This patient is showing features of involvement of fibers in the dorsal column of spinal cord. Dorsal column medial lemniscal system mediates impulses concerned with position sense, vibration sense and discriminative touch. Fibers in the dorsal column ascend ipsilaterally and decussate in the caudal medulla. Lesion of dorsal column of spinal result in ipsilateral loss of proprioception and vibration. Isolated involvement of dorsal column occur in tabes dorsalis a form of teiary syphilis.In patients with syringomyelia decussating fibers of the spinothalamic tract from both sides are involved without affecting other ascending or descending tracts. These patients develop dissociated sensory abnormalities with loss of pain and temperature sensibility in appropriate dermatomes with preservation of vibration and position sense.Ref: Waxman S.G. (2010). Chapter 5. The Spinal Cord. In S.G. Waxman (Ed), Clinical Neuroanatomy, 26e.