subarachnoid Haemorrhage Flashcards
outline a typical presentation for a subarachnoid haemorrhage?
Thunderclap headache, sudden and worse ever, reduced GCS/ LOC, confusion, photophobia
define a subarachnoid haemorrhage?
Arterial haemorrhage into the subarachnoid space
outline the causes of a subarachnoid haemorrhage?
85% - rupture of a saccular aneurysm at the base of the brain (Berry aneurysms of the CIrcle of Willis)
10% - perimesencephalic haemorrhage
5% - arteriovenous malformations, bleeding diathesis, vertebral artery dissection
No cause found in <15%
What are the risk factors of SAH
Hypertension
Smoking
Family history
causes of saccular aneurysms
Excess alcohol intake
Bleeding disorders
Trauma
AVM
Tumour
what conditions are saccular aneurysms associated with?
Polycystic kidney disease
Coarctation of the aorta
Marfan’s syndrome
Ehlers-Danlos syndrome
SLE
Summarise the epidemiology of SAH?
Incidence: 10/100,000
Peak incidence: 40s
what are the presenting symptoms of SAH?
- Sudden-onset worst headache ever – typically occipital (thunder-clap headache) - main symptom!!
- Nausea/vomiting
- Collapse
- Seizures
- Neck stiffness
- Photophobia
- Reduced level of consciousness
- Altered mental status
what are the signs of SAH on physical examination?
Meningism
- Neck stiffness
- Kernig’s sign
- Pyrexia
GCS - check for deterioration
Signs of raised ICP - papilloedema, VI or III nerve palsies, hypertension, bradycardia
- CNIII palsy can suggest the presence of a posterior communicating artery aneurysm compressing on CNIII
Focal neurological signs (e.g. cranial nerve palsies) – suggests site of aneurysm
What are the appropriate investigations for SAH?
CT scan
FBC – nonspecific but will show leukocytosis
U&Es – abnormal (hyponatraemia)
Clotting – elevated INR and prolonged PTT
ECG as quite a few patients with SAH have an abnormal ECG
describe the CT scan in SAH?
Hyperdense areas in the basal regions of the skull (due to blood) - blood along fissures and sulci
If more severe bleeding then midline shift (raised ICP) and intraventricular bleeding is seen
If the CT is normal and you defo suspect a SAH then may do an LP which would show blood staining
What investigation should you consider for SAH and what are the results of the investigation?
Lumbar Puncture – if CT –ve and no contraindication 12h after headache onset
- Can indicate SAH for up to 12dys after headache
- Increased opening pressure
- Increased red cells
- CSF is uniformly bloody early on then becomes xanthochromic - straw-coloured CSF due to breakdown of red blood cells
