In a patient with Miller‑Fisher syndrome who has just completed a 5‑day course of intravenous immunoglobulin (IVIG), should corticosteroids be started?

Miller Fisher Syndrome: Corticosteroids After Completing IVIG

Corticosteroids should NOT be routinely started after completing a 5-day course of IVIG in Miller Fisher Syndrome, as steroids are not recommended for standard idiopathic Guillain-Barré syndrome and its variants. However, in specific contexts—particularly immune checkpoint inhibitor-related cases or treatment-refractory situations—a trial of corticosteroids may be reasonable. 1

Standard Management Approach

First-Line Treatment

• IVIG alone (0.4 g/kg/day for 5 days, total 2 g/kg) is the standard treatment for Miller Fisher Syndrome and typically sufficient for most patients. 1, 2
• Plasmapheresis is an equally effective alternative to IVIG, and sequential therapy (IVIG followed by plasmapheresis or vice versa) is no more effective than either treatment alone and should be avoided. 3

When Corticosteroids Are NOT Recommended

• For standard idiopathic Miller Fisher Syndrome, corticosteroids are usually not recommended as they have not demonstrated benefit in classic Guillain-Barré syndrome variants. 1
• In mechanically ventilated GBS patients, adding corticosteroids to IVIG actually worsens short-term prognosis (only 72.4% showed improvement with combination therapy vs. 97% with IVIG alone). 4
• For bedridden patients without mechanical ventilation, adding corticosteroids to IVIG showed no significant benefit over IVIG alone (89.6% vs. 86.5% improvement rates). 4

Specific Scenarios Where Corticosteroids May Be Considered

Immune Checkpoint Inhibitor-Related Cases

• In checkpoint inhibitor-related Miller Fisher Syndrome or Guillain-Barré syndrome, a trial of corticosteroids is reasonable (methylprednisolone 2-4 mg/kg/day), followed by slow taper. 1
• Pulse corticosteroid dosing (methylprednisolone 1 g/day for 5 days) may be considered for Grade 3-4 severity along with IVIG. 1
• One case report demonstrated that high-dose steroids were "perhaps more effectively" than IVIG in treating checkpoint inhibitor-induced Miller Fisher Syndrome. 5

Treatment-Refractory Cases

• If clinical deterioration occurs or symptoms fail to improve after completing IVIG, consider plasmapheresis rather than adding corticosteroids. 6
• In pediatric recurrent Miller Fisher Syndrome cases, steroids were effective in controlling clinical deterioration when IVIG failed, suggesting a potential role in this specific subgroup. 7
• For severe MFS/GBS overlap syndrome with persistent ophthalmoplegia and bulbar symptoms despite IVIG and methylprednisolone, newer agents like efgartigimod (FcRn antagonist) may be considered. 2

Clinical Decision Algorithm

Assess Disease Severity and Context

1. Grade 3-4 severity (severe weakness, dysphagia, facial weakness, respiratory compromise): Admit to ICU-capable unit, continue IVIG as planned, monitor pulmonary function frequently (NIF/VC). 1
2. Checkpoint inhibitor-related: Consider adding methylprednisolone 2-4 mg/kg/day with slow taper after IVIG completion. 1
3. Standard idiopathic Miller Fisher Syndrome: Do not add corticosteroids; observe for clinical improvement over 2-4 weeks. 1, 4

Monitor Response Post-IVIG

• Perform frequent neurochecks and pulmonary function monitoring. 1
• If no improvement or clinical deterioration occurs within 1-2 weeks post-IVIG, consider plasmapheresis rather than corticosteroids. 6
• Document improvement in ataxia, ophthalmoplegia, and areflexia—the classic Miller Fisher triad. 2

Critical Pitfalls to Avoid

• Do not routinely add corticosteroids "just in case"—this approach is not evidence-based and may worsen outcomes in mechanically ventilated patients. 4
• Do not use sequential IVIG followed by plasmapheresis—this combination is no more effective than either alone. 3
• Avoid medications that can worsen neuromuscular transmission (β-blockers, IV magnesium, fluoroquinolones, aminoglycosides, macrolides). 3
• Do not use IVIG for chronic maintenance therapy in Miller Fisher Syndrome, as it is typically a monophasic disorder. 3