***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 
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    Input: Background Subarachnoid hemorrhage is a common and dangerous disease with an unfavorable prognosis . Patients with poor- grade subarachnoid hemorrhage ( Hunt & Hess Grade s 4–5 ) are unconscious on admission . Because of the high mortality and disability rate associated with poor- grade subarachnoid hemorrhage , it is often treated conservatively . Timing of surgery for poor- grade aneurysmal subarachnoid hemorrhage is still controversial , therefore this study aims to identify the optimal time to operate on patients admitted in poor clinical condition . Methods / design Ninety-nine patients meeting the inclusion criteria were r and omly assigned into three treatment groups . The early surgery group received operation within 3 days after onset of subarachnoid hemorrhage ( day of SAH = day 1 ) ; the intermediate surgery group received operation from days 4 to 7 , and surgery was performed on the late surgery group after day 7 . Follow-up was performed 1 , 3 , and 6 months after aneurysm clipping . Primary indicators of outcome included the Extended Glasgow Outcome Scale and the Modified Rankin Scale , while secondary indicators of outcome were assessed using the Barthel Index and mortality . Discussion This is the first prospect i ve , single-center , observer-blinded , r and omized controlled trial to eluci date optimal timing for surgery in poor- grade subarachnoid hemorrhage patients . The results of this study will be used to direct decisions of surgical intervention in poor- grade subarachnoid hemorrhage , thus improving clinical outcomes for patients .Trial registration Chinese Clinical Trial Registry : Summary Background . There is still lack of evidence on the optimal timing of surgery in patients with aneurysmal subarachnoid haemorrhage . Only one r and omised clinical trial has been done , which showed no difference between early and late surgery . Other studies were observational in nature and most had method ological drawbacks that preclude clinical ly meaningful conclusions . We performed a retrospective observational study on the timing of aneurysm surgery in The Netherl and s over a two-year period . Method . In eight hospitals we identified 1500 patients with an aneurysmal subarachnoid haemorrhage . They were subjected to predefined inclusion criteria . We included all patients who were admitted and were conscious at any one time between admission and the end of the third day after the haemorrhage . We categorised the clinical condition on admission according the World Federation of Neurological Surgeons ( WFNS ) grading scale . Early aneurysm surgery was defined as operation performed within three days after onset of subarachnoid haemorrhage ; intermediate surgery as performed on days four to seven , and late surgery as performed after day seven . Outcome was classified as the proportion of patients with poor outcome ( death or dependent ) two to four months after onset of subarachnoid haemorrhage . We calculated crude odds ratios with late surgery as reference . We distinguished between management results ( reconstructed intention to treat analysis ) and surgical results ( on treatment analysis ) . The results were adjusted for the major prognosticators for outcome after subarachnoid haemorrhage . Findings . We included 411 patients . There were 276 patients in the early surgery group , 36 in the intermediate surgery group and 99 in the late surgery group . On admission 78 % were in good neurological condition ( WFNS I – III).Management results . Overall , 93 patients ( 34 % ) operated on early had a poor outcome , 13 ( 36 % ) of those with intermediate surgery and 37 ( 37 % ) in the late surgery group had a poor outcome . For patients in good clinical condition on admission and planned for early surgery the adjusted odds ratio ( OR ) was 1.3 ( 95 % CI 0.5 to 3.0 ) . The adjusted OR for patients admitted in poor neurologicalcondition ( WFNS IV – V ) and planned for early surgery was 0.1 ( 95 % CI 0.0 to 0.6).Surgical results . For patients in good clinical condition on admission who underwent early operation the adjusted OR was 1.1 ( 95 % CI 0.4 to 3.2 ) ; it was 0.2 ( 95 % CI 0.0 to 0.9 ) for patients admitted in poor clinical condition . Conclusions . In this observational study we found no significant difference in outcome between early and late operation for patients in good clinical condition on admission . For patients in poor clinical condition on admission outcome was significantly better after early surgery . The optimal timing of surgery is not yet settled . Ideally , evidence on this issue should come from a r and omised clinical trial . However , such a trial or even a prospect i ve study are unlikely to be ever performed because of the rapid development of endovascular coiling Background and Purpose — Pilot clinical trials using magnesium sulfate in patients with acute aneurysmal subarachnoid hemorrhage have reported trends toward improvement in clinical outcomes . This Phase III study aim ed to compare intravenous magnesium sulfate infusion with saline placebo among such patients . Methods — We recruited patients with aneurysmal subarachnoid hemorrhage within 48 hours of onset from 10 participating centers . The patients were r and omly assigned to magnesium sulfate infusion titrated to a serum magnesium concentration twice the baseline concentration or saline placebo for 10 to 14 days . Patients and assessors were blinded to treatment allocation . The study is registered at www.strokecenter.org/trials ( as Intravenous Magnesium Sulphate for Aneurysmal Subarachnoid Hemorrhage [ IMASH ] ) and www . Clinical Trials.gov ( NCT00124150 ) . Results — Of the 327 patients recruited , 169 were r and omized to receive treatment with intravenous magnesium sulfate and 158 to receive saline ( placebo ) .  The proportions of patients with a favorable outcome at 6 months ( Extended Glasgow Outcome Scale 5 to 8) were similar , 64 % in the magnesium sulfate group and 63 % in the saline group ( OR , 1.0 ; 95 % CI , 0.7 to 1.6 ) . Secondary outcome analyses ( modified Rankin Scale , Barthel Index , Short Form 36 , and clinical vasospasm ) also showed no significant differences between the 2 groups . Predefined subgroups included age , admission World Federation of Neurological Surgeons grade , pre-existing hypertension , intracerebral hematoma , intraventricular hemorrhage , location of aneurysm , size of aneurysm , and mode of aneurysm treatment . In none of the subgroups did the magnesium sulfate group show a better outcome at 6 months . Conclusions — The results do not support a clinical benefit of intravenous magnesium sulfate infusion over placebo infusion in patients with acute aneurysmal subarachnoid hemorrhage Background and Purpose — The ideal timing of coiling or clipping after aneurysmal subarachnoid hemorrhage is unknown . Within the International Subarachnoid Aneurysm Trial we assessed differences in incidence of delayed cerebral ischemia and clinical outcome between different timings of treatment . Methods — The treated 2106 patients r and omized to coiling or clipping  were divided into 4 categories : treatment < 2 days , on days 3 to 4 , on days 5 to 10 , and > 10 days after the hemorrhage . ORs with 95 % CI were calculated with logistic regression analysis for delayed cerebral ischemia , poor outcome at 2 months , and 1 year for the different timing categories , with treatment < 2 days as reference . Analyses were performed for all patients , and for coiled and clipped patients separately , and were adjusted for baseline characteristics . Results — Adjusted ORs of delayed cerebral ischemia for treatment on days 5 to 10 were 1.18 ( 95 % CI , 0.91–1.53 ) for all patients , 1.68 ( 95 % CI , 1.17–2.43 ) after coiling , and 0.79 ( 95 % CI , 0.54–1.16 ) after clipping . ORs for poor outcome at 2 months were 1.16 ( 95 % CI , 0.89–1.50 ) for treatment ( clipping and coiling combined ) at 3 to 4 days , 1.39 ( 95 % CI , 1.08–1.80 ) for treatment at 5 to 10 days , and 1.84 ( 95 % CI , 1.36–2.51 ) for treatment > 10 days . ORs for coiled and clipped patients separately were in the same range . Results for outcome at 1 year were similar . Conclusions — Our results support the current practice for early aneurysm treatment in subarachnoid hemorrhage patients . The risk for poor outcome was highest when treatment was performed after day 10 ; postponing treatment in patients who are eligible for treatment between days 5 to 10 after subarachnoid hemorrhage is not recommended Objectives : The debate on the timing of aneurysm surgery after subarachnoid haemorrhage ( SAH ) pivots on the balance of the temporal risk for fatal rebleeding versus the risk of surgical morbidity when operating early on an acutely injured brain . By following a strict management protocol for SAH , the hypothesis has been tested that in the modern arena of treatment for aneurysmal SAH the timing of surgery to secure supratentorial aneurysms does not affect surgical outcome . Methods : Over a 6 year period , patients admitted with a diagnosis of SAH to a regional neurosurgical unit have been prospect ively studied . All have been on a management protocol in which early transfer and resuscitation has been followed regardless of age and clinical condition . Angiographic investigation and surgery have been pursued in those who have been able to at least flex to pain . A total of 1168 patients ( 60.7 % female , mean age 54.3 ) with proved SAH were received on median day 1 ( 86.4 % arrived within 3 days ) of the ictus . Of these , 784 ( 67.1 % ) showed aneurysms on angiography and were prepared for surgery . Those who received surgery for a supratentorial aneurysm within 21 days of the ictus were included in the final analysis ( n=550 ) . Patients with an initial negative angiogram , with posterior circulation aneurysms , or aneurysms treated by endovascular means , with aneurysms requiring emergency surgery for space occupying haematomas , with aneurysms which re-bled before surgery , and those who received very late surgery ( after 21 days from ictus ) were excluded . Surgical outcomes at hospital discharge and after 6 months were assessed using the Glasgow outcome score ( GOS ) . Discharge destination and duration of stay in a neurosurgical ward were also documented . The influence of the timing of surgery  ( early group day 1–3 postictus , intermediate group day 4–10 , or late group day 11–21 ) was analysed prospect ively . Results : 60.2 % of cases fell into the early surgery group , 32.4 % into the intermediate group , and 7.5 % into the late operated group . Late surgery was due to delays in diagnosis , transfer , and logistic factors , but not clinical decision . The demographic characteristics , site of aneurysm , and clinical condition of the patients at the time of initial medical assessment were balanced in the three surgical timing groups . There was no significant difference in GOS between the surgical timing groups at 6 months ( favourable GOS score 4 and 5 : 83.2 % , 80.5 % , and 83.8 % respectively ; p=0.47 , Kruskal-Wallis test ) . Outcome was favourable in 84 % of patients under 65 years , and 70 % in those over 65 . The discharge destinations ( home , referring hospital , nursing home , rehabilitation centre ) showed no significant difference between surgical timing groups . There was no significant difference in mean time to discharge after admission to this hospital from the referring hospital ( 16.2 , 16.2 , and 14.6 days for early , intermediate , and late groups respectively ; p=0.789 , Analysis of variance ( ANOVA ) ) . As a result , there was reduction in the mean duration of total hospital inpatient stay in favour of the earliest operated patients ( mean time 18.1 , 22.0 , and 28.3 days respectively ; p=0.001 . ANOVA showed that besides age , the only determinant of surgical outcome and duration of stay was presenting clinical grade ( p<0.0005 ) . Conclusion : The current management of patients presenting with SAH from anterior circulation aneurysms allows early surgery to be followed safely regardless of age . The only independent variables affecting outcome are age and clinical grade at presentation . The timing of surgery did not significantly affect surgical outcome , promoting a policy for early surgery that avoids the known risks of rebleeding and reduces inpatient stay The timing of aneurysm surgery after subarachnoid hemorrhage is a major neurosurgical controversy addressed by the International Cooperative Study on the Timing of Aneurysm Surgery ( 1980 - 1983 ) . The present report examines the results of this trial in the subgroup of patients admitted to North American centers . Methods The method of study was a large , multicenter , prospect i ve , epidemiological survey . Neurosurgeons were required to indicate prospect ively the interval to planned aneurysm surgery at the time of patient admission . Outcome at 6 months was determined by a blinded evaluator , and overall management results were analyzed by the planned surgical interval . Results Seven hundred seventy-two ( 21.9 % of the total study population ) patients admitted from days 0 to 3 after subarachnoid hem 
    Output:
    
Despite the shortcomings of this study , timing of surgery for aSAH did not put a significant impact on overall surgical outcome .
But subgroup analysis indicated a trend with more benefits for early treatment .