Cerebellar Ataxia as the Initial Presentation in Glutamic Acid Decarboxylase Antibody-positive Stiff Person Syndrome: A Case Series
Jose Santos1, Carlos Santos2, Saad Umar3, Aileen Antonio1, Melanie Taylor1
1Trinity Health Saint Mary's Hauenstein Neurosciences, 2Biomedical Engineering, Wayne State University, 3Ross School of Business, University of Michigan
Objective:
A retrospective case series of 3 patients with highly positive antibodies against Glutamic Acid Decarboxylase (GAD) initially presenting with cerebellar ataxia then subsequently developing stiff person syndrome (SPS)
Background:
Elevated GAD antibody levels could present itself in a variety of neurologic conditions including Stiff Person Syndrome (SPS) and cerebellar ataxia. Although intravenous immunoglobulin (IVIG) is the most widely used and preferred treatment for SPS, plasmapheresis (PLEX) and other immunotherapies were used instead.
Design/Methods:
Retrospective case series
Results:
All 3 patients initially presented with dizziness and binocular diplopia. Neuro-ophthalmologic evaluations were remarkable for downbeat nystagmus without findings of body stiffness. Though IVIG was the primary treatment choice for all three, PLEX was done instead because of religious beliefs (Jehovah’s Witness) for the first case and insurance denial for the two other cases. Subsequent to their initial treatment, all three cases were maintained on immune therapy: mycophenolate for the first and second cases, and rituximab for the third case. The second patient had to eventually discontinue mycophenolate due to side effects, and only when she developed SPS was weekly PLEX started. Despite immune therapies, all three patients developed SPS within about 9 years, 3 years, and 4 months, respectively from the time they initially presented with cerebellar ataxia.
Conclusions:
Though IVIG is a recognized treatment for SPS associated with GAD antibody, PLEX and other immunotherapies were used instead for GAD antibody-positive cerebellar ataxia. It is unknown whether treatment with IVIG for these patients would have made a difference -- prevented the progression to SPS, or improved their cerebellar ataxia. Though plasmapheresis and immunosuppressants seem to have resulted in some subjective improvement and prevention of worsening of cerebellar ataxia symptoms, it would seem that it is not an effective enough treatment to prevent progression to SPS.
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