Review Question - QID 5612

A 32-year-old cross-training athlete awakens with severe left neck and shoulder pain after a day of intense upper body training. Aside from a recent viral illness, he is otherwise healthy. His pain improves, but two weeks later he notes significant left shoulder weakness. Examination reveals weakness of shoulder abduction, forward elevation and external rotation with the arm at his side. Radiographs are normal. Electromyography demonstrates 2+ positive sharp waves and fibrillations. Sensory nerve conduction studies show reduced amplitudes. MRI of the brain, cervical spine and shoulder are shown in Figures A-D, respectively. Which of the following is true of his prognosis?