This 77-year-old right-handed man presented to the clinic with a 15-year history of slowly progressive fatigue associated with cognitive difficulties. He reported being slow in his thinking, with difficulties concentrating and multitasking. In the past seven years, his gait slowed, balance declined, and he walked more cautiously to avoid falls. In addition, he developed urinary urgency with occasional incontinence. His neurological exam revealed bradykinesia, cogwheel rigidity and resting tremor, most prominent in the right arm. His gait was mildly wide based, slow with decreased arm swing, and he had stooped posture. On neuropsychological evaluation he was slow in his cognitive processing but, when given additional time, he performed within normal limits in all cognitive domains, including executive function. His brain MRI revealed ventriculomegaly with subcortical and periventricular white matter hyperintensities. The degree of ventriculomegaly was considered disproportionate to the degree of parenchymal atrophy (Figure 50.1). These findings led to the suspicion of normal pressure hydrocephalus (NPH).