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Recognizing the signs and symptoms of aneurysmal subarachnoid hemorrhage Expert Rev. Neurother. 14(7), 757–768 (2014)

S Arthur Moore1, Alejandro A Rabinstein1, Michael W Stewart2 and William David Freeman*3 1 Department of Neurology, Critical Care, Mayo Clinic, Rochester, MN 55902, USA 2 Department of Ophthalmology, Mayo Clinic Florida, Jacksonville, FL, USA 3 Departments of Neurology, Neurosurgery, and Critical Care, Mayo Clinic Florida, Jacksonville, FL 32224, USA *Author for correspondence: Tel.: +90 4953 7103 Fax: +90 4953 0760 [email protected]

Subarachnoid hemorrhage (SAH) is a devastating neurologic condition with a high mortality and long term neurological morbidity in 50% of survivors. In addition, SAH commonly affects young patients causing substantial loss of productive life years and resulting in significant long term healthcare costs. Early recognition of the signs and symptoms of SAH is absolutely critical to earlier intervention, and delays in diagnosis can have devastating consequences. To avoid such delays in SAH diagnosis, the medical provider should recognize its signs and symptoms. Neuroimgaging, cerebrospinal fluid examination and angiography (invasive or non-invasive) facilitate early diagnosis of SAH. The purpose of this review is not to provide an exhaustive critique of the available literature, rather, it is to provide an overview that will better enable a provider to recognize and initiate the workup of patients with SAH. KEYWORDS: aneurysm • cerebral angiography • computed tomography • intracerebral hemorrhage • MRI • subarachnoid hemorrhage • thunderclap headache

Approximately 10–15% of patients with subarachnoid hemorrhage (SAH) die before receiving medical care [1]. This is believed to be from either a massive initial increase in intracranial pressure at the time of aneurysmal rupture, leading to loss of cerebral perfusion and irreversible neurological brain injury, or from cardiopulmonary arrest due to central loss of the respiratory drive or catecholamineinduced cardiac arrhythmias [2]. Approximately 92–98% of patients with SAH who reach a hospital or clinic complain of the sudden onset of a severe headache that reaches maximal intensity within seconds of onset, the so-called ‘thunderclap headache’ (TCH) [3–5]. For adults who have a first-ever TCH, immediate medical evaluation and a non-contrast head CT scan are indicated. Additional important clinical and historical headache descriptors, differential diagnosis of TCH and approach to diagnostic testing are described below. Clinical signs & symptoms

The term TCH has been used to describe a sudden, severe headache and can be seen in a variety of disorders (BOX 1) [6,7]. In Raskin’s original description of TCH, patients had no evidence of SAH either by CT examination or cerebrospinal fluid (CSF) evaluation [8]. While TCH is informahealthcare.com

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commonly referenced in the literature as the ‘worst headache of my life’, many patients who present to the emergency department report the ‘the worst headache ever’ from highly varied underlying pathologies including benign or acute exacerbations of long-standing headache disorders [9]. In those patients with a history of headaches, a better discriminator may be whether their current headache differs in character from their typical headaches. Most SAH patients describe the time from headache onset to maximal intensity as either instantly maximal or measured within seconds. Headaches that take minutes to hours to reach maximal intensity are not usually due to aneurysmal SAH and can constitute an important clinical discriminator. However, caution should be taken, as headache due to SAH can come on slowly in a small number of patients [10]. In addition, in patients with SAH who present with altered levels of consciousness, an appropriate headache history cannot be obtained. In addition to the ‘ictal’ headache, 15–60% of patients with SAH report a severe, sudden headache in the days or weeks prior to the development of frank SAH seen on non-contrast head CT scan [11,12]. The clinical significance of these so-called ‘sentinel headaches’ has been debated. The sentinel headache is believed to

 2014 Informa UK Ltd

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Box 1. Differential diagnosis of thunderclap headache. Vascular and hemorrhagic causes • Subarachnoid hemorrhage • Sentinel headache • Subdural, epidural or intracerebral hematoma Expert Review of Neurotherapeutics Downloaded from informahealthcare.com by Karolinska Institutet University Library on 06/24/14 For personal use only.

• Cerebral venous sinus thrombosis • Cervical artery dissection • Pituitary apoplexy • Retroclival hematoma • Acute ischemic stroke • Reversible cerebral vasoconstriction syndrome • Temporal arteritis

Non-vascular central nervous system causes • Spontaneous intracranial hypotension • Posterior reversible encephalopathy syndrome • Third ventricle colloid cyst • Intracranial infection • Intracranial mass

Primary headache conditions • Primary thunderclap headache • Migraine • Primary cough, sexual and exertional headache • Cluster headache

Non-neurologic and systemic disorders • Hypertensive crisis/emergency • Acute-angle glaucoma • Acute sinusitis • Herpes zoster ophthalmicus • Aortic dissection • Myocardial infarction Data taken from [6,7].

be due to aneurysm growth and compression of adjacent structures or possibly microscopic aneurysmal rupture. Nonetheless, headaches that precede the subsequent TCH should be interpreted within the clinical context since headaches preceding a TCH may also be seen with other diagnoses. Taking into account the possibility of recall bias, one large prospective trial showed that approximately 25% of patients with TCH without neuroimaging-defined SAH went on to develop SAH within the next year [11]. In addition, a statistically significant increase in rebleeding has been shown in those patients who report such sentinel headaches [13,14]. Thus, early or ‘worst or first’ headaches should be evaluated as soon as possible by a thorough history and physical exam, and considered for appropriate neuroimaging depending on the symptom characteristics to prevent the three- to eightfold increase in morbidity and mortality associated with delayed recognition of aneurysmal SAH [15,16]. 758

Focal neurological deficits due to SAH, while relatively uncommon and typically transient in the absence of intraparenchymal extension, may indicate the site of a ruptured or unruptured aneurysm [17,18]. For instance, aphasia may indicate a ruptured leftsided middle cerebral artery aneurysm with or without intraparenchymal hematoma. In other cases, focal neurological deficits may result from direct compression of adjacent cranial nerves or from ischemia due to acute vasospasm surrounding the aneurysm immediately after rupture. Complete or partial third-nerve palsy is a well-recognized sign from compression or rupture of the ipsilateral posterior communicating artery or the adjacent segment of the internal carotid artery (FIGURE 1) [7,19]. Visual complaints in a patient with SAH may be the result of intraocular hemorrhages. Retinal bleeding due to SAH, with or without extension into the vitreous is known as Terson’s syndrome (TS) [20,21]. Conscious patients with TS may complain of ‘large brown blobs within the visual field’ due to subinternal limiting membrane hemorrhages of the retina or diffuse ‘fuzzy vision’ due to breakthrough of the blood into the vitreous. These patterns of vision loss are not representative of chiasmal or post-chiasmal conditions. New visual complaints in a patient with SAH should prompt a dilated funduscopic examination. In comatose patients, severe, vision-threatening TS may be seen on the non-contrast head CT and orbital ultrasound (FIGURE 2). Focal or generalized seizures at the time of SAH have been reported in 4–26% of patients. The large discrepancy in incidences across studies is likely due to disparities in interpretation; seizure-like tonic phenomena caused by herniation or increased intracranial pressure are often misinterpreted as seizures [22–25]. Syncope or collapse at the time of aneurysmal SAH rupture is due to intracranial circulatory arrest from a massive intracranial pressure surge. This was described by Russell and Sargent as an ‘apoplectiform’ onset [26]. Seizures and sudden tonic posturing after hospital admission, particularly before the aneurysm is secured, may indicate rebleeding [27]. Systemic features associated with SAH may include severe hypertension, hypoxemia and ECG abnormalities. Approximately 3% of patients with SAH experience cardiac arrest at the time of hemorrhage [28]. Other cardiac abnormalities in patients with SAH include troponinemia (20–40%) and newonset, transient regional wall motion abnormalities (8%) that may evolve into apical ballooning syndrome (Takotsubo or stress-induced cardiomyopathy) [29–34]. The emergency neurologist must be aware of these complications of SAH as failure to recognize them can lead to an inappropriate diagnosis of acute coronary syndrome and delay appropriate treatment. Pulmonary edema can also occur shortly after aneurysm rupture. Its mechanism can be neurogenic, cardiogenic or combined. Bedside echocardiography can be very useful to guide management in these situations. Other presenting features of SAH may include nausea and vomiting (77%), brief loss of consciousness (53%) and meningismus secondary to blood product irritation (35%) [35,36]. While meningismus or an unexplained loss of consciousness Expert Rev. Neurother. 14(7), (2014)

Recognizing the signs & symptoms of aneurysmal SAH

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Figure 1. Focal deficits in subarachnoid hemorrhage. (A) CT and conventional angiogram (B) showing an 8 mm aneurysm (white arrow) arising from the right posterior cerebral artery in a patient who presented with a pupil-involving third cranial nerve palsy.

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Figure 2. Terson’s syndrome. (A) CT scan of the head showing modified Fisher grade 4 subarachnoid hemorrhage. (B) CT scan of the head in the same patient showing hemorrhage within the retinal body of the right eye (white arrow). (C) Orbital ultrasound showing hyperechoic hemorrhage in the same patient in the right eye (white arrow). (D) Funduscopic examination in the same patient 6 weeks later shows a poor view of the retina due to extension of the retinal hemorrhage into the vitreous.

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Table 1. Presenting features in patients with subarachnoid hemorrhage. Symptom

Percentage

Headache

92–98

Prior sentinel headache

15–60

Focal neurological deficits

30–35

Cranial neuropathy

10–20

Seizure

4–26

Syncope

53

Nausea and/or vomiting

77

Meningismus

35

Coma

16

Pulmonary edema

10

Elevated troponin

20–40

Cardiac regional wall motion abnormalities

8

Data taken from [9–12,17–19,22–26,28–36].

often prompt neurological evaluation, acute onset of severe nausea and vomiting can result in inappropriate evaluation and treatment, as the gastrointestinal symptoms may mask patient reports of acute headache. TABLE 1 summarizes the most common presenting features in patients with SAH. Based on common presenting complaints, patient characteristics and physical examination findings, the Ottawa SAH Rule A

was developed to enhance clinical diagnosis of SAH [37]. In patients presenting with severe, non-traumatic headache, the presence of any one of six findings (age ‡40 years, neck pain or stiffness, witnessed loss of consciousness, onset during exertion, instantly peaking headache pain [TCH] or limited neck flexion during physical examination) had a sensitivity of >99% in predicting SAH [37]. However, the Ottawa SAH Rule has yet to be validated in an independent cohort and its application to decide whether to pursue head imaging could lead to missing other, less common causes of severe headache (brain abscess or mass, hydrocephalus, fungal meningitis, etc.) [38]. Furthermore, the rule may not be reliably applicable to patients who cannot provide a detailed history. Diagnostic approach

The emergency physician or neurologist should maintain a high index of suspicion for SAH, as early detection and intervention are key to improving patient outcomes. Misdiagnosis, especially when the presentation is atypical, occurs in up to 19% of patients and leads to increased morbidity and mortality [15]. The mainstay of SAH identification remains the non-contrast head CT scan, though when clinical suspicion remains high or when the patient presents days after the onset of symptoms, additional testing may be necessary to exclude the diagnosis. CT scans

The high sensitivity and specificity, easy accessibility and rapid image acquisition make the non-contrast head CT scan the ideal diagnostic test for patients with suspected SAH. The B

Figure 3. Predicting aneurysm location with non-contrast CT. (A) CT scan showing diffuse SAH with intraventicular extension with a focal area of hemorrhage (white arrow) in the anterior cerebral artery distribution. (B) Angiogram of the same patient showing an anterior cerebral artery aneurysm (white arrow).

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Recognizing the signs & symptoms of aneurysmal SAH

initial CT scan not only reliably diagnoses SAH, but also serves to indicate its severity through assessment of the extension of the hemorrhage (in the subarachnoid and intraventricular compartments) and the presence of hydrocephalus, intraparenchymal hematomas and global brain edema. Also, the degree of hemorrhage can be very useful to estimate the risk of delayed vasospasm and cerebral ischemia, as discussed below [39]. The distribution of hemorrhage, which appears hyperdense on CT scans, can occasionally suggest the location of an underlying aneurysm. The sensitivity of such predictions is highly variable (45–86%), but is highest for anterior cerebral and anterior communicating arteries (FIGURE 3) [40–42]. In contrast, the presence of an intraparenchymal hematoma, present in approximately 15% of SAH, is highly predictive of the site of an underlying aneurysm (FIGURE 4) [42,43]. The ability of the CT scan to detect SAH is inversely proportional to the time since occurrence of the hemorrhage. Within the first 6 h of symptom onset, the sensitivity and specificity of head CT for SAH may approach 100%; the sensitivity falls to 95% after 24 h, 74% on the third day and approximately 50% after 1 week [44–46]. Recently published studies showing that CT sensitivity approaches 100% for patients with SAH who undergo scanning within 6 h of hemorrhage deserve special discussion. These studies were performed at high volume, tertiary care facilities with 24 h access to third-generation CT scanners and highly experienced neuroradiologists [44,45]. Therefore, the results may not be generalizable to centers with less experienced radiologists. In addition, in one of the studies, only 7% of patients with negative CT scans underwent lumbar puncture and were, instead, evaluated for rebleed by questionnaire at 6 months. Therefore, some patients with subtle SAH and no rebleeding could have been missed [44,47]. In the second study, one patient with SAH due to an arteriovenous malformation had an inconclusive CT scan and an atypical presentation for SAH, but was found to have xanthochromia on lumbar puncture [45]. This raises the possibility that small SAH, regardless of etiology, could be missed. The limitations of CT scans as the sole method to diagnose SAH are highlighted by a recently published case–control series in which the initial CT scan, even when performed within 6 h of symptom onset, failed to identify up to 20% of patients with SAH [47]. Though this number may be falsely elevated, early CT is unlikely to be perfectly sensitive [48]. Given the significant morbidity and mortality associated with delayed diagnosis of SAH, a lumbar puncture (discussed below) is a relatively non-invasive means of ensuring that the diagnosis is not missed. Lumbar puncture should be discussed with the patient on a case-by-case basis with a clear explanation of the risks and benefits. While 80–85% of SAHs are secondary to rupture of an intracranial aneurysm, the CT scan can be instrumental in detecting other causes of SAH, particularly when history is difficult to obtain. Focal blood isolated to the sulci within a cerebral convexity, as opposed to diffuse hemorrhage, is an unusual informahealthcare.com

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Figure 4. Intraparenchymal hematoma with diffuse subarachnoid hemorrhage including intraventricular extension in a patient with a right middle cerebral artery trifurcation aneurysm who initially presented with severe headache and left-sided weakness.

feature of aneurysmal SAH and can suggest trauma, coagulopathy or vasculitis [49,50]. Trauma may also be suggested by skull fractures on the bone-specific windows of the CT scan. Hemorrhage isolated to the prepontine and interpeduncular cisterns

Figure 5. CT scan of the head showing perimesencephalic subarachnoid hemorrhage. No aneurysm was present on digital subtraction angiography.

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Figure 6. Early hydrocephalus in subarachnoid hemorrhage. Early hydrocephalus including enlargement of the fourth ventricle (A; white arrow) and temporal horns of the lateral ventricles (B; black arrows) in a patient at the time of presentation for headache with decreased consciousness secondary to diffuse subarachnoid hemorrhage with intraventricular extension.

(pretruncal or perimesencephalic SAH) may be secondary to a ruptured vein, perforating artery or intramural hematoma (FIGURE 5); though further imaging with conventional angiography is necessary to exclude an underlying posterior circulation aneurysm, perimesencephalic or pretruncal SAH is generally associated with excellent outcome [50–52]. CT scans are excellent for recognizing acute SAH and for identifying acute hydrocephalus (FIGURE 6). Acute hydrocephalus occurs in approximately 20% of patients with SAH and is an independent predictor of poor outcome in the year following hemorrhage [53,54]. Though often initially asymptomatic, hydrocephalus associated with acute neurological deterioration or coma may prompt emergent neurosurgical intervention with an external ventricular drain [53]. The role of advanced CT imaging such as CT perfusion (CTP) scanning in the acute SAH patient has yet to be firmly established. Prolongation of the mean transit time and time to peak on CTP have been correlated with initial neurological status and early clinical outcome, but its primary role is to identify delayed cerebral ischemia and vasospasm, which typically

occur several days following the hemorrhage itself [55,56]. As such, CTP is more commonly used to diagnose sequelae of SAH rather to diagnose the SAH itself. MRI scans

Table 2. Hunt and Hess grading scale for subarachnoid hemorrhage.

Although widespread access along with high sensitivity makes CT scanning the preferred method to document SAH in the acute phase, several studies have suggested that MRI has a higher sensitivity than CT, particularly with the use of sequences such as fluid-attenuated inversion recovery and susceptibility weighted or gradient echo imagining [57–59]. Yet the main practical utility of MRI is when there has been a delay of several days between the ictal headache and initial clinical evaluation. As mentioned previously, the ability of CT to detect SAH is inversely proportional to the time since the hemorrhage, with dropping markedly several days after the event [60]. Conversely, the sensitivity of MRI scans, particularly the susceptibility weighted, gradient echo and fluidattenuated inversion recovery sequences, remain high and approaches 100% in the subacute phase (4–30 days following the ictal event) [57,61,62]. Therefore, MRI is preferred to evaluate for possible SAH when the initial presentation has been delayed.

Grade

Clinical condition

Cerebral angiography

0

Unruptured

1

Asymptomatic or minimal headache, nuchal rigidity

2

Moderate-to-severe headache, nuchal rigidity, no neurological deficit other than cranial nerve palsy

3

Drowsiness, confusion, mild focal deficit

4

Stupor, moderate-to-severe hemiparesis, possible early decerebrate rigidity and vegetative disturbances

5

Deep coma, decerebrate rigidity, moribund appearance

Improving technology together with increasing availability make non-invasive vascular imaging methods, such as CT or MR angiography (CTA and MRA, respectively), attractive for detecting aneurysms. The sensitivity of CTA for aneurysm detection ranges from 88 to 100%, with a recent meta-analysis showing a pooled sensitivity of 98% with newer generation scanners [63–65]. The ability of CTA to identify aneurysms is inversely proportional to their size, with only 53% sensitivity for aneurysms 2 mm in size, though newer generation scanners have improved sensitivity for smaller aneurysms, a trend that will likely continue [60,66].

Data taken from [92].

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Recognizing the signs & symptoms of aneurysmal SAH

MR angiography has been proposed as an initial diagnostic imaging modality in patients with acute SAH [67,68]. However, while MRA has a sensitivity greater than 90% for relatively large aneurysms, it falls to

Recognizing the signs and symptoms of aneurysmal subarachnoid hemorrhage.

Subarachnoid hemorrhage (SAH) is a devastating neurologic condition with a high mortality and long term neurological morbidity in 50% of survivors. In...
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