A Patient with Mild Encephalitis/Encephalopathy with a Reversible Splenial Lesion in Steroid Responsive Encephalopathy Associated with Autoimmune Thyroiditis

Abstract

Background: Mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) is a clinical-radiological entity, characterized by mild encephalitis or encephalopathy associated with a reversible lesion of the corpus callosum, which commonly involves the splenium. MERS with autoimmune thyroid disease has rarely been reported. Case Report: A 37-year-old man with Grave’s disease presented to our institution, with symptoms of confused mentality, visual hallucinations, headache, and fever. Because there was no other etiology for changed mentality, headache, and fever, except for elevated antithyroid antibodies (antimicrosomal antibodies, anti-thyroglobulin antibody, and thyrotropin binding inhibitor immunoglobulin) in the blood and mild pleocytosis in the CSF study, we diagnosed the case as steroid responsive encephalopathy associated with autoimmune thyroiditis (SREAT). A hyperintense signal on T2-weighted images, a hypointense signal on T1-weighted images, and a non-enhancing lesion in the splenium of corpus callosum on initial magnetic resonance imaging (MRI) disappeared on follow-up MRI, which was compatible with the criteria of MERS. Conclusion: Although MRI images in autoimmune thyroid disease have usually been unremarkable, we report a case of MERS in SREAT.

Keywords

• Autoimmune thyroid disease
• Encephalopathy
• Reversible
• Splenium