ICD-9 Diagnosis Code 331.5

Norml pressure hydroceph

Diagnosis Code 331.5

ICD-9: 331.5
Short Description: Norml pressure hydroceph
Long Description: Idiopathic normal pressure hydrocephalus (INPH)
This is the 2014 version of the ICD-9-CM diagnosis code 331.5

Code Classification
  • Diseases of the nervous system
    • Hereditary and degenerative diseases of the central nervous system (330-337)
      • 331 Other cerebral degenerations

Information for Medical Professionals

Convert to ICD-10 Additional informationCallout TooltipGeneral Equivalence Map
The ICD-10 and ICD-9 GEMs are used to facilitate linking between the diagnosis codes in ICD-9-CM and the new ICD-10-CM code set. The GEMs are the raw material from which providers, health information vendors and payers can derive specific applied mappings to meet their needs.
  • G91.2 - (Idiopathic) normal pressure hydrocephalus

  • Dementia associated with normal pressure hydrocephalus
  • Normal pressure hydrocephalus

Index of Diseases and Injuries
References found for the code 331.5 in the Index of Diseases and Injuries:

    • Hydrocephalus (acquired) (external) (internal) (malignant) (noncommunicating) (obstructive) (recurrent) 331.4
      • normal pressure 331.5
        • idiopathic (INPH) 331.5
        • secondary 331.3
    • INPH (idiopathic normal pressure hydrocephalus) 331.5

Information for Patients


Also called: Water on the brain

Hydrocephalus is the buildup of too much cerebrospinal fluid in the brain. Normally, this fluid cushions your brain. When you have too much, though, it puts harmful pressure on your brain.

Hydrocephalus can be congenital, or present at birth. Causes include genetic problems and problems with how the fetus develops. An unusually large head is the main sign of congenital hydrocephalus.

Hydrocephalus can also happen after birth. This is called acquired hydrocephalus. It can occur at any age. Causes can include head injuries, strokes, infections, tumors, and bleeding in the brain. Symptoms include

  • Headache
  • Vomiting and nausea
  • Blurry vision
  • Balance problems
  • Bladder control problems
  • Thinking and memory problems

Hydrocephalus can permanently damage the brain, causing problems with physical and mental development. If untreated, it is usually fatal. With treatment, many people lead normal lives with few limitations. Treatment usually involves surgery to insert a shunt. A shunt is a flexible but sturdy plastic tube. The shunt moves the cerebrospinal fluid to another area of the body where it can be absorbed. Medicine and rehabilitation therapy can also help.

NIH: National Institute of Neurological Disorders and Stroke

  • Brain surgery
  • Brain surgery - discharge
  • Hydrocephalus
  • Normal pressure hydrocephalus (NPH)
  • Radionuclide cisternogram
  • Ventriculoperitoneal shunt
  • Ventriculoperitoneal shunt - discharge

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