To familiarize neurologists with SESA syndrome and its clinical overlap with antibody negative autoimmune encephalitis

A 45-year-old female with a history of alcohol abuse presented with right head version leading to whole body shaking with impaired awareness. Her initial magnetic resonance imaging demonstrated T2 hyperintensities in the left sided limbic structures and medial left thalamus without contrast enhancement. Her EEG showed corresponding left lateralized periodic discharges. She electro-clinically improved with a 60mg/kg loading dose of Levetiracetam followed by maintenance doses. 3 days later, she developed hallucinations and fluctuating mental status. CSF studies were obtained which noted elevated protein of 68, no pleocytosis, and negative HSV PCR. CSF and serum autoimmune encephalopathy panels were negative. She underwent empiric treatment with intravenous methyl prednisone (IVMP) with reported improvement back to baseline and started on an oral prednisone taper. Five days later she developed echolalia and aphasia with forced right gaze deviation. Repeat EEG showed a highly epileptogenic foci on the left hemisphere. Repeat MRI showed unchanged left sided limbic T2 hyperintensities. Clobazam and Vimpat were added with minimal improvement in electro-clinically however her right gaze deviation abated.  CSF and serum autoimmune encephalopathy panels were repeated and were negative. Repeat CSF studies again only showed mildly elevated protein (53). She was empirically treated with IVMP 1g x 5 days and then IVIG 2g/kg over 5 days with mild improvement in her aphasia, echolalia, and lethargy.

SESA and antibody negative autoimmune encephalitis have significant overlap clinically, radiographically, and electro-graphically. They both can present with focal deficits, limbic T2 hyper intensities, and ictal-interictal continuum patterns. Features differentiating SESA from autoimmune encephalitis include lack of pleocytosis, history of significant alcohol use, and significant improvement with anti-seizure medications. Further studies are needed to identify characteristics to help delineate these conditions as treatment paradigms are different.