What is An 80 year old man has a history of progressive gait disturbance and incontinence which had been attributed to old age and prostatism. For the past 4 months he has been forgetful and confused. He has a history of head trauma 25 years ago. His head CT is shown below .The most likely diagnosis and explain in detail?
Normal pressure hydrocephalus triad:

Dementia
Ataxia
Incontinence

CT or MRI brain in these patients shows enlarged frontal and temporal horns of lateral ventricles out of proportion to degree of cortical atrophy.