Subarachnoid Haemorrhage
SAH
• What is it?
– Bleeding into the subarachnoid space (space between
the pia & arachnoid meningeal layers) where blood
vessels lie & CSF flows
• Where does the blood come from?
– An aneursym on a blood vessel in the subarachnoid
space has ruptured (~70%)
– Unknown (~15%)
– AVM (~10%)
– Rare causes (e.g. tumour) (~5%)
• Where does the blood go?
– Anywhere where CSF goes, may get hydrocephalus if
into ventricle & causes obstruction of CSF circulation
SAH
• Incidence = 1/7000 people
• Higher chance if:
– Female
– 3rd trimester of pregnancy
– Middle-aged
– Abuse of stimulant drugs
– Connective tissue disorder
– Family history
– PCKD
What causes aneurysms to form?
• Defects in the media of the arteries
• Defects are thought to expand as a result
of hydrostatic pressure from pulsatile
blood flow and blood turbulence, which is
greatest at the arterial bifurcations
What causes aneurysms to
rupture?
• The probability of rupture is related to the tension on the
aneurysm wall
• The law of La Place states that tension is determined by
the radius of the aneurysm and the pressure gradient
across the wall of the aneurysm
• Therefore, the rate of rupture is directly related to the
size of the aneurysm
• Aneurysms with a diameter of 5 mm or less have a 2%
risk of rupture, whereas 40% of those 6-10 mm have
already ruptured upon diagnosis
SAH – The Problem
• They occur in young people
– 80% in 40-65 year olds
– 15% in 20-40 year olds
• It can kill quickly
– 25% die within 24 hours
– 50% will be dead at 6 months
• It causes significant disability
– Cognitive impairment
– Neurological disability depending on size of bleed &
complications encountered
How do they present?
• Headache
– sudden onset & severe
– small leak may cause minor headache & may be
warning sign of rupture
• Reduced consciousness
• Meningism
– Vomiting
– Neck stiffness
– Photophobia
• Seizures
What causes symptoms & signs?
• Blood leaking from the aneurysm
• Local pressure effects of the aneurysm
• Associated ICH
• Emboli
What causes symptoms & signs?
• Blood leaking from the aneurysm
– Headache
– Meningism
What causes symptoms & signs?
• Local pressure effects of the aneurysm
– Acom
• Visual symptoms due to optic chiasm compression
• Positive babinski
• Bilateral lower limb paresis
– MCA
• Contralateral hand & face paresis
• Contralateral visual neglect
• Aphasia (dominant side)
– ICA/Pcom
• CNIII signs
What causes symptoms & signs?
• Associated ICH
– The aneurysm usually lies within the subarachnoid
cisterns
– It can become adherent to adjacent brain due to
adhesions (e.g. from a previous leak)
– The bleed therefore can also extend into the brain
• MCA = TL causing hemiparesis & aphasia (if dominant)
• Acom = mutism
– AVM is more likely to cause ICH as they usually lie
somewhat in brain parenchyma
Headache
• A sudden onset severe headache IS
caused by a SAH until you have done
investigations which prove otherwise
Sudden onset severe headache
ABCs
History – ask
about
anticoagulants
Routine bloods &
coag & group &
screen
IV access
Non-sedating
analgesia & hold
any anticoagulants
Blood on CT =
SAH
CT brain noncontrast
Investigations
Keep fasting
Examination
Is there any other
pathology on CT?
Where is the
aneurysm?
CT COW +/cerbral angiogram
For angiogram &
coiling if suitable
For craniotomy &
clipping if not
suitable for coiling
Ensure pre-op
ready – consent,
G&S, check bloods,
fasting
Monitor GCS for
any changes from
admission
examination
Meanwhile chart
nimodipne, fluids,
anti-seizure
medication
Sudden onset severe headache
ABCs
Routine bloods &
coag & group &
screen
IV access
Non-sedating
analgesia & hold
any
anticoagulants
No blood on CT
scan
CT brain noncontrast
Investigations
Keep fasting
Examination
Is there any other
pathology on CT?
Lumbar puncture
LP = positive for
SAH
Diagnosis still
uncertain
CT COW +/cerbral angiogram
May repeat
cerebral angio
No aneurysm
History – ask
about anticoagulants
Investigations
• CT scan without contrast
• Lumbar puncture
• CT COW
• Cerebral angiogram
• MRI/MRA
98% sensitive @ 12 hours
80% at day 3
50% at day 7
Also good to see if
any associated ICH
or hydrocephalus.
May help localise the
location of the
aneurysm if there is
more than 1 & may
also see AVM
Where is the aneurysm?
• Where is the blood on the CT scan?
– Basal cisterns – COW aneurysm
– Sylvian fissure – ICA, Pcom, MCA
– Interhemispheric or intraparenchymal - Acom
• A cistern where the
arachnoid extends across
between the two
temporal lobes, and
encloses the cerebral
peduncles including the
structures contained in
the interpeduncular
fossa.
MCA stroke - Emergency neuroradiology. Axial CT scan at the level of the
basal cisterns shows the "hyperdense middle cerebral artery (MCA) sign"
(arrow) representing acute clot within the right middle cerebral artery,
accounting for the patient's clinical symptoms
SAH & LP
• CT & LP are critical to diagnosing SAH
• No need for LP if obvious blood in
subarachnoid space on CT
• Blood may not be evident on CT,
especially if it is performed > few days
after bleed
• LP should only be performed after 12
hours of headache onset
SAH & LP
• When blood enters the CSF (e.g. from SAH or during LP) the
red cells are broken down & oxyhaemoglobin is released
• It then takes 12 hours for the oxyhaemoglobin to be
converted into bilirubin – conversion is via an enzyme found
in the brain.
• Bilirubin in the CSF, therefore, tells us that blood must have
been in the subarachnoid space for at least 12 hours
• Blood which entered the CSF during the LP would not
encounter the enzyme & could not produce bilirubin
• The CSF will look xanthochromic (yellowish discolouration) if
bilirubin is present which they will look for with spectroscopy
in the lab
What may I find on examination?
• Normal exam
• Confusion/memory loss
• Aphasia
• CN abnormalites
– CNII – papilloedema, usually mild initially & retinal
haemorrhages
– CNIII – palsy
• Hemiparesis/neglect
• Obs – HTN, tachycardic, febrile
Treatment
• Main aim is damage control – want to
prevent further bleeding & try to avoid the
complications that SAH patients get
• SAH patients will vary greatly from GCS
15/15 to GCS 3/15
To coil or clip?
• Coiling
– Endovascular technique done
in angiography by
interventional radiologists
under GA
– May be best if small necked
aneurysm
– Used in particularly sensitive
areas e.g. basilar tip
– Must be able to access the
aneurysm (e.g. any stenosis
or tortuous vessels)
– Like dome:neck ratio to be 2:1
or greater
• Clipping
– Craniotomy & careful
dissection using microscope
to reach aneurysm & clip
usually at neck
– May be performed after
failed clipping
– If aneurysm can’t be
reached by the
endovascular root
That’s Dandy
• First to clip an
aneursym successfully
in 1937
• Walter Dandy
Operative microscope
•
Complications with SAH
1. Re-bleeding
2. Hydrocephalus
3. Vasospasm
4. Hyponatraemia
5. Seizures
6. VTE
Complications with SAH
• Re-bleeding
– 80% mortality if re-bleed
– Greatest risk is in the first 24 hours after the
initial bleed
– Aim to prevent by controlling BP to avoid
dramatic changes & isolate the aneurysm
from the circulation (coil or clip)
Complications with SAH
• Hydrocephalus
– Obstructive
• Blood enters the ventricles & can block the flow of CSF e.g.
at the aqueduct or outlet of the 4th ventricle
– Communicating
• Due to blood blocking reabsorption of CSF through the
arachnoid granules
– May need an extraventricular drain to treat
– Keep head of bed at 300 (promote CSF flow & venous
return)
Complications with SAH
• Vasospasm
– Blood vessel goes into spasm causing ischaemia - stroke
– To prevent keep them filled with at least 3L fluid day &
nimodipine IV/PO & insert central line to monitor central venous
pressure – aiming for 8-10
– Suspected with deteriorating GCS/new neurological deficit
– Treatment – Urgent CT brain to rule out a bleed as a cause of
the deterioration then urgent angiogram to diagnose & treat
vasospasm
– Greatest risk of vasospasm is days 4-7 but significant risk for
first 3 weeks after bleed, therefore will use preventative
measures for at least 3 weeks
Complications with SAH
• Hyponatraemia
– Susceptible due to being fluid loaded & cerebral salt
wasting
– Cerebral salt wasting = renal loss of sodium due to
intracranial pathology ? Cause. Loss of water & salt
(whereas SIADH is loss of salt & retention of water)
– Treat with normal or hypertonic saline
– If refractory may need a mineralocorticoid e.g.
fludrocortisone to stimulate renal reabsorption – but
this should only be used under instructions from
consultant endocrinologist
Complications with SAH
• Seizures
– A seizure is a disturbance of sensation, movement or
consciousness
– All seizures originate from the surface of the brain –
cortex
– Blood is an irritant to the cortex
– Prophylaxis with phenytoin or levetiracetam
– Ensure phenytoin levels are therapeutic
– Treat as seizure from any cause & suspect re-bleed
Complications with SAH
• VTE
– On bed rest
– TEDS
– Prophylactic enoxaparin as soon as consultant sees fit
– Always keep VTE in the back of your mind
How are SAH graded?
World Federation
Neurosurgeons
Fischer grading
GCS 15, only
Grade 1
CN deficit if any
GCS 13-14, no Grade 2
deficit
GCS 13-14, with Grade 3
deficit
GCS 7-12, +/- Grade 4
deficit
GCS 3-6 +/deficit
Grade 5
No blood
Diffuse blood,
no clots &
<1mm
Clots & blood
1mm or more
ICH or
intraventricular
clots
Subdural Haematoma
Extra-dural haematoma
Extra-dural haemtoma
Intra-parenchymal haematoma