed for use in highly selected patients with acute ischemic stroke . We aim ed to model the health economic impact of limited use of thrombolytic therapy and to assess whether it was likely to be cost-effective when used more widely in the UK National Health Service ( NHS ) . Methods — The authors formed a discussion panel to develop the decision- analysis model of acute stroke care . It consisted of Markov state-transition processes , with probabilities of different health states determined by certain key variables . The range of estimates of efficacy of recombinant tissue plasminogen activator ( rt-PA ) was taken from an up date to a Cochrane systematic review of r and omized trials of thrombolysis . Data on outcome after stroke were taken from our hospital-based stroke register , supplemented by data derived from relevant literature sources . Results — The model suggested that compared with st and ard care , if eligible patients were treated with rt-PA up to 6 hours , there was a 78 % probability of a gain in quality -adjusted survival during the first year , at a cost of £ 13 581 per quality -adjusted life-year ( QALY ) gained . Over a lifetime , rt-PA was associated with cost-savings of £ 96 565 per QALY . However , the estimates were imprecise and highly susceptible to the assumptions used in the economic model ; under several plausible assumptions , rt-PA was much less cost-effective than st and ard care , and under others , a great deal more cost-effective . Conclusions — The estimates of effectiveness and cost-effectiveness were imprecise . Although the benefits appeared promising , the data did not support the widespread use of thrombolytic therapy outside the terms of the current restricted license in routine clinical practice in the NHS . There is a case for new large-scale r and omized trials comparing thrombolytic therapy with control up to 6 hours to determine more precisely the effects of rt-PA on short-term and long-term survival and its cost-effectiveness when used in a wider range of patients BACKGROUND Trials of endovascular therapy for ischemic stroke have produced variable results . We conducted this study to test whether more advanced imaging selection , recently developed devices , and earlier intervention improve outcomes . METHODS We r and omly assigned patients with ischemic stroke who were receiving 0.9 mg of alteplase per kilogram of body weight less than 4.5 hours after the onset of ischemic stroke either to undergo endovascular thrombectomy with the Solitaire FR ( Flow Restoration ) stent retriever or to continue receiving alteplase alone .  All the patients had occlusion of the internal carotid or middle cerebral artery and evidence of salvageable brain tissue and ischemic core of less than 70 ml on computed tomographic ( CT ) perfusion imaging . The co primary outcomes were reperfusion at 24 hours and early neurologic improvement ( ≥8-point reduction on the National Institutes of Health Stroke Scale or a score of 0 or 1 at day 3 ) . Secondary outcomes included the functional score on the modified Rankin scale at 90 days . RESULTS The trial was stopped early because of efficacy after 70 patients had undergone r and omization ( 35 patients in each group ) . The percentage of ischemic territory that had undergone reperfusion at 24 hours was greater in the endovascular-therapy group than in the alteplase-only group ( median , 100 % vs. 37 % ; P<0.001 ) . Endovascular therapy , initiated at a median of 210 minutes after the onset of stroke , increased early neurologic improvement at 3 days ( 80 % vs. 37 % , P=0.002 ) and improved the functional outcome at 90 days , with more patients achieving functional independence ( score of 0 to 2 on the modified Rankin scale , 71 % vs. 40 % ; P=0.01 ) . There were no significant differences in rates of death or symptomatic intracerebral hemorrhage . CONCLUSIONS In patients with ischemic stroke with a proximal cerebral arterial occlusion and salvageable tissue on CT perfusion imaging , early thrombectomy with the Solitaire FR stent retriever , as compared with alteplase alone , improved reperfusion , early neurologic recovery , and functional outcome . ( Funded by the Australian National Health and Medical Research Council and others ; EXTEND-IA Clinical Trials.gov number , NCT01492725 , and Australian New Zeal and Clinical Trials Registry number , ACTRN12611000969965 . ) BACKGROUND Among patients with acute ischemic stroke due to occlusions in the proximal anterior intracranial circulation , less than 40 % regain functional independence when treated with intravenous tissue plasminogen activator ( t-PA ) alone . Thrombectomy with the use of a stent retriever , in addition to intravenous t-PA , increases reperfusion rates and may improve long-term functional outcome . METHODS We r and omly assigned eligible patients with stroke who were receiving or had received intravenous t-PA to continue with t-PA alone ( control group ) or to undergo endovascular thrombectomy with the use of a stent retriever within 6 hours after symptom onset  ( intervention group ) . Patients had confirmed occlusions in the proximal anterior intracranial circulation and an absence of large ischemic-core lesions . The primary outcome was the severity of global disability at 90 days , as assessed by means of the modified Rankin scale ( with scores ranging from 0 [ no symptoms ] to 6 [ death ] ) . RESULTS The study was stopped early because of efficacy . At 39 centers , 196 patients underwent r and omization ( 98 patients in each group ) . In the intervention group , the median time from qualifying imaging to groin puncture was 57 minutes , and the rate of substantial reperfusion at the end of the procedure was 88 % . Thrombectomy with the stent retriever plus intravenous t-PA  reduced disability at 90 days over the entire range of scores on the modified Rankin scale ( P<0.001 ) . The rate of functional independence ( modified Rankin scale score , 0 to 2 ) was higher in the intervention group than in the control group ( 60 % vs. 35 % , P<0.001 ) . There were no significant between-group differences in 90-day mortality ( 9 % vs. 12 % , P=0.50 ) or symptomatic intracranial hemorrhage ( 0 % vs. 3 % , P=0.12 ) . CONCLUSIONS In patients receiving intravenous t-PA for acute ischemic stroke due to occlusions in the proximal anterior intracranial circulation , thrombectomy with a stent retriever within 6 hours after onset improved functional outcomes at 90 days . ( Funded by Covidien ; SWIFT PRIME Clinical Trials.gov number , NCT01657461 . ) Background and Purpose — The frequent use of a longer time window for recanalization therapy in patients with basilar artery occlusion ( BAO ) in daily practice is not supported by any scientific evidence . We investigated the relationship between time to recanalization therapy and functional outcome in BAO with data from the Basilar Artery International Cooperation Study ( BASICS ) . Methods — BASICS is a prospect i ve multicenter registry of patients ( n=619 ) with radiologically confirmed BAO . We analyzed patients receiving intravenous thrombolysis or intra-arterial treatment .  Patients were divided into 4 groups based on the interval between estimated time of BAO and start of recanalization therapy : ⩽3 hours ( n=134 ) , > 3 to ⩽6 hours ( n=151 ) , > 6 to ⩽9 hours ( n=56 ) , and > 9 hours ( n=68 ) . Primary outcome measure was poor functional outcome ( modified Rankin scale score 4–6 ) after 1 month . We calculated adjusted risk ratios with 95 % CIs using Poisson regression analyses with the ⩽3 hours group as the reference group . Results — Patients had an increased risk of poor functional outcome as time to recanalization therapy became longer ( ⩽3 hours : 62 % ; > 3 to ⩽6 hours : 67 % [ adjusted risk ratio , 1.06 ; 0.91–1.25 ] ; > 6 to ⩽9 hours : 77 % [ adjusted risk ratio , 1.26 ; 1.06–1.51 ] ; > 9 hours : 85 % [ adjusted risk ratio , 1.47 ; 1.26–1.72 ] ) . Conclusions — Early recanalization therapy in patients with BAO is associated with a more favorable outcome with a significant increased chance of a poor outcome when recanalization therapy is started > 6 hours after estimated time of BAO B 
    Output:
    
Regarding intra-arterial treatment , the symptomatic intracerebral hemorrhage and post-procedural recanalization rates were comparable between the two groups , although the posterior circulation stroke group had a higher mortality risk and lower tendency for a favorable functional outcome .
CONCLUSIONS Safety and efficacy of thrombolysis in posterior circulation stroke depends on involvement of large vessel occlusion and reperfusion modality such that intravenous thrombolytics is more effective and safer than in anterior circulation stroke ; the safety and efficacy of intra-arterial treatment is comparable or lower than anterior circulation stroke .