10- subarachnoid haemorrage

Question 1

what are the three layers of the meninges

Answer 1

dura, arachnoid and pia mater

Question 2

2 roles of dural folds

Answer 2

to enclose venous sinuses and to form dural septa

Question 3

4 sural septa

Answer 3

falx cerebri, fax cerebelli, tentorium cerebelli, diaphragma sell

Question 4

describe extradural bleed

Answer 4

• middle meningeal artery
• between endosteal layer of dura and skil
• Lucid interval
• lemon shaped (biconvex) on CT

Question 5

describe subdural bleed

Answer 5

• bridging veins
• between meningeal layer and arachnoid
• concave towards brain on CT (banana)

Question 6

where is subarachnoid space located

Answer 6

between arachnoid and pia

Question 7

how does CSF flow

Answer 7

lateral ventricles
(IV foramina)
3rd ventricle
(cerebral aquaduct)
4th ventricle 
(lateral and median apertures)
subarachnoid space

Question 8

what propels flow of CSF

Answer 8

newly formed fluid, ciliary action of ventricular ependyma, vascular pulsations

Question 9

risk actor subarachnoid haemorrhage

Answer 9

smoking, hypertension, alcohol, CKD, marfans, neurofibromatosis, cocaine, trauma

Question 10

what is a subarachnoid haemorrhage

Answer 10

extravasation of blood into subarachnoid space

Question 11

presentation of subarachnoid haemorrhage

Answer 11

• thunderclap headache
• loss of consciousness
• meningism (neck stiffness, photophobia, headache)
• orbital pain
• visual loss
• diplopia

Question 12

cause of subarachnoid haemorrhage

Answer 12

• rupture of berry aneurysm in circle of willis
• normally at bifurcation points
• occurs due to pressure on arterial wall as intracranial vessels lack adventitia and have weak adventitia

Question 13

short term consequences of subarachnoid haemorrhage

Answer 13

• microthrombi occlude small distal arteries
• vasoconstriction from CSF irritant
• cerebral oedema
• sympathetic activation causing myocardial necrosis

Question 14

long term consequence of subarachnoid haemorrhage

Answer 14

early rebreeding, acute hydrocephalus, global cerebral ischemia

Question 15

investigations for SAH

Answer 15

• CT scan will show prominent filling of basal cisterns and blood within ventricles
• CT angiogram (once diagnosis is confirmed) will show bleeding aneurysm
• lumbar puncture shows increased opening pressure, xanthochromia, high protein, WCC and glucose normal

Question 16

when to do lumbar puncture SAH

Answer 16

6-12 hours after

blood cells need to lyse. to release bilirubin, allows xanthochroomia to be seen.

Question 17

where to do lumbar puncture and what passed through

Answer 17

L4-L5

-between spinous process and through supraspinous ligament, interspinous ligament, ligamentum flavum, dura, arachnoid

Question 18

treatment SAH

Answer 18

• ACBDE
• fluids/O2
• nimodipine (CCB) to stop vasospasm and secondary ischaemia
• operate on patients with good neurological status to prevent re bleeding (craniectomy)
• clipping to clamp aneurysm neck
• coiling to insert wire into aneurysm sack to cause thrombosis of blood in aneurysm,

Question 19

cause of poor outcomes SAH

Answer 19

rebleeding, delayed ischaemia from cerebral vasospasm, intraventricular haemorrhage.