A 70-year-old man is brought to the clinic by his family due to a 9-month history of progressive memory loss, difficulty with planning and organizing, and a 'magnetic' gait where his feet appear to stick to the floor. Neurological exam reveals broad-based, shuffling gait and mild cognitive impairment. MRI of the brain shows ventriculomegaly out of proportion to sulcal atrophy. What is the most appropriate next diagnostic and therapeutic step?

The correct answer to the question "A 70-year-old man is brought to the clinic by his family due to a 9-month history of progressive memory loss, difficulty with planning and organizing, and a 'magnetic' gait where his feet appear to stick to the floor. Neurological exam reveals broad-based, shuffling gait and mild cognitive impairment. MRI of the brain shows ventriculomegaly out of proportion to sulcal atrophy. What is the most appropriate next diagnostic and therapeutic step?" is Option C: Perform a large-volume lumbar puncture.

The other options — A) Prescribe donepezil for symptomatic relief, B) Refer for genetic testing for Alzheimer's disease, D) Initiate physical therapy and gait training — are incorrect for this USMLE Exam Prep question. As explained above: This presentation is classic for Normal Pressure Hydrocephalus (NPH), characterized by the triad of gait disturbance, dementia, and urinary incontinence. A large-volume lumbar puncture is both diagno…