Plasmapheresis for Extrapontine Myelinolysis: A Case Series and a Literature Review.

Central pontine myelinolysis (CPM) and extrapontine myelinolysis (EPM) are syndromes of osmotic demyelination attributed to the rapid correction of hyponatraemia. Isolated EPM is a rare clinical entity which poses a significant diagnostic challenge especially in the absence of a rapid rise in sodium. Typical MRI findings aid in the diagnosis. Treatment for established osmotic demyelination syndrome (ODS) is nonstandardized and the prognosis is considered poor. Therefore, different strategies including plasmapheresis (TPE), immunoglobulins (IVIG), and steroids have been used. We present our findings from a series of successfully treated patients at a high-volume tertiary care center in Sri Lanka, with an appraisal of available literature. A total of 21 patients with established ODS are analyzed here, including 5 cases of EPM managed by the authors over a 2-year period. Thirteen (40.2%) patients were treated with plasmapheresis alone, 6 (28.5%) received dual therapy (TPE + IVIG or steroids) and 2 (9.5%) received triple therapy (TPE + IVIG + steroids). There was complete or near complete response in 18 (85.7%) and complete response in 10 (47.6%) patients. We conclude that although the management of CPM/EPM is largely symptomatic, patients may show a significant response to immunomodulatory therapy. The marked improvement in motor, cognitive, and functional domains supports an immune basis for osmotic demyelination. Plasmapheresis, in particular, leads to favorable outcomes in ODS which is supported by previously published case reports. We propose its utility as standard treatment.