Myelopathy due to vitamin B ₁₂ deficiency presenting only sensory disturbances in upper extremities: A case report

We report a 54-year-old man with vitamin B ₁₂ deficiency myelopathy limited to the upper extremity region. He was well until October, 1995, when he had an onset of exertional dyspnea and general fatigue. Then he noted tingling sensation in bilateral tipper extremities in March, 1996. He had undergone total gastrectomy due to gastric ulcer 15 years ago. Neurological examination revealed superficial and vibratory sensory loss in the upper extremities distal to elbows, and pseudoathetoid movement of the left fingers. Otherwise neurological examination was unremarkable. Laboratory examination revealed macrocytic anemia, and low serum vitamin B ₁₂. However, serum folate was within the normal range. In SEP studies, median nerve stimulation evoked peripheral N9 and N13 potentials, but not cortical N20 one. Posterior tibial nerve stimulation elicited normal responses. MEP, VEP, needle EMG, and nerve conduction studies gave normal findings. T ₂-weighted MRI showed high signal intensity lesions at the C ₁-Th ₁ level in the posterior column, especially in the cuneate fascicles. The gracile fascicles were spared. This is a very rare case of myelopathy due to vitamin B ₁₂ deficiency presenting only sensory disturbances in both upper extremities. The lesions limited in the cuneate fascicle were confirmed by electrophysiological, and neuroradiological examinations.