Subarachnoid Haemorrhage Flashcards
What is the most common type of SAH?
Aneurysmal - local dilation of the artery
Describe the aetiology of an aneurysmal SAH.
Incidence - 8/100,000
Age of presentation: 40-60
3% of all strokes
What causes aneurysm formation in an aneurysmal SAH?
Haemodynamic stress
Extensive inflammatory and immunological reactions are common in unruptured intracranial aneurysms and may be related to aneurysm formation and rupture
Describe formation of aneurysms.
Increased haemodynamic stress on blood vessels normally involves equal outward vascular growth.
In maladaptive vascular remodelling, there is only focal activation of growth.
- only a small area of the blood vessel increases in size
- an aneurysm
Which arteries cause SAH when they rupture?
Cerebral arteries
- anterior
- middle
- posterior
What are the non-aneurysmal causes of an SAH?
AVM - arteriovenous malformation Neoplasia No identifiable cause - angiogram negative - follow a benign course
What are the predisposing risk factors for aneurysmal SAH?
Smoking Female sex Hypertension Positive family history ADPCK (polycystic kidney disease) Ehlers Danlos (connective tissue syndrome) Coarctation of the aorta
What history would you expect from someone with a SAH?
Sudden onset, high intensity (thunderclap) headache Loss of consciousness Seizures Visual, speech and limb disturbances Sentinel headache - headache precedes SAH by days/weeks - small SAH bleed
What do you expect to see on clinical examination if someone has a SAH?
Photophobia Meningism Subhyaloid haemorrhages Vitreous heamorrhage Speech and limb disturbance Pulmonary oedema
Describe the WFNS grading system in SAH prognosis.
Grade 1 - GCS 15
Grade 2 - GCS 13/14 with no neurological deficit
Grade 3 - GCS 13/14 with neurological deficit
Grade 4 - GCS 7/12
Grade 5 - GCS 3/6
Why do you need to do a CT on someone with an SAH?
Confirms the diagnosis and shows location of the aneurysm
Identifies complications
- infarction
- haematoma
- hydrocephalus (CSF accumulation)
Allows estimation of prognosis with the Fisher Grade
- predicts risk of vasospasm
- the thicker the haematoma, the worse the prognosis
What investigations are performed if someone has a suspected SAH?
CT Lumbar Puncture CTA MRA DSA (digital subtraction angiography) - stroke, diabetics
What do you look for in an LP if someone has an SAH?
Used when patients have a negtive CT scan
Xanthochromia
- bilirubin in the CSF (yellowing)
Aside from imaging and xanthochromia, what changes would you see on investigations if a person has an SAH?
Hyponatraemia ECG changes Elevated troponin levels Echo - tako tsubo cardiomyopathy Easy to mistake for an MI
How is a person with an SAH immediately treated?
Bed rest Fluids - 3L of normal saline Anti-embolic stockings Nimodipine - calcium channel blocker - has a neuro-protective effect Analgesia Doppler studies
What are the three long term methods of management of an SAH?
Surgical clipping
Endovascular (coils, stents and glue)
Conservative
How are surgical clippings of aneurysms performed?
Clips are placed along the base of the aneurysm, preventing flow of blood into it
- no longer under stress and goes down
- excluding the aneurysm
- be careful to to clip the perforating arteries that arise around the aneurysm
CTA performed post-clipping to ensure the clips are in place
How are endovascular management of aneurysms performed?
Electrically induced thrombosis within the aneursym
Detachable coils to fill and exclude the aneurysm
Stent to divert the blood and allow healing (e.g. WEB device)
Which aneurysm requires fenestrated clips during surgical clipping treatment?
Anterior communicating artery aneurysm
What complications can occur post aneurysm?
Re-haemorrhage Delayed ischaemia Hydrocephalus Hyponatraemia ECG changes - left ventricular failure (tako-tsubo cardiomyopathy) Lower respiratory tract infection UTI Pulmonary embolism
When is risk of re-haemorrhage highest?
Immediately after initial bleed
In poor grade patients (lower GCS)
Larger aneurysms
Repair isn’t quick enough
If a person develops hydrocephalus, how can they be managed?
Temporarily
- LP
- spinal drain
A shunt to allow CSF drainage can be used
What complication is most common after occlusion of the aneurysm?
Delayed ischaemia
What causes delayed ischaemia?
Angiographic spasm
- microcirculation shutting down due to release of blood products at the time of haemorrhage
How can you recognise delayed ischaemia?
Progressive deterioration in loss of consciousness
- associated with a new deficit
How is delayed ischaemia managed?
Fluid management - colloid infusions Nimodipine Inotropes - increases bp to force the blood through the system Angioplasty (balloon angioplasty)
Name some of the causes of hyponatraemia after SAH.
Cerebral salt wasting syndrome
- blood around the brain causes the patient to leach sodium and loose water
SIADH
- less common
- increased water retention
Can flip from one to the other, affecting treatment
How is a patient with hyponatraemia managed?
Establish the volume status - decreased in CSWS - increased in SIADH CSWS treatement - Fludrocortisone - Hypertonic saline
How does SAH cause cardiopulmonary complications?
Bleeding and pressure release cause cause widespread catecholamine release
This can damage the heart
What heart problems are associated with SAH?
Troponin elevation Arrythmias Wall motion Sudden death Tako-tsubo cardiomyopathy - clot formation - poor pumping
How do seizures after SAH occur?
Blood around the brain irritates the neurons
Often a manifestation of re-rupture
Can be given anti-convulsants
Why is DVT prophylaxis needed after SAH?
Patients lie prone in bed
SAH induces a prothrombotic state
Difficult because the patient is also bleeding
- anti-thrombotic agents are being used
- safest to use sequential compression devices initially (after the aneurysm is secured)
