G91.2 (Idiopathic) normal pressure hydrocephalus

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.

Applicable to

• Normal pressure hydrocephalus NOS

Applies from G91 Hydrocephalus

Includes

• acquired hydrocephalus

Excludes1 (never code together)

• Arnold-Chiari syndrome with hydrocephalus (Q07.-)
• congenital hydrocephalus (Q03.-)
• spina bifida with hydrocephalus (Q05.-)

Risk adjustment (HCC)

• CMS-HCC V28: HCC 127 — Dementia, Mild or Unspecified
• ESRD V24: HCC 51

MS-DRG index

Defines the logic of DRG(s) 056-057 in MDC 01.

Approximate ICD-9-CM (GEMs)

• 331.5 Idiopathic normal pressure hydrocephalus (INPH)

Code annotations containing back-references to G91.2

Back-references to G91

• Type 1 Excludes: Q03 Congenital hydrocephalus ("acquired hydrocephalus (G91.-)")

Diagnosis Index entries for G91.2

• Hydrocephalus (acquired) (external) (internal) (malignant) (recurrent) › normal pressure

Nearby codes

• G91 Hydrocephalus
• G91.0 Communicating hydrocephalus
• G91.1 Obstructive hydrocephalus
• G91.2 (Idiopathic) normal pressure hydrocephalus (this code)
• G91.3 Post-traumatic hydrocephalus, unspecified
• G91.4 Hydrocephalus in diseases classified elsewhere
• G91.8 Other hydrocephalus
• G91.9 Hydrocephalus, unspecified