RT Book, Section A1 Gershanik, Oscar S. A2 Watts, Ray L. A2 Standaert, David G. A2 Obeso, Jose A. SR Print(0) ID 55803743 T1 Chapter 43. Stiff-Person Syndrome T2 Movement Disorders, 3e YR 2012 FD 2012 PB The McGraw-Hill Companies PP New York, NY SN 978-0-07-161312-5 LK neurology.mhmedical.com/content.aspx?aid=55803743 RD 2024/03/28 AB The stiff-person syndrome (SPS) is a rare neurologic disorder of uncertain cause, characterized by severe and incapacitating axial and proximal limb rigidity due to continuous motor unit activity. Rigidity is often enhanced by anxiety, sudden movements, or external stimuli causing intermittent painful muscle spasms, often leading to skeletal deformity. Variants of this disorder include focal involvement of one limb (“stiff-limb syndrome”), or additional neurological symptoms suggestive of involvement of subcortical gray matter (“progressive encephalomyelitis with rigidity and myoclonus”) (PEWR) and occasionally secondary to malignant disease (paraneoplastic SPS). Antineuronal antibodies often associated with other autoimmune diseases are characteristic features of this disorder. The disease follows a progressive, unremitting course, resulting in pronounced disability, if left untreated.