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  • Raised/increased intracranial pressure


  • 331.4 Hydrocephalus


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


  • 5C: Impaired Motor Function and Sensory Integrity Associated with Nonprogressive Disorders of the Central Nervous System—congenital origin or acquired in infancy or childhood1

  • 5D: Impaired Motor Function and Sensory Integrity Associated with Nonprogressive Disorders of the Central Nervous System—acquired in adolescence or adulthood2

  • 5E: Impaired Motor Function and Sensory Integrity Associated with Progressive Disorders of the Central Nervous System3


On a recent visit to her father’s house a woman noted that her 73-year-old father seemed to move slower than he recalled from previous visits. Her father seemed to struggle to follow involved conversations and he got frustrated with “losing” objects around the house. Her father had bruising on his left elbow and forearm but would only say that he lost his balance “a little”. In his past medical history, the man had suffered a mild stroke 4 years ago with subsequent hydrocephalus. At that time, he had a ventriculoperitoneal shunt placed. He had no physical or cognitive sequelae from the stroke after the first year. The woman took her father to his neurologist. Testing revealed that the shunt had malfunctioned and his intracranial pressure (ICP) exceeded 25 mm Hg.



  • ICP beyond what cranium and vertebral column can accommodate

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

Essentials of Diagnosis

  • Two types of hydrocephalus

    • Noncommunicating

    • Communicating

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

  • Normal compliance curve begins steep rise at approximately 25 mm Hg.

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

  • Diagnosis made via monitoring intracranial pressure

    • Above 25 mm Hg considered hydrocephalus


Schematic illustration of the effect of obstruction of reabsorption of CSF causing communicating hydrocephalus. Arrows indicate transependymal flow. Another possible site of obstruction is at the narrow space around the midbrain in the incisura. (From Waxman SG. Clinical Neuroanatomy. 26th ed. Copyright © The McGraw-Hill Companies, Inc. All rights reserved.)

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 5 mm Hg


  • Hydrocephalus can occur in any ...

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