A patient presents with ataxia, urinary incontinence and dementia. The likely diagnosis is:

Answer is D (Normal Pressure Hydrocephalus): Normal Pressure Hydrocephalus This is a communicating hydrocephalus with a aqueduct of sylvius caused by obstruction to normal flow of CSF over the cerebral convexities and delayed absorption into the venous system. The CSF opening pressure is in the high normal range (Hence called Normal Pressure Hydrocephalus). Characteristic Clinical Triad Abnormal Gait (Ataxic or Apractic) Dementia (Usually mild or moderate) Urinary I ncontinance