G91.2
Billable(Idiopathic) normal pressure hydrocephalus
HCC Category Mapping
V28HCC 127 — Dementia, Mild or Unspecified
0.464What This Code Means
Normal pressure hydrocephalus is a condition where cerebrospinal fluid accumulates in the brain despite normal pressure readings, typically causing gait disturbance, cognitive decline, and urinary incontinence.
Coding Tips
- •Classic triad includes gait disturbance, dementia, and incontinence; document which symptoms are present
- •Confirm diagnosis with imaging showing ventricular enlargement and normal opening pressure on lumbar puncture
Clinical Significance
Normal pressure hydrocephalus is characterized by the classic triad of gait disturbance, cognitive impairment, and urinary incontinence, with ventricular enlargement but normal cerebrospinal fluid pressure on lumbar puncture. It is one of the few potentially reversible causes of dementia in the elderly, making accurate diagnosis critical. Risk adjustment captures the significant diagnostic workup and surgical management costs.
Documentation Requirements
- ✓Documentation of the classic triad: gait apraxia, cognitive decline, and urinary incontinence (at least two of three should be present)
- ✓Imaging demonstrating ventriculomegaly disproportionate to cortical atrophy (Evans index >0.3)
- ✓Lumbar puncture results showing normal opening pressure with clinical improvement after large-volume CSF drainage
- ✓Cognitive assessment results (e.g., Mini-Mental State Examination, Montreal Cognitive Assessment)
- ✓Treatment plan including shunt consideration and response to therapeutic lumbar drainage
Commonly Confused Codes
G91.0 — Communicating hydrocephalus: elevated intracranial pressure distinguishes this from NPHF03.90 — Unspecified dementia without behavioral disturbance: NPH is a specific treatable cause of dementiaG30.9 — Alzheimer disease, unspecified: neurodegenerative dementia without the gait/urinary triad or ventriculomegalyR41.81 — Age-related cognitive decline: normal aging rather than pathological hydrocephalus
Code Hierarchy
└G91Hydrocephalus└G91.2(Idiopathic) normal pressure hydrocephalus
└G91.2(Idiopathic) normal pressure hydrocephalus