Neurology/neurosurgery - Subarachnoid haemorrhage (Core clinical problems - unconscious patient/sudden onset headache) Flashcards
What are the symptoms of SAH?
Sudden onset
Short lasting (seconds to minutes) headache
Photophobia
Nausea, vomiting , stiff neck and Kernig’s sign may be present
What is Kernigs sign?
When hip flexed at right angle, pain on extending the knee.
Why do you get meningism in a SAH (photophobia/stiff neck/kernig’s sign?)
Blood irritates the meninges.
Why might an SAH cause reduced or deteriorating consciousness? What else might this manifest as?
ICP rising
May manifest as papilloedema and retinal haemorrhage
Why might we see focal deficit in SAH?
- False localising effect of increasing ICP
- Co-existent intracerebral haemorrhage
- vasospasm due to blood irritation and therefore ischaemia
Systemic features of SAH might include Cushing Reflex - what is this?
Hypertension
Bradycardia
Abnormal breathing
What causes the Cushing Reflex
- Hypertension: CPP = MAP - ICP. Therefore Raised ICP will cause MAP to rise to maintain CCP
- Bradycardia: High MAP will cause baroceptor stretch leading to decreased heart rate in attempt to reduce BP
- Irregular breathing: ?due to damage to respiratory centres in brainstem
What are the most common causes/sites for an SAH?
1) Aneurysm rupture - commonly occurring at junctions in the Circle of Willis
2) AVMs - anomalous malformed vessels, congenital, enlarge during life to present in adult hood
3) Vessels weaken by infection (rarely)
4) Coagulopathy (rarely)
5) Trauma (rarely)
What is the one investigation you want to do if you can only do one?
CT Brain - non-contrast
What percentage of SAH will appear on CT scan?
95%
How does fresh blood appear on CT?
Bright white
Older blood less bright/grey
SAH will be confined to the suture lines true/false?
False: Extra-dural will be confined to suture lines
If no bleed on a CTB - what might you do next? In an SAH, what would you expect to see?
LP at about 12 hours See xanthochromia (straw pink or yellow CSF)
What is a contraindication to an LP?
Any signs on CTB of lesion that would obstruct CSF outflow in the brain
When should angiography be done? Why is it done?
If patient is awake and only mildly drowsy - to find the source to the bleed
How would a bleeding aneurysm be treated?
Either by endovascular coiling or surgical clipping; the former is most common today
If the patient has impaired consciousness or severe bleed, what should be done in regard to angiography and treatment?
This is a specialist decision. These patients have a lower tolerance for treatment and have higher mortality/lower prognosis.
What is the mortality in the first few days of aneurysmal SAH?
30-40%
What is the biggest risk in the first 6weeks post SAH?
Rebleeding
What are the early complications of an SAH?
- CSF obstruction due to formation of blood clot, leading to hydrocephalus
- Rebleeding
What are the late complications of an SAH?
- Blood reabsorption into the arachnoid granulations, blocking CSF reuptake and causing a communicating hydrocephalus
What other things should be considered as the cause of a SAH?
Trauma - usually less worrying
Berry aneurysm - related to polycystic kidney disease