title: Clinical Spectrum of Stiff Person Syndrome: A Review of Recent Reports.
abstract: BACKGROUND
  "Classic" stiff person syndrome (SPS) features stiffness, anti-glutamic acid decarboxylase (anti-GAD) antibodies, and other findings. Anti-GAD antibodies are also detected in some neurological syndromes (such as ataxia) in which stiffness is inconsistently present. Patients with otherwise "classic" SPS may either lack anti-GAD antibodies or be seropositive for others. Hence, SPS cases appear to fall within a clinical spectrum that includes conditions such as progressive encephalomyelitis with rigidity and myoclonus (PERM), which exhibits brainstem and autonomic features. We have compiled herein SPS-spectrum cases reported since 2010, and have segregated them on the basis of likely disease mechanism (autoimmune, paraneoplastic, or cryptogenic) for analysis.
  
  
  METHODS
  The phrases "stiff person syndrome", "PERM", "anti-GAD antibody syndrome", and "glycine receptor antibody neurological disorders" were searched for in PubMed in January 2015. The results were narrowed to 72 citations after excluding non-English and duplicate reports. Clinical descriptions, laboratory data, management, and outcomes were categorized, tabulated, and analyzed.
  
  
  RESULTS
  Sixty-nine autoimmune, 19 paraneoplastic, and 13 cryptogenic SPS-spectrum cases were identified. SPS was the predominant diagnosis among the groups. Roughly two-thirds of autoimmune and paraneoplastic cases were female. Anti-GAD antibodies were most frequently identified, followed by anti-amphiphysin among paraneoplastic cases and by anti-glycine receptor antibodies among autoimmune cases. Benzodiazepines were the most commonly used medications. Prognosis seemed best for cryptogenic cases; malignancy worsened that of paraneoplastic cases.
  
  
  CONCLUSIONS
  Grouping SPS-spectrum cases by pathophysiology provided insights into work-up, treatment, and prognosis. Ample phenotypic and serologic variations are present within the categories. Ruling out malignancy and autoimmunity is appropriate for suspected SPS-spectrum cases.
authors.affiliation: Department of Neurology, Maimonides Medical Center, Brooklyn, NY, USA.
authors.forename: Harini
authors.initials: H
authors.lastname: Sarva
authors.affiliation: Parkinson Disease and Movement Disorders Center, Department of Neurology, University of Pennsylvania, PA, USA.
authors.forename: Andres
authors.initials: A
authors.lastname: Deik
authors.affiliation: Department of Neurology, Maimonides Medical Center, Brooklyn, NY, USA.
authors.forename: Aman
authors.initials: A
authors.lastname: Ullah
authors.affiliation: Department of Neurology, Division of Movement Disorders, Icahn School of Medicine at Mount Sinai, Mount Sinai Beth Israel Medical Center, New York, NY, USA.
authors.forename: William L
authors.initials: WL
authors.lastname: Severt
keywords: Stiff person syndrome; anti-glutamic acid decarboxylase antibodies; anti-glycine receptor antibodies; progressive encephalomyelitis with rigidity and myoclonus; stiff limb syndrome; stiff trunk syndrome