A missed diagnosis could be the ‘worst
headache’ of our lives!
Let’s do a
quick review of one of the major neurological emergencies - the deadly subarachnoid
hemorrhage. Although traumatic SAH is
the most common type presenting to the ED, in this review we will be dealing
with only SAH of non-traumatic etiology as diagnosis and management. This in
the ED is of paramount importance and any delay is associated with significant
morbidity and mortality.
What and where?
Leakage of
blood/bleeding into the subarachnoid space (between arachnoid mater and pia
mater). The picture below should make things easier to understand.
- Rupture of ‘Berry’ aneurysms in the
circle of Willis (commonest cause ~ 85%)
- Arteriovenous malformation
- Rupture of the mycotic aneurysms
- Tumors
- Connective tissue disorders
- Idiopathic ( also translated as ‘’WE STILL
HAVE NO CLUE’’) ~20%
- Drugs
Risk factors for SAH:
- Past H/O SAH
- Hypertension
- Smoking
- Excessive alcohol consumption
- Polycystic Kidney disease
- Family history of SAH*
- Marfan’s syndrome, Ehler-Danlos
syndrome type 4
- Coarctation of aorta
*2% of the
family members of patients will develop SAH. Risk increases with increasing
number of family members having SAH.
History and Clinical Features:
Headache
is the most common presenting complaint. The classic descriptions include,
· “The worst headache of my life”, “my
head is exploding”.
· ‘Thunderclap headache’ – Like a blow
to the back of head.
Severe headache of sudden onset that
reaches maximal intensity within minutes.
Severe headache
with change in the character/difference
in intensity or of unique quality when compared to past headaches. This is
particularly important in patients who are having chronic headache (ex:
Migraine). Never ignore a headache that’s ‘different’, ‘never felt before’,
‘worst’ or not subsiding with ‘usual’ medicines, with associated symptoms
(especially in a patient with chronic headache syndrome where the chances of
missing a diagnosis is more) Ã
need further investigation.
· ‘Warning headaches’ may precede the
onset of SAH.
· In ~25% patients, exertional
activities may precede the event. May also be preceded by sexual intercourse,
exercise, defecation (all activities which increase BP)
Other
associated features may include,
- Neck pain/stiffness
- Vomiting/Nausea (must increase your suspicion)
- Syncope (Yes, SAH too can present
with syncopy!)
- Altered mental status
- Seizures, posturing
- Focal neurological deficits
- Dilated unequal pupils, Unilateral
eye pain, papilledema.
- Fundoscopy may reveal subhyaloid hemorrhages*
*Pathognomonic
of SAH in the absence of blunt trauma; but present only in about 11%-33%
patients
Differential diagnosis:
- Intracerebral hemorrhage
- Cerebral venous thrombosis
- Ischemic stroke
- Meningitis/Encephalitis
- Coital cephalgia
- Metabolic abnormalities
- Intracranial tumor
- Primary headache syndrome (ex: Cluster headache, migraine, etc.)
Always have
a high degree of suspicion when patients who are known to have primary headache
syndromes present to the emergency department with headache that’s ‘different’
from the previous episodes or the headache that’s not responding to their usual
medications.
Investigations and diagnosis:
Initial
diagnostic modality of choice in a patient with suspicion of SAH is non-contrast CT pf the head.
Sensitivity of CT is highest shortly after the onset of symptoms and ~98% when
performed within 12 hours of onset. Sensitivity of CT reduces over time. In
addition, anemic patients are more likely to have false negative CTs.
According to
the guidelines, when SAH is suspected and if the CT is normal, a CSF analysis has to be done to
look for Xanthochromia (Yellow appearance of CSF due to breakdown of hemoglobin
into bilirubin – after 12 hours of onset of symptoms) and RBC count. (Measuring
RBC count is not followed strictly in all centers as many studies have shown
that these are not very reliable indicators of SAH and is time dependent.
Local/departmental protocols can be followed in this regard.)
SAH suspected + Positive CT = SAH
SAH suspected + Negative CT +
Positive CSF findings = SAH most likely
SAH suspected + Normal head CT +
absent xanthochromia and zero or few RBCs in CSF = SAH almost ruled out.
Gold Standard for diagnosis is
Cerebral Angiography
Labs: The SAH checklist
for the first hour of presentation includes:
- Brain imaging
- Labs: CBC, PT, APTT, Electrolytes, Creatinine,
Troponin, Toxicology screen
- 12-Lead ECG
Blood glucose level has to be checked to rule out the
potentially reversible cause of symptoms.
ECG may show Tall T waves, ST depression, Giant T wave
inversions secondary to raised ICP, QT prolongation and arrhythmias.
ECHO may show ‘neurogenic cardiomyopathy’: “Approximately
20% to 30% of patients with SAH manifest a secondary cardiomyopathy and/or
regional wall motion abnormality, which is usually reversible in the absence of
underlying obstructive CAD. This entity has been referred to as neuro-cardiogenic
stunning and neurogenic stress cardiomyopathy”
Troponins may be raised.
Patients may
exhibit hyponatremia due to SIADH or
cerebral salt wasting.
CXR may show neurogenic pulmonary edema.
Coagulation profile may be deranged if the patient is
anticoagulated.
MRI, CTA are not routinely done. May be
helpful in special circumstances and this has to be discussed with the
neurology/neurosurgery teams for a consensus. CTA may be helpful for diagnosis
of aneurysms.
Grading of SAH: There are different systems of
grading based on clinical features, GCS and CT findings. These grades are used
as predictors of prognosis. The most commonly used grading systems are
Hess and Hunt grading system
WFNS (World Federation of Neurosurgical
Society) scale
Grade 1 –
70% survival rate Grade 2 – 60%
survival rate
Grade 3 –
50% survival rate Grade 4 – 40%
survival rate
Grade 5 –
10% survival rate
Complications of SAH
- Re-bleeding:
Risk is highest in the first 24 hours.
- Hydrocephalus:
About 30% develop in the first 3 days.
- Neurogenic pulmonary edema
- Aspiration pneumonia – Sepsis.
- Myocardial infarction, arrhythmias, LV dysfunction and neurogenic
cardiomyopathy.
- SIADH Ã Hyponatremia:
Most common 3days – 14days.
- Vasospasm:
Most common 2days – 3 weeks following SAH.
ED Management of SAH and complications:
Definitive therapy is the obliteration of the aneurysm by
clipping or endovascular coiling as soon as possible.
Airway and breathing:
Adequate
oxygenation is very important. Aim for SpO2 > 94%. Aim for PaCO2 within the
normal range.
Consider
intubation and mechanical ventilation if:
- Airway
not patent.
- Hyperventilation
or hypoxia not responding to supplemental oxygen.
- Anticipated
deterioration or transfer to another center.
Tape the endotracheal
tube in place rather than tie it to avoid increases in ICP
Consider RSI
with drugs, which do not cause hypotension (Ketamine, Etomidate). Also try and
do a quick neurological examination prior to RSI.
Other simple measures to reduce ICP:
Head end elevation
No IJ lines
Circulation:
Avoid
hypotension. But also make sure that BP is not ‘very high’. There’s lack of
adequate data regarding BP control in SAH patients. There is some data that
suggests a higher rate of re-bleeding with SBP > 160mmHg. So try to maintain the MAP between 90-110mmHg (Coming down up to 160/90 appears pretty safe).
IV Labetalol can be used as infusion or can be given intermittent doses.
The idea is
to strike a balance between risks of stroke – HTN associated rebleeding – maintenance
of cerebral perfusion pressure.
Blood sugars: Maintain normoglycemia.
Seizures: Possibly seen due aneurysm rupture
and increased ICP. Use anticonvulsants for treating actual seizures. Use of prophylactic anticonvulsants is
controversial; but AHA and NCS (Neurocritical care Society) suggest
consideration of anti-convulsants in the immediate post hemorrhage period. Use
of Levetiracetam may be considered as use of phenytoin is associated with worse
long term outcomes.
Coagulopathy: Mainly seen in patients on Warfarin therapy. Patients with INR > 1.4
should be treated with combination of FFPs, Vitamin K and PCC. Low platelet
count below 50,000 is treated with platelet transfusions. If they are on
antiplatelets, reverse them with platelet transfusions in consultation with
hematology.
Pain: Short acting IV analgesics like
Fentanyl can be used. Help the patient avoid straining, Valsalva and
coughing. Fentanyl is probably a better
choice here as compared to Morphine, as the latter cause histamine release,
that can lead to vasodilatation and a bump in ICP. Small doses of Lorazepam
might help to relieve anxiety if any. But be cautious that overdose of
medications does not mask change in mental status.
Vasospasm:
Can be treated with Nimodipine 60mg, PO/NGT every 4th hourly. The
use of nimodipine is associated with improved overall outcomes. This should be
initiated within 96 hours of symptom onset unless contraindicated.
Avoid hypothermia and hyperthermia.
Aim for normothermia. This can be achieved by appropriate usage of
warming/cooling blankets, mechanical warmers, antipyretics.
Aspiration and sepsis: Early antibiotics and fluid management if suspected. Follow
sepsis guidelines.
Hydrocephalus: May require EVD insertion. Consult
Neurosurgery team early.
Communication and referrals:
- Always
involve neurology and neurosurgery team early.
- Convey
the present condition of the patient, CT finding, absence/presence of
hydrocephalus, grading, present management, expected course of events and
further investigations like CT angiography that might be required when talking
to the specialist.
- Transfer to the appropriate center if your center doesn’t have neurosurgical
facilities.
Take home points:
- Ask them "Is it different from their previous headaches".
- Ask for any headache preceding syncope!
- Non contrast CT is highly sensitive if done within
early hours of onset of symptoms and a CSF analysis confirms the diagnosis if
CT is negative.
- Reverse anticoagulants when INR > 1.4 and Antiplatelets
when counts < 50,000.
Author
Dr. Apoorva Chandra
Twitter: @apoorvamagic
Resident, Emergency medicine
Apollo Health City, Hyderabad
apoorvamagic@gmail.com
Further reading and references: