What are the unintended consequences of changing the diagnostic paradigm for subarachnoid hemorrhage after brain computed tomography to computed tomographic angiography in place of lumbar puncture?

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.

Headache in the Emergency Department: Avoiding Misdiagnosis of Dangerous Secondary Causes, An Update

In the initial assessment of the headache patient, the emergency physician must consider several dangerous secondary causes of headache. A thorough history and physical examination, along with consideration of a comprehensive differential diagnosis may alert the emergency physician to the diagnosis of a secondary headache particularly when the history is accompanied by any of the following clinical features: sudden/severe onset, focal neurologic deficits, altered mental status, advanced age, active or recent pregnancy, coagulopathy, malignancy, fever, visual deficits, and/or loss of consciousness.

Diagnosis and Initial Emergency Department Management of Subarachnoid Hemorrhage

Atraumatic subarachnoid hemorrhage represents a small proportion of strokes, but is a true medical emergency that results in significant morbidity and mortality. Making the diagnosis can be challenging and misdiagnosis can result in devastating consequences. There are several time-dependent diagnostic and management considerations for emergency physicians and other frontline providers. This article reviews the most up-to-date literature on the diagnostic workup of subarachnoid hemorrhage, avoiding misdiagnosis, and initial emergency department management recommendations.

Clinical Policy: Critical Issues in the Evaluation and Management of Adult Patients Presenting to the Emergency Department With Acute Headache

This clinical policy from the American College of Emergency Physicians addressed key issues in the evaluation and management of adult patients presenting to the emergency department with acute headache. A writing subcommittee conducted a systematic review of the literature to derive evidence-based recommendations to answer the following clinical questions: (1) In the adult emergency department patient presenting with acute headache, are there risk-stratification strategies that reliably identify the need for emergent neuroimaging? (2) In the adult emergency department patient treated for acute primary headache, are nonopioids preferred to opioid medications? (3) In the adult emergency department patient presenting with acute headache, does a normal noncontrast head computed tomography scan performed within 6 hours of headache onset preclude the need for further diagnostic workup for subarachnoid hemorrhage? (4) In the adult emergency department patient who is still considered to be at risk for subarachnoid hemorrhage after a negative noncontrast head computed tomography, is computed tomography angiography of the head as effective as lumbar puncture to safely rule out subarachnoid hemorrhage? Evidence was graded and recommendations were made based on the strength of the available data.

Emergency Neurological Life Support: Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a neurological emergency because it may lead to sudden neurological decline and death and, depending on the cause, has treatment options that can return a patient to normal. Because there are interventions that can be life-saving in the first few hours after onset, SAH was chosen as an Emergency Neurological Life Support (ENLS) protocol.

Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is a neurological emergency with high risk of neurological decline and death. Although the presentation of a thunderclap headache or the worst headache of a patient's life easily triggers the evaluation for SAH, subtle presentations are still missed. The gold standard for diagnostic evaluation of SAH remains noncontrast head computed tomography (CT) followed by lumbar puncture if the CT is negative for SAH. Management of patients with SAH follows standard resuscitation of critically ill patients with the emphasis on reducing risks of rebleeding and avoiding secondary brain injuries.

Acute Headache Presentations to the Emergency Department: A Statewide Cross-sectional Study

OBJECTIVES

The objective of this study was to describe demographic and clinical characteristics including features that were consistent with subarachnoid hemorrhage (SAH), use of diagnostic tests, emergency department (ED) discharge diagnoses, and disposition of adult patients presenting with an acute headache to EDs statewide across Queensland, Australia. In addition, potential variations in the presentation and diagnostic workup between principal-referral and city-regional hospitals were examined.

METHODS

A prospective cross-sectional study was conducted over 4 weeks in September 2014. All patients ≥ 18 years presenting to one of 29 public and five private hospital EDs across the state with an acute headache were included. The headache had to be the principal presenting complaint and nontraumatic. The 34 study sites attend to about 90% of all ED presentations statewide. The treating doctor collected clinical information at the time of the ED visit including the characteristics of the headache and investigations performed. A study coordinator retrieved results of investigations, ED discharge diagnoses, and disposition from state databases. Variations in presentation, investigations, and diagnosis between city-regional and principal-referral hospitals were examined.

RESULTS

There were 847 headache presentations. Median (range) age was 39 (18-92) years, 62% were female, and 31% arrived by ambulance. Headache peaked instantly in 18% and ≤ 1 hour in 44%. It was "worst ever" in 37%, 10/10 in severity in 23%, and associated with physical activity in 7.4%. Glasgow Coma Scale score was < 15 in 4.1%. Neck stiffness was noted on examination in 4.8%. Neurologic deficit persisting in the ED was found in 6.5%. A computed tomography (CT) head scan was performed in 38% (318/841, 95% CI = 35% to 41%) and an lumbar puncture in 4.7% (39/832, 95% CI = 3.4% to 6.3%). There were 18 SAH, six intraparenchymal hemorrhages, one subdural hematoma, one newly diagnosed brain metastasis, and two bacterial meningitis. Migraine was diagnosed in 23% and "primary headache not further specified" in 45%. CT head scans were more likely to be performed in principal-referral hospitals (41%) compared to city-regional hospitals (33%). The headache in patients presenting to the latter was less likely to be instantly peaking or associated with activity, but was no less severe in intensity and was more frequently accompanied by nausea and vomiting. Their diagnosis was more likely to be a benign primary headache. Variations in CT scanning could thus be due to differences in the case mix. The median (interquartile range) ED length of stay was 3.1 (2.2 to 4.5) hours. Patients was discharged from the ED or admitted to the ED short-stay unit prior to discharge in 57 and 23% of cases, respectively.

CONCLUSIONS

The majority of patients had a benign diagnosis, with intracranial hemorrhage and bacterial meningitis accounting for only 3% of the diagnoses. There are variations in the proportion of patients receiving CT head scans between city-regional and principal-referral hospitals. As 38% of headache presentations overall underwent CT scanning, there is scope to rationalize diagnostic testing to rule out life-threatening conditions.

Subarachnoid haemorrhage guidelines and clinical practice: a cross-sectional study of emergency department consultants' and neurospecialists' views and risk tolerances

OBJECTIVES

To establish if emergency medicine and neuroscience specialist consultants have different risk tolerances for investigation of suspected spontaneous subarachnoid haemorrhage (SAH), and to establish if their risk-benefit appraisals concur with current guidelines.

SETTING

4 major neuroscience centres in London.

PARTICIPANTS

58 consultants in emergency medicine and neuroscience specialities (neurology, neurosurgery and neuroradiology) participated in an anonymous survey.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome measure was the highest stated acceptable risk of missing SAH in the neurologically intact patient presenting with sudden onset headache. Secondary outcome measures included agreement with guideline recommendations, risk/benefit appraisal and required performance of diagnostic tests, including lumbar puncture.

RESULTS

Emergency department clinicians accepted almost 3 times the risk of a missed SAH diagnosis compared with the neuroscience specialists (2.8% vs 1.1%; p=0.02), were more likely to accept a higher risk of missed diagnosis for the benefit of a non-invasive test (p=0.04) and were more likely to disagree with current published guidelines stipulating the need for LP in all CT-negative cases (p=0.001).

CONCLUSIONS

Divergence from recognised procedures for SAH investigation is often criticised and attributed to a lack of knowledge of guidelines. This study indicates that divergence from guidelines may be explained by alternative risk-benefit appraisals made by doctors with their patients. Guideline recommendations may gain wider acceptance if they accommodate the requirements of the doctors and patients using them. Further study of clinical risk tolerance may help explain patterns of diagnostic test use and other variations in healthcare delivery.

Headache in the Emergency Department: Avoiding Misdiagnosis of Dangerous Secondary Causes

There are a number of dangerous secondary causes of headaches that are life, limb, brain, or vision threatening that emergency physicians must consider in patients presenting with acute headache. Careful history and physical examination targeted at these important secondary causes of headache will help to avoid misdiagnosis in these patients. Patients with acute thunderclap headache have a differential diagnosis beyond subarachnoid hemorrhage. Considering the "context" of headache "PLUS" some other symptom or sign is one strategy to help focus the differential diagnosis.

Imaging in the evaluation of headache

When deciding to perform imaging for headache, it is important to consider many factors including the pretest probability, prevalence of diseases, sensitivity of imaging, and implications for treatment. For the first presentation of a headache or a change in headache pattern, if the characteristics do not perfectly fit a primary headache type, imaging may be indicated according to the ICHD-2 criteria to exclude a secondary cause before a primary headache is diagnosed. The value of negative imaging should not be underestimated in the cost-benefit analysis, which often only takes into account number needed to treat or likelihood of finding a significant treatable abnormality. One study has shown that some groups of patients are less likely to overuse other parts of the health care system after negative neuroimaging. Further studies with stronger methodologies, finer differentiation of acute and chronic headache presentations, more advanced imaging technology, among other factors, can improve decision making on when to use imaging and assess the impact of imaging on patient satisfaction and quality of life. In addition, functional MRI, MRS, and voxel-based morphometry MRI are only some of the neuroimaging techniques currently used in research to further understand the pathophysiology and mechanisms of headache. In conclusion, although most headaches are a primary headache disorder with a benign course, imaging is an important part of the diagnostic evaluation to exclude the presence of a secondary cause of headache that could cause fatal results or severe neurologic morbidity. In headache patients without focal neurologic examination abnormalities, the yield of neuroimaging for significant intracranial findings is generally low. However, specific subgroups of headache patients and headache presentations can have much higher rates of significant intracranial abnormalities.

Differential diagnostic yield of lumbar puncture in investigation of suspected subarachnoid haemorrhage: a retrospective study

The diagnostic algorithm of computerized tomography (CT) and lumbar puncture (LP) for suspected subarachnoid haemorrhage (SAH) has lately been challenged by the advancement of radiological techniques, such as higher resolution offered by newer generation CT-scanners and increased availability of CT-angiography. A purely radiological workup of suspected SAH offers great advantages for both patients and the health care system, but the risks of abandoning LP in this setting are not well investigated. We have characterized the differential diagnostic yield of LP in the investigation of suspected SAH by a retrospective study. From the hospital laboratory database, we analyzed the medical records of all patients who had undergone CSF-analysis in search of subarachnoid bleeding during 2009-2011. A total of 453 patients were included. In 14 patients (3%) the LP resulted in an alternative diagnosis, the most common being aseptic meningitis. Two patients (0.5%) received treatment for herpes meningitis. Five patients (1%) with subarachnoid haemorrhages were identified. Among these, the four patients presenting with thunderclap headache had non-aneurysmal bleedings and did not require surgical intervention. We conclude that the differential diagnostic yield of LP in investigation of suspected SAH is low, which indicates that alternative diagnoses is not a reason to keep LP in the workup when a purely radiological strategy has been validated. However, algorithms should be developed to increase the recognition of aseptic meningitis. One hundred and fifty-three patients (34%) were admitted to undergo LP, which estimates the number of hospital beds that might be made available by a radiological diagnostic algorithm.

Intracranial hemorrhage

Intracranial hemorrhage refers to any bleeding within the intracranial vault, including the brain parenchyma and surrounding meningeal spaces. This article focuses on the acute diagnosis and management of primary nontraumatic intracerebral hemorrhage and subarachnoid hemorrhage in the emergency department.

Cost-effectiveness of diagnostic strategies for evaluation of suspected subarachnoid hemorrhage in the emergency department

OBJECTIVES

Diagnosing subarachnoid hemorrhage (SAH) in emergency department (ED) patients is challenging. Potential diagnostic strategies include computed tomography (CT) only, CT followed by lumbar puncture (CT/LP), CT followed by magnetic resonance imaging and angiography (CT/MRA), and CT followed by CT angiography (CT/CTA). The objective was to determine the relative cost-effectiveness of diagnostic strategies for SAH.

METHODS

 The authors created a decision model to evaluate the cost-effectiveness of SAH diagnostic strategies in ED patients with suspected SAH. Clinical probabilities were obtained from published data; sensitivity analyses were conducted across plausible ranges.

RESULTS

  In the base-case scenario, CT-only had a cost of $10,339 and effectiveness of 20.25 quality-adjusted life-years (QALYs), and CT/LP had a cost of $15,120 and effectiveness of 20.366 QALYs. Among the alternative strategies, CT/CTA had a cost of $12,840 and effectiveness of 20.24 QALYs, and CT/MRA had a cost of $16,207 and effectiveness of 20.27 QALYs. In sensitivity analyses, probability of severe disability from SAH, sensitivity of noncontrast CT, and specificity of LP and MRA were key drivers of the model, and CT-only and CT/LP were preferable.

CONCLUSIONS

In the base-case scenario, CT-only was preferable to the CT/CTA and CT/MRA strategies. When considering sensitivity analyses and the current medicolegal environment, there are no overwhelming differences between the cost-effectiveness of CT/LP and the alternative strategies to suggest that clinicians should abandon the standard CT/LP approach.

Avoiding misdiagnosis in patients with neurological emergencies

Approximately 5% of patients presenting to emergency departments have neurological symptoms. The most common symptoms or diagnoses include headache, dizziness, back pain, weakness, and seizure disorder. Little is known about the actual misdiagnosis of these patients, which can have disastrous consequences for both the patients and the physicians. This paper reviews the existing literature about the misdiagnosis of neurological emergencies and analyzes the reason behind the misdiagnosis by specific presenting complaint. Our goal is to help emergency physicians and other providers reduce diagnostic error, understand how these errors are made, and improve patient care.