Review Question - QID 213466

A 27-year-old man presents to the emergency department with dizziness. He states he has experienced a sustained sensation of the room spinning that is low grade and constant since this morning. The patient occasionally feels nauseous and has been taking diphenydramine to sleep which helps with his symptoms. The patient is generally healthy, has no other medical conditions, and only endorses eating more garlic recently to get over a cold he had a few days ago. His temperature is 98.7°F (37.1°C), blood pressure is 122/81 mmHg, pulse is 82/min, respirations are 15/min, and oxygen saturation is 99% on room air. Physical exam is notable for a healthy man. The patient is sat upright, his head is turned slightly to the right, and he is laid back flat rapidly. This does not provoke any symptoms even when repeated on the left side. A nystagmus is notable on cranial nerve exam as well as bilateral decreased hearing. The patient’s tandem gait is unstable; however, his baseline gait appears unremarkable despite the patient stating he has a sustained sensation of imbalance. Which of the following is the most likely diagnosis?