Central Pontine Myelinolysis: Don't Rely on the MRI

Alan R. Jacobs, MD


May 31, 2012

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This is the Medscape Neurology Minute. I am Dr. Alan Jacobs. Researchers from the Department of Neurology at the Mayo Clinic in Minnesota have published a retrospective study to characterize the clinical and radiologic features of patients with central pontine myelinolysis and identified variables that predict outcome. Records from 1999 to 2010 were analyzed and diagnoses were made by clinical and radiologic features. Favorable outcomes were defined by a modified Rankin score of 2 or less. A blinded radiologist quantified the volume of MRI signal abnormalities and associations between volume and signal abnormalities, and outcomes at discharge and last follow-up were assessed by Wilcoxon rank sum tests. Of 24 patients, 14 had central pontine myelinolysis and 10 had extrapontine involvement. Hyponatremia was documented in 18 patients with a median sodium nadir of 114 mmol/L. Eighteen patients had alcoholism and 12 had malnutrition. Presenting symptoms included encephalopathy, ataxia, dysarthria, eye movement abnormalities, and seizures. Fifteen patients had variable outcomes at last follow-up. Initial MRI findings were normal in 5 patients, but all MRI scans became abnormal with serial imaging. There was no association between the volume of MRI signal abnormality and outcome. The investigators concluded that clinical outcome in patients with central pontine myelinolysis is not predicated on the volume of MRI T2 signal abnormalities or the severity of hyponatremia, but serial brain imaging is of value given the normality of initial findings in a substantial proportion of patients. This study was selected from Medscape's Best Evidence. I'm Dr. Alan Jacobs.