Successful treatment with rituximab in a refractory Stiffperson syndrome (SPS)

Abstract

Background: SPS is a disorder consisting of rigidity of axial muscles with painful spasms. More than 80 % of SPS patients have high titer antibodies against glutamic acid decarboxylase (GAD). The use of rituximab for the treatment of SPS is a recent therapeutical approach showing promising results. We present a case of SPS treated with rituximab, showing a good and safe response. Case: A 38-year-old female patient presented with a history of rigidity of abdominal and paravertebral muscles associated with painful spasms in lower back region, increased tonus, lumbar lordosis, frequent falls and severe functional limitation. The anti-GAD antibodies were positive in high titles. Electromyography showed continuous motor activity with normal morphology especially on paravertebral muscles. She had a partial response to baclofen and diazepam, but could not tolerate it because of somnolence, and started the treatment with rituximab. After one year, the baclofen was discontinued and the diazepam reduced. The axial stiffness and spasm frequency improved, including postural instability, without new episodes of falls. Discussion: Rituximab is a monoclonal antibody targeting the CD20 antigens on the surface of mature B lymphocytes. After binding to these antigens, it initiates a cascade of biochemical events leading to apoptosis. Its use has been approved for numerous diseases with promising results. The use of rituximab in the treatment of SPS is a recent approach and good results have been reported. Conclusion: Rituximab may be a promising option in SPS treatment. However, this is a preliminary paper showing partial results requiring long-term follow-up.