ICD-9-CM diagnosis code (retired)
331.5 — Idiopathic normal pressure hydrocephalus (INPH)
ICD-9-CM was replaced by ICD-10 on October 1, 2015. These are the ICD-10-CM equivalents from the CMS General Equivalence Mappings.
About ICD-9-CM 331.5
331.5 is an ICD-9-CM diagnosis code for idiopathic normal pressure hydrocephalus (INPH). ICD-9-CM was retired for U.S. claims on October 1, 2015, when ICD-10-CM took over.
The CMS General Equivalence Mappings translate it to one ICD-10-CM code, G91.2 ((Idiopathic) normal pressure hydrocephalus). The match is exact.
ICD-10-CM equivalents
- G91.2(Idiopathic) normal pressure hydrocephalusexact match
Common questions about 331.5
What is the ICD-10 code for ICD-9 331.5?
- The GEMs map 331.5 to ICD-10-CM G91.2.
GEMs are a translation aid, not a substitute for coding from the record. The 2027 ICD-10 code set has changed since the last GEMs release in 2018. Page updated September 29, 2026.