Central nervous system regeneration

Sir, I read with interest Dr A. Williams’ article, ‘Central Nervous System Regeneration—Where Are We’, in which he describes how remyelination can take place in the brain and spinal cord of patients with multiple sclerosis, a process which, until recently, had been thought not to be possible. It is still a dogma that there is no regeneration of neurones. However, it may be that this doctrine can now be challenged. In 1981, John Williams1 and I described the first study of brain changes in Wilson disease, as revealed by computerised tomography scanning, showing multiple anomalies. Fourteen of the 60 patients studied showed hypodense lesions in the basal ganglia, strongly suggesting loss of neurons, changes that corresponded with the cavities shown by Wilson in patients dying of Wilson disease.2 But in our series, patients studied after treatment with penicillamine or trientine showed resolution of these lesions that corresponded with a remarkable recovery of function. A later study3 using magnetic resonance imaging scanning confirmed these findings. It is difficult to understand how such a structural and functional recovery could occur without regeneration of neurones. What other explanation is available?