Anti GAD Negative Autoimmune Limbic Encephalitis in Diabetic Ketoacidosis: A Case Report

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Abstract A 4-year-old boy presented to the emergency room with severe abdominal pain, tachypnea and vomiting followed by progressive obtundation. He was found to have hyperglycemia, ketonuria and metabolic acidosis. A diagnosis of Diabetic ketoacidosis was hence made and the boy was managed as such, with improvement in his laboratory parameters as well as in his level of consciousness. On day 6 after admission, the boy developed a recurrence of altered consciousness and repeated seizures. On examination the boy had spastic quadriparesis lateralizing to the right side. MRI of the brain showed multiple inflammatory lesions involving both temporal lobes. CSF analysis was unremarkable and CSF Herpes Simplex virus PCR was negative. Based on the inflammatory nature of lesions on MRI, with negative PCR for HSV and otherwise unremarkable CSF, together with progressive worsening of level of consciousness and spasticity, the possibility of autoimmune encephalitis was raised and the boy received 2 grams per kilogram of intravenous immunoglobulin with mild improvement in level of consciousness. The boy then received intravenous pulsed methylprednisolone, with a clear improvement in both his motor and mental capabilities. Three months post hospital discharge, the child was back to normal. This case highlights the importance of considering autoimmune encephalitis in the differential diagnosis of altered level of consciousness in a child with type 1 diabetes, especially in the presence of suggestive MRI findings and a lack of an alternative explanation.