Evaluation of Treatment Outcomes in Patients with Stiff Person Syndrome with Rituximab vs. Standard of Care

Stiff Person Syndrome (SPS) is a rare neurological disorder that primarily affects the ability to relax musculature. This results in affected muscle groups remaining in constant contracture, leading to painful spasms that have significant morbidity and impact the patient's quality of life. Disease prevalence is one to two persons in a million, and as a result, very few randomized controlled studies have examined the efficacy of various treatment regimens. One notable study examined intravenous immunoglobulin (IVIG) and its efficacy in the treatment of SPS. This study found that using IVIG was of significant benefit in improving stiffness in SPS. However, beyond this, immune modulating therapy is limited by lack of peer-reviewed evidence. The use of rituximab has been reported in cases of SPS that are refractory to treatment with IVIG and has had mixed outcomes. Our search of the literature involved examining case reports of patients with diagnosed SPS, who had been initially treated with the standard of care and were then placed on treatment with rituximab. Our review of the available case reports demonstrates an increase in SPS remission correlating with the frequency of dose. However, the limited number of case reports available limits conclusions related to the treatment of SPS. More studies are needed to assist in guiding therapy for SPS.