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Background: The natural history and treatment results for spinal glomus (type II) arteriovenous malformations (AVMs) remain relatively obscure., Objective: To calculate spinal glomus (type II) AVM hemorrhages rates and amalgamate results of intervention., Methods: We performed a pooled analysis via the PubMed database through May 2012, including studies with at least 3 cases. Data on individual patients were extracted and analyzed using a Cox proportional hazards regression model to obtain hazard ratios for hemorrhage risk factors., Results: The annual hemorrhage rate before treatment was 4% (95% confidence interval [confidence interval]: 3%-6%), increasing to 10% (95% CI: 7%-16%) for AVMs with previous hemorrhage. The hazard ratio for hemorrhage after hemorrhagic presentation was 2.25 (95% CI: 0.71-7.07), increasing to 13.0 within the first 10 years (95% CI: 1.44-118). The overall rates of complete obliteration were 78% (95% CI: 72%-83%) for surgery and 33% (95% CI: 24%-43%) for endovascular treatment. Long-term clinical worsening occurred in 12% of patients after surgical treatment (95% CI: 8%-16%) and in 13% after endovascular treatment (95% CI: 7%-21%). No hemorrhages occurred after complete obliteration. After partial surgical treatment, the annual hemorrhage rate was 3% (95% CI: 1%-6%); no hemorrhages were reported over 196 patient-years after partial endovascular treatment., Conclusion: Spinal glomus (type II) AVMs with previous hemorrhage, particularly within 10 years, demonstrated a greater risk of hemorrhage. Complete obliteration and even partial endovascular treatment significantly decreased their hemorrhage rate.

Moyamoya disease and moyamoya syndrome (MMD/S) are a considerable source of neurologic morbidity in adults as a result of both ischemic and hemorrhagic events. Unfortunately, there is a paucity of literature detailing the natural course of MMD/S in the USA. To elucidate epidemiological information, stroke rates, hemorrhage rates, and risk factors for these events in patients with MMD/S, we reviewed our own institutional cohort of 42 North American adults with MMD/S. The mean patient age was 38.8 (standard deviation [SD] 12.7) with a 5:1 female-to-male predominance. About 74% of patients had an ischemic presentation while only 17% presented with hemorrhage. The mean Suzuki grade was higher in patients presenting with hemorrhage (3.7 compared to 2.9, p=0.03) but similar in those who presented with a stroke as compared to those who did not (3.00 compared to 3.05, p=0.88). The overall annual stroke and hemorrhage rates were 13.3% and 1.7%, respectively. Statistically significant risk factors for stroke or hemorrhage were female sex (p=0.031) and stroke presentation within 3 years (hazard ratio [HR]=4.08, p=0.035). Smoking was another risk factor, but it did not meet statistical significance (HR=1.56, p=0.38). We conclude that these results favor intervention for MMD/S to mitigate the high annual stroke risk. This particularly applies to females and/or those presenting with a recent stroke/hemorrhage. Our results also serve as a baseline for comparison of hemorrhage rates after intervention., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Background: Previous hemorrhage, deep venous drainage, and deep location are established risk factors for arteriovenous malformation (AVM) hemorrhage. Although pregnancy is an assumed risk factor, there is a relative paucity of data to support this neurosurgical tenet., Objective: To elucidate the hemorrhage rate of AVMs during pregnancy., Methods: We reviewed the records of 54 women with an angiographic diagnosis of an AVM at our institution. Annual hemorrhage rates were calculated as the ratio of the number of bleeds to total number of patient-years of follow-up. Patient-years of follow-up were tallied assuming lesion presence from birth until AVM obliteration. The Cox proportional hazards model for hemorrhage with pregnancy as the time-dependent variable was used to calculate the hazard ratio., Results: Five hemorrhages in 4 patients occurred over 62 pregnancies, yielding a hemorrhage rate of 8.1% per pregnancy or 10.8% per year. Over the remaining 2461.3 patient-years of follow-up, only 28 hemorrhages occurred, yielding an annual hemorrhage rate of 1.1%. The hazard ratio for hemorrhage during pregnancy was 7.91 (P = 2.23 × 10(-4)), increasing to 18.12 (P = 7.31 × 10(-5)) when limiting the analysis to patient follow-up up to age 40., Conclusion: Because of the increased risk of hemorrhage from AVMs during pregnancy, we recommend intervention in women who desire to bear children, particularly if the AVM has bled. If the AVM is discovered during pregnancy, we recommend early intervention if it has ruptured; if it is unruptured, we recommend comprehensive counseling, weighing risks of intervention against continuation of pregnancy without intervention.

Prior rupture is an established risk factor for subsequent hemorrhage from arteriovenous malformations (AVM). Recent natural history studies have reinvigorated the important concept that the re-bleed rate is not constant; rather, it is particularly greater in the first year after hemorrhage. In this study, we reviewed our own cohort of 129 patients with AVMs. Eighty-one presented with hemorrhage (63%), and of these patients, 38 had at least one month of subsequent clinical follow-up and were included in our analysis. Over a total of 140 patient-years, the annual re-hemorrhage rate was 7.9%, though it was 15.8% in the first year. Two-thirds of those AVM that hemorrhaged in the first year were associated with aneurysms. The overall permanent morbidity of re-hemorrhage was 45%; the mortality rate was 9%. Although the re-hemorrhage rate in the first year varied from 6% to 15.8% across series in the literature, it was generally double the overall re-hemorrhage rate provided in each study. These results have significant therapeutic implications, favoring surgical treatment of ruptured AVM and/or their associated aneurysm when feasible to avoid the incumbent greater risk of early rehemorrhage., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

BackgroundCranial dural arteriovenous fistulas with cortical venous drainage are rare lesions that can present with hemorrhage. A high rate of rebleeding in the early period following hemorrhage has been reported, but published long-term rates are much lower. No study has examined how risk of rebleeding changes over time. Our objective was to quantify the relative incidence of rebleeding in the early and later periods following hemorrhage.MethodsPatients with dural arteriovenous fistula and cortical venous drainage presenting with hemorrhage were identified from the multinational CONDOR (Consortium for Dural Fistula Outcomes Research) database. Natural history follow-up was defined as time from hemorrhage to first treatment, rebleed, or last follow-up. Rebleeding in the first 2 weeks and first year were compared using incidence rate ratio and difference.ResultsOf 1077 patients, 250 met the inclusion criteria and had 95 cumulative person-years natural history follow-up. The overall annualized rebleed rate was 7.3% (95% CI, 3.2-14.5). The incidence rate of rebleeding in the first 2 weeks was 0.0011 per person-day; an early rebleed risk of 1.6% in the first 14 days (95% CI, 0.3-5.1). For the remainder of the first year, the incidence rate was 0.00015 per person-day; a rebleed rate of 5.3% (CI, 1.7-12.4) over 1 year. The incidence rate ratio was 7.3 (95% CI, 1.4-37.7; P, 0.026).ConclusionsThe risk of rebleeding of a dural arteriovenous fistula with cortical venous drainage presenting with hemorrhage is increased in the first 2 weeks justifying early treatment. However, the magnitude of this increase may be considerably lower than previously thought. Treatment within 5 days was associated with a low rate of rebleeding and appears an appropriate timeframe.

Background: The goal of this study was to investigate the association of tracheostomy timing with outcomes after aneurysmal subarachnoid hemorrhage (SAH) in a national population.Methods: Poor-grade aneurysmal SAH patients were extracted from the Nationwide Inpatient Sample (2002-2011). Multivariable linear regression was used to analyze predictors of tracheostomy timing and multivariable logistic regression was used to evaluate the association of timing of intervention with mortality, complications, and discharge to institutional care. Covariates included patient demographics, comorbidities, severity of subarachnoid hemorrhage (measured using the NIS-SAH severity scale), hospital characteristics, and other complications and length of stay.Results: The median time to tracheostomy among 1380 poor-grade SAH admissions was 11 (interquartile range: 7-15) days after intubation. The mean number of days from intubation to tracheostomy in SAH patients at the hospital (p < 0.001) was the strongest predictor of tracheostomy timing for a patient, while comorbidities and SAH severity were not significant predictors. Mortality, neurologic complications, and discharge disposition did not differ significantly by tracheostomy time. However, later tracheostomy (when evaluated continuously) was associated with greater odds of pulmonary complications (p = 0.004), venous thromboembolism (p = 0.04), and pneumonia (p = 0.02), as well as a longer hospitalization (p < 0.001). Subgroup analysis only found these associations between tracheostomy timing and medical complications in patients with moderately poor grade (NIS-SAH severity scale 7-9), while there were no significant differences by timing of intervention in very poor-grade patients (NIS-SAH severity scale > 9).Conclusions: In this analysis of a large, national data set, variation in hospital practices was the strongest predictor of tracheostomy timing for an individual. In patients with moderately poor grade, later tracheostomy was independently associated with pulmonary complications, venous thromboembolism, pneumonia, and a longer hospitalization, but not with mortality, neurological complications, or discharge disposition. However, tracheostomy timing was not significantly associated with outcomes in very poor-grade patients. [ABSTRACT FROM AUTHOR]

S100 calcium binding protein B (S100B), a well-studied marker for neurologic injury, has been suggested as a candidate for predicting outcome after subarachnoid hemorrhage. We performed a pooled analysis summarizing the associations between S100B protein in serum and cerebrospinal fluid (CSF) with radiographic vasospasm, delayed ischemic neurologic deficit (DIND), delayed cerebral infarction, and Glasgow Outcome Scale (GOS) outcome. A literature search using PubMed, the Cochrane Library, and the EMBASE databases was performed to identify relevant studies published up to May 2015. The weighted Stouffer’s Z method was used to perform a pooled analysis of outcome measures with greater than three studies. A total of 13 studies were included in this review. Higher serum S100B level was found to be associated with cerebral infarction as diagnosed by CT (padj = 3.1 x 10−4) and worse GOS outcome (padj = 5.5 x 10−11). There was no association found between serum and CSF S100B with radiographic vasospasm or DIND. S100B is a potential prognostic marker for aSAH outcome. [ABSTRACT FROM AUTHOR]

Cavernous malformations (CMs) are angiographically-occult clusters of dilated sinusoidal channels that may present clinically with seizures, focal neurological deficits and/or hemorrhage. Across natural history studies, the annual hemorrhage rate ranged from 1.6-3.1% per patient-year, decreasing to 0.08-0.2% per patient-year for incidental CMs and to 0.3-0.6% for the collective group of unruptured CMs. Prior hemorrhage is a significant risk factor for subsequent CM hemorrhage. Hemorrhage clustering, particularly within the first 2 years, is an established phenomenon that may confound results of natural history studies evaluating the rate of rehemorrhage. Indeed, rehemorrhage rates for hemorrhagic CMs range from 4.5-22.9% in the literature. Surgical resection is the gold standard treatment for surgically-accessible, symptomatic CMs. Incidental CMs or minimally symptomatic, surgically inaccessible eloquent lesions may be considered for observation. Stereotactic radiosurgery is a controversial treatment approach of consideration only for cases of highly aggressive, surgically inaccessible CMs. [ABSTRACT FROM AUTHOR]

Since the initial publication of the International Study of Unruptured Intracranial Aneurysms (ISUIA), management of unruptured intracranial aneurysms has been mainly based on the size of the aneurysm. The contribution of morphological characteristics to treatment decisions of unruptured aneurysms has not been well studied in a systematic and location specific manner. We present a large sample of basilar artery tip aneurysms (BTA) that were assessed using a diverse array of morphological variables to determine the parameters associated with ruptured aneurysms. Demographic and clinical risk factors of aneurysm rupture were obtained from chart review. CT angiograms (CTA) were evaluated with Slicer, an open source visualization and image analysis software, to generate 3-D models of the aneurysms and surrounding vascular architecture. Morphological parameters examined in each model included aneurysm volume, aspect ratio, size ratio, aneurysm angle, basilar vessel angle, basilar flow angle, and vessel to vessel angles. Univariate and multivariate analyses were performed to determine statistical significance. From 2008–2013, 54 patients with BTA aneurysms were evaluated in a single institution, and CTAs from 33 patients (15 ruptured, 18 unruptured) were available and analyzed. Aneurysms that underwent reoperation, that were associated with arteriovenous malformations, or that lacked preoperative CTA were excluded. Multivariate logistic regression revealed that a larger angle between the posterior cerebral arteries (P1-P1 angle, p = 0.037) was most strongly associated with aneurysm rupture after adjusting for other morphological variables. In this location specific study of BTA aneurysms, the larger the angle formed between posterior cerebral arteries was found to be a new morphological parameter significantly associated with ruptured BTA aneurysms. This is a physically intuitive parameter that can be measured easily and readily applied in the clinical setting. [ABSTRACT FROM AUTHOR]

Abstract: Leptomeningeal venous drainage and symptomatic presentation are known risk factors for cerebral dural arteriovenous fistula (dAVF) hemorrhage. An evaluation of potentially modifiable risk factors such as hypertension and medication usage has not been undertaken to our knowledge. The authors thus reviewed a cohort of 45 consecutive patients with cerebral dAVF with leptomeningeal venous drainage and compared the rate of hemorrhagic presentation for patients with and without a history of hypertension, hyperlipidemia or the usage of certain medications. Logistic regression was performed to determine the statistical significance of associations of each factor with hemorrhagic presentation. On univariate analysis, angiotensin-converting enzyme (ACE)-inhibitors (odds ratio [OR] 0.100, 95% confidence interval [CI] 0–0.764, p =0.024) and statins (OR 0.142, 95% CI 0.025–0.825, p =0.030) were associated with a statistically significant lower rate of hemorrhagic presentation. A trend toward a lower rate of hemorrhagic presentation was seen for patients taking aspirin (OR 0.153, 95% CI 0.016–1.43, p =0.10). These trends continued on multivariate analysis; however they did not meet statistical significance (p >0.05). Beta-blockers, calcium channel blockers, warfarin and selective serotonin reuptake inhibitors did not have a statistically significant association with the rate of hemorrhagic presentation (p >0.05). Although limited by small sample size, these results may suggest a beneficial effect of statins and ACE-inhibitors on the rate of dAVF hemorrhagic presentation, potentially as a result of anti-inflammatory, anti-angiogenic or even venous antithrombotic mechanisms. Despite this study’s limitations, we hope it encourages further evaluation of potentially modifiable risk factors for vascular malformation hemorrhage. [Copyright &y& Elsevier]

Background: Although cerebral revascularization is an accepted treatment for moyamoya, the precise impact of direct or indirect bypass methods on subsequent event rates is infrequently addressed in adult cohorts. Methods: We reviewed 45 consecutive adults with 69 hemispheres affected by moyamoya. We evaluated stroke and hemorrhage rates prior to and following revascularization. Results: Direct revascularization was performed for 35 hemispheres (51 %) in 29 patients (64 %). The annual stroke, hemorrhage and overall event rates in this cohort diminished from 8.9 %, 2.0 %, and 11 % per hemisphere-year to 4.5 %, 0 %, and 4.5 % per hemisphere-year after treatment, respectively ( p = 0.06). Excluding perioperative events, no events occurred over 41.1 hemisphere-years of follow-up ( p = 0.0017). After a mean clinical follow-up period of 1.3 years, 72 % of patients were improved, 24 % the same, and 3 % worse in this cohort. Indirect revascularization was performed for 18 hemispheres (26 %) in 13 patients (29 %). The annual stroke, hemorrhage and overall event rates were 13 %, 0 %, and 13 % per hemisphere-year prior to treatment, and 6.8 %, 4.5 %, and 11 % per hemisphere-year after treatment, respectively ( p = 0.67). Excluding perioperative events, the overall annual event rate was 7.1 % ( p = 0.69). After a mean clinical follow-up of 2.7 years, 46 % of patients were improved, 38 % were the same and 15 % were worse. Conclusion: Direct revascularization is the optimal choice to prevent subsequent events in adult patients with moyamoya. A favorable impact of indirect revascularization was less clear in this cohort, and should be reserved for patients with an inadequate donor vessel. [ABSTRACT FROM AUTHOR]

Objective: Vasospasm and resultant clinical deterioration caused by delayed cerebral ischemia (CD-CDI) are a considerable source of morbidity after aneurysmal subarachnoid hemorrhage (SAH). Although they are a relatively common cause of spontaneous SAH, AVM rupture and ensuing vasospasm are rarely reported. Methods: We reviewed our own series of 122 patients with AVMs. Seventy-three patients sustaining 84 hemorrhages were analyzed. In addition, we performed a review of the literature of vasospasm after AVM rupture. Results: Seventy of 84 hemorrhages (83%) had an intraparenchymal component, 27 (32%) a subarachnoid component, and 51 (61%) had an intraventricular component. No patients experienced CD-DCI, and of the 84 hemorrhages reported, only one patient experienced mild angiographic vasospasm (1.1%). Alternatively, this finding represents 1 in 34 cases (2.9%) who underwent definitive angiography between the fourth and fifteenth day after the hemorrhage. Nineteen additional cases of angiographic vasospasm after AVM rupture are reported in the literature. The mean age of these patients was 33 years; there was a 1.25:1 female to male predominance in this group. One-half of these patients had an intraparenchymal hemorrhage, and only 56% of them had SAH. All patients had intraventricular hemorrhage when assessed. The median time to onset of vasospasm was nine days. Across four series, the rate of angiographic spasm after SAH from an AVM was 6.3% (9/142 cases). Conclusions: Even in cases of SAH from AVMs, angiographic vasospasm after AVM rupture is relatively rare. We thus do not recommend empiric delayed angiography to assess for vasospasm in these patients. Nevertheless, it does remain a rare possibility and should be considered in those with CD-DCI. [Copyright &y& Elsevier]

Background: Angiogram-negative subarachnoid hemorrhage (anSAH) accounts for 15% of spontaneous SAH. Recent studies suggest the outcome and diagnostic yield in anSAH differ based on initial bleeding pattern. We present a single-center experience in managing patients with SAH and negative initial digital-subtracted angiogram (DSA). Methods: Records of all patients with anSAH were reviewed. Bleeding pattern was determined from computed tomography (CT) and was categorized as perimesencephalic (PMN), diffuse, cortical, or xanthochromia (blood not detectable by CT). Diagnostic yield, in-hospital complications, and outcome parameters were analyzed. Results: Of 352 patients admitted with spontaneous SAH from 2003 to 2008, 68 (19.3%) had negative initial DSA. Mean age was 59.5 ± 14, and 33 were female. By CT, 27 (39.7%) patients exhibited PMN SAH, 33 (48.5%) diffuse SAH, 6 (8.8%) cortical SAH, and 2 (2.9%) xanthochromia only. Sixty-one patients had good Hunt and Hess (H/H) grades (I-III) and seven had poor grades (IV-V). Additional diagnostic studies included repeat angiogram (54), brain and C-spine magnetic resonance imaging (20), and repeat CTA (15). A structural bleeding cause was determined in six (8.8%) patients, 4 of which had diffuse SAH and 2 cortical SAH. Among these, two aneurysms (2.9%) were detected and surgically clipped, and both had diffuse SAH. Twenty-nine patients (42.6%) experienced medical complications, with infection (18), cardiovascular problems (12), and vasospasm (10) being the most frequent events. Additional surgeries included 13 ventriculoperitoneal shunts, 4 tracheostomies, and 9 gastric tube placements. Favorable outcome (mRS = 0-2) was recorded in 49 (72.1%) patients and unfavorable (3-6) in 19 (17.49%), with 1 (1.2%) in-hospital death. Multivariable logistic regression revealed older age and diffuse bleeding pattern were significant predictors of unfavorable outcome. Conclusions: The overall incidence of true aneurysms in patients with angiogram-negative SAH is low (2.9%). Initial bleeding pattern strongly correlates with diagnostic yield and clinical outcome. Diffuse bleeding pattern is associated with significantly higher diagnostic yield, more in-hospital complications, and worse clinical outcome. Patients with initial imaging characteristics other than diffuse pattern SAH developed few disease related complications, with the majority of in-hospital adverse events treatment related. [ABSTRACT FROM AUTHOR]

Abstract: An increasing number of patients with arteriovenous malformations (AVM) are being screened with expedient, safe, and non-invasive methods such as computed tomography angiography (CTA), MRI, and magnetic resonance angiography (MRA). Only a paucity of small series have examined the sensitivity of these modalities in detecting AVMs. In this study, we reviewed 125 patients with AVMs, demonstrating overall sensitivities of 90% for CTA, 89% for T2-weighted MRI, and 74% for MRA. The greater sensitivity of CTA in detecting AVMs compared to MRA did meet statistical significance (p CTA, MRA =0.036). For unruptured AVMs, the sensitivities were 96%, 97% and 71% (p CTA, MRA =0.043) and for ruptured AVMs, they were 87%, 83% and 77%, respectively. The sensitivity was 100% for both CTA and T2-weighted MRI for AVMs larger than 3cm. Importantly, associated aneurysms were best detected via CTA, with a sensitivity of 88%, as compared to 29% for MRI and 27% for MRA (p CTA, MRA =1.2×10−6), with the greatest distinction occurring within the subgroup of intranidal aneurysms with a sensitivity of 83% for CTA compared to 0% for both MRI and MRA (p CTA, MRA =0.005). [Copyright &y& Elsevier]

Introduction: Recent studies have reinforced anterior communicating (AComm) artery location as a significant risk factor for aneurysm rupture in addition to posterior circulation/posterior communicating (PComm) artery location. However, studies stratifying aneurysm location in greater detail are sparse. Methods: We reviewed the records of 747 consecutive patients with 1013 aneurysms seen at our institution over a 7 year period, noting aneurysm location and rupture status at the time of presentation. Results: High proportions of ruptured aneurysms were seen among frontopolar/pericallosal (59%, OR 3.07, p = 0.011), vertebral/posteroinferior cerebellar (PICA; 53%, OR 2.49, p = 0.0037), AComm (50%, OR 2.46, p < 0.0001), and PComm aneurysms (44%, OR 1.77, p = 0.0016). Low proportions of ruptured aneurysms were seen among superior hypophyseal artery (SHA; 6%, OR 0.12, p = 0.0001), internal carotid artery (ICA) bifurcation (12%, OR 0.27, p = 0.0012), and ophthalmic artery aneurysms (15%, OR 0.33, p = 0.0002). The proportion of ruptured PComm aneurysms demonstrated a trend toward being greater than anterior choroidal artery aneurysms (OR 2.14, p = 0.09); however the proportion was significantly greater among anterior choroidal artery aneurysms as compared to nonPComm intradural ICA aneurysms (OR 2.78, p = 0.03). Notably, the lower rupture rate of SHA aneurysms as compared to ophthalmic artery aneurysms neared statistical significance (OR 0.38, p = 0.10). Conclusion: Aneurysm location has a significant impact on risk of rupture and should be stratified in greater detail in future studies of aneurysm natural history. [ABSTRACT FROM AUTHOR]

Objective: Although vasculopathy and de novo aneurysm formation are known complications of traditional radiation therapy, their occurrence following AVM SRS is rare and thus infrequently addressed in the literature. We sought to evaluate these phenomena through a review of our institutional experience. Methods: Our review afforded 32 patients treated with LINAC-based SRS over an eight year period. We noted obliteration rates, complication rates and long-term outcomes, with particular attention paid to follow-up angiographic studies. Results: After a mean follow-up of 4.3 years, the overall obliteration rate was 50%, increasing to 87% for AVMs less than 3 cm. Eight patients had nine hemorrhages following SRS (25%). One occurred in the context of a de novo arterial pseudoaneurysm and another in the context of a new venous varix. Two patients with post-SRS hemorrhage had intranidal aneurysms that were not as apparent on initial angiography. Two patients that did not suffer from latency period hemorrhage developed dysplastic changes of feeding arteries, and one patient suffered from early venous thrombosis with resultant permanent hemiparesis from infarction. After a mean follow-up of 4.3 years, 8 patients were clinically improved (25%), 19 were the same (59%), and 5 were worse (16%), including 2 that died as a result of latency period hemorrhage. Conclusion: While radiosurgery of AVMs is safe and successful in the vast majority of cases, vasculopathic complications including de novo aneurysm and varix development, early venous occlusion and stenotic vasculopathy, while infrequent, can occur. Closer long-term angiographic surveillance of these patients may thus be warranted. [ABSTRACT FROM AUTHOR]

Objective Recent evidence has suggested a potential beneficial effect of aspirin on the risk of aneurysm rupture. This benefit must be weighed against its potential adverse effects as an antiplatelet agent in the setting of acute aneurysmal subarachnoid hemorrhage (SAH). Methods A total of 747 consecutive patients with cerebral aneurysms were reviewed, comparing demographics, aneurysm features, presenting clinical and radiographic grades, vasospasm, and outcome at 1 year between patients with aneurysmal SAH taking aspirin on presentation and those who were not. Results The rate of hemorrhagic presentation was significantly greater in patients not taking aspirin (40% vs. 28%; P = 0.016). Among 274 patients presenting with aneurysmal SAH, there was no significant difference in presenting clinical (Hunt and Hess) and radiographic (Fisher) grade between patients taking aspirin and those who were not. There was also no significant difference in the rate of subsequent angiographic and delayed cerebral ischemia. Multivariate analysis of outcome at 1 year found only increasing age (odds ratio [OR] 1.07, 95% confidence interval [CI] 1.04–1.12), Hunt and Hess grade (OR 3.01, 95% CI 1.81–5.03), and associated hypertension (OR 3.30, 95% CI 1.39–7.81) to be statistically significant risk factors for poor outcome (death or dependence), whereas aspirin use was not associated with poor outcome (OR 1.19, 95% CI 0.35–4.09; P = 0.78). Conclusions In the present study, patients taking aspirin had a lower rate of hemorrhagic presentation. In addition, taking aspirin did not adversely impact presenting clinical grade or radiographic grade, vasospasm, and outcome in the setting of aneurysmal SAH. [ABSTRACT FROM AUTHOR]