Increased Intracranial Pressure (ICP)

Intracranial pressure or ICP is the pressure or force exerted on the skull by the brain and fluid inside the skull cavity. These include:

  • 80% brain tissue and water
  • 10% blood
  • 10% cerebrospinal fluid (CSF)


Increase in intracranial pressure can be due to increase in cerebrospinal fluid pressure, brain lesion, or swelling of the brain. The following conditions can lead to increased ICP:

  • Severe head injury

  • Subdural hematoma
    A hematoma or localized swelling filled with blood that occurs in the dura matter and the arachnoid membrane of the brain.

  • Hydrocephalus
    Abnormal accumulation of fluid in cerebral ventricles

  • Brain tumor

  • Brain hemorrhage
    Bleeding in the brain
  • Meningitis
    Inflammation of the meninges (membrane that covers the brain) due to bacterial or viral infection.

  • Encephalitis or cephalitis
    Inflammation of the brain

  • Aneurysm
    Localized dilation of a blood vessel

  • Status epilepticus
    Rapid and successive attacks of epilepsy

  • Stroke
    Rupture or a blood vessel in the brain


Symptoms of increased ICP in infants include:

  • Bulging fontanelle or soft spot
    Infants have soft, membranous gaps between the incompletely formed bones of the skull called fontanelle or soft spot. Increased ICP can show up as bulging fontanelle.
  • Lethargy
  • Vomiting

Symptoms of increased ICP in older children and adults include:

  • Vomiting
  • Headache
  • Blurred vision
  • Seizure
  • Changes in behavior
  • Loss of consciousness
  • Lethargy
  • Neurological symptoms


Increased ICP is diagnosed by:

  • Computed tomography (CT) scan or magnetic resonance imaging (MRI)
  • Measuring intracranial pressure through a spinal tap or lumbar puncture, by drilling through the skull to measure pressure on the surface of the brain, and by inserting a catheter to measure the pressure inside the brain

Compensatory Mechanism

The skull is rigid and does not allow much expansion of the brain, so increases in ICP is a critical medical condition that can lead to brain damage. To compensate for increased ICP, the brain will reduce the volume of fluid inside the skull cavity by:

  • Limiting blood flow to the head
  • Moving the cerebrospinal fluid into the spinal canal
  • Increasing the absorption of CSF
  • Decreasing the production of CSF

With large ICP, however, these compensatory measures can be overwhelmed and small changes in fluid volumes can lead to large changes in pressure inside the skull.

Left untreated, ICP can lead to:

  • Brain hypoxia
    Lack of blood flow to the brain can lead to deficiency in oxygen reaching the brain tissues.

  • Brain herniation
    Increased pressure causes displacement of the brain tissue, CSF, and blood vessels outside its normal space in the head. This displacement (called herniation) can occur through a natural opening at the base of the skull or formen occipitalis, or between compartments inside the skull through the rigid tentorium membrane.

  • Brain death


Immediate medical attention is necessary to decrease the swelling and improve drainage of the cerebrospinal fluid to lower the pressure in the brain. If the condition is due to tumor or hemorrhage, then the root cause of increased ICP needs to be treated.


Increased ICP is a critical medical condition and can lead to disability, permanent neurological deficit and even fatality if not treated immediately.


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