November 28, 2016 E-Pearl of the Week: Reversible lesion of the corpus callosum

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November 28, 2016

Reversible lesion of the corpus callosum 

The boomerang sign, also known as mild encephalitis/encephalopathy with a reversible splenial (MERS)1 lesion, or reversible splenial lesion syndrome (RESLES),2 is a finding of isolated diffusion restriction without contrast enhancement in the central portion of the splenium. It's a non-specific finding described in seizures, antiepileptic withdrawal, neuroleptic malignant syndrome, hemicrania continua, high altitude cerebral edema, herbicide toxicity, metabolic derangements (i.e. hyponatremia, hypoglycemia) and certain infections. Most patients are children and young adults. Symptoms are nonspecific without a clear disconnection syndrome. Radiographic findings resolve within one month. 


  1. Tada H, Takanashi J, Barkovich AJ, et al. Clinically mild encephalitis/encephalopathy with a reversible splenial lesion. Neurology 2004; 63: 1854-1858.
  2. Jeong TO, Yoon JC, Lee JB, Jin YH, Hwang SB. Reversible splenial lesion syndrome (RESLES) following glufosinate ammonium poisoning. J Neuroimaging 2015; 25: 1050-1052. 

Submitted by Asya Izraelit Wallach, MD, Neurology Resident, New York University School of Medicine, New York, NY. Dr. Wallach reports no disclosures.

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