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Condition/Disorder Synonym

  • Raised/increased intracranial pressure

ICD-9-CM Code

  • 331.4 Hydrocephalus

ICD-10-CM Code

  • G91.9 Hydroycephalus (acquired) (external) (internal) (malignant) (recurrent)

Preferred Practice Patterns

Key Features


  • Increased intracranial pressure (ICP) beyond what cranium and vertebral column can accommodate

  • Reduced cerebrospinal fluid (CSF) production, decreased cerebral blood volume

Essentials of Diagnosis

  • Change in ICP for a given change in intracranial volume is called intracranial compliance

  • Normal compliance curve begins steep rise at approximately 25 mmHg

  • If brain, blood, CSF volumes continue to increase, accommodative mechanisms fail and ICP rises exponentially

  • Diagnosis made via monitoring intracranial pressure

    • Above 25 mmHg considered hydrocephalus

General Considerations

  • Numerical difference between ICP and mean blood pressure in cerebral vessels is the cerebral perfusion pressure

    • A widespread reduction in cerebral perfusion occurs as ICP approaches the mean systemic blood pressure, resulting in ischemia and brain death

    • Reduced cerebral perfusion pressure can result in cerebral infarction

  • Normal ICP range between 2 to 5mmHg


  • Hydrocephalus can occur in any age group

Clinical Findings

Signs and Symptoms

  • Headache

  • Neck pain

  • Nausea

  • Vomiting

  • Drowsiness

  • Ocular palsy

  • Papilledema

  • Confusion

  • Gait disturbance

  • Positive Babinski

  • Increased tone in limbs

Functional Implications

  • Decreased cognitive or physical interaction with environment

  • Poor safety with gait and balance activities

  • Decline in judgment or problem solving

  • Decline or loss of independence with ADLs

  • Inability to participate school, work, recreational activities

Possible Contributing Causes

  • Cerebral or extracerebral mass (tumor, edema, abscess)

  • Generalized brain swelling

  • Increased venous pressure (venous sinus thrombosis, heart failure)

  • Choroid plexus tumor

  • Meningitis

  • Ventricle obstruction

  • Chiari malformation

  • Arteriovenous malformation

  • Myelomeningocele

Differential Diagnosis

  • Chiari malformation

  • Cerebrovascular accident

  • Parkinson's disease

  • Brain tumor

Means of Confirmation or Diagnosis


  • CT for detailed imaging of brain

Diagnostic Procedures

  • ICP monitoring

  • Lumbar puncture with progressive fluid reduction


  • To ER physician if acute onset

  • To neurologist for monitoring

  • To neurosurgeon for shunt placement if patient is a candidate

  • Other services as needed based on impairments (occupational therapy, speech therapy, neuropsychologist)


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