Idiopathic normal pressure hydrocephalus (INPH)

This code identifies a specific type of hydrocephalus characterized by enlarged cerebral ventricles and normal cerebrospinal fluid (CSF) pressure, typically presenting with a classic triad of gait disturbance, urinary incontinence, and dementia. It is considered idiopathic, meaning the cause is unknown, and is often responsive to CSF shunting.

Apply this code when documentation explicitly states a diagnosis of idiopathic normal pressure hydrocephalus. This diagnosis is often supported by clinical presentation (gait, incontinence, cognitive decline), imaging studies showing ventriculomegaly, and sometimes a positive response to a high-volume lumbar puncture (tap test).

• Differentiate from other forms of hydrocephalus (e.g., obstructive, communicating, congenital) which have distinct ICD-9 codes.
• Ensure the "idiopathic" nature is clearly documented; if a cause is identified, a more specific hydrocephalus code should be used.
• Consider sequencing this code as a primary diagnosis when it is the reason for the encounter, especially for evaluation or management of the condition.