A Case of Treatment Resistance and Complications in a Patient with Stiff Person Syndrome and Cerebellar Ataxia
Background: Antibodies against glutamic acid decarboxylase (GAD) are associated with Stiff Person Syndrome (SPS).
Case report: A 50-year-old woman presented with symptoms progressed over 9 years, resulting in a cerebellar ataxia and right upper limb tremor. Investigations revealed elevated serum and CSF anti-GAD antibody titres (98.6 and 53.4 μ/ml, respectively). Treatment included intravenous immunoglobulin and immunomodulation (infliximab and rituximab), improving her stiffness, but with no impact on the ataxia-related symptoms. Subsequent high-dose steroids led to diabetic ketoacidosis and unmasking of an insulin-dependent diabetes mellitus.
Discussion: This case illustrates several key features: (1) the combined clinical picture of SPS and cerebellar ataxia is a rare phenotype associated with anti-GAD antibodies; (2) the cerebellar ataxia described was progressive and poorly responsive to immunomodulatory therapy; and (3) the potential for development of further autoimmune sequelae in response to immunosuppression, namely, the development of insulin-dependent diabetes in response to treatment with high-dose oral steroids.
Keywords: Stiff Person Syndrome, GAD autoantibodies, cerebellar ataxia, movement disorder, cerebellum, autoimmune, anti-GAD, treatment
Citation: Jones LA, Baber W, Wardle M, Robertson NP, Morris HR, Church A, et al. A Case of Treatment Resistance and Complications in a Patient with Stiff Person Syndrome and Cerebellar Ataxia. Tremor Other Hyperkinet Mov. 2019: 9. doi: 10.7916/tohm.v0.677