Ruptured aneurysmal subarachnoid hemorrhage in the emergency department: Clinical outcome of patients having a lumbar puncture for red blood cell count, visual and spectrophotometric xanthochromia after a negative computed tomography

Visual inspection versus spectrophotometry for xanthochromia detection in patients with sudden onset severe headache-A diagnostic accuracy study

OBJECTIVE

There is still disagreement about whether to routinely use spectrophotometry to detect xanthochromia in cerebrospinal fluid (CSF) or whether visual inspection is adequate. We aimed to evaluate the diagnostic accuracy of these methods in detecting an aneurysmal subarachnoid hemorrhage in patients with sudden onset severe headache.

BACKGROUND

When a patient presents to the emergency department with a headache for which there is suspicion of a subarachnoid hemorrhage, the gold standard to rule this out is to perform a CSF analysis for xanthochromia with or without spectrophotometry if the cranial non-contrast computed tomography (CT) upon admission is negative.

METHODS

Having applied the gold standard, we retrospectively included patients with acute headache who underwent both CT scan and CSF spectrophotometry at our hospital in the period 2002-2020. Patients were excluded if the cranial CT was interpreted as positive, there was a bloody CSF, or if visual assessment data of the CSF was unavailable. We scrutinized the patients' medical records and evaluated the benefit of spectrophotometry compared to visual inspection. The net bilirubin absorbance cut-off for support of subarachnoid hemorrhage was set at >0.007 absorbance units. The spectrophotometry was also considered positive if the net bilirubin absorbance was ≤0.007 and net oxyhemoglobin absorbance was ≥0.1 absorbance units. We calculated and compared the sensitivity and specificity of CSF spectrophotometry and visual inspection of the CSF.

RESULTS

In total, 769 patients, with a mean age of 42.3 ± (standard deviation [SD] = 17.3) years, were included. The headache onset was classified as a thunderclap headache in 41.5%, and 4.7% had a sudden loss of consciousness. Fifteen patients (2%) were finally diagnosed with a subarachnoid hemorrhage, six (0.8%) had an aneurysmal subarachnoid hemorrhage, seven (0.9%) had a perimesencephalic hemorrhage, one (0.1%) had a cortical cerebral sinus venous thrombosis, and one (0.1%) had a spinal epidural hematoma. Four patients (0.5%) had a subarachnoid hemorrhage that was not detected by visual inspection, and two were caused by an aneurysmal rupture. One of these two patients died just before intervention, and the other underwent coiling for an anterior communicating aneurysm. The number needed for lumbar puncture to detect a subarachnoid hemorrhage was 51, but 128 to detect an aneurysmal hemorrhage. The corresponding numbers needed for CSF spectrophotometric analysis were 192 and 385, respectively. Spectrophotometry was positive in 31 patients (4.0%), of whom 18 (2.3%) also had visually detected xanthochromia (11 true positive). The mean net bilirubin absorbance in the 13 samples with visually clear CSF was 0.0111 ± (SD = 0.0103) absorbance units, compared to 0.0017 ± (SD = 0.0013) in the CSF with negative spectrophotometry. The corresponding figures for net oxyhemoglobin absorbance were 0.0391 ± (SD = 0.0522) versus 0.0057 ± (SD = 0.0081). The sensitivity of spectrophotometric xanthochromia detection was 100% (95% confidence interval [CI], 78-100), compared to 73% (95% CI, 45-92) for visual xanthochromia detection. The specificity of spectrophotometric xanthochromia detection was 98% (95% CI, 97-99) compared to 99% (95% CI, 98-100) for visual xanthochromia detection. Both methods had high negative predictive values: 100% (95% CI, 99.5-100) versus 99.5% (95% CI, 98.6-99.9), respectively.

CONCLUSIONS

Both visual inspection and spectrophotometry have high diagnostic accuracy for detecting CSF xanthochromia, but the lower sensitivity of visual assessment makes it unreliable, and we recommend the use of spectrophotometry in clinical practice.

Shifts in Diagnostic Testing for Headache in the Emergency Department, 2015 to 2021

Importance

Subarachnoid hemorrhage is typically diagnosed by noncontrast head computed tomography (CT); lumbar puncture is recommended if computed tomography is nondiagnostic, although CT cerebral angiography has been promoted as an alternative to lumbar puncture in this diagnostic pathway. The outcomes of this debate in practice have not been studied.

Objective

To determine whether CT cerebral angiography use has increased in lieu of lumbar puncture among emergency department (ED) patients with headache, with an increase in unruptured intracranial aneurysm detection.

Design, Setting, and Participants

This retrospective cohort study took place in 21 community EDs of an integrated health care system in Northern California between 2015 and 2021. Participants were adult (aged >17 years) health plan members with a chief concern of headache. Exclusions were prior diagnoses of subarachnoid hemorrhage, unruptured intracranial aneurysm, cerebral arteriovenous malformation, or cerebrospinal fluid shunt. Data were analyzed from October to November 2023.

Exposures

CT cerebral angiography and/or lumbar puncture during the ED encounter.

Main Outcomes and Measures

Primary and secondary outcomes were 14-day and 90-day unruptured intracranial aneurysm detection, respectively. Safety outcomes were missed diagnoses of subarachnoid hemorrhage or bacterial meningitis. The annual incidence of unruptured intracranial aneurysm detection was normalized to the incidence of subarachnoid hemorrhage (UIA:SAH ratio). Average annualized percentage changes were quantified using joinpoint regression analysis.

Results

Among 198 109 included ED encounters, the mean (SD) age was 47.5 (18.4) years; 140 001 patients (70.7%) were female; 29 035 (14.7%) were Black or African American, 59 896 (30.2%) were Hispanic or Latino, and 75 602 (38.2%) were White. Per year, CT cerebral angiography use increased (18.8%; 95% CI, 17.7% to 20.3%) and lumbar punctures decreased (-11.1%; 95% CI, -12.0% to -10.4%), with a corresponding increase in the 14-day UIA:SAH ratio (3.5%; 95% CI, 0.9% to 7.4%). Overall, computed tomography cerebral angiography use increased 6-fold relative to lumbar puncture, with a 33% increase in the detection of UIA. Results were similar at 90 days and robust to sensitivity analyses. Subarachnoid hemorrhage (1004 cases) and bacterial meningitis (118 cases) were misdiagnosed in 5% and 18% of cases, respectively, with no annual trends (P = .34; z1003 = .95 and P = .74; z117 = -.34, respectively).

Conclusions and Relevance

In this cohort study of ED patients with headache, increases in CT cerebral angiography use were associated with fewer lumbar punctures and higher detection of unruptured intracranial aneurysms, with no significant change in missed diagnoses of subarachnoid hemorrhage or bacterial meningitis. While this shift in diagnostic strategy appeared safe in the short-term, the long-term consequences remain unclear.

Subarachnoid haemorrhage or traumatic lumbar puncture. Differentiation by cerebrospinal fluid parameters in a multivariable approach

Lumbar puncture (LP) is recommended in patients with thunderclap headache and negative computed tomography to rule out spontaneous subarachnoid haemorrhage (SAH). Blood contamination of cerebrospinal fluid (CSF) due to traumatic LP poses a diagnostic dilemma. Therefore, routine CSF parameters were investigated to distinguish between SAH and a traumatic LP. CSF red blood cell (RBC), white blood cell (WBC) count, total protein, CSF colour and supernatant were used for group comparisons of patients with SAH and 'symptomatic controls'. Due to variable time intervals between bleeding onset and LP in SAH patients in contrast to patients with traumatic LP, where blood contamination of CSF occurs at the time of LP, CSF variables were adjusted for decay in time to allow comparability. Logistic regression analysis identified bloody CSF [odds ratio (OR) 32.6], xanthochromic supernatant [OR 15.5] and WBCadjusted [OR 4.5 (per increase of 100/µl)] as predictors of SAH, while age, sex and CSF total proteinadjusted were no predictors. Optimal cut-point of RBCadjusted (determined at day 1 after bleeding) was > 3667/µl to identify SAH patients with a 97% sensitivity and 94% specificity. Combination of low RBC and clear CSF supernatant was found in none of SAH patients. Combined CSF RBC count and CSF supernatant reliably distinguished traumatic LP from SAH.

Worth the risk? Contemporary indications, yield and complications of lumbar punctures in a metropolitan Australian health service

BACKGROUND

Performing lumbar punctures carries a risk of harm to the patient, but the information cerebrospinal fluid provides often makes this procedure necessary. Clinicians in the Australian setting would benefit from having more information on these procedures, in order to help them in a risk versus benefit analysis.

AIMS

To describe the contemporary indications, cerebrospinal fluid findings and complications of lumbar punctures in a metropolitan Australian health service.

METHODS

Retrospective electronic medical records audit of lumbar punctures performed on 525 adults within three acute hospitals between 1 July 2018 and 30 June 2019. Main outcome measures include frequency of indication for lumbar puncture by category, normal versus abnormal cerebrospinal fluid for each category, and frequency, severity and type of complications of lumbar punctures.

RESULTS

Of 525 adult lumbar punctures that were assessed in this study, 466 were performed for a diagnostic indication. The most common diagnostic indications were acute severe headache (156 procedures; 33.5%) and encephalopathy (128 procedures; 27.5%). The yield of abnormal results varied by indication category, with the above indications yielding abnormal results in 85 (54.5%) and 72 (56.3%) cases respectively. A complication was recorded in 54 (10.3% of total) procedures. The majority (45; 8.6%) of complications were minor in severity and most frequently consisted of post-dural puncture headache (PDPH).

CONCLUSIONS

In the era of an increased reliance on high quality neuroimaging, lumbar puncture has a high diagnostic yield with a low rate of major complications. The most common complication is PDPH, which is mild and self-limiting in most cases.

Management of patients presenting to the emergency department with sudden onset severe headache: systematic review of diagnostic accuracy studies

Objective

Advances in imaging technologies have precipitated uncertainty and inconsistency in the management of neurologically intact patients presenting to the Emergency Department (ED) with non-traumatic sudden onset severe headache with a clinical suspicion of subarachnoid haemorrhage (SAH). The objective of this systematic review was to evaluate diagnostic strategies in these patients.

Methods

Studies assessing any decision rule or diagnostic test for evaluating neurologically intact adults with a severe headache, reaching maximum intensity within 1 hour, were eligible. Eighteen databases (including MEDLINE and Embase) were searched. Quality was assessed using QUADAS-2. Where appropriate, hierarchical bivariate meta-analysis was used to synthesise diagnostic accuracy results.

Results

Thirty-seven studies were included. Eight studies assessing the Ottawa SAH clinical decision rule were pooled; sensitivity 99.5% (95% CI 90.8 to 100), specificity 24% (95% CI 15.5 to 34.4). Four studies assessing CT within 6 hours of headache onset were pooled; sensitivity 98.7% (95% CI 96.5 to 100), specificity 100% (95% CI 99.7 to 100). The sensitivity of CT beyond 6 hours was considerably lower (≤90%; 2 studies). Three studies assessing lumbar puncture (LP; spectrophotometric analysis) following negative CT were pooled; sensitivity 100% (95% CI 100 to 100), specificity 95% (95% CI 86.0 to 98.5).

Conclusion

The Ottawa SAH Rule rules out further investigation in only a small proportion of patients. CT undertaken within 6 hours (with expertise of a neuroradiologist or radiologist who routinely interprets brain images) is highly accurate and likely to be sufficient to rule out SAH; CT beyond 6 hours is much less sensitive. The CT–LP pathway is highly sensitive for detecting SAH and some alternative diagnoses, although LP results in some false positive results.

Evaluating xanthochromia in the diagnosis of subarachnoid haemorrhage in Scotland in the Era of modern computed tomography

AIM

Cerebrospinal fluid (CSF) analysis for xanthochromia is routinely used to exclude subarachnoid haemorrhage (SAH). In this study, we evaluated the sensitivity and specificity of xanthochromia (by NEQAS-spectrophotometry) in routine clinical practice in three acute hospitals, in patients with suspected SAH. We explored whether including CSF red cell count (RCC) with xanthochromia improved diagnostic accuracy.

METHODS

In this retrospective analysis, all xanthochromia results were assessed over three consecutive years. Clinical information and Registry data were analysed to find all patients diagnosed with SAH. We correlated xanthochromia data with clinical and radiological findings.

RESULTS

There were 1761 xanthochromia performed. Of these, 26 (1.5%) were positive, 1624 (92%) negative and 72 (4.1%) were inconclusive. Of the 26 tests that were positive, 9 (35%) had confirmed SAH, 17 (65%) were falsely positive, with no false negative tests in our series. Xanthochromia identified 6% of all SAH diagnosed in the study. Incorporating RCC <1000 with xanthochromia, reducing false positive tests by 38% and inconclusive test by 85%.

CONCLUSION

The positive yield of xanthochromia is low but identified 6% of SAH. NEQAS-spectrophotometry is an excellent diagnostic method with 100% sensitivity, 99% specificity. Incorporating RCC markedly reduces false positive and inconclusive tests reducing need for further imaging.

Diagnosis and Treatment of Unruptured Intracranial Aneurysms and Aneurysmal Subarachnoid Hemorrhage

Unruptured intracranial aneurysms (UIAs) are commonly acquired vascular lesions that form an outpouching of the arterial wall due to wall thinning. The prevalence of UIAs in the general population is 3.2%. In contrast, an intracranial aneurysm may be manifested after rupture with classic presentation of a thunderclap headache suggesting aneurysmal subarachnoid hemorrhage (SAH). Previous consensus suggests that although small intracranial aneurysms (<7 mm) are less susceptible to rupture, aneurysms larger than 7 mm should be treated on a case-by-case basis with consideration of additional risk factors of aneurysmal growth and rupture. However, this distinction is outdated. The PHASES score, which comprises data pooled from several prospective studies, provides precise estimates by considering not only the aneurysm size but also other variables, such as the aneurysm location. The International Study of Unruptured Intracranial Aneurysms is the largest observational study on the natural history of UIAs, providing the foundation to the current guidelines for the management of UIAs. Although SAH accounts for only 3% of all stroke subtypes, it is associated with considerable burden of morbidity and mortality. The initial management is focused on stabilizing the patient in the intensive care unit with close hemodynamic and serial neurologic monitoring with endovascular or open surgical aneurysm treatment to prevent rebleeding. Since the results of the International Subarachnoid Aneurysm Trial, treatment of aneurysmal SAH has shifted from surgical clipping to endovascular coiling, which demonstrated higher odds of survival free of disability at 1 year after SAH. Nonetheless, aneurysmal SAH remains a public health hazard and is associated with high rates of disability and death.

Subarachnoid hemorrhage in the emergency department

BACKGROUND

Subarachnoid hemorrhage accounts for more than 30,000 cases of stroke annually in North America and encompasses a 4.4% mortality rate. Since a vast number of subarachnoid hemorrhage cases present in a younger population and can range from benign to severe, an accurate diagnosis is imperative to avoid premature morbidity and mortality. Here, we present a straightforward approach to evaluating, risk stratifying, and managing subarachnoid hemorrhages in the emergency department for the emergency medicine physician.

DISCUSSION

The diversities of symptom presentation should be considered before proceeding with diagnostic modalities for subarachnoid hemorrhage. Once a subarachnoid hemorrhage is suspected, a computed tomography of the head with the assistance of the Ottawa subarachnoid hemorrhage rule should be utilized as an initial diagnostic measure. If further investigation is needed, a CT angiography of the head or a lumbar puncture can be considered keeping risks and limitations in mind. Initiating timely treatment is essential following diagnosis to help mitigate future complications. Risk tools can be used to assess the complications for which the patient is at greatest.

CONCLUSION

Subarachnoid hemorrhages are frequently misdiagnosed; therefore, we believe it is imperative to address the diagnosis and initiation of early management in the emergency medicine department to minimize poor outcomes in the future.

The value of repeated lumbar puncture to test for xanthochromia, in patients with clinical suspicion of subarachnoid haemorrhage, with CT-negative and initial traumatic tap

OBJECTIVES

For the diagnosis of subarachnoid haemorrhage (SAH), the presence of cerebrospinal fluid (CSF) xanthochromia is still considered the gold standard for patients with a thunderclap headache, in the absence of blood on brain CT scan. However, a traumatic lumbar puncture (LP) typically results in high concentrations of oxyhaemoglobin in CSF, impairing the detection of xanthochromia and preventing the reliable exclusion of SAH. In this context, the value of a repeat lumbar puncture has not yet been described.

MATERIALS AND METHODS

A retrospective case series of suspected SAH patients, with a negative CT scan and initial traumatic LP, managed with a repeat LP to assess for CSF xanthochromia. Clinical notes, laboratory and imaging results were reviewed.

RESULTS

Between August 2011 and January 2020, 31 patients with suspected SAH were referred to our neurosurgical unit following negative CT and traumatic LP. A repeat LP was performed in 7 of the 31 patients, 2.4 days (±0.79 SD) after the first traumatic LP. CSF spectrophotometry analysis from repeated LP in all 7 patients was negative for xanthochromia. No adverse clinical events were recorded on average 18 months following discharge.

CONCLUSION

A repeat LP performed following a traumatic tap can still yield xanthochromia-negative CSF, thereby, excluding SAH, avoiding unnecessary invasive angiography and overall promoting the safer management of these patients.

Epigenetic mechanisms of neurodegenerative diseases and acute brain injury

Epigenetic modifications are emerging as major players in the pathogenesis of neurodegenerative disorders and susceptibility to acute brain injury. DNA and histone modifications act together with non-coding RNAs to form a complex gene expression machinery that adapts the brain to environmental stressors and injury response. These modifications influence cell-level operations like neurogenesis and DNA repair to large, intricate processes such as brain patterning, memory formation, motor function and cognition. Thus, epigenetic imbalance has been shown to influence the progression of many neurological disorders independent of aberrations in the genetic code. This review aims to highlight ways in which epigenetics applies to several commonly researched neurodegenerative diseases and forms of acute brain injury as well as shed light on the benefits of epigenetics-based treatments.

Is there a role for lumbar puncture in early detection of subarachnoid hemorrhage after negative head CT?

To investigate the role of lumbar puncture (LP) after a negative head computed tomography (CT) when ruling out subarachnoid hemorrhage (SAH) within 24 h of symptom onset. In a single-center, retrospective cohort study, we studied a consecutive series of patients from 2011 to 2015. All patients underwent CT or CT following LP to rule out SAH. Patients were categorized into four groups depending on the time of symptom onset to initial head CT: 0-6 h, 6-12 h, 12-24 h, and over 24 h. Experienced radiologists interpreted all CT scans. We investigated the sensitivity, specificity, and negative predictive value (NPV) of noncontrast CT in detecting SAH. Of 539 patients with suspected SAH and negative CT, 280 (51.9%) had their CT performed within 24 h of symptom onset. None of these patients had SAH. Five (1.9%) out of 259 patients with CT performed after 24 h of symptom onset had SAH diagnosed, and two turned out to be aneurysmal. When CT was performed within 24 h of symptom onset it had a sensitivity of 100% (95% CI 95-100%), specificity of 98% (95% CI 96-99.7%), and NPV of 100% (95% CI 98-100%) in detecting SAH. Modern CT scanners seem to have high sensitivity and specificity in the diagnosis of SAH when performed within 24 h of symptom onset. Beyond this point, CT seems to lack sensitivity and further investigation with LP is required.

Toward Understanding Non-coding RNA Roles in Intracranial Aneurysms and Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a common and frequently life-threatening cerebrovascular disease, which is mostly related with a ruptured intracranial aneurysm. Its complications include rebleeding, early brain injury, cerebral vasospasm, delayed cerebral ischemia, chronic hydrocephalus, and also non neurological problems. Non-coding RNAs (ncRNAs), comprising of microRNAs (miRNAs), small interfering RNAs (siRNAs) and long non-coding RNAs (lncRNAs), play an important role in intracranial aneurysms and SAH. Here, we review the non-coding RNAs expression profile and their related mechanisms in intracranial aneurysms and SAH. Moreover, we suggest that these non-coding RNAs function as novel molecular biomarkers to predict intracranial aneurysms and SAH, and may yield new therapies after SAH in the future.

Spontaneous Subarachnoid Hemorrhage: A Systematic Review and Meta-analysis Describing the Diagnostic Accuracy of History, Physical Examination, Imaging, and Lumbar Puncture With an Exploration of Test Thresholds

BACKGROUND

Spontaneous subarachnoid hemorrhage (SAH) is a rare, but serious etiology of headache. The diagnosis of SAH is especially challenging in alert, neurologically intact patients, as missed or delayed diagnosis can be catastrophic.

OBJECTIVES

The objective was to perform a diagnostic accuracy systematic review and meta-analysis of history, physical examination, cerebrospinal fluid (CSF) tests, computed tomography (CT), and clinical decision rules for spontaneous SAH. A secondary objective was to delineate probability of disease thresholds for imaging and lumbar puncture (LP).

METHODS

PubMed, Embase, Scopus, and research meeting abstracts were searched up to June 2015 for studies of emergency department patients with acute headache clinically concerning for spontaneous SAH. QUADAS-2 was used to assess study quality and, when appropriate, meta-analysis was conducted using random effects models. Outcomes were sensitivity, specificity, and positive (LR+) and negative (LR-) likelihood ratios. To identify test and treatment thresholds, we employed the Pauker-Kassirer method with Bernstein test indication curves using the summary estimates of diagnostic accuracy.

RESULTS

A total of 5,022 publications were identified, of which 122 underwent full-text review; 22 studies were included (average SAH prevalence = 7.5%). Diagnostic studies differed in assessment of history and physical examination findings, CT technology, analytical techniques used to identify xanthochromia, and criterion standards for SAH. Study quality by QUADAS-2 was variable; however, most had a relatively low risk of biases. A history of neck pain (LR+ = 4.1; 95% confidence interval [CI] = 2.2 to 7.6) and neck stiffness on physical examination (LR+ = 6.6; 95% CI = 4.0 to 11.0) were the individual findings most strongly associated with SAH. Combinations of findings may rule out SAH, yet promising clinical decision rules await external validation. Noncontrast cranial CT within 6 hours of headache onset accurately ruled in (LR+ = 230; 95% CI = 6 to 8,700) and ruled out SAH (LR- = 0.01; 95% CI = 0 to 0.04); CT beyond 6 hours had a LR- of 0.07 (95% CI = 0.01 to 0.61). CSF analyses had lower diagnostic accuracy, whether using red blood cell (RBC) count or xanthochromia. At a threshold RBC count of 1,000 × 10(6) /L, the LR+ was 5.7 (95% CI = 1.4 to 23) and LR- was 0.21 (95% CI = 0.03 to 1.7). Using the pooled estimates of diagnostic accuracy and testing risks and benefits, we estimate that LP only benefits CT-negative patients when the pre-LP probability of SAH is on the order of 5%, which corresponds to a pre-CT probability greater than 20%.

CONCLUSIONS

Less than one in 10 headache patients concerning for SAH are ultimately diagnosed with SAH in recent studies. While certain symptoms and signs increase or decrease the likelihood of SAH, no single characteristic is sufficient to rule in or rule out SAH. Within 6 hours of symptom onset, noncontrast cranial CT is highly accurate, while a negative CT beyond 6 hours substantially reduces the likelihood of SAH. LP appears to benefit relatively few patients within a narrow pretest probability range. With improvements in CT technology and an expanding body of evidence, test thresholds for LP may become more precise, obviating the need for a post-CT LP in more acute headache patients. Existing SAH clinical decision rules await external validation, but offer the potential to identify subsets most likely to benefit from post-CT LP, angiography, or no further testing.

False-negative Interpretations of Cranial Computed Tomography in Aneurysmal Subarachnoid Hemorrhage

OBJECTIVES

Prior studies examining the sensitivity of cranial computed tomography (CT) for the detection of subarachnoid hemorrhage (SAH) have used the final radiology report as the reference standard. However, optimal sensitivity may have been underestimated due to misinterpretation of reportedly normal cranial CTs. This study aims to estimate the incidence of missed CT evidence of SAH among a cohort of patients with aneurysmal SAH (aSAH).

METHODS

We performed a retrospective chart review of emergency department (ED) encounters within an integrated health delivery system between January 2007 and June 2013 to identify patients diagnosed with aSAH. All initial noncontrast CTs from aSAH cases diagnosed by lumbar puncture (LP) and angiography following a reportedly normal noncontrast cranial CT (CT-negative aSAH) were then reviewed in a blinded, independent fashion by two board-certified neuroradiologists to assess for missed evidence of SAH. Reviewers rated the CT studies as having definite evidence of SAH, probable evidence of SAH, or no evidence of SAH. Control patients who underwent a negative evaluation for aSAH based on cranial CT and LP results were also included at random in the imaging review cohort.

RESULTS

A total of 452 cases of aSAH were identified; 18 (4%) were cases of CT-negative aSAH. Of these, seven (39%) underwent cranial CT within 6 hours of headache onset, and two (11%) had their initial CTs formally interpreted by board-certified neuroradiologists. Blinded independent CT review revealed concordant agreement for either definite or probable evidence of SAH in nine of 18 (50%) cases overall and in five of the seven (71%) CTs performed within 6 hours of headache onset. Inter-rater agreement was 83% for definite SAH and 72% for either probable or definite SAH.

CONCLUSIONS

CT evidence of SAH was frequently present but unrecognized according to the final radiology report in cases of presumed CT-negative aSAH. This finding may help explain some of the discordance between prior studies examining the sensitivity of cranial CT for SAH.

Clinical Guidelines for the Emergency Department Evaluation of Subarachnoid Hemorrhage

BACKGROUND

Subarachnoid hemorrhage (SAH) is frequently caused by the rupture of an intracranial aneurysmal vessel or arteriovenous malformation, leading to a cascade of events that can result in severe disability or death. When evaluating for this diagnosis, emergency physicians have classically performed a noncontrast computed tomography (NCCT) scan, followed by a lumbar puncture (LP). Recently, however, as CT technology has advanced, many studies have questioned the necessity of the LP in the SAH diagnostic algorithm and have instead advocated for noninvasive techniques, such as NCCT alone or NCCT with CT angiogram (CTA).

OBJECTIVE

The primary goal of this literature search was to determine the appropriate emergency department (ED) management of patients with suspected SAH.

METHODS

A MEDLINE literature search from October 2008 to June 2015 was performed using the keywords computed tomography AND subarachnoid hemorrhage AND lumbar puncture, while limiting the search to human studies written in the English language. General review articles and single case reports were omitted. Each of the selected articles then underwent a structured review.

RESULTS

Ninety-one articles were identified, with 31 papers being considered appropriate for analysis. These studies then underwent a rigorous review from which recommendations were developed.

CONCLUSIONS

The literature search supports that NCCT followed by CTA is a reasonable approach in the evaluation of ED patients with possible SAH.