What is the treatment for Hashimoto encephalitis?

Treatment of Hashimoto Encephalopathy

High-dose corticosteroids are the first-line treatment for Hashimoto encephalopathy, with most patients showing rapid clinical improvement when started at 0.5-1 mg/kg/day of prednisolone or equivalent. 1

Immediate Management Approach

Start high-dose corticosteroids immediately upon clinical suspicion without waiting for antibody confirmation, as delayed treatment results in significantly poorer outcomes. 1 The British guidelines emphasize that early immune suppression for antibody-mediated encephalitis is critical for optimal recovery. 1

Diagnostic Confirmation (While Initiating Treatment)

Before or concurrent with immunosuppression, confirm the diagnosis by:

• Demonstrating elevated anti-thyroid antibodies (anti-thyroid peroxidase or anti-thyroglobulin). 1
• Excluding infectious causes of encephalitis through CSF analysis and microbiological testing. 1
• Identifying characteristic clinical features: subacute confusion, seizures, altered mental status, orofacial dyskinesia, choreoathetosis, or faciobrachial dystonic seizures. 1
• Checking for hyponatremia (present in approximately 60% of cases). 1
• MRI findings: hippocampal high signal intensity (in 60% of cases). 1
• EEG abnormalities and elevated CSF protein (non-specific but supportive). 2, 3

First-Line Treatment Protocol

Prednisolone 0.5-1 mg/kg/day orally (or equivalent corticosteroid). 1 Most patients demonstrate rapid clinical improvement within days to weeks of initiating therapy. 1, 4

Treatment Duration and Tapering

• Continue high-dose steroids until clinical response is achieved, typically showing improvement in consciousness, cognition, and seizure control. 1
• Taper gradually over 12 months to prevent relapse, as premature discontinuation is associated with symptom recurrence. 1
• Antibody levels typically normalize within 3-6 months of steroid therapy. 1

Second-Line Treatments for Steroid-Refractory Cases

If response to corticosteroids is incomplete or inadequate after initial treatment:

Intravenous Immunoglobulin (IVIg)

Administer IVIg at 0.4 g/kg/day for 5 days as an escalation therapy. 1 Do not use IVIg alone as first-line therapy without steroids, as this approach may be less effective at reducing antibody levels and achieving optimal clinical outcomes. 1

Plasmapheresis

Plasmapheresis can achieve complete remission when steroids alone are insufficient. 1, 5 This should be considered when high-dose steroids produce suboptimal clinical response. 5

Rituximab for Refractory Cases

Rituximab (anti-CD20 monoclonal antibody) can be valuable in steroid-refractory Hashimoto encephalopathy, particularly in adolescents and cases resistant to conventional immunosuppression. 6 However, careful monitoring for immunoglobulin depletion and infection risk is essential. 6

Long-Term Immunomodulatory Management

For patients requiring prolonged treatment beyond initial steroid taper:

• Consider maintenance immunomodulatory agents such as azathioprine or mycophenolate mofetil in conjunction with low-dose steroids for relapsing cases. 3
• Long-term steroid therapy combined with other immunomodulatory agents has demonstrated excellent outcomes in preventing relapses. 3

Tumor Screening Protocol

Screen all patients for underlying malignancy, particularly those with VGKC-complex or NMDA receptor antibodies. 1

• Perform CT chest/abdomen/pelvis to evaluate for thymoma or small cell lung cancer (the most common associated tumors). 1
• Pelvic ultrasound in females to screen for ovarian teratoma. 1

Critical Pitfalls to Avoid

• Do not delay steroid treatment while awaiting antibody results if clinical suspicion is high, as early intervention significantly improves outcomes. 1
• Do not use IVIg alone without steroids as first-line therapy, as this is less effective. 1
• Do not mistake Hashimoto encephalopathy for infectious encephalitis and treat only with antivirals/antibiotics, which are ineffective. 5, 2
• Do not taper steroids too rapidly (faster than 12 months), as this increases relapse risk. 1
• Do not assume all cases require immunosuppression indefinitely—some patients achieve spontaneous remission after initial treatment, though this is uncommon. 4