Subarachnoid haemorrhage (A&E) Flashcards
Define subarachnoid haemorrhage.
Bleeding into the subarachnoid space (between arachnoid and pia) and is an emergency
What are the two types of causes of subarachnoid haemorrhage? (2+4)
- traumatic subarachnoid haemorrhage (head trauma)
- non-traumatic subarachnoid haemorrhage:
- ruptured intracranial aneurysm - most common in Circle of Willis (berry aneurysm) - 85%
- perimesencephalic haemorrhage - 10%
- arteriovenous malformations - 5%
- anticoagulant use
What are the clinical features of subarachnoid haemorrhage? (3+5)
- thunderclap headache - severe, sudden-onset, occipital headache within 1-5mins and lasts >1h
- reduced level of consciousness
- meningismus:
- neck stiffness
- muscle aches
- photophobia
- N&V
- seizures
What might you see on examination in subarachnoid haemorrhage? (4)
- meningism - neck stiffness, Kernig’s sign, pyrexia
- GCS - check for deterioration
- signs of raised ICP - papilloedema, III/IV nerve palsies, hypertension, bradycardia
- focal neurological signs - CN palsies suggest site of aneurysm
What are some risk factors for subarachnoid haemorrhage? (6)
- hypertension
- smoking
- excess alcohol
- bleeding disorders
- age>50
- saccular aneurysms - polycystic kidney disease, coarctation of aorta, Marfan’s, EDS, SLE
What is the first-line investigation in all patients with suspected subarachnoid haemorrhage (thunderclap headache)?
Non-contrast CT head –> diagnostic test for SAH
What would we see on non-contrast CT head in subarachnoid haemorrhage?
Hyperdense area in subarachnoid space - particularly in outline of Circle of Willis and vasculature (base of skull)
What do we do if CT head is done <6h after symptom onset in suspected subarachnoid haemorrhage, and it is normal?
Do not do lumbar puncture, consider alternative diagnosis
When do we do lumbar puncture for suspected subarachnoid haemorrhage?
If CT head -ve and no contraindications 12h from onset of Sx - to allow development of xanthochromia (presence of bilirubin in CSF due to RBC breakdown –> yellow discolouration)
What investigation do we do in confirmed subarachnoid haemorrhage after non-contrast CT head?
CT angiogram - to find location of bleed in vessel and underlying cause
What other scan is done in subarachnoid haemorrhage? (1+3)
ECG:
- arrhythmias
- prolonged QT intervals - torsades de pointes
- ST segment or T-wave abnormalities
Which electrolyte imbalance is most common in subarachnoid haemorrhage?
Hyponatraemia
What are some differential diagnoses for subarachnoid haemorrhage? (12)
- non-aneurysmal perimesencephalic SAH
- arterial dissection
- cerebral and cervical AV malformation
- dural AV fistulae
- vasculitis
- saccular aneurysms of spinal arteries
- cardiac myxoma
- septic aneurysm
- pituitary apoplexy
- cocaine abuse
- anticoagulants
- sickle cell disease
What medication must be stopped immediately in subarachnoid haemorrhage?
Anticoagulants
What medication can be given in subarachnoid haemorrhage to prevent vasospasm?
Nimodipine (CCB) - vasospasm –> blood vessel narrowing –> block circulation –> ischaemia
