A 62-Year-Old Woman Presented to the Office Complaining of Left

A 62-year-old woman presented to the office complaining of left arm weakness for the last month. The patient noticed that left arm weakness is exacerbated by over-the-head movements. The weakness is associated with neck pain radiating to the left arm. She has no history of trauma or medical illnesses. Physical examination shows loss of shoulder abduction and biceps reflex on the left side. Additionally, there is decreased pinprick sensation over the left lateral arm and forearm. Which of the following is the pathophysiology underlying the patient's symptoms?

A) Axonal loss in the corticospinal tracts
B) Cystic expansion of the central canal
C) Degenerative changes in the vertebral joints
D) Microinjury and tear of the rotator cuff tendons
E) Rupture of the long head of the biceps tendon