Negative Subarachnoid Hemorrhage Research Articles

Difference in Predictors of Seizure in Angiogram Negative Non-perimesencephalic Subarachnoid Hemorrhage Cases and Aneurysmal Cases (P7-5.020)

Difference in Predictors of Seizure in Angiogram Negative Non-perimesencephalic Subarachnoid Hemorrhage Cases and Aneurysmal Cases (P7-5.020)

Re-evaluating patient communication and care in angiographically negative subarachnoid hemorrhage: Balancing realism and optimism.

Angiographically negative subarachnoid hemorrhage (anSAH) has traditionally been considered a benign condition, mainly because of favorable outcomes in the acute stage in comparison to the often negative acute outcomes of aneurysmal subarachnoid hemorrhage. However, a growing body of research in recent years shows that anSAH often leads to cognitive impairments, emotional distress, and difficulties in resuming work or other daily life activities. Therefore, in this position paper, we call for a change in neurological care and a shift in patient communication, emphasizing the importance of addressing patient needs and fostering realistic expectations rather than solely focusing on the benign nature of the condition.

Risk stratification of delayed causative aneurysm detection and long-term outcome in angiographically negative spontaneous subarachnoid haemorrhage.

The risk factors of aetiology and poor outcome in angiographically negative subarachnoid haemorrhage (anSAH) were unclearly. The authors performed a retrospective review of a prospectively maintained database for anSAH patients between 2014 and 2018. AnSAH was defined as SAH presents in CT with no underlying vascular abnormality on initial digital subtraction angiography (DSA) within 72 hours of admission. Baseline and follow-up information, including medical history, bleeding pattern (perimesencephalic angiogram-negative SAH (PAN-SAH) and non-PAN-negative SAH (NPAN-SAH)), modified Fisher Scale (mFS), Glasgow Coma Score (GCS), Hunt-Hess grade, repeated imaging and causative vascular lesions and follow-up modified Rankin Scale (mRS) were reviewed. Poor outcome was defined as mRS scored 3-6 at last clinical follow-up. Among 303 enrolled patients, 272 patients underwent at least once repeated imaging examination (median follow-up time, 3.0 months). Twenty-one (7.7%) aneurysms were detected. Multivariate logistic analysis showed that NPAN-SAH and mFS 3-4 were associated with a high rate of aneurysm detection in anSAH patients. Based on risk stratification, the aneurysm detection rate in the high-risk group (both NPAN-SAH and mFS 3-4) was as high as 20.370 per 100 person-years. Furthermore, of 251 non-aneurysm anSAH patients, after a total follow-up time of 1265.83 patient-years, poor outcome occurred in 18 (7.2%) patients. Multivariate Cox analysis found that NPAN-SAH and GCS 3-12 were associated with a high rate of poor outcome of anSAH. The cumulative 5-year incidence rate for poor outcome in the non-aneurysm anSAH patients in the high-risk group (both NPAN-SAH and GCS 3-12) was as high as 75.302 per 100 person-years. Even in anSAH confirmed by initial DSA, patients with NPAN-SAH and mFS 3-4 should be monitored for delayed causative aneurysm detection, meanwhile in non-aneurysm anSAH patients, NPAN-SAH and initial functional impairment are associated with poor prognosis.

Automated magnetic resonance imaging quantification of cerebral parenchymal and ventricular volume following subarachnoid hemorrhage: associations with cognition

This study aims to investigate cerebral parenchymal and ventricular volume changes after subarachnoid hemorrhage (SAH) and their potential association with cognitive impairment. 17 patients with aneurysmal SAH (aSAH) and 21 patients with angiographically negative SAH (anSAH) without visually apparent parenchymal loss on conventional magnetic resonance imaging (MRI) were included, along with 76 healthy controls. Volumetric analyses were performed using an automated clinical segmentation and quantification tool. Measurements were compared to on-board normative reference database (n = 1923) adjusted for age, sex, and intracranial volume. Cognition was assessed with tests for psychomotor speed, attentional control, (working) memory, executive functioning, and social cognition. All measurements took place 5 months after SAH. Lower cerebral parenchymal volumes were most pronounced in the frontal lobe (aSAH: n = 6 [35%], anSAH n = 7 [33%]), while higher volumes were most substantial in the lateral ventricle (aSAH: n = 5 [29%], anSAH n = 9 [43%]). No significant differences in regional brain volumes were observed between both SAH groups. Patients with lower frontal lobe volume exhibited significantly lower scores in psychomotor speed (U = 81, p = 0.02) and attentional control (t = 2.86, p = 0.004). Additionally, higher lateral ventricle volume was associated with poorer memory (t = 3.06, p = 0.002). Regional brain volume changes in patients with SAH without visible parenchymal abnormalities on MRI can still be quantified using a fully automatic clinical-grade tool, exposing changes which may contribute to cognitive impairment. Therefore, it is important to provide neuropsychological assessment for both SAH groups, also including those with clinically mild symptoms.

White matter abnormalities in aneurysmal and angiographically negative subarachnoid hemorrhage: A diffusion kurtosis imaging study

ObjectiveAneurysmal subarachnoid hemorrhage (aSAH) and angiographically negative subarachnoid hemorrhage (anSAH) cause an abrupt rise in intracranial pressure, resulting in shearing forces, causing damage to the white matter tracts. This study aims to investigate whole-brain white matter abnormalities with diffusion kurtosis imaging (DKI) after both aSAH and anSAH and explores whether these abnormalities are associated with impaired cognitive functioning. MethodsFive months post-ictus, 34 patients with aSAH, 24 patients with anSAH and 17 healthy controls (HC) underwent DKI MRI scanning and neuropsychological assessment (measuring verbal memory, psychomotor speed, executive control, and social cognition). Differences in DKI measures (fractional anisotropy, mean diffusivity, axial diffusivity [AD], radial diffusivity, and mean kurtosis) were examined using tract-based spatial statistics. Significant voxel masks were then correlated with neuropsychological scores. ResultsAll DKI measures differed significantly between patients with aSAH and HC, but no significant differences were found between patients with anSAH and HC. Although the two SAH groups did not differ significantly on all DKI parameters, effect sizes indicated that the anSAH group might be more similar to HC. Cognitive impairments were found for both SAH groups relative to HC. No significant associations were found between these impairments and white matter abnormalities in the aSAH group, but lower psychomotor speed scores were associated with higher AD values (r = -0.41, p = 0.04) in patients with anSAH. ConclusionsPatients with aSAH showed significant white matter diffusion abnormalities, while the anSAH group, despite cognitive deficits, did not. However, there were no significant differences between the SAH groups, and no correlations between DKI metrics and cognitive measures, except for one test on psychomotor speed in the anSAH group. Overall, this study suggests that while anSAH may not be as severe as aSAH, it is still not a benign condition. Further research with larger anSAH cohorts is necessary to gain a more precise understanding of white matter injuries, particularly regarding their prevalence.

The Diagnostic Dilemma in Delayed Subarachnoid Hemorrhage: A Case Report.

Radiologically negative subarachnoid hemorrhage (SAH) has a low incidence and is associated with good clinical outcomes. We present the case of a 44-year-old male with new-onset headaches, which began one week prior while bike riding. At an outside hospital, he had normal computed tomography head and angiogram. He declined a lumbar puncture. Over the following week, the headache was persistent. He lacked meningeal signs. Repeat studies were normal. Lumbar puncture was positive for xanthochromia. Radiologically negative SAH should be included in the differential diagnosis of patients presenting with unremitting headache in the setting of recent exercise, despite negative imaging, and meningeal signs.

Long-term Course of Cognitive Functioning After Aneurysmal and Angiographically Negative Subarachnoid Hemorrhage.

Cognitive impairment is a common consequence of subarachnoid hemorrhage (SAH), negatively affecting everyday functioning. This study is the first to investigate the long-term course of cognitive functioning after SAH and its associations with long-term well-being (ie, anxiety and depression), cognitive complaints, and return to work, separately for patients with aneurysmal SAH (aSAH) and angiographically negative SAH (anSAH) in a longitudinal design. Cognitive functioning was measured at 2 time points (T1: 3-6 months post-SAH; T2: 2-4 years post-SAH) in 58 patients with aSAH and 22 patients with anSAH with neuropsychological tests for (working) memory, psychomotor speed, and attention/executive functioning. Questionnaires were used to measure cognitive complaints and well-being at T1 and T2 and return to work at T2. At T2, patients with aSAH only showed improvements in memory and on an executive functioning and psychomotor speed subtest, whereas in contrast, patients with anSAH had significantly poorer scores on tests for psychomotor speed. A significant amount of patients with aSAH and anSAH still reported cognitive complaints, anxiety, and depression in the chronic stage. Cognitive functioning was not significantly associated with cognitive complaints in both SAH groups. On the other hand, cognitive complaints were related to well-being at the long-term in both SAH groups. More cognitive complaints were also associated with more difficulties in return to work in patients with aSAH. Patients with aSAH and anSAH have cognitive impairments at the subacute stage post-SAH, and these impairments persist into the chronic stage. Moreover, both SAH groups still reported decreased well-being in the chronic stage post-SAH, related to cognitive complaints but not to cognitive impairment. For clinical practice, an early neuropsychological assessment will already provide relevant information to estimate long-term cognitive impairment, but in addition, it is important to pay attention to psychological distress at the long-term.

Investigating Recovery After Subarachnoid Hemorrhage With the Imaging, Cognition and Outcome of Neuropsychological Functioning After Subarachnoid Hemorrhage (ICONS) Study: Protocol for a Longitudinal, Prospective Cohort Study

BackgroundA subarachnoid hemorrhage is a hemorrhage in the subarachnoid space that is often caused by the rupture of an aneurysm. Patients who survive a subarachnoid hemorrhage have a high risk of complications and a negative long-term outcome.ObjectiveThe aim of the Imaging, Cognition and Outcome of Neuropsychological functioning after Subarachnoid hemorrhage (ICONS) study is to investigate whether and to what extent deficits exist in multiple domains after subarachnoid hemorrhage, including cognition, emotion and behavior, and to investigate whether brain damage can be detected in patients with subarachnoid hemorrhage. We aim to determine which early measures of cognition, emotion and behavior, and brain damage in the subacute stage play a role in long-term recovery after subarachnoid hemorrhage. Recovery is defined as functioning at a societal participation level, with a focus on resuming and maintaining work, leisure activities, and social relationships over the long term.MethodsThe ICONS study is an observational, prospective, single-center cohort study. The study includes patients with subarachnoid hemorrhage admitted to the Neurosurgery Unit of the University Medical Centre Groningen in the Netherlands. The inclusion criteria include diagnosis of an aneurysmal subarachnoid hemorrhage or an angiographically negative subarachnoid hemorrhage, sufficient ability in the Dutch language, and age older than 18 years. Patients will undergo neuropsychological assessment and magnetic resonance imaging 6 months after the subarachnoid hemorrhage. Furthermore, patients will be asked to fill in questionnaires on multiple psychosocial measures and undergo a structured interview at 6 months, 1 year, and 2 years after the subarachnoid hemorrhage. The primary outcome measure of the ICONS study is societal participation 1 year after the subarachnoid hemorrhage, measured with the Dutch version of the Impact on Participation and Autonomy questionnaire.ResultsThe study was launched in December 2019 and recruitment is expected to continue until June 2023. At the time of the acceptance of this paper, 76 patients and 69 healthy controls have been included. The first results are expected in early 2023.ConclusionsThe ICONS study is the first to collect and combine data after subarachnoid hemorrhage in a variety of domains, including cognition, emotion and behavior, and brain damage. The results will contribute to a more comprehensive understanding of the consequences of both aneurysmal subarachnoid hemorrhage and angiographically negative subarachnoid hemorrhage, which may ultimately optimize timely treatment for this patient group by setting realistic and attainable goals to improve daily functioning.Trial RegistrationNetherlands Trial Register NL7803; https://trialsearch.who.int/Trial2.aspx?TrialID=NL7803International Registered Report Identifier (IRRID)DERR1-10.2196/38190

Physical exertion as a risk factor for perimesencephalic nonaneurysmal subarachnoid hemorrhage

BackgroundPerimesencephalic and nonperimesencephalic nonaneurysmal subarachnoid hemorrhage (PM‐naSAH and NPM‐naSAH) have a different bleeding pattern and clinical course. The etiology and risk factors for PM‐naSAH and NPM‐naSAH are unclear. The objective of this study was to compare risk factors and triggering events between PM‐naSAH and NPM‐naSAH.MethodsWe reviewed retrospectively all patients (n = 3475) who had undergone cerebral digital subtraction angiography between 2003 and 2020 at our tertiary hospital. Of these, 119 patients had 6‐vessel angiography negative subarachnoid hemorrhage (47 (39%) PM‐naSAH and 72 (61%) NPM‐naSAH) and accurate information about the triggering event was available in 42 (89%) PM‐NASAH and 64 (89%) NPM‐naSAH patients.ResultsPM‐naSAH were younger compared to NPM‐naSAH (mean age [SD]; 55.3 [11.1] years vs. 59.6 [12.2] years, p = .045. PM‐naSAH was triggered during the physical exertion in 79% of patients and 16% of patients with NPM‐naSAH (relative risk 5.4; 95% CI, 2.9‐10.1, p < .0001). There were no significant difference in sex, smoking, alcohol abuse, hypertension, diabetes, hyperlipidemia, or anticoagulation/antithrombotic usage between PM‐naSAH and NMP‐naSAH, p > .05.ConclusionPhysical exertion was a triggering factor in most of the PM‐naSAH cases and the risk was five times greater than in NMP‐naSAH. More studies are needed to confirm our results and to study pathophysiology of PM‐naSAH and NPM‐naSAH.

The Potential Value of 320-Row Computed Tomography Angiography in Digital Subtraction Angiography–Negative Spontaneous Subarachnoid Hemorrhage Patients

ObjectiveThis study aimed to investigate the clinical value of multiphase and multiparametric 320-row computed tomography (CT) in the long-term follow-up of spontaneous subarachnoid hemorrhage (SAH) with initially negative CT angiography (CTA) and digital subtraction angiography (DSA) results.MethodsWe retrospectively analyzed the clinical data of 35 patients with nontraumatic angiographically negative SAH results from February 2012 to December 2015. Regular follow-up was performed with 320-row CTA, CT venography, and CT perfusion.ResultsAll patients received 320-row CT follow-up for 0.5 to 4 years. The diagnostic yield of the follow-up examinations was 4 of 35 (11.4%), 3 of 31 (9.7%), and 1 of 28 (3.6%) for the first, second, and third time points, respectively. Two patients were admitted to the hospital because of recurrent subarachnoid hemorrhage during the follow-up period and diagnosed with ruptured aneurysms.ConclusionsPatients with SAH with negative findings in the first DSA examination require to follow up. Follow-up using 320-row CTA, CT venography, and CT perfusion allows for a noninvasive diagnostic test for cerebrovascular diseases with higher compliance and fewer complications when compared with follow-up using DSA.

Retrospective 6 month-outcomes and prognostic factors following spontaneous angiogram-negative non-perimesencephalic subarachnoid hemorrhage

Our objective was to analyze functional outcomes and prognostic factors in patients suffering from angiogram-negative non-perimesencephalic subarachnoid hemorrhage (non-PMH). In total, 1601 patients presenting with spontaneous SAH between January 2009 to December 2019 admitted to our institution were reviewed. Among them, 51 patients with angiogram negative non-perimesencephalic subarachnoid hemorrhage were analyzed. We divided patients into groups according to hemorrhage pattern and duration. Prognostic factors were assessed according to initial neurologic grade, early hydrocephalus, fisher grade, and duration of hemorrhage. Outcomes were assessed according to the modified Rankin Scale after 6 months. Overall, 41 patients (80.3%) with angiogram-negative non-PMH achieved a favorable outcome. In univariate analysis, good initial neurologic grade, absence of early hydrocephalus, non-Fisher-type 3 bleeding pattern, and short term hemorrhage (blood wash out <7 days after onset) duration were significantly associated with a favorable outcome. In multivariate analysis, a non-Fisher-type 3 hemorrhagic pattern (p < 0.05) and good initial neurologic state (p < 0.01) were independent predictors of favorable outcomes in angiogram-negative non-PMH patients. Patients with angiogram-negative non-PMH generally had favorable outcomes. A non-Fisher-type 3 hemorrhagic pattern and good initial neurologic state were prognostic factors of a favorable outcome in non-PMH. Furthermore, patients with long-term SAH were more likely to develop hydrocephalus. Evaluating the pattern and duration of subarachnoid hemorrhage may allow better prediction of outcomes in patients with angiogram negative and non-PMH.

Repeat Catheter Angiography in Patients with Aneurysmal-Pattern Angiographically Negative Subarachnoid Hemorrhage.

A significant proportion of patients with subarachnoid hemorrhage have a normal cerebral angiogram. Patients with angiographically negative subarachnoid hemorrhage (anSAH) with either perimesencephalic- (panSAH) or aneurysmal-pattern hemorrhage (aanSAH, also known as diffuse anSAH) have an excellent prognosis, but only if underlying vascular abnormalities are completely excluded. The rate of occult aneurysms in patients with aanSAH varies widely across studies. The purpose of this study was to quantify the value of repeat DSA in these patients. We reviewed the records of all patients initially diagnosed with aanSAH after a screening DSA at a single tertiary neurovascular referral center from January 2006-April 2018. Patients with panSAH and traumatic SAH were excluded. We also performed a systematic review and meta-analysis of positive second DSAs in previously published case series of patients with aanSAH who underwent two serial DSAs. For meta-analysis, PubMed Central, MEDLINE and Cochrane Library databases were searched for pertinent studies up to November 2019. The rate of aneurysm detection on repeat angiography was extracted from each study. Pooled rates for positive second angiogram were calculated as untransformed proportions in a binary random-effects model meta-analysis. Inter-study heterogeneity was calculated using an I2 statistic. Three of 27 patients (11.1%) with aanSAH and at least two DSAs were subsequently found to have a cerebral aneurysm in our institutional dataset. Twenty-six studies in our systematic review met inclusion criteria, and the pooled rate of positive second angiogram was 10.4% (95% CI 7.3%-13.5%, P < 0.001). Substantial inter-study heterogeneity was observed in the meta-analysis (I2 = 61.7%, P < 0.001). One in 10 patients with aanSAH has an occult ruptured aneurysm. A second-look DSA should be strongly considered in these cases.

In Reply to the Letter to the Editor Regarding “Determining the Diagnostic Utility of Lumbar Punctures in CT Negative Suspected Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis”

In Reply to the Letter to the Editor Regarding “Determining the Diagnostic Utility of Lumbar Punctures in CT Negative Suspected Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis”

Letter to the Editor Regarding “Determining the Diagnostic Utility of Lumbar Punctures in CT Negative Suspected Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis”

Letter to the Editor Regarding “Determining the Diagnostic Utility of Lumbar Punctures in CT Negative Suspected Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis”

Determining the Diagnostic Utility of Lumbar Punctures in Computed Tomography Negative Suspected Subarachnoid Hemorrhage: A Systematic Review and Meta-analysis

While headache is a common neurologic symptom, subarachnoid hemorrhage (SAH) is a rare and potentially catastrophic cause of sudden-onset severe headache. The utility of the imaging modalities and interventional procedures are central to the investigation of the causes of headache; however, they are not without their limitations, risks, and complications. A meta-analysis in accordance with the Preferred Reporting for Systematic Reviews and Meta-analysis guidelines was conducted searching PubMed, EMBASE, and Google Scholar. Patients investigated for suspected subarachnoid hemorrhage (SAH) with a negative computed tomography (CT) and positive lumbar puncture (LP) and final diagnosis of SAH were included. The sensitivity of LP in the context of a negative CT and vsubsequent imaging confirming the cause of SAH (computed tomography angiography, magnetic resonance angiography, digital subtraction angiography [DSA]) was quantified. The pooled data were analyzed using the DerSimonian-Laid random effects model. Four studies with 2782 patients who presented with headache suspicious for SAH were included with an initial negative CT report and a subsequent LP to rule out SAH. All included studies had an observational prospective cohort design. A combined pooled proportion of 0.383 (0.077, 0.756); 0.086 (0.007, 0.238); and 0.22 (0.04, 0.49) forLP+, DSA+, and DSA/computed tomography angiography+ investigations were estimated with a 95% confidence interval. The current clinical workflow of an LP after a negative CT head for a patient presenting with a sudden-onset severe headache is observed to have a high enough proportion to warrant its continued use despite the sensitivity of modern CT scanners of ≥97%.

CT negative subarachnoid hemorrhage in emergency department

CT negative subarachnoid hemorrhage in emergency department

Cognitive impairment in angiographically negative subarachnoid haemorrhage: A case-matched prospective study 1-year post-incident

IntroductionFew studies investigate cognitive outcomes in patients with angiographically negative subarachnoid haemorrhage (anSAH), which is traditionally viewed as a condition with an excellent prognosis. The aim of this study was to assess neuropsychological outcomes in a prospective cohort of anSAH patients 1-year post-event. MethodThis prospective case-controlled study of cognitive function in patients with anSAH (n = 38) recruited from the national centre for neurosurgery and compared matched controls (n = 28). The cognitive battery assessed memory, executive function, attention, visuo-spatial function, processing speed, social cognition, language, and mood. Patients were matched to controls on age, education, and premorbid intelligence. ResultsMultivariate Analysis of Variance (MANOVA) were used. Patients performed significantly worse than controls on all cognitive domain composite scores. anSAH patients had a higher frequency of impairment within encoding, executive, and processing speed domains when compared to healthy controls. Discriminant Function Analysis (DFA) indicated high sensitivity and specificity to detect cognitive impairment between groups. ConclusionAlthough the majority of patients with anSAH make an excellent physical recovery, our data show a high rate of cognitive dysfunction in patients 1-year post-incident. Cognitive impairment in anSAH is not a universal feature, and its manifestations may be more heterogeneous than previously recognised. Some impairment may be mediated by impaired speed of processing which negatively influences other cognitive domains. The profile of cognitive impairment supports a neurotoxicity hypothesis, which suggests that blood in the subarachnoid space, rather than the bleed per se, results in a diffuse pattern of cognitive deficits.

Comprehensive review of imaging of intracranial aneurysms and angiographically negative subarachnoid hemorrhage.

Intracranial aneurysms confer the risk of subarachnoid hemorrhage (SAH), a potentially devastating condition, though most aneurysms will remain asymptomatic for the lifetime of the patient. Imaging is critical to all stages of patient care for those who harbor an unruptured intracranial aneurysm (UIA), including to establish the diagnosis, to determine therapeutic options, to undertake surveillance in patients who elect not to undergo treatment or whose aneurysm(s) portends such a low risk that treatment is not indicated, and to perform follow-up after treatment. Neuroimaging is equally as important in patients who suffer an SAH. DSA remains the reference standard for imaging of intracranial aneurysms due to its high spatial and temporal resolution. As noninvasive imaging technology, such as CTA and MRA, improves, the diagnostic accuracy of such tests continues to increasingly approximate that of DSA. In cases of angiographically negative SAH, imaging protocols are necessary not only for diagnosis but also to search for an initially occult vascular lesion, such as a thrombosed, ruptured aneurysm that might be detected in a delayed fashion. Given the crucial role of neuroimaging in all aspects of care for patients with UIAs and SAH, it is incumbent on those who care for these patients, including cerebrovascular neurosurgeons, interventional neurologists and neuroradiologists, and diagnostic radiologists and neurointensivists, to understand the role of imaging in this disease and how individual members of the multispecialty team use imaging to ensure best practices to deliver cutting-edge care to these often complex cases. This review expounds on the role of imaging in the management of UIAs and ruptured intracranial aneurysms and in the workup of angiographically negative subarachnoid hemorrhage.

Radiological Management of Angiographically Negative, Spontaneous Intracranial Subarachnoid Hemorrhage: A Multicenter Study of Utilization and Diagnostic Yield.

The optimal diagnostic evaluation for patients with angiographically negative subarachnoid hemorrhage (AN-SAH) remains controversial. To assess the utilization rate and diagnostic yield of imaging tests routinely obtained in identifying a structural cause for AN-SAH. In this retrospective multicenter study, consecutive adult patients admitted with nontraumatic, AN-SAH between 01/2010 and 12/2015 were included. Patients with intraparenchymal, subdural, or epidural hematomas in addition to SAH were excluded. Outcomes studied included utilization rate, diagnostic yield, and median time from admission for the following imaging tests: initial computed tomography angiography (CTA) and digital subtraction angiography (DSA), brain and cervical spine magnetic resonance imaging (MRI), and any repeat DSA or CTA performed either during initial admission or at long-term follow-up. A total of 752 patients were included (mean age, 53 yr; 54% male). Initial CTA and DSA were performed in 89% and 100% of patients, respectively. Brain MRI was performed in 75% of patients and was positive in 0.7% of cases. Cervical spine MRI was performed in 61% of patients and was positive in 0.2% of cases. Repeat, same-admission follow-up DSA and CTA were performed in 48% and 51% of patients and were positive in 3.3% and 1% of cases, respectively. Delayed follow-up DSA and CTA after discharge were performed in 26% and 7% of patients and were positive in 2% and 3.7% of cases, respectively, all with negative prior imaging studies. Cervical spine and brain MRI have extremely low diagnostic yield, both are commonly utilized in patients with AN-SAH; while repeat DSA and CTA are utilized less commonly and have slightly higher diagnostic yield.

Short- and Long-Term Outcomes After Angiographically Negative Subarachnoid Hemorrhage

For patients with nontraumatic subarachnoid hemorrhage (SAH), the failure to identify a source of hemorrhage on a catheter angiogram (i.e.,