Hashimoto's encephalopathy in a patient with severe hypothyroidism

ABSTRACT

Introduction: Hashimoto's encephalopathy (HE) manifests itself with neuro-psychiatric disorders, which can reach coma;HE usually occurs in euthyroid, being less frequent states of thyroid dysfunction. We present the case of a patient with HE and severe hypothyroidism. Case Description A 71-year-old woman;history of rheumatoid arthritis, hypertension and cerebral infarction without sequelae. The family referred a 3-week history of illness characterized by disorientation and "jerking" movements, she progressed to drowsiness with left hemiparesis, focal epileptic seizures and myoclonus. The brain CT showed atrophy and left frontal malacia;diagnosed status epilepticus and cerebral infarction, indicating phenytoin. During hospitalization she was added valproic acid and levetiracetam, without improvement. Brain MRI showed cerebral atrophy and periventricular leukoaraiosis. The study of the CSF hyperproteinorraquia;EEG diffuse slowing and periodic lateralized discharges in the right hemisphere. They request an endocrinology evaluation for TSH > 75uIU/ml, Free T4 0.31ng/dl, we expand with Anti-TPO > 1000 and Anti-thyroglobulin > 3000, and we indicate treatment for severe hypothyroidism with levothyroxine for nasogastric tube and intravenous hydrocortisone for 5 days and with minimal recovery from sensory disorder. After the withdrawal of hydrocortisone, she developed drowsiness and intensified myoclonus despite an improvement in the blood concentration of thyroid hormones. Having excluded infectious, metabolic and paraneoplastic etiology of encephalopathy, with the presence of elevated antithyroid antibodies in blood and CSF, the diagnosis of Hashimoto's encephalopathy was raised, receiving methylprednisolone (1 g/day for 5 days), then human immunoglobulin (25g for 5 days) Faced with poor response, she received 5 sessions of plasmapheresis with favorable clinical and paraclinical evolution. After overcoming hospital infection by COVID-19, she was discharged at 3 months. In the follow-up, cognitive deterioration, partial dependence, without epileptic seizures or myoclonus were reported. Discussion: HE is rare, with variable clinical presentation. HE has a good response to corticosteroids, although it sometimes requires other interventions. The alteration of thyroid function itself can be confusing at the time of diagnosis. Severe hypothyroidism can present neurological complications such as seizures, dementia, or psychosis;but it differs from HE in that manifestations improve when thyroxine is replaced.