Review Question - QID 6837

An 82-year-old man is seen in consultation after being admitted for a fall from ground level. There was no loss of consciousness and the patient recalls striking his head and sustaining a hyperextension-type injury to the cervical spine. Examination reveals an 8-cm head laceration with only mild axial neck tenderness. He has generalized weakness throughout the upper extremities and maintained motor function of the lower extremities. There are no obvious sensory deficits, and the bulbocavernous reflex and deep tendon reflexes are maintained. What is the most appropriate diagnosis at this time?