A pernicious leucoencephalopathy.

Pernicious anaemia may manifest various neurological symptoms and signs ranging from the subtle to the dramatic. We describe a young man with cobalamin deficiency presenting with sensorimotor deficits, ataxia, dysarthria, mild cognitive deterioration and altered mood of insidious onset. The MRI brain findings were in keeping with a leucoencephalopathy without evidence of MRI changes in the spinal cord. This constellation of features has been reported rarely. His response to treatment as well as the marked improvement of the leucoencephalopathy on imaging suggests at least partial reversibility of the neurological deficits.