Clinical spectrum of stiff person syndrome associated with glutamic acid decarboxylase antibodies
Memon AB, Rathnam AS, Zaman I, Sripathi N. Clinical spectrum of stiff person syndrome associated with glutamic acid decarboxylase antibodies. Neurology 2020; 94(15):3.
Objective: The aim of this study was to examine the clinical characteristics and associated diagnosis of the SPS.
Background: Stiff person syndrome (SPS) is an immune-mediated neurological disorder that can cause rigidity of the axial and limb muscles. About 80% of patient with SPS have had high-titer antibodies against glutamic acid decarboxylase (GAD), and 15% have antibodies to glycine receptors.
Design/Methods: Retrospective chart review of patients with SPS and positive GAD antibody who were seen over 5 years was performed. Demographics, detailed clinical information, and diagnostic data were recorded. Coexisting autoimmune diseases and serologies were reviewed.
Results: Nine patients were included in this study, 7 women and 2 men. The median age at symptom onset was 47 years. Six patients had positive Gad antibody and 3 were negative. Primary diagnosis was stiff person syndrome (n=4), cerebellar ataxia (n=2), PERM (n=2) and sensory neuropathy/neuronopathy (n=1). Commonly associated antibodies were islet cell antibody and neuronal voltage-gated potassium channel. Type 1 diabetes, seizures, and thyroid disease were commonly associated with the diagnosis. Three patients had an EMG finding suggestive of SPS and two of these patients had negative GAD antibody.
Conclusions: Women are commonly affected by the disease. There is a phenotypic variation of the disease as previously reported in the literature. EMG is helpful in the diagnosis of negative GAD antibody patients where clinical suspicion for SPS is high.