[Central pontine myelinolysis and hyponatremia]

Central pontine myelinolysis is a rare, but probably underreported, complication of the treatment of severe hyponatraemia. The typical presentation, with pseudobulbar palsy, quadriplegia and locked-in syndrome, made the diagnosis clinically possible in the two new cases reported. It was confirmed by computed tomography (CT). Serial CT scans in one case showed the chronological dissociation, as there was complete resolution of the pontine lucency several months after complete clinical recovery. Osmotic demyelination is suspected, but it remains unproven. Although recent evidence has suggested that too rapid a correction of severe hyponatraemia may be a possible factor, the two cases described occurred after slow correction. It would seem that rapid correction to a level of mild hyponatraemia (128-132 mmol.l-1) may be safe, reducing the morbidity of severe hyponatraemia without having central pontine myelinolysis.