the neurological disorder complicating a deficiency of vitamin B12 and pernicious anaemia. There is selective damage to the motor and sensory nerve fibres in the spinal cord, resulting in spasticity of the limbs and a sensory ataxia. It may also be accompanied by damage to the peripheral nerves and the optic nerve and by dementia. It is treated by giving vitamin B12 injections.
Medical dictionary. 2011.