|About This Issue|
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Headache is the fourth most common reason for emergency department encounters, accounting for 3% of all visits in the United States. Though troublesome, 90% are relatively benign primary headaches --migraine, tension, and cluster headaches. The other 10% are secondary headaches, caused by separate underlying processes, with vascular, infectious, or traumatic etiologies, and they are potentially life-threatening. This issue details the important pathophysiologic features of the most common types of life-threatening headaches, the key historical and physical examination information emergency clinicians must obtain, the red flags that cannot be missed, and the current evidence for best-practice testing, imaging, treatment, and disposition.
A previously healthy 30-year-old man presents to the ED complaining of the “worst headache of my life.” He describes it as sharp, nonradiating, with an abrupt onset 5 hours ago. You are concerned for subarachnoid hemorrhage. You provide pain medication and obtain a noncontrast CT scan of the head, which is negative. The patient is feeling better and wants to go home. You wonder whether a negative CT is sufficient to rule out an SAH or whether a lumbar puncture should be done...
A 55-year-old man with history of nonsmall cell lung cancer who is on cisplatin presents with an acute headache and lethargy for 6 hours. His vital signs are remarkable for a blood pressure of 210/120 mm Hg, heart rate of 70 beats/min, and a temperature of 36.7°C (98°F). His physical exam reveals a lethargic patient with no localizing neurologic signs and no meningismus. You order a noncontrast CT of the head and consider lowering this patient’s blood pressure, though you wonder how much and how fast it should be reduced...
A 45-year-old woman presents to the ED complaining of a severe occipital headache, neck pain, and dizziness. Earlier in the day, she was involved in a motor vehicle crash and suffered “whiplash.” Her neurologic exam is normal, including no nystagmus and normal cerebellar function, but you are concerned that this patient may have a vertebral artery dissection, and you order a CTA head and neck. You wonder: if it’s positive, should the treatment include anticoagulation or antiplatelet therapy...or both?
The third edition of the International Classification of Headache Disorders (ICHD-3), published in January 2018, is the most up-to-date and widely accepted standard criteria for the classification of headaches.1 The ICHD-3 classifies headaches into 3 distinct categories: (1) primary headache disorders, including migraine, tension, and cluster headaches; (2) secondary headaches, including potentially life-threatening forms of headaches such as those secondary to vascular disorders, traumatic injury, and disorders in hemostasis; and (3) cranial neuropathies, such as trigeminal neuralgia.
The National Hospital Ambulatory Medical Care Survey reviewed over 10,000 patients presenting to emergency departments (EDs) for acute headache and found that 2% represented secondary headaches.2 Although they are rare, life-threatening headaches require prompt diagnosis and treatment, as delays in some diagnoses can have a mortality rate approaching 50%.3
Evaluating complaints of acute headache is a common practice in the ED, and distinguishing benign from serious pathology can be a diagnostic challenge. A focused workup begins with a careful, well-organized clinical history and physical examination. Physical examination findings such as abnormal vital signs, papilledema, cranial nerve palsies, and neck pain are suggestive of more concerning headache etiologies.4 Resources such as ocular ultrasound, neuroimaging, and lumbar puncture are important strategies, but the sensitivity and specificity of the results must be understood in order to apply them correctly. This issue of Emergency Medicine Practice focuses on the most commonly encountered causes of life-threatening secondary headaches and provides best-practice recommendations on their initial evaluation and management.
A literature search from 1993 to 2018 was conducted using PubMed and Ovid MEDLINE®, with the search terms headaches AND emergency, sudden onset, fever, visual symptoms, neurologic deficits, high-risk, trauma, immunocompromised, pregnancy, coagulopathy, and life threatening. The National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews were searched. Guidelines published by the American College of Emergency Physicians (ACEP) and the American Academy of Neurology were searched. International guidelines, including the Canadian and European neurology guidelines, were also reviewed. Over 500 abstracts published within the last 25 years were examined, and 89 of these full-text articles were reviewed and included for reference. Many of the identified articles were prospective studies, meta-analyses, clinical guidelines, and literature reviews.
1. “I got a CT scan, and the lumbar puncture revealed no xanthochromia, so I discharged him, thinking he didn’t have a SAH.”
Xanthochromia is time-dependent and takes 2 to 12 hours to develop, so its absence in patients presenting within this timeframe may not be helpful. If the diagnosis for SAH is still unclear after noncontrast CT and lumbar puncture, additional diagnostic imaging may include CT angiogram and magnetic resonance angiography.
2. “When evaluating the pregnant patient for CVT, I didn’t want to subject her to any radiation, so I obtained a D-dimer in lieu of a CT scan.”
The diagnosis of CVT should be made using the clinical examination and imaging studies. Several small studies have looked at the utility of D-dimer to screen patients presenting to the ED with headache suspicious for CVT. Pregnancy is a risk factor for CVT, so this patient is not low-risk.
3. “My patient complaining of headache and neck pain had no focal neurologic deficits, so I had a very low clinical suspicion for carotid or vertebral artery dissection.”
Patients with CAD may initially present with head or neck pain, but without any neurologic deficits; the goal is to diagnose and treat before the dissection causes thrombus, which can embolize and cause stroke.
Evidence-based medicine requires a critical appraisal of the literature based upon study methodology and number of subjects. Not all references are equally robust. The findings of a large, prospective, randomized, and blinded trial should carry more weight than a case report.
To help the reader judge the strength of each reference, pertinent information about the study, such as the type of study and the number of patients in the study is included in bold type following the references, where available. In addition, the most informative references cited in this paper, as determined by the author, are highlighted.
Points and Pearls Excerpt
Most Important References
The Ottawa SAH rule has very specific inclusion and exclusion criteria that must be followed closely for appropriate application:
Why to Use
It is challenging to rule out SAH in patients who present with headache and no neurologic deficits. SAH is rare, accounting for approximately 1% of patients presenting to the ED with headache (Vermeulen 1990), but missed diagnoses ave potentially devastating results. A tool that reliably rules out SAH is useful to avoid unnecessary workups.
Lumbar puncture is often performed as the confirmatory test if a noncontrast head CT scan is negative but the clinical suspicion for SAH remains high. Lumbar puncture is painful and carries the risk of bleeding and of headache that may be worse than the original presenting headache.
When to Use
Use the Ottawa SAH rule in patients aged ≥ 15 years who present with headache and are neurologically intact.
In patients who have any positive criteria for the Ottawa SAH rule (ie, SAH cannot be ruled out), workup for SAH typically begins with a noncontrast head CT. Consider lumbar puncture and/or cerebral angiography if clinical suspicion remains. In their 2013 validation study, Perry et al provided insight into the appropriate workup for patients with possible SAH.
Neurology and neurosurgical consultation should be obtained for patients with suspected or confirmed SAH.
Abbreviations: CT, computed tomography; ED, emergency department; SAH, subarachnoid hemorrhage..
Consider workup for SAH in patients who have any positive criteria; however, given the low specificity of the rule, not every patient who fails the rule will require workup for SAH. In patients for whom all criteria are negative, consider avoiding further SAH-specific workup.
Patients in whom SAH has been ruled out may still have other causes of headache that require workup or intervention. The differential diagnosis should be broad.
The first iteration of what is now known as the Ottawa SAH rule was derived by Perry et al in 2010. The study prospectively enrolled 1999 patients with headache who were from 5 Canadian tertiary care centers; 130 of these patients had confirmed SAH. Sixteen variables were identified as predictive for SAH (13 on history and 3 on physical examination). Recursive partitioning was used to identify combinations of these variables and create the 3 separate decision rules with the highest sensitivity for SAH.
Perry et al (2013) prospectively validated these findings in a study of 2131 patients at 10 sites, using the following inclusion and exclusion criteria for enrollment:
The variables were again run through recursive partitioning and the final Ottawa SAH rule was found to be 100% sensitive for SAH (95% confidence interval [CI], 25.6%-29.5%). Specificity was 15.3% (95% CI, 13.8%-16.9%).
Not all patients in the validation study underwent a full workup with CT scan and lumbar puncture (80% had a CT scan and 45% had lumbar puncture). The patients who were discharged without undergo-ing a CT scan and lumbar puncture were assessed using a follow-up tool that included structured telephone interviews and medical records review.
The authors acknowledged that some patients with small nonaneurysmal SAH may have been missed.
Bellolio et al (2015) also externally validated the Ottawa SAH rule by retrospectively applying it to 454 patients who presented to the ED with headache. Sensitivity was 100% (95% CI, 62.9%-100%) but specificity was lower than in the validation by Perry et al (7.6%, 95% CI 5.4%-10.6%), so the authors concluded that the rule’s clinical use may be limited.
According to the hierarchy of evidence for clinical decision rules that was developed by McGinn et al (2000), the Ottawa SAH rule is a level 2 clinical decision rule, with established accuracy in at least 1 large prospective study, but no impact analysis completed as of yet.
Jeffrey J. Perry, MD, MSc
Copyright © MDCalc • Reprinted with permission.
David Zodda, MD, FACEP; Gabrielle Procopio, PharmD, BCPS; Amit Gupta, MD
Mert Erogul, MD; Steven A. Godwin, MD, FACEP
February 1, 2019
February 28, 2022
4 AMA PRA Category 1 Credits™, 4 ACEP Category I Credits, 4 AAFP Prescribed Credits, 4 AOA Category 2-A or 2-B Credits. Specialty CME Credits:Included as part of the 4 credits, this CME activity is eligible for 4 Stroke CME and 1 Pharmacology CME credits
Physician CME Information
Date of Original Release: February 1, 2019. Date of most recent review: January 15, 2019. Termination date: February 1, 2022.
Accreditation: EB Medicine is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians. This activity has been planned and implemented in accordance with the accreditation requirements and policies of the ACCME.
Credit Designation: EB Medicine designates this enduring material for a maximum of 4 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.
ACEP Accreditation: Emergency Medicine Practice is approved by the American College of Emergency Physicians for 48 hours of ACEP Category I credit per annual subscription.
AAFP Accreditation: This Enduring Material activity, Emergency Medicine Practice, has been reviewed and is acceptable for credit by the American Academy of Family Physicians. Term of approval begins 07/01/2018. Term of approval is for one year from this date. Physicians should claim only the credit commensurate with the extent of their participation in the activity. Approved for 4 AAFP Prescribed credits.
AOA Accreditation: Emergency Medicine Practice is eligible for up to 48 American Osteopathic Association Category 2-A or 2-B credit hours per year.
Specialty CME: Included as part of the 4 credits, this CME activity is eligible for 4 Stroke CME and 1 Pharmacology CME credits, subject to your state and institutional approval.
Needs Assessment: The need for this educational activity was determined by a survey of medical staff, including the editorial board of this publication; review of morbidity and mortality data from the CDC, AHA, NCHS, and ACEP; and evaluation of prior activities for emergency physicians.
Target Audience: This enduring material is designed for emergency medicine physicians, physician assistants, nurse practitioners, and residents.
Goals: Upon completion of this activity, you should be able to: (1) demonstrate medical decision-making based on the strongest clinical evidence; (2) cost-effectively diagnose and treat the most critical presentations; and (3) describe the most common medicolegal pitfalls for each topic covered.
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