Stiff-man syndrome and variants: Clinical course, treatments, and outcomes

Abstract

Background: Little information is available about the incidence of stiff-man syndrome (SMS) (the classic form or its variants) or about long-term treatment responses and outcomes. Objective: To comprehensively describe the characteristics of a cohort of patients with SMS. Design: Observational study. Setting: Mayo Clinic, Rochester, Minnesota. Patients: Ninety-nine patients with classic SMS vs variants of the disorder, both glutamic acid decarboxylase 65 kD isoform (GAD65) antibody seropositive and seronegative. Main Outcome Measures: Neurological, autoimmune, serological, and oncological findings; treatments; and outcomes between January 1984 and December 2008. Results: The median follow-up duration was 5 years (range, 0-23 years). Seventy-nine patients (59 having classic SMS, 19 having partial SMS, and 1 having progressive encephalomyelitis with rigidity and myoclonus [PERM]) were GAD65 antibody seropositive. Sixty-seven percent (53 of 79) of them had at least 1 coexisting autoimmune disease, and 4% (3 of 79) had cancer. GAD65 antibody values at initial evaluation were significantly higher among patients with classic SMS (median value, 623 nmol/L) than among patients with partial SMS (median value, 163 nmol/L) (P