Neurologic examination reveals an extensor plantar reflex and hyperreflexia on the left side, a loss of pain and temperature sensation on the right side, ptosis and miosis on the left side. A lesion that causes this constellation of deficits would most likely be found in the:

Above symptoms point towards Brown-Sequard syndrome: hemisection of the cervical spinal cord- result in I/L Horner syndrome, I/L spastic paresis and C/L loss of pain and temperature sensation. Horner syndrome -always manifested on the ipsilateral side. Paracentral lobule control higher centres of micturation.