WASHINGTON, DC—Stiff person syndrome leads to disability if therapy is not initiated early in the disease course, according to a prospective study presented at the 2018 Annual Meeting of the American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM). In addition, patients with stiff person syndrome may have “faster progression of disablement than originally reported and believed,” said lead study author Goran Rakocevic, MD. Dr. Rakocevic is Associate Professor of Neurology, Director of the Neuromuscular Electrodiagnostic Laboratory, Clinical Director of the Jefferson Weinberg ALS Center, and Director of the Neuromuscular Medicine Fellowship Program at Thomas Jefferson University in Philadelphia.
Stiff person syndrome is a disorder characterized by muscle rigidity and episodic spasms in axial and limb musculature, as well as heightened sensitivity to external stimuli. To describe the natural history of stiff person syndrome, the extent of accumulated disability, and associated clinical features, Dr. Rakocevic and his research colleagues conducted a prospective cohort study in patients followed for up to eight years in a single center.
The cohort included 57 patients with mean age at disease onset of 42 (range, 22 to 60). Of these, 32 patients were examined every six months for two years without receiving immune therapies. The investigators assessed disease progression using quantitative scales of stiffness and heightened sensitivity.
Patients’ most frequent initial symptoms were leg stiffness, paraspinal muscle rigidity, and painful spasms. Although no patients required assistance for ambulation during the first two years of the disease, 46 patients (80%) lost the ability to walk independently during follow-up, despite symptomatic medications. In the longitudinal cohort, the number of stiff areas increased, which was consistent with worsening functional status and quality of life. The researchers confirmed a strong association between stiff person syndrome and the HLA-DR and DQ haplotypes.
The study is the largest prospective study of patients with stiff person syndrome and the first to provide longitudinal data on the natural course of the disorder in a large patient subgroup using objective clinical measures, Dr. Rakocevic and colleagues said. “The study shows that stiff person syndrome is a progressive autoimmune disease that leads to disability if ... immunotherapy is not applied,” said the investigators.
“Early diagnosis and management of stiff person syndrome can be challenging,” said A. Gordon Smith, MD, Cochair of the AANEM Annual Meeting Program Committee. The study by Dr. Rakocevic’s team demonstrates “that stiff person syndrome causes progressive stiffness and functional decline, with 80% [of patients] becoming unable to walk independently,” he said. “Their research emphasizes the need to treat early and will help clinicians recognize stiff person syndrome earlier in its course.”
The study adds to neurologists’ understanding of the rare disorder, and its strengths include the length of follow-up and the number of patients, said Robert W. Irwin, MD, Cochair of the AANEM Annual Meeting Program Committee.