ICD-10-CM > G00-G99 > G89-G99 > G91 G91 Hydrocephalus Non-Billable/Non-Specific Includes acquired hydrocephalus Type 1 Excludes Arnold-Chiari syndrome with hydrocephalus (Q07.-)congenital hydrocephalus (Q03.-)spina bifida with hydrocephalus (Q05.-) Codes G91.0Communicating hydrocephalusG91.1Obstructive hydrocephalusG91.2(Idiopathic) normal pressure hydrocephalusG91.3Post-traumatic hydrocephalus, unspecifiedG91.4Hydrocephalus in diseases classified elsewhereG91.8Other hydrocephalusG91.9Hydrocephalus, unspecified