Subarachnoid haemorrhage Flashcards

1
Q

Define SAH.

A

Bleeding into space between pia mater and arachnoid membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the aetiology of SAH?

A

Traumatic or spontaneous

Rupture of blood vessel in subarachnoid space –> release of blood into CSF –> rapid rise in ICP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the causes of SAH?

What is the most common cause?

A

Traumatic - head injury e.g. bridging vein tear
Spontaneous - arterial origin e.g. saccular ‘berry’ aneurysm (85% of all SAH cases) rupture, AVM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the risk factors for SAH?

A
  • Female, elderly
  • Smokers
  • Associated conditions e.g. saccular aneurysms, Ehlers-Danlos syndrome, Marfan syndrome, PCKD
  • SCD
  • Coagulopathy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the complications of SAH?

A
  • Rebleeding - most occur within 12hrs, affects 10% of cases and has 70% mortality. May occur 2 weeks after SAH, increased in those with HTN, anxiety, seizures post-SAH
  • Vasospasm (delayed cerebral ischaemia) - usually 7-14 days after onset
  • Hydrocephalus
  • Sympathetic hyperactivity due to increased ICP –> raised adrenaline levels, pulmonary vasoconstriction –> neurogenic pulmonary oedema
  • Hyponatraemia (SIADH)
  • Meningitis
  • Seizures
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the clinical features of SAH?

A
  • Thunderclap headache
  • Severe headache (‘worst ever’)
  • Nausea, vomiting
  • Focal neurological deficit e.g. CNIII palsy (ptosis, down and out eye, mydriasis, loss of pupillary reflex), CNVI palsy
  • Aseptic meningitis due to irritation –> neck pain, stiffness, photophobia
  • Optic disc swelling, retinal haemorrhages, tachycardia
  • ECG changes- wide QRS, long QT, short PR, U waves, dysrhythmias
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How is SAH graded on CT?

A

Fisher scale grading
* Group 1 - no haemorrhage
* Group 2 - blood depositions <1mm without blood clots
* Group 3 - blood depositions >1mm with localised clots
* Group 4 - diffuse/lack of SAH with extension to ventricles, brain parenchyma

Hydrocephalus - causes a “mickey mouse” ventricular system appearance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What do investigations show in SAH?

A
  • CT (first line) - hyperdense/bright bleed on CT typically seen in basal cisterns, sulci and ventricles in severe cases
  • LP - raised erythrocytes, yellow colouration on centrifugation due to xanthochromia (only positive about 3-4 weeks after SAH)
  • Bloods - may show coagulopathy abnormalities
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the management of SAH?

A

Needs to be done within 24hrs otherwise rise of rebleeding.

Medical:
* Antihypertensives - beta-blockers, hydralazine, calcium channel blockers, ACE inhibitors - keep BP < 140 to avoid rebleed
* Anti-vascoconstriction treatment - CCB (nimodipine), recombinant TPA
* ICP treatment - osmotic, loop diuretics
* IV midazolam
* Seizure tx - penytoin, phenobarbital
* Pulmonary oedema treatment - diuretics, dobutamine

Once CT or LP confirms SAH give medical treatment and prepare to have CT angiography +/- coiling if there are aneurysms.

Surgical:
* Endovascular coiling
* Craniotomy with clipping/coiling of aneurysm
* CSF drainage
* Transluminal balloon angioplasty
* Shunt
* Ventriculostomy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What % of cases of SAH is CT negative in?

A

7%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What distinguishes true SAH from ‘traumatic tap’ on LP?

A

Xanthochromia helps to distinguish true SAH from a ‘traumatic tap’ (blood introduced by the LP procedure).

NB: LP is performed at least 12 hours following the onset of symptoms and up to 2 weeks, to allow the development of xanthochromia (the result of red blood cell breakdown).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What should be done once SAH is confirmed on CT?

A

Referral to neurosurgery as soon as SAH confirmed
Need to identify cause of spontaneous SAH:
* CT angiogram
* +/- digital subtraction angiogram (catheter angiogram)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is shown on this CT?

A

CT image shows:
* diffuse subarachnoid haemorrhage in all basal cisterns, bilateral sylvian fissures and the inter-hemispheric fissure.

This case demonstrates the typical distribution that takes the blood into the subarachnoid space in a subarachnoid hemorrhage.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How is vasospasm prevented in SAH?

A

Nimodipine (CCB) which targets brain vasculature - not fully understood how it works

How well did you know this?
1
Not at all
2
3
4
5
Perfectly