Case History: Case Z

A 35-year-old woman presented with the onset of paresthesias, weakness, and numbness in her arms and hands over a period of several weeks. Neurological exam indicated ataxic gait, positive Romberg test, decreased strength in lower extremities, bilateral Babinski signs, loss of vibration and joint position sensation in the lower limbs. What is the most likely location of lesions? If the patient also had megaloblastic anemia, what would be the most likely diagnosis?