***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: Subarachnoid hemorrhage ( SAH ) often leads to hydrocephalus , which is commonly treated by placement of a ventriculoperitoneal ( VP ) shunt . There is controversy over which factors affect the need for such treatment . In this study , data were prospect ively collected from 389 consecutive patients who presented with an aneurysm-associated SAH at a single center .  External ventricular drainage placement was performed as part of the treatment for acute hydrocephalus , and VP shunts were placed in patients with chronic hydrocephalus . The data were retrospectively analyzed using two- sample t-tests , Fisher 's exact test and logistic regression analysis . Overall , shunt dependency occurred in 91 of the 389 patients ( 23.4 % ) . Using logistic regression analysis , two factors were found to be significantly associated with VP shunt placement : an initial Glasgow Coma Scale ( GCS ) score of 8 - 14 ( 8 - 14 versus 3 - 7 , p = 0.016 ; 15 versus 3 - 7 , p = 0.55 ) ; and aneurysm coiling ( p = 0.017 ) . Patients with an initial GCS score of 8 - 14 after aneurysm-associated SAH had a 2.5-fold higher risk of receiving a VP shunt than those with a GCS score of 3 - 7 . Those with a GCS of 15 had a 50 % lower risk of becoming shunt dependent than did the subgroup with a GCS score of 8 - 14 . To clarify and strengthen these observations , prospect i ve , r and omized trials are needed OBJECTIVE Chronic hydrocephalus requiring shunt placement and cerebral vasospasm are common complications after aneurysmal subarachnoid hemorrhage . Recent publications have investigated the possibility that microsurgical fenestration of the lamina terminalis during aneurysm surgery may reduce the incidence of shunt-dependent hydrocephalus and cerebral vasospasm . We review ed a single-surgeon series to compare postsurgical outcomes of patients who underwent fenestration of the lamina terminalis  against those who did not . METHODS This study is a retrospective review of the medical records of 369 consecutive patients with aneurysmal subarachnoid hemorrhage admitted to Columbia University Medical Center between January 2000 and July 2006 . All patients underwent craniotomy and clipping of at least one ruptured cerebral aneurysm by a single neurosurgeon ( ESC ) . The incidences of shunt-dependent hydrocephalus , conversion from acute hydrocephalus on admission to chronic hydrocephalus , and clinical cerebral vasospasm were compared in patients who underwent fenestration of the lamina terminalis with those who did not . The patient cohort was thus divided into three subgroups : 1 ) patients whose operative records clearly indicated that they underwent fenestration of the lamina terminalis , 2 ) patients whose operative records clearly indicated that they did not undergo fenestration of the lamina terminalis , and 3 ) patients whose operative records did not indicate one way or another whether they received fenestration of the lamina terminalis . We performed two separate analyses by comparing the postsurgical outcomes in those patients who were fenestrated versus those who were definitively not fenestrated and comparing the postsurgical outcomes in those patients who were fenestrated versus those who were not plus those whose records did not document fenestration . To further control for any cohort differences , we performed a comparison between patients who were fenestrated and those who were not after matching 1:1 for presenting radiographic and clinical characteristics predictive of hydrocephalus and vasospasm . Outcomes were compared using logistic regression and multivariable analysis . RESULTS In the first model , fenestrated patients had a shunt rate , conversion rate , and rate of clinical vasospasm of 25 , 50 , and 23 % , respectively , versus 20 , 27 , and 27 % in nonfenestrated patients , respectively ( P = 0.28 , 0.21 , and 0.32 , respectively ) . In the second model , the nonfenestrated patients plus nondocumented patients had a shunt rate , conversion rate , and rate of clinical vasospasm of 16 , 40 , and 20 % , respectively ( P = 0.19 , 0.33 , and 0.60 , respectively ) . In the matched cohort , fenestrated patients had a shunt rate , conversion rate , and rate of clinical vasospasm of 29 , 67 , and 20 % , respectively , versus 20 , 25 , and 25 % in nonfenestrated patients , respectively ( P = 0.30 , 0.24 , and 0.20 , respectively ) . CONCLUSION In contrast to other retrospective multisurgeon series , our retrospective single-surgeon series suggests that microsurgical fenestration of the lamina terminalis may not reduce the incidence of shunt-dependent hydrocephalus or cerebral vasospasm after aneurysmal subarachnoid hemorrhage . A prospect i ve multicenter trial is needed to definitively address the use of this maneuver BACKGROUND Shunt-dependent hydrocephalus is a common complication of aneurysmal subarachnoid hemorrhage ( aSAH ) . There is a need to identify patients who require ventriculoperitoneal shunt ( VPS ) insertion  so that any modifiable risk factors can be addressed early after aSAH . METHODS Exploratory analysis was performed on 413 patients enrolled in CONSCIOUS-1 , a prospect i ve r and omized controlled trial of patients with aSAH treated with clazosentan .  The association between clinical and neuroimaging covariates and VPS placement was first determined by univariate analysis . Covariates with P < 0.15 on univariate analysis were then analyzed in a multivariate logistic regression model . Receiver operating characteristic curve analysis was used to define optimal predictive thresholds . The published literature was review ed to determine the overall rate of VPS insertion after aSAH . RESULTS Overall , 17.2 % ( 71/413 ) of patients required VPS insertion . Multivariate analysis demonstrated that insertion of an external ventricular drain ( odds ratio , 6.21 ; 95 % confidence interval , 2.51 - 16.91 ) and increasing volume of cerebrospinal fluid ( CSF ) drainage per day ( odds ratio , 1.004 ; 95 % confidence interval , 1.000 - 1.009 ) were associated with VPS insertion . Receiver operating characteristic curve analysis revealed an optimal daily CSF output threshold of 78 mL was predictive of VPS insertion . Among 41,789 patients with aSAH from 66 published studies , the overall VPS insertion rate was 12.7 % . CONCLUSIONS The presence of an external ventricular drain and increased daily CSF output ( above 78 mL/day ) seems to be predictive of subsequent VPS insertion after aSAH . Although we could not identify modifiable risk factors for needing a VPS , nevertheless , these findings identify patients at greatest risk of VPS placement and inform treatment decisions as well as patient expectations OBJECTIVE The goals of this study were to investigate the risk factors , indications , complications , and outcome for patients with ventriculoperitoneal shunts ( VPSs ) after subarachnoid hemorrhage and to define a subgroup eligible for future prospect i ve studies design ed to clarify indications for placement of a VPS . METHODS Clinical characteristics of 236 prospect ively evaluated patients with subarachnoid hemorrhage and 6 months of follow-up were analyzed . Hydrocephalus was estimated by the relative bicau date index ( RBCI ) measured on computed tomographic scans at the time of shunting . Patients were divided into three groups by ventricle size : Group 1 included 121 patients with small ventricles ( RBCI < 1.0 ) , Group 2 included 88 patients with borderline ventricle size ( RBCI 1.0–1.4 ) , and Group 3 included 27 patients with markedly enlarged ventricles ( RBCI > 1.4 ) . RESULTS Initially , 86 patients ( 36 % ) underwent ventriculoperitoneal shunting : 19 in Group 1 ( 16 % ) , 43 in Group 2 ( 49 % ) , and 24 in Group 3 ( 90 % ) . Indications for placement of a VPS , risk factors , and outcome differed markedly by group . Four patients ( 3 % of those not initially shunted ) developed delayed hydrocephalus requiring a VPS , including one in Group 2 ( 2 % ) . The 6-month shunt complication rate was 13 % . Evaluation of patients in Group 2 indicated that functional status was an important factor in selecting c and i date s for shunting , and that patients receiving shunts and shunt-free patients demonstrated improvement in functional status during follow-up . CONCLUSION Although we currently use a proactive shunting paradigm for posthemorrhagic hydrocephalus , this report demonstrates that a conservative approach to patients with borderline ventricle size ( i.e. , RBCI of 1.0–1.4 ) and normal intracranial pressure should be evaluated in a prospect i ve r and omized trial Background Hydrocephalus ( HC ) after aneurysmal subarachnoid hemorrhage ( aSAH ) is a common sequel . Proper selection of patients in need of permanent cerebrospinal fluid ( CSF ) diversion is , however , not straightforward . The aim of this study was to identify predictors of CSF shunt dependency following aSAH . Methods We re-analyzed data acquired from aSAH patients previously enrolled in a prospect i ve , controlled single-center clinical trial in which shunt dependency was not one of the end points . In the present study patients were allocated into two groups : those receiving a shunt ( here denoted as shunt dependent ) and those not receiving a shunt , based on a clinical decision process . Predictors of shunt dependency were identified by applying uni- and multivariable analysis . We tested a set of predefined possible risk factors based on the results of the clinical trial , including the impact of CSF drainage volume exceeding 1,500 ml during the 1st week after ictus . Results Ninety patients were included in the study . Significant predictors of shunt dependency were poor clinical grade at admission [ odds ratio ( OR ) 4.7 , 95 % confidence interval ( CI ) 1.2–18.4 ] , large amounts of subarachnoid blood ( OR 3.8 , 95 % CI 1.0–14.0 ) , large ventricular size on preoperative cerebral computer tomographic ( CT ) scans ( OR 1.0 , 95 % CI 1.0–1.1 ) , and CSF volume drainage exceeding 1,500 ml during the 1st week after the ictus ( OR 16.3 , 95 % CI 4.0–67.1 ) . Age ≥70 years , larger amounts of intraventricular blood , vertebrobasilar aneurysm , and endovascular treatment tended to increase the likelihood of receiving a shunt . Outcome was not significantly different between shunted and non-shunted patients . Conclusions In this cohort of patients with clinical grade aSAH at admission , larger amounts of subarachnoid blood and large ventricular size on preoperative cerebral CT , and CSF drainage in excess of 1,500 ml during the 1st week after the ictus were significant predictors of shunt dependency . Shunt dependency did not hamper outcome BACKGROUND  Acute hydrocephalus  is a well-known sequela of aneurysmal subarachnoid hemorrhage ( SAH ) . Controversy exists about whether open microsurgical methods serve to reduce shunt dependency compared with endovascular techniques . OBJECTIVE To determine predictors of shunt-dependent hydrocephalus and functional outcomes after aneurysmal SAH . METHODS A total of 471 patients who were part of a prospect i ve , r and omized , controlled trial from 2003 to 2007 were retrospectively review ed . All variables including demographic data , medical history , treatment , imaging , and functional outcomes were included as part of the trial . No additional variables were retrospectively collected . RESULTS Ultimately , 147 patients ( 31.2 % ) required a ventriculoperitoneal shunt ( VPS ) in our series . Age , dissecting aneurysm type , ruptured vertebrobasilar aneurysm , Fisher grade , Hunt and Hess grade , admission intraventricular hemorrhage , admission intraparenchymal hemorrhage , blood in the fourth ventricle on admission , perioperative ventriculostomy , and hemicraniectomy were significant risk factors ( P < .05 ) associated with shunt-dependent hydrocephalus on univariate analysis . On multivariate analysis , intraventricular hemorrhage and intraparenchymal hemorrhage were independent risk factors for shunt dependency ( P < .05 ) .  Clipping  vs  coiling  treatment was not statistically associated with VPS after SAH on both univariate and multivariate analyses . Patients who did not receive a VPS at discharge had higher Glasgow Outcome Scale and Barthel Index scores and were more likely to be functionally independent and to return to work 72 months after surgery ( P < .05 ) . CONCLUSION There is no difference in shunt dependency after SAH among patients treated by endovascular or microsurgical means . Patients in whom shunt-dependent hydrocephalus does not develop after SAH tend to have improved long-term functional outcomes OBJECT This study was design ed to determine whether the frequency of shunt-dependent hydrocephalus in patients suffering from aneurysmal subarachnoid hemorrhage ( SAH ) differs when comparing surgical clip application with endov 
    Output:
    
Several new predictors of SDHC after aSAH were identified that may assist with the early recognition and prevention of SDHC .
The controversial evidence found in this study was insufficient to support the potential of neurosurgical clipping for reducing the risk of shunt dependency .