International Delphi Survey of Clinical Practice in Stiff Person Syndrome and Related Disorders: Treatment and Monitoring

ObjectiveTo establish expert consensus and identify practice variation in treatment and monitoring approaches for stiff person syndrome (SPS) and related disorders. BackgroundInternational consensus guidance on the treatment and monitoring of SPS and related disorders is lacking, and management approaches may vary across centers, countries, and resource settings. Design/MethodsForty international experts in SPS were identified based on peer-reviewed authorship. A modified Delphi survey was designed to evaluate agreement on treatment and monitoring. Consensus was predefined as greater than 80% agreement. ResultsOf 40 invited expert clinicians, 33 (83%) from 15 countries participated. Consensus was achieved for a 2-pronged treatment approach combining symptomatic therapy and immunotherapy in SPS. Consensus was also reached for benzodiazepines as first-line symptomatic treatment; adjunctive baclofen and botulinum toxin in selected patients; avoidance of opioids; use of intravenous immunoglobulin (IVIg) as first-line acute immunotherapy and first-line maintenance immunotherapy; plasma exchange for refractory or acutely worsening disease; individualized maintenance IVIg adjustment and tapering after sustained stability; rituximab for partial or nonresponders to IVIg; immunotherapy as the cornerstone of treatment for progressive encephalomyelitis with rigidity and myoclonus (PERM) and glutamic acid decarboxylase 65 (GAD65)-associated cerebellar ataxia and epilepsy; the preferred role of rituximab in glycine receptor alpha1 antibody-associated PERM; concomitant antiseizure therapy for seizure phenotypes; consideration of anti-CD19 chimeric antigen receptor T-cell therapy (CAR-T) for selected SPS patients; monitoring using objective functional measures; psychiatric screening; and diagnostic reassessment at follow-up. Consensus was not reached after Round 1 regarding initial IVIg dose and interval strategies, the use of hematopoietic stem-cell transplantation, pregnancy-specific treatment strategies, and several adjunctive symptomatic therapies. ConclusionsThis international Delphi survey helps identify areas of expert agreement and variation in the treatment and monitoring of SPS and related disorders across diverse clinical settings. These findings, supplemented by the round 2 data, may help inform future consensus recommendations.