CSF and physiology of ICP

Question 1

Where is CSF produced?

Answer 1

By choroid plexus in lateral ventricles

Question 2

What are functions of CSF?

Answer 2

Buoyancy
Protection
Waste clearance
Homeostasis (rapid signalling between cells)
ICP regulation to enable optimal brain perfusion
Immune surveillance

Question 3

CSF opening pressure

Answer 3

Do not consider LP if any possibility of space occupation
Normal OP <20cm water
21-29 intermediate
>30cm definitely elevated
Cannot estimate pressure if patient is sitting for LP

Question 4

Complications of LP

Answer 4

Headache (low pressure, worst standing up and eased lying down, often with N&V)
Coning/death
Bleeding/bruising
Nerve damage
Infection

Question 5

What happens when CSF circulation blocks?

Answer 5

Depends where in system and at what age and what speed
If sutures not fused, hydrocephalus with expanded cranium

If sutures fused and occurs very slowly then maybe normal
If occurs fast, can caused raised ICP, drowsiness and coma
Causes include congenital and acquired (infections, inflammation, tumours, vascular)
IIH

Question 6

IIH

Answer 6

Idiopathic intracranial hypertension (IIH/BIH)
More common in overweight females
Present with symptoms of raised ICP, visual disturbances, diplopia (double vision)
Papilloedema
May be associated with cerebral venous sinus thrombosis
Risk of blindness ao keep checking on visual acuity and fields
Tx is weight loss, acetazolamide, repeated LP, shunt

Question 7

Low pressure headaches

Answer 7

Eased inlying down, worse standing up

Can occur spontaneously (rare) but usually post-LP