ESPE Abstracts (2019) 92 P3-254

Encephalitis Associated with Autoimmune Thyroiditis: A Rare Cause of Encephalopathy In Children

Julie Fudvoye, Marie-Christine Lebrethon, Patricia Leroy, Marie-Christine Seghaye, Anne-Simone Parent


University hospital, Liège, Belgium


A ten year old girl was brought by the emergency mobile service for a persistent status epilepticus despite administration of Diazepam on site. She had presented headaches for the last three days and one episode of fever was suspected but not measured four days earlier. She had one episode of dizziness five days earlier.

Persistent status epilepticus required invasive ventilation as well as deep sedation with Levetiracetam, Midazolam, ketamine, phenytoin, valproic acid and frisium.

Biological assessment, brain scan and bacteriological and viral cerebrospinal fluid (CSF) analysis were normal. Magnetic resonance imaging of the brain showed a vasogenic oedema. The initial search for autoimmune antibodies on CSF was negative. Moderate hypothyroidism with high anti-TPO antibodies was noticed. Thyroid ultrasound confirmed the appearance of thyroiditis. Because of a likely autoimmune etiology, a high-dose corticosteroid therapy was introduced followed by plasmapheresis which lead to clinical improvement.

Hashimoto encephalitis is also known as Steroid responsive encephalopathy associated with autoimmune thyroiditis (SREAT). The estimated prevalence is 2.1 per 100 000 and is relatively rare in peadiatric population. Association of acute encephalopathy with elevated antithyroid antibodies after exclusion of other etiologies (infection, tumor, toxic, metabolic) suggests the diagnosis. Most pediatric patients present with slowly progressive encephalopathy with epileptic seizures as the most common symptom (60–80%) which require intensive treatment in order to limit brain damage.

Thyroiditis is noticed with increased anti-thyroglobulin and / or anti-thyroperoxidase antibodies. It appears that thyroid antibodies are not directly responsible for braindamages, and the abnormalities in thyroid hormone levels are generally too mild to explain the brain disease. Other auto-immunue encephalopathies in children are associated with other autoantibodies, such as anti- NMDAR or GABA-B-R.

The standard treatment consists in a systemic corticosteroid therapy and/or plasma exchange, while other lines of immunotherapy are sometimes needed. Antithyroid antibody titer can be used to predict responsiveness to treatment in the acute stage, but cannot be used as a marker of relapse.

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