Neurocrit Care (2012) 17:47-53
Emergency Neurological Life Support:
Jonathan A. Edlow, Owen Samuels,
Wade S. Smith & Scott D. Weingart
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Emergency Neurological Life Support: Subarachnoid
Jonathan A. Edlow•Owen Samuels•
Wade S. Smith•Scott D. Weingart
Published online: 30 August 2012
? Neurocritical Care Society 2012
logical 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 hour of onset, SAH was chosen as an
Emergency Neurological Life Support protocol.
Subarachnoid hemorrhage (SAH) is a neuro-
Hydrocephalus ? Protocol
Aneurysm ? Ventriculostomy ?
Subarachnoid hemorrhage (SAH) is a neurological emer-
gency. Although trauma is the most common cause of
blood in the subarachnoid space, this section will focus
on non-traumatic SAH, of which the predominant cause
is a ruptured intracranial aneurysm or arteriovenous
malformation (AVM). At least half of the remainder of
atraumatic SAH cases are caused by non-aneurysmal
bleeding from a ‘‘perimesencephalic’’ SAH.
The American Heart Association (AHA) updated
guidelines for the evaluation and treatment of patients with
SAH in 2012 , and the Neurocritical Care Society
recently released SAH guidelines as well . These
guidelines discuss issues of diagnosis and very early
management of SAH upon admission to the emergency
department (ED) and provide an evidence based review of
The ENLS suggested algorithm for the initial manage-
ment of SAH is shown in Fig. 1. Suggested items to
complete within the first hour of evaluating a patient with
SAH are shown in Table 1.
The vast majority of patients with SAH experience abrupt
onset of a severe headache, which may be associated with a
brief loss of consciousness, vomiting, neck pain, or stiff-
ness. In approximately 40–50 % of patients, mental status
is normal, and there are no focal neurological deficits.
Patients often describe this as the ‘‘worst headache of my
life’’ or ‘‘like my head is exploding.’’
This headache is often referred to as a thunderclap
headache, which has a differential diagnosis beyond SAH
[3, 4]. The headache is almost always unique, as compared
with prior headaches the patient may have had. Some of
these patients will have meningismus, which is a physical
exam finding to be distinguished from neck pain or stiff-
ness that the patient may have by history. The remaining
50 % of patients have various neurological findings rang-
ing from minor mental status changes to focal deficits
J. A. Edlow (&)
Department of Emergency Medicine, Beth Israel Deaconess
Medical Center, Harvard Medical School, Boston, MA, USA
Department of Neurosurgery, Emory University School
of Medicine, Atlanta, GA, USA
W. S. Smith
ENLS Course Co-Chair, Department of Neurology,
University of California, San Francisco,
San Francisco, CA, USA
S. D. Weingart
ENLS Course Co-Chair, Division of ED Critical Care,
Mount Sinai School of Medicine, New York, NY, USA
Neurocrit Care (2012) 17:S47–S53
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associated with the headache. Patients who present coma-
tose will obviously not complain of headache.
Although the classic presentation of SAH includes onset
of headache with exertion or a Valsalva maneuver, this
finding (headache developing with exertion) actually occurs
in a minority of patients, some of whom develop symptoms
during sleep .Some patients with abnormalities in mental
status may not be able to give a cogent history of the head-
suddenly. A favorable response of the pain to any type of
evidence of a benign etiology [6, 7].
Historic studies suggest that 12–25 % of patients with
SAH are misdiagnosed  and that approximately 5 % of
ED patients with SAH presenting with headache are mis-
diagnosed on their first visit . Well-appearing patients
with normal neurological exams may be mistaken to have
migraine or ‘‘sinus headache’’ [3, 8]. In one study, the most
common reason for misdiagnosis was failure to perform a
Fig. 1 ENLS Subarachnoid Hemorrhage protocol
Table 1 Subarachnoid hemorrhage checklist for the first hour
h Brain imaging
h Labs: PT, PTT, CBC, platelets, electrolytes, creatinine,
troponin, toxicology screen
h 12 lead ECG
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computed tomographic (CT) scan . Not surprisingly,
patients with smaller hemorrhages and normal mental sta-
tus are more often misdiagnosed, and their outcomes are
worse than they had been correctly diagnosed [3, 8, 10].
Some SAH patients present with specific symptoms
or combinations of symptoms suggest another diagnosis
[3, 8]. These include:
Isolated neck pain (cervical strain or degenerative
Prominent nausea and vomiting (gastroenteritis [note
the absence of diarrhea] and peripheral vertigo).
Elevated blood pressure (BP) or electrocardiographic
abnormalities (hypertensive encephalopathy or query
acute coronary syndrome).
In other situations, a particular physical examination
finding, such as a third nerve palsy or a retinal hemorrhage,
may suggest the diagnosis of SAH. All patients with a new,
severe headache and a new abnormality in their neuro-
logical exam should be investigated further.
Among neurologically intact patients, physicians should
severe, unique headache for that patient, especially if the
One recent, large prospective study that has not yet been
independently validated suggested a derivation set of clinical
decision rules for which acute severe headache patients
require further work-up. The various characteristics found to
BP, increased age, vomiting, onset with exertion, loss of
consciousness, and neck pain or stiffness .
For patients presenting with isolated headache who are
neurologically intact, there are no specific pre-hospital
interventions, apart from consideration of analgesics. For
patients presenting with headache who are neurologically
or comatose or are vomiting repeatedly may need to have
their airways controlled by tracheal intubation in the field.
The first step in the diagnosis of SAH in the ED is non-
contrast brain CT [1, 3, 8]. The CT in patients with
aneurysmal SAH will show blood (appears white) in the
subarachnoid space, typically in the basal cisterns around
the circle of Willis; major fissures; and occasionally iso-
lated intraventricular location. Subarachnoid blood that is
present high along the convexity is often due to non-
aneurysmal causes, most commonly with head trauma.
Less common causes include AVMs, cerebral amyloid
angiopathy, vasculitis, and other toxic and inflammatory
Negative CT scans can occur in several settings. The
two most important bleeds are too small to be detectable
and the bleeds that have occurred hours to days before the
CT scan (CT is more sensitive soon after the bleed). The
first factor is self-evident. The second, timing bias is due to
the normal circulation of cerebrospinal fluid (CSF). Other
possibilities include incorrect interpretation (CT is actually
positive), patients whose hematocrits are B30 (blood is
isodense with brain), and technical factors (poor CT
quality) [3, 8].
Again, CT sensitivity drops over time . Studies relying
on older CT technology suggest that CT sensitivity is
approximately 90 % on the day of the hemorrhage, falls to
60–85 % on day 5, and is approximately 50 % at one week.
Modern scanners are likely more sensitive; however, in one
patients with a normal mental status was still only 91 % .
The normal volume of CSF present in the body (150 ml)
turns over 3 times daily. This circulation accounts for the
drop-off in CT sensitivity. One recent study suggests that
CT was 100 % sensitive within 3 days of the headache
onset . However, nearly 60 % of patients in this
referral to a neurosurgical center had SAH, so this was not
a typical ED population in which one would expect an
incidence of SAH between 8 and 12 % .
The last relevant article—a multi-center, ED-based
study that has not yet been independently verified—sug-
gests that CT is 100 % sensitive if performed within 6 h of
headache onset . Of the 240 of 3,132 (7.7 %) ED
patients with headache in the study, CT was 93 % sensitive
overall. However, of the 953 patients scanned within 6 h of
headache onset, 121 had SAH (12.7 %). CT revealed the
SAH in all of these early presenters.
CT Confirms SAH
Although there are rare occasions in which CT is falsely
positive, patients whose CT shows SAH should be assumed
to have SAH and managed accordingly [2, 3].
CT Negative for SAH/LP Positive
Based on current evidence, patients under evaluation
for SAH whose CT scans are negative, equivocal, or
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non-diagnostic should undergo lumbar puncture (LP) [1, 3,
8]. As with CT, CSF results are also time-dependent. Large
amounts of red blood cells (generally in the thousands) are
initially present but rapidly diminish with time (due to the
circulatory cycle discussed in the ‘‘Brain Imaging’’ section
Xanthochromia—the yellowish discoloration of CSF
that results from in vivo degradation of hemoglobin into
bilirubin (as well as oxyhemoglobin and methemoglo-
bin)—begins to develop and is nearly universally present
by 12 h after the onset of the bleed . It can be measured
by visual inspection of the centrifuged CSF or by
Although some recommend that spectrophotometry can
be used as a more sensitive method to detect xanthochro-
mia, this method leads to a high proportion of false
positives . Further, nearly all hospital clinical labora-
tories in North America use visual inspection following
sample centrifusion to assess xanthochromia . Finally,
CSF deemed ‘‘clear’’ by visual inspection is very unlikely
to be compatible with SAH ; however, this visual
inspection should be performed in a conical-base test tube
(typically supplied in the LP kit) and not in a capillary tube.
The tube of fluid should be compared with water against a
white background in neutral lighting.
Measuring the opening pressure is recommended, and it
will be elevated in approximately 2/3 of SAH cases .
The presence of elevated opening pressure may also help to
distinguish traumatic taps from true SAH . The best
indicator is the absence of xanthochromia.
Alternative Diagnostic Pathways
Other diagnostic pathways have been suggested, including
an LP-first strategy based on mathematical modeling that
indicated improved resource management and a higher rate
of LP (it should be noted that this method has not been
clinically tested in the CT era) . Another model
includes the use of magnetic resonance imaging (MRI),
which is quite sensitive for blood, including SAH, and is
superior to CT in terms of timing the bleed. However, due
to greater availability, lower cost, and greater experience
with its interpretation, CT remains the recommended first
test [1, 3]. If MRI is used as the initial imaging test, an LP
is still necessary if the MRI is negative .
More recently, primary CT followed by CT angiography
(CTA) has been suggested as a possible diagnostic pathway
[22, 23]. Among other issues, however, the CT (if nega-
tive) followed by CTA will primarily diagnose an
aneurysm as opposed to diagnosing a bleed. There are
many downstream implications of this technique that cli-
nicians should consider .
Once SAH is confirmed by any means (CT, LP, or other),
several management steps must be addressed. In addition to
the specific steps below, the patient should be placed on
bed rest with cardiac monitoring, and a 12-lead electro-
cardiogram should be obtained. Blood should be sent to the
laboratory for a complete blood count as well as coagula-
tion tests, electrolytes, renal function, and troponin.
Definitive therapy is the obliteration of the aneurysm,
either by clipping or endovascular coiling; both of these
isolate the aneurysm from the general circulation and
should be carried out as soon as feasible . Several
studies have shown that patient outcomes are improved
when they are treated at high volume centers defined as
those that treats >35 cases per year [1, 25, 26]. Low
volume centers should strongly consider transfer of the
patient to a high volume center as soon as feasible. Ideally,
pre-arranged transfer agreements should be in place.
Once the diagnosis of SAH is made and the patient is
stabilized, the physician should speak to a cerebrovascular
specialist. The ‘‘Communication’’ section below (Table 2)
includes the checklist of communications that should be
discussed in this conversation.
In addition to the standard communication about a
patient, the conversation should ideally include the clinical
status of the patient (often measured using the Hunt and
Hess or the World Federation of Neurological Surgeons
scores), results of brain imaging and/or CSF analysis, air-
way status, and the presence or absence of hydrocephalus.
The discussion should also include goals of BP control,
review of administered medications for pain and anxiety,
and treatments for rebleeding, seizure, and vasospasm
prophylaxis, as well as which clinician will take respon-
sibility for vascular imaging.
Airway: Need for Intubation
The determination to place an endotracheal intubation
follows standard factors: ability of the patient to control his
or her airway; hyperventilation or hypoxia resistant to
supplemental oxygen; or anticipated clinical decompensa-
tion over time, especially if a transfer to another facility is
involved (see the Airway, Ventilation, and Sedation
Fewer than 20 % of SAH patients have seizures, but when
they occur, they can result in aneurysm rerupture and
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increased intracranial pressure (ICP). Actual seizures
should be treated with anti-convulsants, but prophylactic
anti-convulsants are optional. Also, in patients with altered
mental status, non-convulsive status epilepticus may be
present, which can only be diagnosed by electroencepha-
Both the AHA and NCS guidelines [1, 2] suggest con-
sideration of anti-convulsants in the immediate post-
hemorrhage period , while other experts recommend
against this practice . Here, a very short course
(<7 days) of prophylactic anti-convulsant is recom-
mended in the period following diagnosis and before
definitive aneurysm treatment. As phenytoin may lead to
worse long-term cognitive outcomes, use of a different
drug, such as levetiracetam, could be considered.
Decline in Neurological Status
Some patients with SAH will experience an early deterio-
ration in neurological status. It is important in these
patients to consider the full differential diagnosis, since the
causes, and thus treatments, will vary.
Reassessment of the vital signs and telemetry monitor is
critical. New hypotension will decrease cerebral perfusion
pressure. New hypoxia may result from neurogenic pul-
monary edema. Arrhythmias may also lead to hypotension.
Cardiovascular collapse could be the result of increasing
response) or, infrequently, neurocardiogenic shock from
Takasubu’s syndrome or respiratory failure from neuro-
genic pulmonary edema. Physical examination may show
further evidence of herniation or a new seizure requiring
A repeat CT scan is also necessary, as it may show
herniation, ultra-early rebleeding, development of or
increase in hydrocephalus, or, rarely, development of an
intraparenchymal or subdural hematoma.
Coagulopathy should be treated (see the algorithms in the
Intracerebral Hemorrhage protocol for more details).
Warfarin therapy is the most common source of coagu-
lopathy. Patients with an international normalized ration
(INR) >1.4 should be treated with some combination of
fresh frozen plasma, intravenous (IV) vitamin K, and
prothrombin complex concentrates, depending upon many
different factors. Low platelet count below 50,000 can be
treated with platelet transfusions.
There are no specific management guidelines to address
patients with SAH taking anti-platelet agents, such as
cloprideral or prasergril. These agents can potentially
increase the risk and severity of aneurysm rerupture.
Moreover, profound platelet inhibition with clopridergal
has been associated with significant procedural related
complications. Reversal with platelet transfusions and
other hemostatic agents should consider risk benefit for the
individual patient in consultation with local experts in
Treat Pain and Anxiety
In addition to a primary motive of achieving the patient’s
comfort, treatment of pain, vomiting, and anxiety is clini-
cally important. Judicious amounts of short-acting IV
analgesics, such as fentanyl, should be used to help the
patient avoid straining, Valsalva, and stress. Treating
vomiting with anti-emetics may also be helpful. If there is a
significant component of anxiety, small doses of IV lora-
zepam may help. All of these steps may help to control the
elevated BP. Over-medication, which could mask subtle
mental status changes, should be avoided.
AHA and Neurocritical Care Society guidelines [1, 2]
acknowledge the lack of quality data about BP control in
SAH patients and suggest only that the blood pressure
should be monitored and controlled to ‘‘balance the risk of
stroke, hypertension-associated rebleeding, and mainte-
nance of the cerebral perfusion pressure’’ . That said,
retrospective data suggest a higher rate of rebleeding with
systolic BPs above 160 mmHg.
Current guidelines suggest treating extreme hyperten-
sion in patients with an unsecured ruptured aneurysm.
Modest BP (mean arterial pressure, or MAP, <110) does
not require treatment. Pre-morbid BPs should be consid-
ered and used to inform the risks and benefits of treatment.
Experts in the field use anti-hypertensive medications that
are short acting, easily titratable, and can be administered
as an IV drip to reduce the systolic pressure to below
160 mmHg, or the MAP <110, keeping in mind the
The clinician should carefully evaluate the CT scan for
hydrocephalus, which occurs in up to 30 % of SAH
patients in the first 3 days. This may be asymptomatic but
is more often seen in severely affected patients. If the
hydrocephalus is symptomatic, it can be treated with an
external ventricular drain, although some data suggest that
this may be associated with rebleeding . In addition,
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comatose patients with hydrocephalus may have elevated
ICP, so placement of a drain will not only reduce ICP by
allowing draining of CSF, but it will also provide a means
to monitor ICP throughout the hospitalization.
Prevention of rebleeding before definitive aneurysm treat-
ment is an important strategy. In the past, when surgical
treatment was delayed for weeks, pre-operative anti-fibri-
nolytic treatment was standard. Currently, early definitive
treatment of the aneurysm is generally recommended .
Thus, there has been an increased interest in early, short-
term anti-fibrinolytic treatment with either amino-epsilon
caproic acid or tranexamic acid in situations, where sur-
gical options are not readily available. One study of
immediate use of tranexamic acid to SAH patients, most of
whom were treated within 24 h, demonstrated an 80 %
reduction in rebleeding before the definitive treatment
Calcium Channel Blockers
The use of oral (or per nasogastric tube) nimodipine has
been shown in multiple randomized trials to decrease
cerebral ischemia and improve overall outcomes of SAH
patients . This is not mediated by amelioration of
angiographically documented vasospasm; rather, nimodi-
pine works via a presumed cellular neuroprotective
mechanism. Other IV calcium channel blockers, such as
nicardipine, have not been shown to improve outcomes
(although they do improve vasospasm) . Caution
should be exercised to avoid drops in BPs with all of these
agents, including oral nimodipine.
When communicating to an accepting or referring physi-
cian about this patient, consider including the key elements
listed in Table 2.
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Table 2 Subarachnoid
assessment and referral
h Clinical presentation (level of consciousness, motor exam, pupils)
h WFNS and Hunt–Hess Grade
h Hydrocephalus present?
h Airway status
h Medications given, including sedatives, analgesics, seizure
prophylaxis, anti-hypertensives, and nimodipine
h Coordination of other vascular imaging
h Results of initial imaging
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