Raised Intracranial Pressure

Question 1

Aetiology of raised intracranial pressure

Answer 1

Vascular: haematoma, aneurysm, Haemorrhage (subdural, extradural subarachnoid, intracerebral, intraventricular)
Infection: meningitis, encephalitis, brain abscess
Trauma → cerebral oedema
A
M: Malignant hypertension
I
Neoplasm: Space-occupying Lesion (tumour, abscess, cyst)
Benign intracranial hypertension, hydrocephalus, cerebral oedema
Status epilepticus
Idiopathic (occurs mainly in overweight women of child-bearing years)

Question 2

Describe the Monroe Kelly

Answer 2

the cranium is a rigid box; therefore, the total volume of the intracranial contents must remain constant if ICP is not to change – the CSF/blood compensatory mechanism can compensate for ~100mL

Question 3

Symptoms of raised intracranial pressure

Answer 3

Depends on the cause

Headache
Worse in the morning or when bending over or coughing
Early morning nausea/vomiting
Transient visual obscuration
Pulse-synchronous tinnitus
Photophobia
Retrobulbar pain
Diplopia

Question 4

Signs of raised intracranial pressure on examination

Answer 4

General
- Altered GCS (drowsiness, listlessness, irritability, oedema)
- Cheyne-Stokes respiration
Obs
- Cushing’s response - low HR and high BP
Fundoscopy and visual
- Optical disc swelling - papilloedema
- Large blind spots with peripheral field constriction the eyes
- Decreased visual acuity (peripheral field loss)
- Ocular motility defects
- RAPD
- Pupil changes (constriction first then dilation)

Question 5

Investigations for raised intracranial pressure

Answer 5

Visual field testing:
- Visual field defects
- Enlarged blind spot
- Inferonasal loss
- Other nerve fibre bundle defects or constriction of the field

FBC
U&Es
LFT
Glucose
Serum osmolality
Clotting
Toxicology screen

MRI
CT + LP
CXR

Question 6

Management for raised intracranial pressure

Answer 6

Urgent neurosurgery referral

Fluid restriction

1. A-E
2. Brief examination
3. Elevate head of bed 30-40 degrees
4. If intubated → hyperventilate them (reduce PaCO2 → cerebral vasoconstriction → reduce ICP)
5. Osmotic agents (mannitol) – n.b. can lead to rebound raised ICP with prolonged use (12-24hrs)
6. ?Steroids (only useful for oedema surrounding tumours)
7. Consider sedation, anti-epileptics, therapeutic hypothermia
8. Fluid restriction <1.5L/d
9. Monitor closely and treat any exacerbating factors