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Subarachnoid Subarachnoid HaemorrhageHaemorrhage
SAHSAH• What is it?What is it?
– Bleeding into the subarachnoid space (space Bleeding into the subarachnoid space (space between the pia & arachnoid meningeal layers) between the pia & arachnoid meningeal layers) where blood vessels lie & CSF flowswhere blood vessels lie & CSF flows
• Where does the blood come from?Where does the blood come from?– An aneursym on a blood vessel in the An aneursym on a blood vessel in the
subarachnoid space has ruptured (~70%)subarachnoid space has ruptured (~70%)– Unknown (~15%)Unknown (~15%)– AVM (~10%)AVM (~10%)– Rare causes (e.g. tumour) (~5%)Rare causes (e.g. tumour) (~5%)
• Where does the blood go?Where does the blood go?– Anywhere where CSF goes, may get Anywhere where CSF goes, may get
hydrocephalus if into ventricle & causes hydrocephalus if into ventricle & causes obstruction of CSF circulationobstruction of CSF circulation
SAHSAH• Incidence = 1/7000 peopleIncidence = 1/7000 people
• Higher chance if:Higher chance if:– FemaleFemale
– 33rdrd trimester of pregnancy trimester of pregnancy
– Middle-agedMiddle-aged
– Abuse of stimulant drugsAbuse of stimulant drugs
– Connective tissue disorderConnective tissue disorder
– Family historyFamily history
– PCKDPCKD
What causes aneurysms to What causes aneurysms to form?form?
• Defects in the media of the arteries Defects in the media of the arteries
• Defects are thought to expand as a Defects are thought to expand as a result of hydrostatic pressure from result of hydrostatic pressure from pulsatile blood flow and blood pulsatile blood flow and blood turbulence, which is greatest at the turbulence, which is greatest at the arterial bifurcations arterial bifurcations
What causes aneurysms to What causes aneurysms to rupture?rupture?
• The probability of rupture is related to the tension The probability of rupture is related to the tension on the aneurysm wall on the aneurysm wall
• The law of La Place states that tension is The law of La Place states that tension is determined by the radius of the aneurysm and determined by the radius of the aneurysm and the pressure gradient across the wall of the the pressure gradient across the wall of the aneurysm aneurysm
• Therefore, the rate of rupture is directly related to Therefore, the rate of rupture is directly related to the size of the aneurysm the size of the aneurysm
• Aneurysms with a diameter of 5 mm or less have Aneurysms with a diameter of 5 mm or less have a 2% risk of rupture, whereas 40% of those 6-10 a 2% risk of rupture, whereas 40% of those 6-10 mm have already ruptured upon diagnosismm have already ruptured upon diagnosis
SAH – The ProblemSAH – The Problem• They occur in young peopleThey occur in young people
– 80% in 40-65 year olds80% in 40-65 year olds– 15% in 20-40 year olds15% in 20-40 year olds
• It can kill quicklyIt can kill quickly– 25% die within 24 hours25% die within 24 hours– 50% will be dead at 6 months50% will be dead at 6 months
• It causes significant disabilityIt causes significant disability– Cognitive impairmentCognitive impairment– Neurological disability depending on size of Neurological disability depending on size of
bleed & complications encounteredbleed & complications encountered
How do they present?How do they present?• HeadacheHeadache
– sudden onset & severesudden onset & severe– small leak may cause minor headache & may small leak may cause minor headache & may
be warning sign of rupturebe warning sign of rupture
• Reduced consciousnessReduced consciousness
• MeningismMeningism– VomitingVomiting– Neck stiffnessNeck stiffness– PhotophobiaPhotophobia
• SeizuresSeizures
What causes symptoms & What causes symptoms & signs?signs?
• Blood leaking from the aneurysmBlood leaking from the aneurysm
• Local pressure effects of the aneurysmLocal pressure effects of the aneurysm
• Associated ICHAssociated ICH
• EmboliEmboli
What causes symptoms & What causes symptoms & signs?signs?
• Blood leaking from the aneurysmBlood leaking from the aneurysm– HeadacheHeadache
– MeningismMeningism
What causes symptoms & What causes symptoms & signs?signs?
• Local pressure effects of the aneurysmLocal pressure effects of the aneurysm– AcomAcom
•Visual symptoms due to optic chiasm Visual symptoms due to optic chiasm compressioncompression
•Positive babinskiPositive babinski•Bilateral lower limb paresisBilateral lower limb paresis
– MCAMCA•Contralateral hand & face paresisContralateral hand & face paresis•Contralateral visual neglectContralateral visual neglect•Aphasia (dominant side)Aphasia (dominant side)
– ICA/PcomICA/Pcom•CNIII signsCNIII signs
What causes symptoms & What causes symptoms & signs?signs?
• Associated ICHAssociated ICH– The aneurysm usually lies within the The aneurysm usually lies within the
subarachnoid cisternssubarachnoid cisterns
– It can become adherent to adjacent brain due It can become adherent to adjacent brain due to adhesions (e.g. from a previous leak)to adhesions (e.g. from a previous leak)
– The bleed therefore can also extend into the The bleed therefore can also extend into the brainbrain• MCA = TL causing hemiparesis & aphasia (if MCA = TL causing hemiparesis & aphasia (if
dominant)dominant)
• Acom = mutismAcom = mutism
– AVM is more likely to cause ICH as they usually AVM is more likely to cause ICH as they usually lie somewhat in brain parenchymalie somewhat in brain parenchyma
HeadacheHeadache
• A sudden onset severe headache A sudden onset severe headache IS IS caused by a SAH caused by a SAH untiluntil you have done you have done investigations which prove otherwiseinvestigations which prove otherwise
Sudden onset severe Sudden onset severe headacheheadache
Sudden onset severe Sudden onset severe headacheheadache
InvestigationsInvestigations• CT scan without contrastCT scan without contrast
• Lumbar punctureLumbar puncture
• CT COWCT COW
• Cerebral angiogramCerebral angiogram
• MRI/MRAMRI/MRA
98% sensitive @ 12 hours80% at day 350% 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 What may I find on examination?examination?
• Normal examNormal exam
• Confusion/memory lossConfusion/memory loss
• AphasiaAphasia
• CN abnormalitesCN abnormalites– CNII – papilloedema, usually mild initially & retinal CNII – papilloedema, usually mild initially & retinal
haemorrhageshaemorrhages– CNIII – palsyCNIII – palsy
• Hemiparesis/neglectHemiparesis/neglect
• Obs – HTN, tachycardic, febrileObs – HTN, tachycardic, febrile
TreatmentTreatment
• Main aim is damage control – want to Main aim is damage control – want to prevent further bleeding & try to prevent further bleeding & try to avoid the complications that SAH avoid the complications that SAH patients getpatients get
• SAH patients will vary greatly from SAH patients will vary greatly from GCS 15/15 to GCS 3/15GCS 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 DandyThat’s Dandy
• First to clip an First to clip an aneursym aneursym successfully in successfully in 19371937
• Walter DandyWalter Dandy
Operative microscope
•
Complications with SAHComplications with SAH1.1. Re-bleedingRe-bleeding
2.2. HydrocephalusHydrocephalus
3.3. VasospasmVasospasm
4.4. HyponatraemiaHyponatraemia
5.5. SeizuresSeizures
6.6. VTEVTE
Complications with SAHComplications with SAH
• Re-bleedingRe-bleeding– 80% mortality if re-bleed80% mortality if re-bleed
– Greatest risk is in the first 24 hours after Greatest risk is in the first 24 hours after the initial bleed the initial bleed
– Aim to prevent by controlling BP to avoid Aim to prevent by controlling BP to avoid dramatic changes & isolate the aneurysm dramatic changes & isolate the aneurysm from the circulation (coil or clip)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?How are SAH graded?
GCS 15, only GCS 15, only CN deficit if CN deficit if anyany
Grade 1Grade 1 No bloodNo blood
GCS 13-14, no GCS 13-14, no deficitdeficit
Grade 2Grade 2 Diffuse blood, Diffuse blood, no clots & no clots & <1mm<1mm
GCS 13-14, GCS 13-14, with deficitwith deficit
Grade 3Grade 3 Clots & blood Clots & blood 1mm or more1mm or more
GCS 7-12, +/- GCS 7-12, +/- deficitdeficit
Grade 4Grade 4 ICH or ICH or intraventriculintraventricular clotsar clots
GCS 3-6 +/- GCS 3-6 +/- deficitdeficit
Grade 5Grade 5
World Federation Neurosurgeons
Fischer grading
Subdural HaematomaSubdural Haematoma
Extra-dural haematomaExtra-dural haematoma
Extra-dural haemtomaExtra-dural haemtoma
Intra-parenchymal Intra-parenchymal haematomahaematoma
