What is the management of Hashimoto (Hashimoto's thyroiditis) encephalitis?

Management of Hashimoto Encephalitis

Initiate high-dose intravenous corticosteroids immediately as first-line therapy, with methylprednisolone 1 g IV daily for 3-5 days, as this is the cornerstone treatment for Hashimoto encephalitis with excellent response rates in most patients. 1, 2, 3

Initial Assessment and Stabilization

• Obtain urgent neurological specialist consultation within 24 hours of presentation, as patients with encephalitis require specialized care to optimize outcomes 1
• Assess airway protection and ventilatory support needs immediately in patients with declining consciousness, as rapid deterioration can occur requiring ICU-level management 1
• Monitor for seizures closely, as epilepsy (including status epilepticus) occurs in approximately 79% of pediatric cases and is a common presenting feature 3, 4

Diagnostic Workup

• Measure anti-thyroid peroxidase (aTPO) antibodies, which are elevated in all patients with Hashimoto encephalitis and are essential for diagnosis 3
• Obtain MRI of the brain within 48 hours (preferred over CT), as neuroimaging abnormalities are common and patients with imaging changes require longer recovery 1
• Perform lumbar puncture for CSF analysis with results within 24-48 hours, typically showing elevated protein without infection 2
• Order EEG to detect subclinical seizures and assess disease activity, as EEG is abnormal in >80% of encephalitis cases and can reflect ongoing inflammation even after clinical improvement 1, 5
• Check thyroid function tests, though most patients are euthyroid or have subclinical hypothyroidism 2

First-Line Treatment

• Administer high-dose intravenous methylprednisolone 1 g IV daily for at least 3-5 days as initial therapy 1, 2
• Transition to oral prednisone after initial IV course, with gradual taper over weeks to months based on clinical response 2
• Continue long-term immunomodulatory therapy in many cases, as relapsing/remitting or progressive courses are common 2

Second-Line Treatment for Steroid-Refractory Cases

• Add plasma exchange (plasmapheresis) if inadequate response to corticosteroids within 3-5 days, particularly in severe cases such as drug-resistant status epilepticus 1, 4
• Consider intravenous immunoglobulin (IVIg) when plasma exchange is difficult or contraindicated, though plasma exchange may be preferred in refractory cases 1, 3
• Rituximab (anti-CD20 monoclonal antibody) can be considered for steroid-refractory cases, especially in adolescents, though careful monitoring for immunoglobulin levels and infections is warranted due to potential side effects 6

Treatment Algorithm

1. Start with high-dose IV methylprednisolone 1 g daily for 3-5 days 1, 2
2. If inadequate response within 3-5 days, add plasma exchange 1, 4
3. For persistent refractory cases, consider rituximab with close monitoring 6
4. Maintain long-term immunosuppression with oral steroids and/or other immunomodulatory agents (azathioprine, mycophenolate) to prevent relapse 2

Common Pitfalls and Caveats

• Do not delay treatment while awaiting complete diagnostic workup, as early aggressive immunotherapy improves outcomes 1
• Monitor for "smoldering" encephalitis, where subclinical seizures and hippocampal hypermetabolism on FDG-PET can persist despite clinical improvement, requiring additional steroid therapy 5
• Avoid stopping steroids too quickly, as relapsing courses are common and many patients require prolonged immunosuppression 2
• Screen for immunosuppression-related complications when using rituximab, particularly hypogammaglobulinemia and opportunistic infections 6

Rehabilitation and Follow-Up

• Arrange comprehensive rehabilitation assessment before discharge, as neurological and psychiatric sequelae may not be immediately apparent 1
• Monitor for late sequelae in approximately 16% of pediatric patients, most commonly epilepsy, behavioral problems, and cognitive deficits 3
• Establish clear outpatient follow-up plans with ongoing therapy and rehabilitation, as 30-50% of survivors develop long-term complications 1
• Consider repeat FDG-PET and EEG to assess disease activity in patients with persistent symptoms, as these can guide additional immunotherapy 5