Stiff person syndromes

Abstract

Stiff person syndrome is an uncommon neurological disease characterised by symmetrical muscle stiffness and spasms that often lead to skeletal deformity. Variants of this syndrome include the ‘stiff leg syndrome’ in which only one limb is involved and ‘progressive encephalomyelitis with rigidity and myoclonus’ in which we can find a variety of additional neurological symptoms and signs such as eye movement disturbances, ataxia or Babinski sign. It can also be associated with malignant disease in the ‘paraneoplastic SPS’. The condition is frequently misinterpreted as psychogenic movement disturbance, but electromyographic abnormalities and the presence of autoantibodies against glutamic acid decarboxylase (GAD) in both serum and cerebrospinal fluid help to establish the correct diagnosis. The cause of the condition is unknown, but the finding of antibodies against GAD in approximately 60 % of patients has suggested an autoimmune basis. In line with this hypothesis, immunomodulation with a methylprednisolone regimen reduces stiffness and spasms and improves other neurological symptoms in the majority of patients. Plasmapheresis or intravenous immunoglobulins can also be effective. For symptomatic treatment, the benzodiazepines are drugs of first choice.