Raised ICP Flashcards
Clinical features of raised ICP
- Headache
- Nocturnal or morning (usually upon waking)
- Worse on coughing, straining, leaning forwards
- Vomiting
- Altered GCS
- Cushing’s triad
- irregular respiration
- bradycardia
- systolic hypertension (with wide pulse pressure)
- Visual problems
- ocular palsies
- papilloedema
- pupil irregularities
Causes of raised ICP
- Primary or metastatic tumours
- Head injury
- Harmorrhage (subdural, extramural, subarachnoid, intracerebral, intraventricular)
- Infection (meningitis, encephalitis, brain abscess)
- Hydrocephalus
- Cerebral oedema
- Status epilipticus
Investigations of raised ICP
- CT head
- LP if safe; measure the opening pressure
Immediate management of raised ICP
- Correct hypotension, maintain MAP >90mmHg and treat seizures
- Elevate head of bed to 30-40 degrees
- If intubated, hyperventilate to decrease PaCO2 (aim 3.5-4kPa), this causes vasoconstriction and reduces ICP almost immediately. Maintain PaO2 >12kPa
- Osmotic agents (eg mannitol) can be useful (may later cause rebound increase in CSF)
- Restrict fluid to <1.5L/d
- Definitive treatment if possible
Definitive treatment of raised ICP
Urgent neurosurgery - via craniotomy or burr hole
Long term solution - ventriculoperitoneal shunt
What is hydrocephalus?
Hydrocephalus refers to an increase in the circulating volume of CSF within the cerebral ventricles, beyond normal limits.
Hydrocephalus is classified into four forms:
- Communicating
- Non-communicating (obstructive)
- Normal pressure hydrocephalus
- Hydrocephalus ex vacuo
Describe communicating hydrocephalus
- Impaired absorption of CSF
- No obstruction to CSF flow within the ventricles
- Causes include subarachnoid haemorrhage, meningitis (possibly increased CSF protein)
Describe non-communicating (obstructive) encephalitis
Caused by a blockage to the natural ventricular drainage system and CSF flow.
May be due to congenital abnormalities or acquired (eg bleeding, infection, tumours).
Describe normal pressure hydrocephalus
Causes?
Ventricular dilation present in the absence of raised CSF pressure.
Around 50% are idiopathic, with the remainder due to SAH, meningitis, head injury, or malignancy.
Normal pressure hydrocephalus presentation
Triad of Parkinsonian gait, urinary incontinence and dementia.
Normal pressure hydrocephalus investigations
- CT imaging - ventricular enlargement, sulcal atrophy, periventricular lucency
- Lumbar puncture - CSF pressure will be normal
Normal pressure hydrocephalus treatment
Surgical insertion of a CSF shunt
Hydrocephalus ex vacuo
Compensatory dilation of ventricle and spaces in response to brain atrophy eg in dementia
Cerebral vein thrombosis possible presentations
May present:
- Similarly to idiopathic intracranial hypertension
- Stroke-like features
- Seizures
