What is the recommended steroid regimen for patients with steroid-responsive encephalopathy associated with autoimmune thyroiditis, including dosage and duration of treatment?

Steroid Regimen for Steroid-Responsive Encephalopathy Associated with Autoimmune Thyroiditis (SREAT)

Start with high-dose intravenous methylprednisolone 1 gram daily for 3-5 days, followed by oral prednisone 1 mg/kg/day (typically 60-80 mg daily), then taper gradually over at least 4-6 weeks. 1

Initial Acute Treatment

For patients with SREAT, corticosteroids are the first-line treatment and should be initiated once infection is ruled out. 1

Pulse Dosing for Severe Presentations

• Administer methylprednisolone 1 gram IV daily for 3-5 days for patients with severe symptoms, rapid progression, or significant neurological impairment 1
• This pulse dosing approach is specifically recommended for steroid-responsive conditions including SREAT 1
• Consider adding IVIG 2 g/kg over 5 days (0.4 g/kg/day) or plasmapheresis if symptoms are severe or progressing despite initial corticosteroid therapy 1

Moderate Presentations

• For moderate symptoms, start with oral prednisone 1-2 mg/kg/day (typically 60-100 mg daily for most adults) 1
• Alternatively, methylprednisolone 1-2 mg/kg/day IV can be used 1

Tapering Protocol

The taper must be gradual over at least 4-6 weeks following acute management to prevent relapse. 1

• After the initial high-dose phase (3-5 days of pulse therapy or 1-2 weeks of high-dose oral therapy), begin a slow taper 1
• The exact tapering schedule should account for clinical response—continue high doses until clear improvement is documented 1
• A typical taper might reduce by 10-20 mg every 1-2 weeks, but this must be adjusted based on symptom control 2

Maintenance and Long-Term Management

Approximately 16% of SREAT patients experience at least one relapse, necessitating vigilant monitoring. 2

Bridging Therapy

• Start bridging therapy with gradual oral prednisone taper or monthly intravenous methylprednisolone after the acute phase 1
• Some patients require maintenance immunosuppression for months to prevent relapse 2, 3

Monitoring for Relapse

• Patients who present with initial coma have higher relapse rates (26% vs 13%) and may require more aggressive long-term management 2
• Those with a relapsing course show persistent intrathecal CD4+ T-cell activation, suggesting they may need prolonged immunosuppression 3

Second-Line Options for Refractory Cases

If there is no clinical or radiological improvement 2-4 weeks after completion of combined acute therapy, consider second-line immunosuppression. 1

• Rituximab is the preferred second-line agent for antibody-mediated autoimmune encephalitis like SREAT 1
• Consider rituximab particularly in patients with persistent symptoms or frequent relapses despite adequate corticosteroid therapy 1
• Novel approaches such as tocilizumab or bortezomib may be considered in treatment-resistant cases, though evidence is limited 1

Critical Pitfalls to Avoid

Never delay corticosteroid treatment while waiting for antibody results or additional testing if SREAT is clinically suspected. 1

• The diagnosis of SREAT is primarily clinical and should be suspected in any patient with unexplained encephalopathy and elevated anti-thyroid antibodies 2, 4
• Thyroid function tests are typically normal (median TSH 2 IU/mL), so euthyroid status does not exclude the diagnosis 2
• EEG abnormalities are present in 82% of cases, most commonly showing diffuse slowing consistent with encephalopathy 2
• CSF may show elevated anti-TPO antibodies (53% of cases) but can be normal in many patients 2

Treatment Response and Prognosis

At median follow-up of 12 months, 91% of patients show complete or partial neurological response to corticosteroids. 2

• Improvement typically begins within days to weeks of initiating high-dose corticosteroids 5, 4, 6
• The hallmark response to glucocorticoids is considered the "sine qua non" for confirming the diagnosis 6
• Anti-thyroid antibody titers often remain elevated despite clinical improvement and should not guide treatment decisions 2