Hashimoto Encephalopathy With Status Epilepticus

Hashimoto encephalopathy (HE) is a heterogenous neurological syndrome that can manifest with encephalopathy, seizures, headaches, and variable neuropsychiatric disturbances. The underlying mechanism remains unclear; however, autoimmune pathogenesis is suspected due to its association with autoimmune thyroid disease, high titers of anti-thyroid antibodies, and quick response to steroid therapy. We report a 59-year-old female patient with a remote history of hypothyroidism who presented with status epilepticus and complaints of chronic headaches and cognitive impairment. The presence of sharp frontal waves was identified on her EEG. The patient was initially started on anti-epileptics only; however, her headaches and memory loss escalated, further diagnostic workup was pursued, which revealed high antithyroid peroxidase antibodies with normal thyroid function tests. The only cerebrospinal fluid (CSF) abnormality noticed was an elevated protein concentration. MRI showed non-specific right frontal lobe pial enhancement. Remaining infectious, rheumatologic, and neurologic testing was unremarkable. The patient was started on a steroid regimen with successful resolution of symptoms and return of cognitive baseline. Hashimoto's encephalopathy is a diagnosis of exclusion; however, it should be considered in patients with high titers of anti-thyroid antibodies and neurological symptoms that cannot be explained by thorough infectious, metabolic, and autoimmune testing. It is essential to recognize this neurological entity as fast clinical improvement may be achieved with steroids and other immunotherapies.