Article

The neurology literature 2016

a b s t r a c t

Emergency neurology is a complex and rapidly changing field. Its evolution can be attributed in part to in- creased imaging options, debates about optimal treatment, and simply the growth of emergency medicine as a specialty. Every year, a number of articles published in emergency medicine or other specialty journals should become familiar to the emergency physician. This review summarizes neurology articles published in 2016, which the authors consider crucial to the practice of emergency medicine. The articles are catego- rized according to disease process, with the understanding that there can be significant overlap among articles.

(C) 2017

Introduction

Emergency neurology is a complex and rapidly changing field. Its evolution can be attributed in part to increased imaging options, de- bates about optimal treatment, and simply the growth of emergency medicine as a specialty. Every year, a number of articles published in emergency medicine or other specialty journals should become familiar to the emergency physician. This review summarizes neurology articles published in 2016, which the authors consider crucial to the practice of emergency medicine. The articles are categorized according to disease process, with the understanding that there can be significant overlap among articles.

Transient ischemic attack

Lo BM, Carpenter CR, Hatten BW, et al. Clinical policy: critical issues in the evaluation of adult patients with suspected transient ischemic attack in the emergency department. Ann Emerg Med 2016; 68(3): 354370

Transient ischemic attack is a perplexing entity for emergency physicians because patients are at risk for progression to acute ischemic

* Corresponding author at: 110 South Paca Street, 6th Floor, Suite 200, Baltimore, MD 21201, USA.

E-mail address: [email protected] (M.K. Abraham).

stroke (AIS), which carries significant morbidity and mortality. Early identification of TIA and risk factor modification can prevent this progression. Unfortunately, how much of this responsibility rests in the emergency department (ED) versus the inpatient or outpatient arena is debatable. The American College of Emergency Physicians (ACEP) published a clinical policy that tackles four main questions (presented below). To address each question, the committee members evaluated and graded current literature and then formulated their rec- ommendations.

In adults with suspected TIA, are there any clinical decision rules that can identify patients at very low Short-term risk for stroke who can be safely discharged from the ED? ACEP’s Level B recommendations state that none of the available Risk-stratification tools is reliable enough to properly identify low-risk patients who can be discharged from the ED. The most widely studied tool is the ABCD2 score, which, based on current data, falls short of the specificity and sensitivity needed to reliably predict outcomes.
  • In adult patients with suspected TIA, what imaging can be safely de- layed from the initial ED workup? There are no Level A or B recom- mendations on this question. The Level C recommendations suggest that emergency physicians should obtain a least a CT scan to evalu- ate for mimics. If MRI is feasible and readily available, diffusion-
  • http://dx.doi.org/10.1016/j.ajem.2017.08.060

    0735-6757/(C) 2017

    weighted imaging (DWI) is preferred along with carotid vascular imaging (ultrasound [US], CTA, or MRA), as they both predict short-term stroke risk.

    In adult patients with suspected TIA, is carotid ultrasonography as accurate as neck CTA or MRA in identifying severe carotid stenosis? The ACEP committee concluded that US is as accurate as CT and MRA for the detection of severe carotid stenosis, with a Level C recommendation.
  • In adult patients with suspected TIA, can a rapid ED-based diag- nostic protocol safely identify patients at short-term risk for stroke? The ACEP committee concluded, in a Level B recommen- dation, that if patients do not have High-risk conditions, they can be discharged safely from the ED after proper workup. The workup includes the appropriate neuro-imaging including a DW-MRI, if available, some carotid and cerebral vascular imaging (US/CTA/MRA) and possibly an echocardiogram. High-risk condi- tions include abnormal initial head CT results, atrial fibrillation or other Embolic source, known or identified carotid stenosis, previ- ous AIS, and crescendo TIAs.
  • This article does a very good job of evaluating and summarizing cur- rent data pertaining to TIA in the ED. It is comprehensive and addresses many of the pertinent questions that plague both emergency physicians and neurologists on a daily basis. It also provides an example of a clinical pathway for the optimal treatment of these patients, who are often treated with a large amount of clinical variability.

    Acute ischemic stroke

    Tziomalos K, Ntaios G, Miyakis S, et al. Prophylactic antibiotic treatment in severe acute ischemic stroke: the Antimicrobial chemopRrophylaxis for Ischemic STrokEIn MaceDonlaThrace Study (ARISTEIDIS). Intern Emerg Med 2016; 11(7): 953958

    This study evaluated the use of prophylactic antibiotics given to pa- tients who were diagnosed with ischemic strokes. The reasoning that led to this study was that a large number of AIS patients ultimately die as the result of an infectious process. Tziomalos and colleagues con- ducted a prospective multicenter study based on medical records. Pa- tients with obvious signs of infection were excluded, and the decision to use antibiotics as part of the treatment course was left to the treating physician. Of the 110 patients who were enrolled, 31 received antibi- otics. The average NIH Stroke Scale (NIHSS) scores for patients who re- ceived an antibiotic and those who did not were not statistically different. One of the most interesting findings is that 33.6% of patients developed an infection during hospitalization, with pneumonia being the most common. More than half of these patients had received pro- phylactic antibiotics. Independent risk factors for infection were a high NIHSS score and administration of prophylactic antibiotics. Admin- istration of antibiotics had no effect on the short-term mortality rate. This study has a number of limitations, namely that it had a very small sample size and that the decision to use antibiotics was left to the treating physician. A number of confounding variables limit the mes- sage that can be taken away from this study, mainly that more severely affected AIS patients have significant morbidity and mortality. Current- ly, no data support the use of prophylactic antibiotics in AIS patients, and this article even suggests that doing so may cause harm.

    Anaissie JE, Monlezun DJ, Siegler JE, et al. Intravenous tissue plasmino- gen activator for wake-up stroke: a propensity score-matched analysis. J Stroke Cerebrovasc Dis 2016; 25(11): 26032609

    As many emergency physicians can attest, the time restrictions on administration of systemic tissue plasminogen activator to

    patients with ischemic stroke are very constraining. Some data suggest that patients have better outcomes when tPA is administered early in the disease process. The data are equivocal when tPA is administered at the other extreme of the time limit, especially more than 6 h after onset. When patients present with a wake-up stroke (WUS), it is dif- ficult to determine time of onset, which invariably limits the ability to administer tPA. Anaissie and colleagues conducted a retrospective analysis of patients who presented to a single center, assigning them to one of three groups: AIS <= 4.5 h with tPA, WUS treated with tPA, and WUS with Conventional treatment. This study was designed to identify the presence of symptomatic intracranial hemorrhage (sICH) in the three groups. Its main limitations are that it was a ret- rospective study done in a single center study and that it was under- powered to detect significant differences among the groups. With these very important limitations in mind, the authors reported that they did not find any difference in the rates of the primary endpoint, sICH, between the treatment groups (calculated as 3%, 2.2%, and 0.7%, respectively). One might conclude that patients who were treated with tPA within 4.5 h or for WUS had a higher Incidence of sICH and that the study was not adequately powered to detect a dif- ference. Although time considerations are the most common reason for not administering tPA, the data from this report do not inspire confidence that administering tPA to patients with WUS is a safe practice.

    Goyal M, Menon BK, van Zwam WH, et al. endovascular thrombectomy after large-vessel ischaemic stroke: a meta-analysis of Individual patient data from five randomised trials. Lancet 2016; 387(10029): 17231731

    Treatment for acute ischemic stroke has been long under de- bate. In the correct population, endovascular thrombectomy has been accepted as standard of care, based on the results of five ran- domized clinical trials published in 2015. However, most of these studies were stopped early and were therefore underpowered to determine efficacy in groups such as those who presented to treat- ment late, are elderly, have mild deficits, and are not eligible for in- travenous tPA.

    For the meta-analysis, investigators from the five studies (MR CLEAN, ESCAPE, REVASCAT, SWIFT PRIME, and EXTEND IA) formed

    the Highly Effective Reperfusion evaluated in Multiple Endovascular Stroke Trials (HERMES) collaboration and pooled their patient data. These five trials were chosen specifically because they used vessel imaging to identify patients with proximal occlusion of large vessels in the anterior circulation and second-generation Mechanical thrombectomy devices.

    The HERMES collaboration analyzed data for 1287 participants from 89 international sites (634 assigned to endovascular thrombectomy in addition to standard medical treatment and 653 assigned to standard medical treatment alone). Their Pooled analysis showed a reduced level of disability on the Modified Rankin scale (mRS) at 90 days in pa- tients assigned to endovascular thrombectomy. The number needed to treat for one patient to have reduced disability of at least 1 point on the mRS was 2.6. There was no difference in terms of mortality rate or risk of symptomatic intracranial hemorrhage between the groups. In subgroup analyses of patients older than 80 years, of those randomized more than 300 min after symptom onset, and of those not eligible to re- ceive IV tPA, endovascular thrombectomy was associated with reduced disability.

    Because it used individual patient data rather than study-level data, HERMES provided a robust meta-analysis of the effect of endovascular thrombectomy in large-vessel ischemic stroke. The findings support the benefit of endovascular thrombectomy, even in previously underrepresented groups.

    Saver JL, Goyal M, van der Lugt A, et al. Time to treatment with endovascular thrombectomy and outcomes from ischemic stroke: a meta- analysis. JAMA 2016; 316(12): 12791288

    Acute ischemic stroke is a time-sensitive emergency. Previous stud- ies demonstrated that intravenous tissue plasminogen activator (IV tPA) is associated with greatest benefit in patients treated within 3 h after symptom onset. National guidelines and consensus statements in the United States, Europe, and Canada recommend endovascular recan- alization less than 6 h after symptom onset. The US Food and Drug Ad- ministration approved Mechanical thrombectomy devices for use within 8 h of symptom onset. However, uncertainty remains regarding the benefit and risk of endovascular intervention when performed more than 6 h after symptom onset.

    As mentioned above, the Highly Effective Reperfusion evaluated in Multiple Endovascular Stroke Trials (HERMES) collaboration pooled individual patient data from five international randomized clinical trials for meta-analysis. Overall, 634 participants were assigned to the endovascular and medical therapy group and 653 to the medical therapy alone group. Although all trials administered IV tPA to eligible patients in both treatment groups, there was a slightly less frequent use in the endovascular group than in the med- ical treatment group.

    Endovascular intervention was associated with reduced disabili- ty; earlier treatment yielded a higher magnitude of benefit. This ben- efit became nonsignificant at 7.3 h after the onset of symptoms. Although the treatment effect was not modified by the time between symptom onset and arrival at an emergency department (ED), delays between ED arrival and reperfusion were associated with worse outcomes.

    This study by the HERMES collaboration provides additional evi- dence regarding the association between treatment time and outcome after acute ischemic stroke, consistent with prior studies of endovascular intervention and intravenous thrombolysis. These find- ings highlight the importance of speed of care processes in the treat- ment of acute ischemic stroke.

    Intracerebral hemorrhage

    Baharoglu MI, Cordonnier C, Al-Shahi Salman R, et al. Platelet transfu- sion versus Standard care after acute stroke due to spontaneous cerebral haemorrhage associated with antiplatelet therapy (PATCH): a randomised, open-label, phase 3 trial. Lancet. 2016; 387(10038): 26052613

    spontaneous intracerebral hemorrhage (ICH) is associated with sig- nificant morbidity and mortality. Individuals on antiplatelet therapy have an increased likelihood of death when they experience ICH [1]. Ob- servational studies have reported variable associations with outcomes after platelet transfusion for ICH in individuals on antiplatelet therapy [2].

    The multicenter, randomized, open-label, parallel-group PATCH trial compared platelet transfusion with standard of care in patients with nontraumatic supratentorial ICH who had been on antiplatelet therapy within the 7 days preceding the event. Platelet transfusion was initiated within 6 h after symptom onset and within 90 min after diagnostic brain imaging. Based on previous in-vitro experi- ments, patients taking a cyclooxygenase (COX) inhibitor were given 1 platelet concentrate, whereas patients taking an adenosine diphosphate (ADP) receptor inhibitor were given 2 platelet concen- trates. Patients with infratentorial or large intraventricular hemor- rhages were not included because they were more likely to undergo surgical intervention, which would confound the effects of platelet transfusion on outcome.

    A total of 190 participants were enrolled in the trial; 97 were assigned to receive platelet transfusion in addition to standard care

    and 93 were assigned to standard care alone. Platelet transfusion was associated with higher odds of death or dependency at 3 months, even when adjusted for baseline ICH volume. There was no difference in outcomes between those who received platelet transfusion within 3 h after symptom onset versus those who received transfusion be- tween 3 and 6 h.

    The PATCH trial showed that platelet transfusion is inferior to standard care for spontaneous ICH associated with antiplatelet ther- apy. Although the differences were not statistically significant, seri- ous adverse events due to thromboembolism and complications of ICH were more common in the platelet transfusion group. A similar randomized trial in Finland is underway and may provide additional evidence guiding the treatment of ICH in patients on antiplatelet therapy.

    Qureshi AI, Palesch YY, Barsan WG, et al. Intensive blood-pressure low- ering in patients with acute cerebral hemorrhage. N Engl J Med. 2016; 375(11): 10331043

    Systemic hypertension is common in ED presentations of Acute intracerebral hemorrhage and is associated with Hematoma expansion, Neurologic deterioration, and increased mortality. Previ- ous studies demonstrated that Rapid reduction of systolic blood pres- sure (SBP) to less than 140 mm Hg is safe. The Intensive Blood pressure reduction in Acute Cerebral Hemorrhage Trial (INTER- ACT2) showed a nonsignificant lower rate of death or major disabil- ity among patients assigned to intensive reduction of SBP to less than 140 mm Hg [3].

    The Antihypertensive treatment of Acute Cerebral Hemorrhage II (ATACH-2) trial was a multicenter, randomized, open-label trial de- signed to determine the relative efficacy of intensive versus standard antihypertensive treatment initiated within 4.5 h after symptom onset and continued for 24 h in patients with spontaneous supratentorial ICH. The trial included adults with a Glasgow Coma Scale score of 5 or more on presentation to the emergency department and an ICH volume of less than 60 cm3.

    ATACH-2 randomized 500 patients into an intensive-treatment group and 500 to a standard-treatment group. The trial was stopped early for futility before the targeted enrollment of 1280 participants. The mean SBP at baseline was 200.6 +- 27.0 mm Hg and the mean SBP during the first 2 h was 128 +- 16 mm Hg in the intensive-treatment group and 141.1 +- 14.8 mm Hg in the standard-treatment group. There was no significant difference in rates of death or disability. There was also no difference between the groups in neurologic deterio- ration within 24 h. The rate of renal adverse events within 7 days was higher in the intensive treatment group than in the standard treatment group.

    While ATACH-2 did not provide evidence to support intensive blood pressure lowering in patients with acute ICH, it is important to note several limitations of this study. The recruitment window was extended from 3 to 4.5 h during the trial based on evidence sug- gesting that hematoma expansion was equally prevalent among pa- tients who presented between 0 and 3 h after symptom onset and those who presented between 3 and 4.5 h after symptom onset. A time-dependent benefit of intensive reduction in blood pressure is possible, though it was not observed in the subgroup analysis of IN- TERACT2. More notably, when comparing the mean SBP during the first 24 h between the treatment groups, the intensive-treatment group achieved a SBP of 120 to 130 mm Hg whereas the standard- treatment group achieved a SBP of 140 to 150 mm Hg. One may argue that both treatment groups received aggressive blood pressure management compared with the current guideline recommendation of a target SBP of less than 180 mm Hg and that tight blood pressure control contributed to the lower-than-anticipated rates of death and disability in the standard-treatment group.

    Migraine

    Singhal AB, Maas MB, Goldstein JN, et al. High-flow oxygen therapy for treatment of acute migraine: a randomized crossover trial. Celphalgia 2016 May 20 [Epub ahead of print]

    High-flow oxygen has been shown to be effective in the treatment of Cluster headache [4], and in patients with all types of headaches [5], but had not been adequately studied specifically in adults with migraine. One of the reasons that oxygen could be effective in the management of migraines is that hypoxia causes cerebral vasodilation, whereas hyperoxia causes cerebral vasoconstriction [6].

    This study was fairly small, with 22 adults randomized to self-ad- minister oxygen or medical air at 10 to 15 L per minute via facemask for 30 min soon after symptom onset. These patients were all previ- ously diagnosed with migraine headaches, and the treatment was self-administered at home. The oxygen therapy group reported more relief from pain, nausea, and visual symptoms at 60 min. Of note, more than half of the patients in the study had a history of se- verely disabling symptoms during their migraine occurrences.

    This study has some limitations, the most significant being that it does not clarify the timing of treatment in relation to symptom onset. This information would have the utmost impact on its applicability in the ED population. However, given the lack of adverse effects and low cost of this intervention, it appears to be worth the investment of fur- ther studies to test this treatment on the undifferentiated primary head- ache patient in the ED.

    Subarachnoid hemorrhage

    Dubosh NM, Bellolio MF, Rabinstein AA, Edlow JA. Sensitivity of early brain computed tomography to exclude aneurysmal subarachnoid hemor- rhage: a systematic review and meta-analysis. Stroke 2016; 47(3): 750755

    Hyperosmolar therapy“>spontaneous subarachnoid hemorrhage (SAH) remains a difficult di- agnosis to make in the ED. Numerous studies have attempted to exam- ine the safety of diverting away from the “standard of care,” which is noncontrast CT of the brain and, if that is negative, then lumbar punc- ture [7]. Lumbar puncture is not without complication, either directly related to the procedure or secondary to the testing necessitated by a traumatic tap.

    A few studies have examined the sensitivity of brain CT alone, most famously the one by Perry and colleagues, which revealed 100% sensi- tivity for CT done within 6 h after headache onset but had many limita- tions [8].

    The systematic review by Dubosh and colleagues analyzed five arti- cles regarding the sensitivity of non-contrast brain CT in detecting spon- taneous SAH within 6 h after headache onset. The study group comprised 8907 patients. SAH was missed in 13 of them, which makes the overall sensitivity of the CT 98.7% and its specificity 99.9%.

    Specifically, the studies included adults who underwent imaging within 6 h after the onset of headache using modern generation multi- detector CT scanners (16 slices or more). The authors concluded “in pa- tients presenting with thunderclap headache and normal Neurological examination, normal brain CT within 6 hours of headache is extremely sensitive in ruling out aneurysmal SAH.” Of note, some studies employed general radiologists to read the CT (as opposed to neuroradi- ologists), which makes these results more universally applicable than those from studies involving institution-based neuroradiologists.

    In conclusion, this meta-analysis suggests that a negative Brain CT scan obtained within 6 h after a clear time of headache onset, a normal neurologic examination, the use of a modern CT scanner, and a reading by an attending radiologist are sufficient to rule out nonTraumatic SAH.

    Traumatic brain injury

    Carney N, Totten AM, O’Reilly C, et al. Guidelines for the management of severe traumatic brain injury, Fourth edition. Neurosurgery 2017; 80(1): 615

    Traumatic brain injury remains one of the leading causes of morbidity and mortality in the United States and the world. It is the reason for 2.5 million ED visits yearly in the US alone and is respon- sible for 56,000 deaths [9]. The 2016 Brain Trauma Foundation Guidelines serve as an update to the third edition, published in 2007. The scope of the guidelines is to examine current evidence and synthesize it into recommendations when the evidence is strong enough to support doing so, rather than provide a comprehensive management guide. They exclude topics that are related to good clin- ical care but are not TBI specific. While the article focuses on the sur- gical aspects of TBI care, a number of aspects are pertinent to the emergency physician and they are discussed below. Of note, the levels of recommendation are based on the quality of the body of ev- idence. Level I recommendations were based on a high-quality body of evidence, whereas Level II A recommendations were based on a moderate-quality body of evidence, and Level II B and III recommen- dations were based on a low-quality body of evidence.

    Prophylactic hypothermia

    Hypothermia is well recognized as a neuroprotective therapy in the setting of cardiac arrest and has been shown to improve outcome after out-of-hospital cardiac arrests from a cardiac cause [10]. In ad- dition to its neuroprotective properties, hypothermia decreases ICP. Studies have looked at whether using it “prophylactically,” early after the injury and before ICP elevation, improves outcome. The Level II B statement is that it is not recommended. This is a change from the third edition, which included a Level III recommendation for prophylactic hypothermia, stating decreased morbidity and a trend toward decreased mortality, with the caveat of limited evidence.

    Hyperosmolar therapy

    Hyperosmolar therapy is a mainstay in the management of elevated ICP and herniation syndromes. However, the optimal agent, dose, and administration continue to be investigated. Although the fourth edition clearly recognizes the need for hyperosmolar therapy to reduce ICP, it acknowledges the lack of sufficient evidence to support any hyperosmolar agent, whether hypertonic saline or mannitol, for pa- tients with severe TBI. This is a change from the third edition, which ex- plicitly stated the lack of evidence for hypertonic saline and made a restricted use Level II recommendation for mannitol and restricted its use.

    Ventilation therapy

    The majority of patients with severe TBI are intubated for airway protection. Optimizing the partial pressure of carbon dioxide in arte- rial blood (PaCO2) is a key determinant of cerebral blood flow (CBF) and of the subsequent risk of cerebral hyperemia or cerebral ische- mia. The guidelines are essentially unchanged, with a Level II B rec- ommendation that prolonged prophylactic hyperventilation with PaCO2 of 25 mm Hg or less is not recommended. The authors contin- ue the same Level III recommendations of using hyperventilation as a temporizing measure for acute reduction of ICP and avoiding hyper- ventilation in the first 24 h after injury because CBF is most critically reduced at that time.

    Steroids

    Steroids were introduced in the 1960s as a treatment for cerebral edema, but ample evidence has shown their lack of benefit in TBI as well as the induction of harm with high doses. The recommendations

    are unchanged from the previous edition, although slightly stronger ev- idence is available.

    Seizure prophylaxis

    Seizures can occur as a result of severe TBI, either early (within 7 days after injury) or late (after 7 days). Prophylactic antiepileptics have been used in an attempt to decrease the incidence of seizures, and the recommendations have not changed from the previous edi- tion. A Level II A recommendation supports administration of pro- phylactic phenytoin to decrease early post-traumatic seizures. Neither phenytoin nor valproate is recommended for preventing late post-traumatic seizures. Of note, evidence supporting the use of levetiracetam (Keppra) in TBI is limited despite its widespread use.

    Anesthetics, analgesics, and sedatives

    Anesthetics, analgesics, and sedatives are commonly used in pa- tients with TBI, for a variety of reasons, with the most specific to TBI being control of ICP and seizures. The recommendations are un- changed, although slightly stronger evidence is available. The cur- rent Level II B recommendation is that administration of barbiturates as prophylaxis against elevated ICP is not recommend- ed; however, high-dose barbiturates are recommended to control el- evated ICP refractory to maximum standard medical and surgical treatment. In addition, although propofol is recommended for con- trol of ICP, it does not decrease the mortality rate or improve 6- month outcomes.

    Blood pressure thresholds

    As has been known for decades, the SBP plays a critical role in preventing secondary injuries after severe TBI, as the brain’s auto- regulation mechanism is disrupted and is therefore unable to main- tain adequate brain perfusion, which then becomes dependent on the SBP. Hypotension must be avoided in this population. Achieving a target SBP of >= 100 mm Hg in patients 50 to 69 years old and

    >= 110 mm Hg in patients 15 to 49 years of age and those over 70 years of age may decrease mortality and improve outcomes.

    This is a Level III recommendation and is different from the previous edition, which had an even lower threshold SBP of 90 mm Hg across all age groups as a Level II recommendation at the time.

    Dizziness

    Venhovens J, Meulstee J, Verhagen WIM. Acute vestibular syndrome: a critical review and diagnostic algorithm concerning the clinical differentia- tion of peripheral versus central aetiologies in the emergency department. J Neurol 2016; 263(11): 21512157 and Edlow JA, Newman-Toker D. Using the physical examination to diagnose patients with acute dizziness and vertigo. J Emerg Med 2016; 50(4): 617628 and Atzema CL, Grewal K, Lu H, Kapral MK, Kulkarni G, Austin PC. Outcomes among patients discharged from the emergency department with a diagnosis of peripheral vertigo. Ann Neurol 2016; 79(1): 3241

    Last year was the year of vertigo, with the publication of numerous articles addressing acute vestibular syndrome (AVS), dizziness, and missed strokes. The three that we discuss here are among the most clin- ically relevant articles on the subject. Current literature on the subject follows one theme: the standard method of addressing dizziness and/ or vertigo in the ED is insufficient, is not evidence-based, and can lead to worsened mortality and morbidity.

    Prior to delving into the literature, it is important to clarify what AVS actually means. For a patient to be identified as having AVS (which is a

    syndrome, not a diagnosis), he or she needs to have all of the following symptoms and signs [11]:

    • Acute onset of dizziness and/or vertigo
    • Head motion intolerance
    • Spontaneous or gaze-evoked nystagmus
    • Gait unsteadiness
    • Nausea and/or vomiting
    • Duration of at least 24 h to several weeks

    Patients with AVS were considered to have a Benign condition, until various studies revealed that vertebrobasilar insufficiency can actually present with isolated vertigo and with no other neurologic symptoms, leading to a miss rate of up to 35% [12].

    Venhovens’ article thoroughly goes through studies that delin- eate the clinical characteristics of central causes of AVS and uses these data to devise a clinical algorithm that initially depends on the bedside HINTS oculomotor examination (Head Impulse test, Nystagmus assessment, and Test of Skew deviation) [13]. The au- thors then added the features of acute hearing loss, severe postural instability, and hyperacute onset of symptoms to further delineate the cause of AVS. Use of the algorithm is limited by the lack of evi- dence on its applicability, as it is yet to be studied in an adequate population, which is explicitly discussed in the paper. Another major limitation is that, although the algorithm is geared toward use in the ED, the studies it was derived from use techniques per- formed by neurologists (and sometimes neuro-otologists) and are not necessarily applicable or reproducible in the ED setting.

    As with most neurologic complaints, AVS is a clinically complex problem with significant overlap between benign and serious dis- ease processes. Atzema and colleagues propose an algorithm to elucidate and isolate the serious causes of dizziness but does not completely solve the puzzle.

    References

    1. Thompson BB, Bejot Y, Caso V, et al. prior antiplatelet therapy and outcome following intracerebral hemorrhage: a systematic review. Neurology 2010;75(15): 1333-42.
    2. Batchelor JS, Grayson A. A meta-analysis to determine the effect on survival of platelet transfusions in patients with either spontaneous or traumatic anti- platelet medication-associated intracranial haemorrhage. BMJ Open 2012; 2(2):e000588.
    3. Qureshi AI, Palesch YY, Barsan WG, et al. Intensive blood-pressure lowering in patients with acute cerebral hemorrhage. N Engl J Med 2016;375(11): 1033-43.
    4. Cohen AS, Burns B, Goadsby PJ. High-flow oxygen for treatment of cluster headache: a randomized trial. JAMA 2009;302:2451-7.
    5. Ozkurt B, Cinar O, Cevik E, et al. Efficacy of high-flow oxygen therapy in all types of headache: a prospective, randomized, placebo-controlled trial. Am J Emerg Med 2012;30:1760-4.
    6. Wolff HG, Lenox WG. Cerebral circulation: 12. The effects on pial vessels of varia- tions in the oxygen and carbon dioxide concentrations of the blood. Arch Neurol Psychiatry 1930;23.
    7. Connolly Jr ES, Rabinstein AA, Carhuapoma JR, Derdeyn CP, Dion J, Higashida RT, et al, American Heart Association Stroke Council, Council on Cardiovascular Radiology and Intervention, Council on Cardiovascular Nursing, Council on Cardiovascular Surgery and Anesthesia, Council on Clinical Cardiology. Guidelines for the management of Aneurysmal subarachnoid hemorrhage: a guideline for healthcare professionals from the American Heart Association/American Stroke As- sociation. Stroke 2012;43:1711-37.
    8. Perry JJ, et al. Sensitivity of computed tomography performed within six hours of onset of headache for diagnosis of subarachnoid haemorrhage: prospective cohort study. BMJ 2011;343:d4277.
    9. Taylor CA, Bell JM, Breiding MJ, Xu L. Traumatic brain injury-related emergency de- partment visits, hospitalizations, and deaths — United States, 2007 and 2013. MMWR Surveill Summ 2017; 66 (SS-9):1-16.
    10. Mark DG, Hung YY, Offerman SR, Rauchwerger AS, Reed ME, Chettipally U, et al. nontraumatic subarachnoid hemorrhage in the setting of negative cranial computed

      tomography results: external validation of a clinical and imaging prediction rule. Ann Emerg Med 2013;62 (1.e1-10.e1).

      Venhovens J, Meulstee J, Verhagen WIM. Acute vestibular syndrome: a critical review and diagnostic algorithm concerning the Clinical differentiation of pe- ripheral versus central aetiologies in the emergency department. J Neurol 2016;263:2151-7.

    11. Kerber KA, Brown DL, Lisabeth LD, Smith MA, Morgenstern LB. Stroke among pa- tients with dizziness, vertigo, and imbalance in the emergency department: a pop- ulation-based study. Stroke 2006;37:2484-7.
    12. Edlow JA, Newman-Toker D. Using the physical examination to diagnose patients with acute dizziness and vertigo. J Emerg Med 2016;50(4):617-28.

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