Skip to the content
 

Raised intracranial Pressure

The intracranial space is a non-compliant cavity of fixed volume. Contents include brain, blood, CSF, supporting interstitium, and neuronal tissue. The space is separated into compartments by rigid dural layers. The compliance of both the total space and the subcompartments is limited, thus pressures can increase rapidly as a result of small changes in volumes of contents, and herniation between compartments or through the foramen magnum may result. Similarly, dramatic decreases in pressure can be obtained with small decreases in contents, which is the principal underlying medical management of raised ICP.

Increased intracranial pressure is a medical/surgical emergency. It is the common endpoint of a wide variety of disorders. Symptoms and signs are non-specific.

Aetiology:

  • Meningitis, encephalitis, intracranial abscess
  • Subarachnoid haemorrhage
  • Subdural / extradural haemorrhage
  • Head trauma - blunt or penetrating
  • Hydrocephalus and shunt blockage in treated hydrocephalus
  • CNS tumours
  • Post-anoxic insult
  • Reye's syndrome
  • Benign intracranial hypertension

Symptoms:

  • Headache - usually frontal and classically worse after lying down
  • Vomiting - classically early morning, and without associated nausea
  • Blurred vision

Signs:

  • Tense fontanelle in infants
  • Depressed conscious state
  • Cushing's triad: hypertension, bradycardia, apnoea
  • Pupillary changes: uni or bilateral pupillary dilation
  • VI nerve palsy (false localising sign)
  • Papilloedema - may not be present if increase in ICP is of recent onset (< 24 hours)

With the exception of VI nerve palsy, focal neurological signs generally relate to
underlying pathology rather than the raised ICP per se.

Management:

RAISED ICP IS A MEDICAL EMERGENCY. THE PAEDIATRIC INTENSIVIST ON CALL SHOULD BE IMMEDIATELY NOTIFIED. IN MOST CASES THE NEUROSURGICAL REGISTRAR WILL ALSO NEED TO BE INVOLVED.

Management is directed towards the underlying disease. However, in the intervening period there are several therapies that will decrease the ICP.

  • Elevate head of bed - do not lay patient flat
  • Give mannitol 0.5 gram / kg IV or lasix 1 mg/kg IV in less severe cases
  • Hyperventilate. Indications for intubation are GCS < 8, or any pupil dilation.
    Patient should be ventilated to a PaCO2 of around 30 mmHg
  • Dexamethasone 0.5 - 1 mg/kg IV is particularly useful in vasogenic cerebral oedema - eg. CNS tumours
  • Avoid hypotension. Blood pressure should be maintained with a mean arterial pressure >= normal for age in order to maintain cerebral perfusion pressure (CPP = MAP - ICP)