Spectrophotometry or Visual Inspection to Most Reliably Detect Xanthochromia in Subarachnoid Hemorrhage: Systematic Review

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.

Thunderclap headache syndrome presenting to the emergency department: an international multicentre observational cohort study

BACKGROUND

Most headache presentations to emergency departments (ED) have benign causes; however, approximately 10% will have serious pathology. International guidelines recommend that patients describing the onset of headache as 'thunderclap' undergo neuroimaging and further investigation. The association of this feature with serious headache cause is unclear. The objective of this study was to determine if patients presenting with thunderclap headache are significantly more likely to have serious underlying pathology than patients with more gradual onset and to determine compliance with guidelines for investigation.

METHODS

This was a planned secondary analysis of an international, multicentre, observational study of adult ED patients presenting with a main complaint of headache. Data regarding demographics, investigation strategies and final ED diagnoses were collected. Thunderclap headache was defined as severe headache of immediate or almost immediate onset and peak intensity. Proportion of patients with serious pathology in thunderclap and non-thunderclap groups were compared by χ² test.

RESULTS

644 of 4536 patients presented with thunderclap headache (14.2%). CT brain imaging and lumbar puncture were performed in 62.7% and 10.6% of cases, respectively. Among patients with thunderclap headache, serious pathology was identified in 10.9% (95%CI 8.7% to 13.5%) of cases-significantly higher than the proportion found in patients with a different headache onset (6.6% (95% CI 5.9% to 7.4%), p<0.001.). The incidence of subarachnoid haemorrhage (SAH) was 3.6% (95% CI 2.4% to 5.3%) in those with thunderclap headache vs 0.3% (95% CI 0.2% to 0.5%) in those without (p<0.001). All cases of SAH were diagnosed on CT imaging. Non-serious intracranial pathology was diagnosed in 87.7% of patients with thunderclap headache.

CONCLUSIONS

Thunderclap headache presenting to the ED appears be associated with higher risk for serious intracranial pathology, including SAH, although most patients with this type of headache had a benign cause. Neuroimaging rates did not align with international guidelines, suggesting potential need for further work on standardisation.

Assessment of diagnostic strategies based on risk stratification for aneurysmal subarachnoid hemorrhage: a retrospective chart review

BACKGROUND AND IMPORTANCE

Current guidelines recommend noncontrast computed tomography (NCCT) followed by lumbar puncture for the diagnosis of subarachnoid hemorrhage (SAH). Alternative strategies, including clinical risk stratification and CT angiography (CTA), are emerging.

OBJECTIVE

To evaluate alternative strategies to current guidelines through clinical risk stratification.

DESIGN, SETTING AND PARTICIPANTS

Single-site, retrospective observational study of patients with SAH suspicion, from 2011 to 2016. We combined results of each investigation (NCCT, CTA and lumbar puncture) with a clinical risk assessment, including Ottawa score.

EXPOSURE

Comparing the current strategy (NCCT ± lumbar puncture if negative CT) to alternative strategies (NCCT + CTA ± lumbar puncture if high clinical risk or negative CT and onset of headache ≥12 h o dds ratio ≥24 h).

OUTCOME MEASURE AND ANALYSIS

Main outcome was diagnosis of SAH at hospital discharge. Secondary outcomes were death from all causes and need for invasive procedures at 28 days. We used sensitivity, specificity, positive predictive value and negative predictive value (NPV) to evaluate the diagnostic performance of three strategies.

MAIN RESULTS

310 patients were included. SAH was diagnosed in 8 cases (2.6%), none died and 7 (2.2%) had a surgical procedure. Performances of different strategies were not statistically different. NPVs were 99.7% [95% Confidence interval (CI), 98.2-100%] for strategy 1 and 100% (95% CI, 98.8-100%) for strategies 2 and 3. More than 4000 lumbar punctures are needed to diagnose one SAH when CTA is performed within 24 h of symptoms' onset and absence of high-risk criteria.

CONCLUSION

Clinical risk stratification and CTA strategy are well-tolerated and effective for diagnosis of SAH, avoiding systematic use of lumbar puncture.

Uninterpretable cerebrospinal fluid absorbance scans caused by antibiotic therapy

BACKGROUND

The revised national guidelines for analysis of cerebrospinal fluid for bilirubin in suspected subarachnoid haemorrhage (UK) provide an objective means of assessing cerebrospinal fluid samples to determine the risk of subarachnoid haemorrhage. The guidelines are intended for general use, but samples rendered uninterpretable due to the presence of the antibiotic doxycycline have been described. Here, further cases of antibiotic-based interference, and their implications, are presented.

METHODS

An archival search of cerebrospinal fluid spectra performed at Hallands County Hospital Halmstad was performed for the years 2011 and 2016-2019 in an attempt to locate instances of interference. Each case of suspected interference was further investigated with in vitro reproduction experiments as a means of confirmation and assessment of potential clinical impact.

RESULTS

A total of 10 cases of cerebrospinal fluid curve interference were discovered: six due to doxycycline, three due to metronidazole and one due to tetracycline. Interference caused by the tetracycline class was revealed through in vitro experimentation to cause an apparent decrease in the sample's net bilirubin absorbance; the presence of xanthochromia on visual inspection was, however, conserved.

CONCLUSIONS

The problem of cerebrospinal fluid absorbance curve interference might be more common than previously suspected. Due to the potential net bilirubin absorbance-lowering effect of tetracyclines, the author recommends visual examination of cerebrospinal fluid samples in every case.

A step-by-step guide for microsurgical collection of uncontaminated cerebrospinal fluid from rat cisterna magna

BACKGROUND

Cerebrospinal fluid (CSF) analysis is of significant clinical importance for the diagnosis of diseases. In humans, CSF is easily accessible and can be collected using minimally invasive methods. However, obtaining uncontaminated CSF from rats is still challenging.

NEW METHOD

This study described a microsurgical technique for sampling large quantities (>200 μL) of clear and non-blood-contaminated CSF from the rat cisterna magna in a comprehensible step-by-step guide and provided a graphical visualization.

RESULTS

CSF was sampled in 5-10 min (n = 29 animals; average surgical time 7.6 min). In visual control, 28 samples (97 %) of clear and uncontaminated CSF were obtained. The volume of CSF collected was 124-337 μL, with an average volume of 207 μL/sample. Using the Valsalva maneuver, we could collect higher volumes (up to 400 μL) several times.

COMPARISON WITH EXISTING METHOD(S)

There is no need for special surgical skills to perform this method accurately. The method takes a few minutes longer than a percutaneous puncture (<1 min in pups). However, the volume of CSF obtained using the percutaneous approach in adult rats (50-70 μL) is comparatively low.

CONCLUSIONS

We described a practical method of sampling CSF from rats that enables large volumes of CSF to be collected without blood contamination. No special surgical skills are required to use this method. With proper practice, the time between skin incision and CSF sampling is <10 min. Depending on the experimental design requirements, some additional time must be planned for wound closure.

Analysis of blood degradation products and ferritin in the cerebrospinal fluid of dogs with acute thoracolumbar intervertebral disk extrusion, a prospective pilot study

Background

Hemorrhage in the spinal canal leads to further damage of the spinal cord influencing outcome in dogs with intervertebral disk (IVD) extrusion. The aim of the study was to evaluate blood degradation products and ferritin in the cerebrospinal fluid (CSF) of dogs with thoracolumbar IVD extrusion, and their association to clinical parameters and MRI findings.

Results

In the CSF of dogs with IVD extrusion, both net oxyhemoglobin absorption (NOA) and net bilirubin absorption (NBA) were significantly higher compared to the control groups of dogs with steroid responsive meningitis arteritis (SRMA) and idiopathic epilepsy (IE) (P < 0.001), but NOA compared to the idiopathic epilepsy group contaminated artificially with blood (IEc) was not (P = 0.890). Ferritin concentration was significantly higher in dogs with IVD extrusion compared to dogs with IE (P = 0.034), but not to dogs with SRMA (P = 0.526). There was no association between NOA, NBA or ferritin concentration and severity or duration of clinical signs. In dogs with a higher ferritin concentration the outcome was better (P = 0.018). In dogs with evidence of hemorrhage on MRI, NOA and NBA were significantly higher (P = 0.016, P = 0.009), but not ferritin (P = 0.0628).

Conclusion and clinical importance

Quantification of blood degradation products and ferritin in the CSF of dogs to assess subarachnoidal hemorrhage is feasible; however, larger case numbers are needed to evaluate the relevance of NBA and ferritin as prognostic indicators.

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.

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.

Clinical and diagnostic findings in patients with elevated cerebrospinal bilirubin

INTRODUCTION

Cerebrospinal fluid (CSF) spectroscopy can identify subarachnoid haemorrhage (SAH) when CT is negative in patients presenting with acute severe headache. The primary objective of this study was to evaluate the clinical use and usefulness of CSF spectrophotometry. Secondary objectives were to identify other causes of elevated CSF bilirubin, to analyse headache descriptions and to compare clinical features in patients with an elevated CSF bilirubin among those with and without an intracranial vascular cause of SAH (avSAH).

METHODS

Consecutive patients admitted to two hospitals in Enniskillen and Londonderry between 1 January 2004 and 30 September 2014 with CSF spectroscopy bilirubin results were identified from a clinical chemistry laboratory dataset. Patients with elevated CSF bilirubin were studied. Clinical demographics, delays to investigation and final diagnoses were recorded. Patients with avSAH were compared with patients without avSAH.

RESULTS

Among 1813 patients with CSF spectrophotometry results, requests increased more than threefold during the study (p<0.001). Fifty-six patients had elevated CSF bilirubin. Ten (17.9%) had avSAH, of which 8 (14.3%) had aneurysmal SAH. Non-vascular causes of elevated CSF bilirubin included meningitis, spontaneous intracranial hypotension and carcinomatous meningitis. Headache descriptions varied. Time from headache onset to admission, CT scan and lumbar puncture did not differ significantly for patients with avSAH and non-avSAH. CSF red cell counts were higher among patients with avSAH than patients with non-avSAH (p=0.005).

CONCLUSIONS

CSF bilirubin measurement has an important role in identifying avSAH in CT-negative patients presenting with a thunderclap headache. Better clinical selection of patients is required as CSF spectrophotometry, although sensitive, is not specific for SAH.

Differentiation between traumatic tap and aneurysmal subarachnoid hemorrhage: prospective cohort study

OBJECTIVES

To describe the findings in cerebrospinal fluid from patients with acute headache that could distinguish subarachnoid hemorrhage from the effects of a traumatic lumbar puncture.

DESIGN

A substudy of a prospective multicenter cohort study.

SETTING

12 Canadian academic emergency departments, from November 2000 to December 2009.

PARTICIPANTS

Alert patients aged over 15 with an acute non-traumatic headache who underwent lumbar puncture to rule out subarachnoid hemorrhage.

MAIN OUTCOME MEASURE

Aneurysmal subarachnoid hemorrhage requiring intervention or resulting in death.

RESULTS

Of the 1739 patients enrolled, 641 (36.9%) had abnormal results on cerebrospinal fluid analysis with >1 × 10(6)/L red blood cells in the final tube of cerebrospinal fluid and/or xanthochromia in one or more tubes. There were 15 (0.9%) patients with aneurysmal subarachnoid hemorrhage based on abnormal results of a lumbar puncture. The presence of fewer than 2000 × 10(6)/L red blood cells in addition to no xanthochromia excluded the diagnosis of aneurysmal subarachnoid hemorrhage, with a sensitivity of 100% (95% confidence interval 74.7% to 100%) and specificity of 91.2% (88.6% to 93.3%).

CONCLUSION

No xanthochromia and red blood cell count <2000 × 10(6)/L reasonably excludes the diagnosis of aneurysmal subarachnoid hemorrhage. Most patients with acute headache who meet this cut off will need no further investigations and aneurysmal subarachnoid hemorrhage can be excluded as a cause of their headache.

Benefit of cerebrospinal fluid spectrophotometry in the assessment of CT scan negative suspected subarachnoid haemorrhage: a diagnostic accuracy study

This study aimed to determine if performing cerebrospinal fluid spectrophotometry in addition to visual inspection detects more ruptured cerebral aneurysms than performing cerebrospinal fluid visual inspection alone in patients with a normal head CT scan but suspected of suffering an aneurysmal subarachnoid haemorrhage (SAH). We performed a single-centre retrospective study of patients presenting to the emergency department of a tertiary hospital who underwent both head CT scan and lumbar puncture to exclude SAH. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of an approach utilising both spectrophotometry and visual inspection (combined approach) was compared to visual inspection alone. A total of 409 patients (mean age 37.8 years, 56.2% female) were recruited and six (1.5%) had a cerebral aneurysm on angiography. The sensitivity of visual inspection was 50% (95% confidence interval [CI]: 12.4-82.6%), specificity was 99% (95% CI: 97.5-99.7%), PPV was 42.9% (95% CI: 10.4-81.3%) and NPV was 99.2% (95% CI: 97.8-99.8%). The combined approach had a sensitivity of 100% (95% CI: 54.1-100%), specificity of 79.7% (95% CI: 75.4-83.5%), PPV of 6.8% (95% CI: 2.6-14.3%) and a NPV of 100% (95% CI: 98.8-100%). The sensitivity of the combined approach was not significantly different to that of visual inspection alone (p=0.25). Visual inspection had a significantly higher specificity than the combined approach (p<0.01). The combined approach detected more cases of aneurysmal SAH than visual inspection alone, however the difference in sensitivity was not statistically significant. Visual xanthochromia should prompt angiography because of a superior specificity and PPV. Due to its reduced sensitivity, caution should be applied when using only visual inspection of the supernatant.