UNEXPECTED BENEFIT OF PROPOFOL IN STIFF-PERSON SYNDROME

Stiff person syndrome (SPS) is a rare autoimmune disorder characterized by severely increased axial muscular tone with superimposed “progressive fluctuating muscular rigidity and spasms,” despite an otherwise normal neurologic examination.¹ An association with autoimmune disease was noted early on, and in 1988 high titers of autoantibodies directed against glutamic acid decarboxylase (GAD) were found in patients with SPS.² GAD catalyzes the rate-limiting step in the synthesis of gamma-aminobutyric acid (GABA), the principal inhibitory neurotransmitter of the CNS. These observations, along with the known beneficial effects of drugs that enhance GABAergic neurotransmission, underlie the current concept of SPS as an immune-mediated pathologic impairment of central inhibition. This concept is supported by various electrophysiologic studies.³ SPS has also been described as a paraneoplastic syndrome in association with several types of tumors, including breast and small cell lung cancer. Paraneoplastic SPS may be associated with anti-GAD antibodies, as well as amphiphysin 1, gephyrin, or Ri antibodies.⁴

Although the pathophysiology of non-paraneoplastic SPS is incompletely understood, effective treatments include immunomodulating therapies and drugs that enhance GABAergic neurotransmission. Unfortunately, these treatments may lose …