Ferro_Eu Neuro Rev_EU Neurology 08/03/2010 16:10 Page 39
Subarachnoid Haemorrhage – Current Thinking and Future Strategy
being migraine, tension headache and headache related to high scans. Perimesencephalic SAH is rarely due to aneurysmal rupture
blood pressure. (<10%), and is considered to be of venous origin or due to intramural
dissection. Perimesencephalic SAH has a benign course, although it
Confirmation of Diagnosis can be complicated by hydrocephalus. In subpial SAH, haematic
SAH is confirmed by the presence of subarachnoid haematic densities densities are restricted to a small zone of the brain convexity,
on an early brain computed tomography (CT) scan. The sensitivity of a usually between two convolutions. Subpial SAH may have several
CT scan ranges from 90 to 100%.
10
Sensitivity is influenced by the causes including mycotic or distal aneurysms, arteriovenous
amount of blood in the cerebrospinal fluid (CSF) and by the time malformations, dural fistulae, cortical vein thrombosis, reversible
elapsed since the onset of symptoms. Thirty per cent of scans will be cerebral vasoconstriction syndromes and amyloid angiopathy.
16
negative within four days after the initial bleeding.
Clinical Course and Prognosis
If the CT scan is negative and SAH is still suspected, a delayed The most important neurological complications found in SAH
(>12-hour) lumbar puncture must be performed to detect CSF are re-bleeding,
17
intracerebral haematoma and intraventricular
xanthochromia. Xanthochromia in the CSF is due to bilirubin from haemorrhage, vasospasm, delayed cerebral ischemia, hydrocephalus
haemoglobin. It develops between two and 12 hours after bleeding and seizures. Re-bleeding peaks in the first days after the first
and takes at least two weeks to clear. Spectrophotometry of the CSF bleeding and is more frequent in patients with poor clinical condition
is the recommended method of analysis. This should be performed on and in those with large aneurysms. If the aneurysm is not treated, the
the final bottle of CSF collected.
11
The sensitivity of CT scan combined risk of re-bleeding within four weeks is estimated to be 35–40%
.18
After
with lumbar puncture for confirmation of the diagnosis of SAH is the first month, the risk decreases gradually from 1–2%/day to
100%.
12
Magnetic resonance imaging with fluid-attenuated inversion 3%/year.
19
Vasospam peaks between the fourth and 15th day. The
recovery (FLAIR) and T
2
* sequences is also useful for detecting cases presence of vasopasm can be monitored daily using a transcranial
with delayed presentation. Doppler. This has a high specificity (99%) and high positive predictive
value (97%), but moderate sensitivity (67%) values when vasopasm
Aetiological Diagnosis involves the middle cerebral artery, and lower sensitivity and
The main cause (three-quarters of cases) of SAH is a ruptured specificity for the anterior cerebral artery (76% specificity and 42%
intracranial aneurysm. Less common causes include: sensitivity).
20
Systemic complications include fever, infections,
electrolyte imbalance, deep venous thrombosis and pulmonary
cranio-cerebral trauma; embolism, hypertension and cardiac complications. Cardiac
arterio-venous malformations; complications are more frequent than in other strokes and include
dural fistulae; cardiac arrest, sudden death, pulmonary oedema and several rhythm
dural sinus thrombosis; and other electrocardiogram (ECG) changes that may even mimic
intracranial arterial dissection; acute myocardial infarction.
21,22
mycotic aneurysms;
bleeding diseases; and The major prognostic factor in SAH is the severity of the initial
drugs. bleeding. The clinical severity of SAH can be measured by grading
scales, such as the Glasgow Coma Scale, Hunt and Hess, World
Exceptionally, aneurysmal SAH is due to monozygotic disorders, such Federation of Neurological Surgeons and Prognosis on Admission of
as primary connective tissue diseases (Ehlers-Danlos, Marfan’s Aneurysmal Subarachnoid Heamorrhage (PAASH)
23
scales. The
syndrome, pseudoxantoma elasticum), neurofibromatosis type 1 and severity of subarachnoid bleeding can be measured by the Fisher’s or
polycystic kidney disease. Hidja’s scales,
24
which score the haematic densities in the admission
scan. Unfavourable outcome is also associated with increasing age,
To identify the aneurysm and allow urgent treatment to prevent posterior circulation and large aneurysms,
25
intracerebral and
re-rupture, angiography must be performed as soon as possible. intraventricular haemorrage, hypertension and time to treatment.
26
Magnetic resonance angiography can detect an aneurysm of >3mm, but
is less sensitive than intra-arterial angiography and produces false- SAH mortality ranges from 32 to 67%.
27
Up to 15% of SAH patients die
positive results.
13
CT angiography is increasingly being used in before arriving at the hospital. Twenty to 30% of the survivors are left
the detection and treatment planning of intracranial aneurysms. The with disablilities. Fewer than one-third of patients can return to their
sensitivity of CT angiography compared with intra-arterial angiography is previous occupation and lifestyle.
27
Epilepsy occurs in 7–12% of SAH
around 95%.
14
If no aneurysm or other cause is found, angiography must survivors and is associated with cerebral infarction and subdural
be repeated within days to two weeks, although the yield of repeat haematoma.
28
Seizures are more frequent in patients treated
angiography is very low (~2%). Aneurysms are multiple in about 25% of surgically.
29
Memory and executive deficits distress a number of SAH
cases. Patients with multiple aneurysms are usually younger than those survivors, especially those with anterior communicating aneurysms.
with single aneurysms and more often have a family history of SAH. Among other less well-known effects are anosmia, neuroendocrine
Repeat angiography is not warranted if the first angiography is negative. disturbances (pituitary deficiency)
30
and sleep and wake disorders.
31
Localised variants of SAH include perimesencephalic and subpial Current Evidence-based Treatment
SAH. In perimesencephalic SAH, haematic densities are limited to the Patients with SAH should be referred urgently to a tertiary care
perimesencephalic cisterns, with no blood on the convexity, the centre with expertise in cerebral aneurysm treatment, including
interhemispheric fissure or the vertical part of the Sylvian fissure.
15
endovascular, neurosurgical and neurointensive care. SAH patients
This pattern only applies to patients with early (less than four days) CT should be admitted to a stroke or a neurological intensive care unit.
EUROPEAN NEUROLOGICAL REVIEW 39
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