Idiopathic Normal Pressure Hydrocephalus Presenting as Psychosis.

Background Normal pressure hydrocephalus (NPH) is a syndrome characterized by gait disturbance, dementia, urinary incontinence, and dilation of ventricular system with normal opening cerebrospinal fluid pressure. Idiopathic NPH (i NPH) presenting as psychosis is uncommon. Objectives The objective of this study is to describe idiopathic NPH presenting as Psychosis. Subjects and methods Patients availing dementia care service from three tertiary care hospitals, across Kerala, with a diagnosis of psychosis were evaluated. Results Three patients with NPH, diagnosed as per the consensus criteria, presenting as psychosis are described. Patient 1: Fifty-five-year-old lady with psychosis was found to have iNPH. She gave history of psychosis relieved with successful shunting of the hydrocephalus. She developed recurrence of psychosis each time the hydrocephalus recurred due to shunt malfunction and was relieved with correction of hydrocephalus with shunting. Patient 2 was a 67-year-old gentleman with long history of pyschosis with paranoid ideas. Five years after onset of illness, he developed gait apraxia, and a CT scan done showed normal pressure hydrocephalus. Patient 3 had bipolar illness since age of 60 years of age. He also developed gait apraxia 5 years into the illness and was diagnosed as having iNPH following imaging. Conclusions All the patients had psychosis much before other features of iNPH developed. One of the patient's psychosis was temporally associated with onset and offset of hydrocephalus, thereby strongly supporting the causative nature of iNPH. iNPH though rare can be one of the causes for late onset secondary psychosis.