26th June 2023

An 80-year-old man with a history of hypertension and Alzheimer’s Dementia is brought in by his daughter with progressively worsening mobility

An 80-year-old man with a history of hypertension and Alzheimer’s Dementia is brought in by his daughter with progressively worsening mobility over the last few days. His daughter discloses that he has also had worsening sleep and seems to be acting out nightmares over the past few months. On examination, you note that he has a blank staring appearance with a resting tremor and increased rigidity in his limbs. The appearance of his forehead is normal, and he has normal eye movements in all directions.

Given his likely diagnosis, which cranial nerve is most likely to have abnormal?