Supplementary Material for: Childhood Stiff-Person Syndrome Improved with Rituximab

Introduction: Stiff-person syndrome (SPS) is manifested by fluctuating rigidity of axial musculature with painful episodic spasms due to simultaneous co-contraction of agonist and antagonist muscles. We present a case report and video illustrating response to treatment with rituximab. Materials and Methods: Case description and video are provided. A literature search for other reports of treatment with rituximab was performed. Results: Nine cases in addition to our case were described. Substantial clinical benefit was reported in 7/9 (78%) cases. Four out of 9 (44%) cases displayed persistent anti-glutamic acid decarboxylase (GAD) antibody positivity. Conclusion: Rituximab is an important treatment strategy in SPS. The persistence of anti-GAD antibody positivity even with clinical remission remains to be elucidated.