Review Question - QID 214980

A 65-year-old man presents to the emergency department after an accident with his bicycle 3 hours ago. He explains that he was riding in the woods and fell on his left side when a deer jumped in front of him. After getting back up, the patient noticed he had difficulty hearing on his left side and decided to visit the hospital. His temperature is 97°F (36.1°C), blood pressure is 129/79 mmHg, pulse is 90/min, and respirations are 14/min. The patient is alert and oriented and demonstrates understanding of his situation. On his visual exam, the patient’s visual fields are intact. When the patient asked to smile, it is asymmetric and his left forehead is not wrinkled. On otoscope, there is a dark fluid pushing on his left tympanic membrane. The patient is also unable to walk in a straight line without feeling unsteady. The patient is admitted for observation. A day later, bruising over his left mastoid process is noted. Which of the following is the most likely cause of the patient’s symptoms?