Subacute combined degeneration of the spinal cord due to vitamin B12 deficiency

A previously healthy 82-year-old lady presented with abnormal sensation in her fi ngers which she described as 'feeling like bananas'.There was an additional history of deteriorating handwriting and a sense of imbalance when walking dating back 6 months.She obtained a score of 26 out of 30 on the mini mental state examination.She had gait ataxia, being unable to perform tandem gait.There was no convincing pseudoathetosis of the outstretched hands.She had slow, clumsy fi ne fi nger movements and her diary entries had become progressively illegible.Proprioception was abnormal in the toes and vibration sense was lost to the level of the costal margins.Refl exes were brisk in the arms but depressed in the legs.Plantar responses were fl exor.Her serum vitamin B 12 level was 83 (160-800) ng/l.Intrinsic factor antibodies were negative.Parietal cell