Central pontine and extra-pontine myelinolysis: a complication of lithium toxicity in a pregnant woman.

Osmotic demyelinating syndromes consisting of central pontine and extra-pontine demyelination are very uncommon disorders characterized by non-inflammatory lesions involving the pons and sometimes spreading to other areas. Rapid changes in serum sodium concentration are usually regarded as the main pathophysiological mechanism. We report herein the case of a 23-year-old woman in the 24th week of pregnancy, who demonstrated both central pontine and extra-pontine demyelination occurring at the time of a recently introduced treatment with lithium. The disorder was related to the rapid correction of pregnancy-related hyponatremia, as a consequence of lithium-induced diabetes insipidus. Hence, lithium toxicity is a rare cause of osmotic demyelinating syndromes and appears to correlate with disturbances in sodium homeostasia.