Subarrachnoid haemorrhage Flashcards
What is xanthochromia?
Yellowish appearance of cerebrospinal fluid that occurs several hours after bleeding into the subarachnoid space caused by certain medical conditions, most commonly subarachnoid hemorrhage.
What are vascular causes of a thunderclap headache?
- SAH
- Venous sinus thrombosis
- Arterial dissection
- Stroke
- ICH
- Vasculitis
- Reversible cerebrovascular vasoconstriciton syndrome
What are non-vascular causes of thunderclap headache?
- Spontaneous intracranial hypotension
- Hypertensive encephalopathy
- Meningitis
- SOL
- Pituitary apoplexy
- Sinusitis
What is the definition of thunderclap headache?
It is defined as a severe headache/worst ever that takes seconds to minutes to reach maximum intensity (1-5 minutes)
What primary headache disorders would you consider if someone presented with thunderclap headache?
- Primary cough
- Coital
- Exertional headache
- Primary thunderclap headache
- Migraine
- Cluster headaches
What investigations would you do in someone with thunderclap headache?
- Bloods - U+E, LFTs, FBC, Coag, CRP, BC if pyrexial
- ECG
- Urgent CT angio brain - DSA
- Consider LP after 12 hours - if CT negative but strong clinical suspicion
- Consider MRI - AVM malformation better viewed
What would you be looking for on LP in someone presenting with thunderclap headache?
- Xanthochromia
- Opening Pressure and constituents
What is a subarachnoid haemorrhage?
Spontaneous arterial bleeding into the subarachnoid space, and is usually clearly recognizable clinically from its dramatic onset
What age range does subarachnoid haemorrhage?
35-65
What are causes of a subarachnoid haemorrhage?
- Saccular (berry) aneurysm (80%)
- AVM (15%)
- Other rare causes (5%) - bleeding disorders, cavernous haemoangiomas, traumatic SAH, neoplasm, cortical thrombosis, encephalitis
What are common sites for berry aneurysms to occur?
Junctions of:
- PCA and internal carotid
- ACA and anterior cerebral artery
- Bifurcation of MCA
- Others - basilar, posterior inferior cerebellar, Intracavernous internal carotid
How do berry aneurysms cause symptoms?
Either by rupture or compression on surrounding structures
What are arteriovenous malformations?
Vascular developmental malformations, often with a fistula between arterial and venous systems causing high flow through the AVM and high pressure arterialization of draining veins
What is the risk of first haemorrhage in someone with an AVM?
2-3% per year
What is the risk of rebleed in someone with AVM?
10% per year
What is the following?
Subarachnoid haemorrhage
What are features of subarachnoid haemorrhage on CT?
Hyperattenuating material is seen filling the subarachnoid space. Most commonly this is apparent around the circle of Willis, on account of the majority of berry aneurysms occurring in this region (~65%), or in the Sylvian fissure (~30%)
What are symptoms of a subarachnoid haemorrhage?
- Sudden onset excruciating headache (thunderclap) - typically occipital
- Other features of Meningism - Neck stiffness, photophobia, nausea/vomiting
- Collapse
- Seizures
- Coma
What can preceed a thunderclap headache caused by SAH?
Sentinal headache - indicative of small bleed before big from offending aneurysm
What are signs of SAH?
- Neck stiffness
- Kernig’s sign - typically at least 6 hrs after
- CNIII nerve palsy
- Retinal, subhyaloid and vitrous haemorrhage - tracking below retinal hyaloid membrane
- Papilloedema
- Focal neurology indicating site
A berry aneurysm in which location can cause a CNIII palsy?
Posterior communicating artery (PCOM) - sits next to CNIII
If someone presented with symptoms of a sudden headache and features of meningism, what two main diagnoses would you want to rule out?
- Subarachnoid haemorrhage
- Meningitis
Why does subarachnoid haemorrhage cause meningism?
Blood irritates the meninges, leading to inflammation
When is LP most sensitive for xanthochromia?
12 hours post haemorrhage
What are risk factors for SAH?
- Previous SAH
- Smoking
- Alcohol
- HTN
- Bleeding Disorders
- Family History
- Polycystic kidneys
- Coarctation of Aorta
- Ehlers Danlos syndrome
What would your differential diangosis be for sudden onset headache?
- SAH
- Meningitis
- Migraine
- Intracerebral bleed
- Cortical vein thrombosis
- Carotid/vetebral artery dissection
- Benign thunderclap headache
Why would you perform U+E’s in someone with thunderclap headache?
Look for hyponatraemia + hypovolaemia from SAIDH or cerebral salt wasting -> worsens vasopasm
Why might you do Coag screen and LFTs in someone with thuinderclap headache?
Look for signs of bleeding disorders which could cause SAH
How would you manage a SAH?
Refer to neurosurgery immediately
- ABCDE
- Continuous neuro exam
- Fluids - keep well hydrated
- If seizures - anticonvulsants
- Analgesia
- Nimodipine - reduces vasospasm
- Surgery
What surgical interventions are available for SAH repair?
- Endovascular coiling
- Surgical clipping
What is the more preferable surgical intervention for SAH?
Endovascular coiling
What are complications of SAH?
- Rebleeding
- Cerebral ischaemia due to vasospasm
- Obstructive hydrocephalus
- Hyponatraemia
What can occur after the initial haemorrhage that occurs in SAH?
Vasospasm causing ischaemia and secondary brain damage
What proportion of those with SAH present with signs of TIA/Stroke?
25% - due to secondary vasospasm
When is risk of cerebral oedema and vasospasm greatest following a SAH?
Between 72 hrs and 10 days
What is the overal mortality rate of SAH?
35-50% - About 30% die within a few days, and another 10-15% within a few weeks.
When does someone who has had a SAH have the best prognosis?
When no lesion is detected - worst prognosis for aneurysms
Why might you do an ECG in someone with SAH?
50% of patients with SAH have an abnormal ECG on admission
- Arrhythmias
- Prolonged QTc
- ST segment/T wave abnormalities.
What is the most accurate method for visualising aneurysms?
Digital subtraction angiography
When should an LP be performed in someone with SAH?
If CT is unrevieling - wait 12 hours for RBCs to start lysing
