Central pontine myelinolysis at autopsy; a twelve year retrospective analysis

Central pontine myelinolysis (CPM) was first described in 1959 and only later was associated with a rapid, sustained rise in serum sodium from a hyponatremic baseline. This discovery in 1981 led to modifications in recommendations for clinical treatment of hyponatremia. Our interest has been in tracking the incidence of CPM found at autopsy by year to see whether changes in medical treatment in hyponatremia have resulted in a decrease in CPM over time. Clinically asymptomatic CPM found at autopsy has always been at least as frequent as cases diagnosed premortem and serves as a reasonable indicator for the incidence of the disease. In over 3,000 autopsies, on most of which the brain was examined macroscopically and microscopically by the same neuropathologist, we have discovered 15 cases of asymptomatic, small pontine CPM. Of these 15, 6 were active lesions and 9 were remote; in the active group, 5 of the 6 cases were associated with a rapid, sustained rise in serum sodium during the appropriate time period. The incidence of asymptomatic CPM has remained steady over the 13-year time period. In contrast, we have encountered no cases of CPM diagnosed premortem that have come to autopsy in the same time period. These cases emphasize that CPM still occurs, but most often as an asymptomatic disorder with small, midline pontine lesions. When small active CPM is found, it still is associated with a rapid sustained rise in serum sodium.