“Classic” stiff person syndrome (SPS) features stiffness, anti-glutamic acid decarboxylase (anti-GAD) antibodies, and other findings (1,2)
- dates back to as long as 1956 where Moersch and Woltman first described the tightness of the back, abdominal, and thigh muscles in 14 patients
- is a rare neurological disorder, which is an autoimmune disorder frequently associated with the presence of serum anti-glutamic acid decarboxylase (GAD) antibody
- characterised by fluctuating muscle rigidity and spasms
- are many variants of SPS, these include the classical SPS, Stiff Leg Syndrome (SLS), paraneoplastic variant, gait ataxia, dysarthria, and abnormal eye movements
- SPS has an estimated prevalence rate of 1 per million per year and classic SPS affects women twice as many as men, almost all in the 20-60 year range (median age is 40 years) (2)
- incidence rate remains very low because the diagnosis of SPS is difficult in clinical practice, with only about 60%-80% of classic SPS cases seropositive for anti-GAD Ab (2)
- exact pathophysiology of SPS is unclear
SPS is strongly associated with other autoimmune diseases, such as (2):
- type 1 diabetes mellitus (T1DM),
- autoimmune thyroid disease (AITD),
- pernicious anemia,
- vitiligo,
- and Sjogren syndrome
Most patients have autoantibodies to glutamic acid decarboxylase.
Electromyographic (EMG) findings are supportive of continuous motor activity
Management
- seek expert advice
- aim is to improve symptoms
- agents used in this condition include GABAergic agonists, such as diazepam or other benzodiazepines, steroids, plasmapheresis, and intravenous immunoglobulin (IVIG)
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