Subarachnoid Haemorrhage Flashcards
What is a subarachnoid haemorrhage?
haemorrhage into subarachnoid space
What is the most common cause of SAH?
Head injury- traumatic SAH
(absence of trauma is rarer- Spontaneous SAH)
Give 4 causes of spontaneous subarachnoid haemorrhage
85%: rupture of a saccular aneurysm at the base of the brain (Circle of Willis- Berry aneurysms)
Arteriovenous malformations
Pituitary apoplexy
Mycotic (infective) aneurysm
List 4 conditions associated with saccular aneurysms
Polycystic kidney disease
Ehlers-Danlos syndrome
Coarctation of the aorta
Marfan’s syndrome
List 5 risk factors for SAH
HTN
Smoking
Excess alcohol intake
FH
Methamphetamine + Cocaine
Describe the epidemiology of subarachnoid haemorrhage
Incidence: 10/100,000
Peak incidence: 50s
List 5 symptoms of subarachnoid haemorrhage
Sudden-onset worst headache ever (Hit in the back of the head with baseball bat/ Thunderclap) Meningeal signs: Photophobia, Neck stiffness, N+V Impaired consciousness + GCS Fever (blood irritating meninges) Sweating, haemodynamic instability
Where may the headache in SAH radiate?
Neck + back
What signs may arise in subarachnoid haemorrhage due to mass effect?
Cranial nerve palsies (III, VI)
Altered mental status
Focal neurological deficits
Seizures
What may be seen on Fundoscopy in SAH?
Subhyaloid haemorrhage
Give 3 signs of raised ICP in SAH
Papilloedema
HTN
Bradycardia
What prodromal symptoms may be experienced prior to a SAH? When?
Sudden severe headache
Transient diplopia
30-50% report Sx days-weeks prior
What bloods should be taken in SAH?
FBC
U+Es
ESR/CRP
Clotting
Once spontaneous subarachnoid haemorrhage is confirmed, what further investigations are necessary?
CT intracranial angiogram:
visualise aneurysm (accumulation of contrast)
detect extravasation of contrast if active bleeding
provides info to plan repair
What is the gold standard investigation for cerebral vessel imaging?
Digital subtraction angiography (DSA- catheter angiogram)
Detects small aneurysms
What is xanthochromia?
Straw-coloured CSF due to breakdown of RBCs
What may be seen on ECG in SAH?
ST elevation
What is the firstline investigation in SAH? What may be seen
Non-contrast CT head
Acute blood (hyperdense) typically distributed in the basal cisterns, sulci + in severe cases the ventricular system.
If CT head is done within 6h of symptom onset and is normal, what further investigations should be performed?
DONT do LP
Consider alternate dx
If a CT head scan done >6h after symptom onset and is normal, what further investigations should be performed?
Lumbar puncture 12h after symptom onset to allow for development of xanthochromia
What CSF findings are consistent with SAH?
Xanthochromia (distinguishes true SAH from traumatic tap blood)
Normal/ raised opening pressure
What is the initial management of a patient with spontaneous SAH?
A-E, secure airway
Anticoagulant reversal
BP Mx: IV antihypertensives if necessary, if raised ICP consider permissible HTN
ICP Mx: mannitol IV, raise head of bed
What surgical interventions are performed in aneurysmal SAH?
Microsurgical Clipping
Endovascular Coiling
Most are now treated with a coil by interventional neuroradiologists, but a minority require a craniotomy + clipping by a neurosurgeon
Compare the advantages and disadvantages of coiling and clipping
Coil: minimally invasive, higher risk of incomplete obliteration + recurrent bleeding
Clip: more invasive, higher rate of complete aneurysmal occlusion, lower risk recurrent bleeding
Give 3 indications for endovasacular coiling
Poor surgical candidates
Posterior circulation aneurysms
Vasospasm
Give 4 indications for microsurgical clipping
Large intracerebral haematoma (e.g. with increased ICP)
Middle cerebral artery aneurysm
Difficult endovascular access
Failed endovascular Tx
Describe the procedure of endovascular coiling
Insertion of catheter under fluoroscopic guidance
Placement of metal coils in the aneurysm lumen to interrupt blood flow + induce thrombotic occlusion
Describe the procedure of microsurgical clipping
Craniotomy + exposure of aneurysm
Mechanical occlusion of the neck of aneurysm using titanium clips
What non-surgical management is required in spontaneous SAH?
Nifedipine PO (prevents vasospasm)
Tx of hydrocephalus (external ventricular drain/ lumbar drainage)
Detect cardiopulmonary complications: CXR, ECG, trop
Describe management of traumatic SAH
Supportive
Aim to prevent secondary brain injury
List 3 complications of SAH
Vasospasm- can lead to ischaemic stroke
Recurrent bleeding- highest risk in first 12h
Hydrocephalus: acute obstructing or chronic communicating
Describe re-bleeding as a complication of SAH
Happens in ~10% of cases + most common in first 12h
If suspected (e.g. sudden worsening of neurological Sx) then a repeat CT should be arranged
a/w a high mortality (up to 70%)
Describe management of hydrocephalus post SAH
Temporarily treated with an external ventricular drain (CSF diverted into a bag at the bedside) or, if required, a long-term ventriculoperitoneal shunt
Describe management of vasospasm post SAH
Ensure euvolaemia (normal blood volume)
Consider Tx with a vasopressor if Sx persist
List 3 predictive factors in SAH
Conscious level on admission
Age
Amount of blood visible on CT head
