Subarachnoid Hemorrhage Diagnosis: Lumbar Puncture Is Still Needed When the Computed Tomography Scan Is Normal

Objectives: To determine the sensitivity of third-generation CT scanners for diagnosed nontraumatic subarachnoid hemorrhage (SAH) and to assess the impact of symptom duration on sensitivity.
Methods: A retrospective chart review was performed in a university-affiliated tertiary care hospital with an annual ED volume of >100,000 patients. The target population was all patients who presented to the ED from January 1991 to September 1994 with symptoms suggestive of SAH and who had a final diagnosis of nontraumatic SAH based on either a positive CT scan or positive spinal fluid analysis. Patients referred from outside facilities were included if they had a CT done at the study site. All CT scans were done using third-generation scanners. Official CT scan reports were used to categorize scans as positive or negative.
Results: There were 140 patients identified with SAH, with a mean age of 56 years (range 10–88). The sensitivity of CT in the diagnosis of nontraumatic SAH when performed at or before 12 hours of symptom duration was 100% (80/80), and 81.7% (49/60) after 12 hours of symptom duration (95% CI 95–100% and 69.5–90.4%, respectively; p < 0.0001). Eleven of the 140 patients had a negative CT and positive spinal fluid analysis, yielding an overall sensitivity of 92.1% (129/140).
Conclusion: The sensitivity of third-generation CT scans for SAH decreases with time from the onset of symptoms. In this sample population, CT was able to detect all patients scanned ^12 hours after symptom onset. Although the study demonstrated good sensitivity of CT scan reports for SAH when the scan was performed after S12 hours of symptom onset, additional real-time experience is needed to better define the potential risk of a missed SAH should this population not receive the customary lumbar puncture examination in the setting of a negative CT scan.     

Sensitivity of newer-generation computed tomography scanners for subarachnoid hemorrhage: a Bayesian analysis

Background

Subarachnoid hemorrhage (SAH) is a life-threatening condition considered in patients presenting to the emergency department (ED) with acute and severe-onset headache. Currently, the practice pattern for suspected SAH is to perform a non-contrasted computed tomography (CT) scan of the head, followed by lumbar puncture (LP) if the CT is negative. Newer-generation 16-slice CT scanners have been shown in one study to be very sensitive for SAH.

Objective

We sought to validate these findings at our institution by retrospectively analyzing the sensitivity of our 16-slice or better CT scanner and performing a bayesian analysis with the results.

Methods

We utilized ED electronic medical records and the Department of Neurosurgery research database to search for patients admitted from the ED with a diagnosis of SAH from January 1, 2005 to December 31, 2008. We found a total of 134 patients admitted with SAH during this time frame.

Results

Average age was 53.8 years; 62% were female. Presenting complaint was headache in 57%, paresthesia or weakness in 7%, unresponsive in 10%, confusion or altered mental status in 5%, and “other” in 10%. Sensitivity of 16-slice or better CT scanner in our study was 131/134, or 97.8% (95% confidence interval 93.1–99.4%). No patient with a negative CT had a lesion requiring intervention.

Conclusion

Our study confirms the high sensitivity of 16-slice or better CT scanners for SAH. This calls into question the need for LP after negative head CT when 16-slice CT or better is used.     

Subarachnoid hemorrhage diagnosis by computed tomography and lumbar puncture: Are fifth generation CT scanners better at identifying subarachnoid hemorrhage?

This study sought to determine the sensitivity and specificity of modern computed tomography (CT) scans for the diagnosis of subarachnoid hemorrhage (SAH). No studies have been done recently with fifth generation CT scanners to look at the diagnosis of SAH. A retrospective chart review was done of Emergency Department (ED), laboratory, and hospital records at Pitt County Memorial Hospital in Greenville, North Carolina over 1 year from January 1, 2002 to December 31, 2002. Patients presented with headache and had a CT scan of the head with a fifth generation multi-detector CT scanner followed by a lumbar puncture (LP) to rule out SAH. There were 177 patients who presented to the ED with headache and went on to have a CT scan and an LP to rule out SAH. No patients who had a negative CT were found to have a subarachoid hemorrhage. It is concluded that fifth generation CT scanners are probably more sensitive than earlier scanners at detecting SAH.     

Computed Tomographic Angiography for the Evaluation of Aneurysmal Subarachnoid Hemorrhage

Objectives: Computed tomography (CT) followed by lumbar puncture (LP) is currently the criterion standard for diagnosing subarachnoid hemorrhage (SAH) in the emergency department (ED); however, this is based on studies involving a limited number of patients. The authors sought to assess the ability of CT angiography (CTA), a new diagnostic modality, in conjunction with CT/LP to detect SAH. Methods: Consecutive patients presenting to the ED with symptoms concerning for SAH were approached. All patients had an intravenous catheter placed and underwent a noncontrast head CT followed by CTA. Patients whose CT did not reveal evidence of SAH or other pathology underwent LP in the ED. CTAs were read within 24 hours by a neuroradiologist blinded to the patient's history. Results: A total of 131 patients were approached, 116 were enrolled, and 106 completed the study. In six of 116 patients (5.1%), aneurysm was found on CTA with normal CT and positive findings on LP; three had a positive CTA with normal CT and LP findings (one of which had a negative cerebral angiogram), and there was one false‐positive CTA. Follow‐up of all 131 patients showed no previously undiagnosed intracranial pathology. In this patient population, 4.3% (5/116) were ultimately found to have an SAH and/or aneurysm. Conclusions: In this pilot study, CTA was found to be useful in the detection of cerebral aneurysms and may be useful in the diagnosis of aneurysmal SAH. A larger multicenter study would be useful to confirm these results.     

Lumbar Puncture First: An Alternative Model for the Investigation of Lone Acute Sudden Headache

Subarachnoid hemorrhage (SAH) is a diagnosis often considered in patients presenting to the ED with acute sudden headaches, but with normal physical examinations. Standard of care today is for these patients to be investigated by noncontrast CT scan followed by lumbar puncture (LP) for negative CTs. However, given that most investigated patients have benign headaches, most of the CT and LP results are normal. The authors studied, by means of a theoretical analysis, the impact of an alternative diagnostic model, in which LP would be the first (and, in most cases, only) diagnostic test for patients suspected of SAH who met lone acute sudden headache (LASH) criteria. Given reasonable assumptions, for every 100 patients investigated, the "LP-first" model would result in 79 to 83 fewer CT scans and only seven to 11 additional LPs, as compared with traditional strategies. Among ED headache patients meeting LASH criteria, the authors believe use of this model could result in more efficient use of resources, minimal additional morbidity, and equal diagnostic accuracy for SAH.     

Can Computed Tomography Angiography of the Brain Replace Lumbar Puncture in the Evaluation of Acute‐onset Headache After a Negative Noncontrast Cranial Computed Tomography Scan?

Objectives: The primary goal of evaluation for acute‐onset headache is to exclude aneurysmal subarachnoid hemorrhage (SAH). Noncontrast cranial computed tomography (CT), followed by lumbar puncture (LP) if the CT is negative, is the current standard of care. Computed tomography angiography (CTA) of the brain has become more available and more sensitive for the detection of cerebral aneurysms. This study addresses the role of CT/CTA versus CT/LP in the diagnostic workup of acute‐onset headache. Methods: This article reviews the recent literature for the prevalence of SAH in emergency department (ED) headache patients, the sensitivity of CT for diagnosing acute SAH, and the sensitivity and specificity of CTA for cerebral aneurysms. An equivalence study comparing CT/LP and CT/CTA would require 3,000 + subjects. As an alternative, the authors constructed a mathematical probability model to determine the posttest probability of excluding aneurysmal or arterial venous malformation (AVM) SAH with a CT/CTA strategy. Results: SAH prevalence in ED headache patients was conservatively estimated at 15%. Representative studies reported CT sensitivity for SAH to be 91% (95% confidence interval [CI] = 82% to 97%) and sensitivity of CTA for aneurysm to be 97.9% (95% CI = 88.9% to 99.9%). Based on these data, the posttest probability of excluding aneurysmal SAH after a negative CT/CTA was 99.43% (95% CI = 98.86% to 99.81%). Conclusions: CT followed by CTA can exclude SAH with a greater than 99% posttest probability. In ED patients complaining of acute‐onset headache without significant SAH risk factors, CT/CTA may offer a less invasive and more specific diagnostic paradigm. If one chooses to offer LP after CT/CTA, informed consent for LP should put the pretest risk of a missed aneurysmal SAH at less than 1%. ACADEMIC EMERGENCY MEDICINE 2010; 17:444–451 © 2010 by the Society for Academic Emergency Medicine     

Attitudes and Judgment of Emergency Physicians in the Management of Patients with Acute Headache

OBJECTIVES: There is little evidence guiding physicians in the evaluation of acute headache to rule out nontraumatic subarachnoid hemorrhage (SAH). The authors assessed emergency physicians in: 1) their pretest accuracy for predicting SAH, 2) their comfort with not ordering either head computed tomography (CT) or lumbar puncture (LP) in patients with acute headache, and 3) their comfort with not ordering head CT before performing LP in patients with acute headache. METHODS: This two-and-a-half-year prospective cohort study was conducted in three tertiary care university emergency departments with 51 emergency physicians. Consecutive patients more than 15 years of age with a nontraumatic, acute headache (onset to peak headache less than one hour) and normal results on neurologic examination were enrolled. Patients known to have cerebrospinal fluid shunt, aneurysm, or brain neoplasm, and patients with recurrent headaches of the same intensity/character as their current headache were excluded. Physicians recorded their pretest probability for SAH and their comfort with performing either no tests or an LP without first obtaining head CT. RESULTS: The authors enrolled 747 patients (mean age 42.8 years; 60.1% female; 77.0% their worst headache; 83.4% had CT and/or LP), including 50 (6.7%) with SAHs. Physicians reported being "uncomfortable" or "very uncomfortable" with performing no test in 75.4% of cases and being "uncomfortable" or "very uncomfortable" with performing LP without CT in 49.6% of cases. The area under the receiver operating characteristic (ROC) curve for SAH was 0.85 (95% CI = 0.80 to 0.91). CONCLUSIONS: Physicians were able to moderately discriminate SAH from other causes of headache before diagnostic testing.     

动脉瘤性蛛网膜下腔出血后头痛病因学分析

目的分析动脉瘤性蛛网膜下腔出血(SAH)后头痛的病因。方法对107例发病后24h内CT诊断为SAH,并经全脑动脉造影(DSA)明确存在颅内动脉瘤的患者,分别在出血后1、2、3、5、7、10、14d行头痛数字评分(NRS),对中、重度头痛患者行头颅CT和经颅三维多普勒(TCD)检查,分析头痛发生原因,观察不同类型头痛的临床特点。结果86.9%(93/107)的动脉瘤性SAH患者病程中存在中、重度头痛,其中9.7%(9/93)源自动脉瘤再出血,其临床特点是突然出现剧烈头痛或原有头痛骤然加重,常伴有意识障碍或其他神经系统阳性体征;16.1%(15/93)的头痛患者CT显示继发性脑积水,且头痛多持续性加重,但有时可突然自行缓解;TCD检查显示12.9%(12/93)的头痛患者存在颅内血管痉挛,并可因病情持续加重出现局灶性神经功能缺损及意识障碍,61.3%(57/93)的患者无阳性发现,但临床表现类似。结论大多数动脉瘤性SAH患者存在中、重度头痛。     

Prevalence of Herniation and Intracranial Shift on Cranial Tomography in Patients With Subarachnoid Hemorrhage and a Normal Neurologic Examination

Objectives: Patients frequently present to the emergency department (ED) with headache. Those with sudden severe headache are often evaluated for spontaneous subarachnoid hemorrhage (SAH) with noncontrast cranial computed tomography (CT) followed by lumbar puncture (LP). The authors postulated that in patients without neurologic symptoms or signs, physicians could forgo noncontrast cranial CT and proceed directly to LP. The authors sought to define the safety of this option by having senior neuroradiologists rereview all cranial CTs in a group of such patients for evidence of brain herniation or midline shift. Methods: This was a retrospective study that included all patients with a normal neurologic examination and nontraumatic SAH diagnosed by CT presenting to a tertiary care medical center from August 1, 2001, to December 31, 2004. Two neuroradiologists, blinded to clinical information and outcomes, rereviewed the initial ED head CT for evidence of herniation or midline shift. Results: Of the 172 patients who presented to the ED with spontaneous SAH diagnoses by cranial CT, 78 had normal neurologic examinations. Of these, 73 had initial ED CTs available for review. Four of the 73 (5%; 95% confidence interval [CI] = 2% to 13%) had evidence of brain herniation or midline shift, including three (4%; 95% CI = 1% to 12%) with herniation. In only one of these patients was herniation or shift noted on the initial radiology report. Conclusions: Awake and alert patients with a normal neurologic examination and SAH may have brain herniation and/or midline shift. Therefore, cranial CT should be obtained before LP in all patients with suspected SAH. ACADEMIC EMERGENCY MEDICINE 2010; 17:423–428 © 2010 by the Society for Academic Emergency Medicine     

蛛网膜下腔出血的DSA和CT结果研究

研究蛛网膜下腔出血的数字减影血管造影和ＣＴ检查的价值。材料与方法：对８０例２４小时内ＣＴ检查和ＳＡＨ无颅内血肿的患者行ＤＳＡ检查。结果：一次ＳＡＨ患者脑动脉瘤３２例,正常２９例,１９例二次ＳＡＨ患者全部为脉其中１６例再次出血发生在发病后７－１８天。     

Physician utilization of a portable computed tomography scanner in the intensive care unit

OBJECTIVE: To determine the utilization of a portable computed tomography (CT) scanner for critically ill adult patients in an intensive care unit (ICU). DESIGN: Survey study and retrospective review. SUBJECTS: Critical care attending staff and fellows and neurosurgery residents. SETTING: A university hospital and Level I trauma center with a multitrauma ICU, a neurotrauma ICU, and a neurosurgical ICU. INTERVENTIONS: We surveyed all physicians who ordered portable CT scans from December 1996 through June 1998. Ordering physicians included critical care attending staff and fellows (anesthesiology, surgery, internal medicine) and neurosurgery residents. Physicians who no longer worked at the institution were contacted by mail or fax. Radiology records were reviewed to determine the actual number and type of scans performed. MEASUREMENTS AND MAIN RESULTS: The survey response was 100%. Most physicians reported ordering portable head CT scans (97%), followed by chest CT (88%), abdominal CT (78%), and pelvic CT (34%) scans. Analysis of the actual number of scans performed correlated with these reports (511 head, 115 chest, 88 abdomen, and 87 pelvis). The indication for portable CT scans (as opposed to a "fixed" or "stationary" scans) cited most often was patient severity of illness (77%). Patients on extracorporeal support (93%), those with cardiovascular instability (70%), followed by those with respiratory instability (57%) and neurologic instability (40%) were deemed too ill to transport. If the portable CT scanner was unavailable, however, most physicians (67%) ordered a fixed helical CT scan and the patient was transported to the radiology suite, regardless of medical condition. CONCLUSIONS: Access to a portable CT scanner impacts the physician ordering patterns for ICU patients. We found that 100% of surveyed physicians used the portable CT scanner for critically ill patients when the patient was unstable. If the diagnostic study was deemed medically necessary, and the portable scanner was unavailable, most surveyed physicians ordered a "fixed" helical scan and the patient was transported by an experienced transport team for the study. The portable CT offered an alternative and potentially safer means of obtaining diagnostic studies.     

CT、MRI联合应用对诊断脑梗死的价值

目的：为探讨CT和MRI在对诊断脑梗死中的联合运用价值。材料与方法：对临床怀疑脑梗塞的237例病例经CT扫描，其中经CT、MRI联合扫描92例。并将结果进行对照分析。结果：急性脑梗塞CT诊断21例(N=188)。MRI诊断57例(N=65)，发病在24小时后的诊断率分别为61．2％、100％。讨论：CT和MRI联合应用对诊断脑梗死有互补作用。虽然CT扫描可以作为首选，但对早期脑梗死的诊断和确诊梗死血管的位置，应经MRI扫描，这对临床的及时处理和治疗有利。     

EPs do not accept the strategy of "lumbar puncture first" in subarachnoid hemorrhage

It has been proposed that the workup of suspected subarachnoid hemorrhage should begin with lumbar puncture (LP) rather than computed tomography (CT) scan. We investigated whether EPs would in fact advocate this strategy in an index hypothetical case and in variations of the index case. An eight-question survey was distributed to EM physicians attending national continuing medical education meetings. Questions included whether the responders would advocate "LP first" in the following scenarios: (1) the index case in which the patient's symptoms had been present for more than 12 hours, other diagnoses were very unlikely, the patient was fully insured, and CT scan was available immediately; (2) a case in which the patient is not insured; (3) a case in which the respondent is the patient; and (4) a case in which there is a delay in obtaining a CT scan. Two hundred forty-one of 275 surveys were completed for a response rate of 88%. Given the index scenario, only 22.8% of the respondents would advise patients to have an LP first versus 17.9% if they themselves were the patient (P=.11). Compared with the index scenario, 34.0% of respondents would advise LP first if their patient did not have insurance (P<.0001); a majority, 57.1%, would advise LP first if the CT were delayed (P<.0001). The "LP first" strategy for workup of subarachnoid hemorrhage was rejected by most EM physicians except when the CT scan would entail delay. Compared with the index case, an added number of physicians would advocate this strategy if the patient was uninsured. The ethical implication of advocating a strategy because of financial concerns and that most physicians would not favor for themselves or their patients merits attention.     

Computed Tomography Scanning and Delirium in Elder Patients

Objective: 1 ) To examine the ordering of head CT scans in elder patients with delirium and cognitive impairment; and 2) to report CT scan findings associated with these conditions.
Methods : This was a 2-part study. Part 1 was a prospective, observational study of 560 adults >70 years of age evaluated at 3 separate EDs using a 200-hour stratified sampling process at each ED. During Part 1, the frequencies of specific findings (i.e., delirium, impaired consciousness, and impaired cognition) and CT scan rates for these groups were determined. Part 2 was a retrospective analysis of CT scan reports and medical records ( n = 279) for patients >70 years of age in the prospective sample ( n = 79) and from a sample ( n = 200) of CT scans obtained at a fourth ED. Part 2 examined clinical findings detected in the ED to determine those factors that were associated with acute findings on CT scan.
Results : Part 1: There were 333 (59.4%) patients prospectively classified as having impaired cognition, impaired consciousness, or delirium; 79 (23.7%) of these patients had a head CT scan. Of these 3 groups, delirious patients were more frequently scanned (p < 0.001). Part 2: Of 279 CT scans, 42 (15.0%) were positive for an acute condition (hemorrhage, hematoma, space-occupying lesion, infarct). Of 42 positive scans, 40 (95.1%) were found in the 102 (36.6%) patients with either impaired consciousness or a new focal neurologic finding detected in the ED.
Conclusions : Considerable variability in ED CT scan ordering exists for elder patients with neurologic findings. Impaired consciousness and/or new focal neurologic signs are associated with acute findings on CT scan in elder patients. Acute CT abnormalities are uncommon in elder ED patients with other neurologic findings. Additional prospective evaluation is warranted prior to guideline development for CT scans in this patient population.     

蛛网膜下腔炎性抑制对蛛网膜下腔出血后脑室扩大的预防作用

目的：研究蛛网膜下腔出血（SAH）后蛛网膜下腔的炎性抑制对交通性脑积水发生的预防作用。方法：按急性期CT显示的蛛网膜下腔出血量参照Hijdra方法评分，选取积分为4分以上的SAH患者，常规治疗组（对照组）和常规治疗加地塞米松鞘内注射组（治疗组），分别于病程的初期和20天后在头颅CT上行脑室各值测量，包括哈（Huckman）氏值、三脑室宽度、前角指数、侧脑室体宽指数等。结果：全部75例患者各脑室测量值在病程后期均有不同程度的脑室扩大（P〈O．001），而对照组较治疗组脑室扩大明显（哈氏值、前角指数P〈0．05）。结论：蛛网膜下腔炎性抑制对SAH后脑室扩大有预防作用。     

Identification of Ethanol-intoxicated Patients with Minor Head TVauma Requiring Computed Tomography Scans

Objective: To determine whether clinical parameters and neurologic scores can be used to guide the decision to obtain computed tomography (CT) head scans for ethanol-intoxicated patients with presumed-minor head injuries.
Methods: In a prospective cohort analysis, 107 consecutive adult patients who presented to a county emergency department (ED) with serum ethanol levels >80 mg/dL and minor head trauma were studied. Commonly used clinical variables were determined for each patient. Each patient also underwent an abbreviated neurologic scoring examination and a Glasgow coma scale (GCS) score evaluation at the time of presentation and one hour later, after which a cranial CT scan was done. For purposes of analysis, patients with and patients without intracerebral injuries visible on CT scans of the head were compared.
Results: Nine of 107 patients (8.4%; 95% confidence interval [CI] = 3.9–15.4%) had CT scans that were positive for intracerebral injury. Two patients (1.9%; 95% CI = 0.2–6.6%) needed craniotomy. Five patients had hemotympanum and two patients had bilateral periorbital ecchy-mosis, but CT scans were negative for intracerebral injury in these patients. There was no statistically significant difference between the patients with and without CT scan abnormalities, based on the clinical variables, the GCS scores, or the abbreviated neurologic scoring examinations at presentation or at one hour.
Conclusion: The prevalence of intracerebral injury in CT scans of ethanol-intoxicated patients with minor head injuries was 8.4%. Commonly used clinical parameters and neurologic scores at presentation and one hour later were unable to predict which patients would have intracerebral injuries as evidenced by CT scans. Our low (1.9%) neurosurgical intervention rate supports the need to develop a selective approach to CT scanning in this population.     

三维CT血管重建成像在急性蛛网膜下腔出血的应用分析

目的：探讨三维CT血管重建成像在急性蛛网膜下腔出血的应用及局限性分析。方法：对147例CT表现为急性蛛网膜下腔出血患者进行CTA检查,由神经和放射两名医生对结果分析,对CTA阴性以及诊断有争议患者进行DSA检查。结果：在147例急性蛛网膜下腔出血患者中,109例患者3D-CTA结合出血CT图像确诊动脉瘤,瘤体直径2-12mm,均在手术或者介入治疗中证实;其余病例中,7例CT图像有明显的责任灶的蛛网膜下腔出血,3D-CTA阴性,通过DSA发现并经手术证实为动脉瘤,23例普通CT表现为中脑周围出血以及均匀弥漫蛛网膜下腔出血病例CTA提示阴性患者DSA检查也为阴性;3例CTA可疑动脉瘤均被DSA证实为动脉起始的壶腹,CTA在诊断颅内动脉瘤的敏感性和特异性分别为94％和100％。结论：对急性蛛网膜下腔出血患者使用CTA筛查是相对快捷、低风险检查方式,但结果的分析需结合CT图像出血形式以及放射和神经外科医生共同阅片可以完成CTA的诊断效能。     

Failure of the Miller Criteria to Predict Significant Intracranial Injury in Patients with a Glasgow Coma Scale Score of 14 after Minor Head Trauma

Objective: To determine the utility of the Miller criteria (presence of headache, nausea, vomiting, and signs of depressed skull fracture) for predicting the need for CT in patients with minor head trauma and a Glasgow Coma Scale score (GCS) of 14.
Methods: The study was a prospective, consecutive series of all patients undergoing head CT scans with a GCS of 14 following head trauma. A data sheet was completed for all patients prior to obtaining a head CT scan.
Results: 264 patients were entered into the study and 35 patients were found to have traumatic abnormalities on head CT scan. The use of the Miller criteria to select those patients who would require head CT scan would have resulted in missing 17 of the 35 abnormal scans, including 2 patients who required neurosurgical intervention. These 2 patients were markedly intoxicated upon presentation.
Conclusion: The use of the Miller criteria as the only criteria for screening patients with a GCS of 14 after minor head trauma who require a head CT scan is not recommended. While the authors have identified ethanol intoxication as one confounding factor, further refinement of this risk-stratification tool is required.     

蛛网膜下腔出血的多层螺旋CT血管造影诊断价值

目的：评价多层螺旋CT血管造影(MSCTA)在蛛网膜下腔出血(SAH)的病因诊断价值。材料与方法：24例SAH患者进行MSCTA检查，均经CT平扫及腰穿明确诊断，18例MSCTA检查后行DSA检查。结果：24例SAH中经MSCTA显示动脉瘤ll例，脑动静脉畸形7例，另6例正常。ll例脑动脉瘤中MSCTA显示动脉瘤13个，检出率为92．9％。7例脑动静脉畸形中MSCTA显示与DSA一致。结论：MSCTA是简单，快速，无创伤和可靠性的血管成像技术，对危急重SAH患者可随时检查；MSCTA对颅内动脉瘤具有极高价值，可补充DSA诊断信息。MSCTA对脑动静脉畸形的敏感性极高。     

Aneurysmal subarachnoid hemorrhage: update for emergency physicians

Aneurysmal subarachnoid hemorrhage (SAH) is a serious cause of stroke that affects 30,000 patients in North America annually. Due to a wide spectrum of presentations, misdiagnosis of SAH has been reported to occur in a significant proportion of cases. Headache, the most common chief complaint, may be an isolated finding; the neurological examination may be normal and neck stiffness absent. Emergency physicians must decide which patients to evaluate beyond history and physical examination. This evaluation--computed tomography (CT) scanning and lumbar puncture (LP)--is straightforward, but each test has important limitations. CT sensitivity falls with time from onset of symptoms and is lower in mildly affected patients. Traumatic LP must be distinguished from true SAH. Cerebrospinal fluid analysis centers on measuring xanthochromia. Debate exists about the best method to measure it--visual inspection or spectrophotometry. An LP-first strategy is also discussed. If SAH is diagnosed, the priority shifts to specialist consultation and cerebrovascular imaging to define the offending vascular lesion. The sensitivity of CT and magnetic resonance angiography are approaching that of conventional catheter angiography. Emergency physicians must also address various management issues to treat or prevent early complications. Endovascular therapy is being increasingly used, and disposition to neurovascular centers that offer the full range of treatments leads to better patient outcomes. Emergency physicians must be expert in the diagnosis and initial stabilization of patients with SAH. Treatment in a hospital with both neurosurgical and endovascular capability is becoming the norm.