Objective: Highlight treatment challenges in SPS patients with symptom onset above the age of 60 due to delayed diagnosis and poor tolerance or incomplete response to therapies

Background: SPS is an autoimmune disorder characterized by stiffness of the axial and limb muscles, painful spasms, hyperexcitability and very-high GAD-65 antibody titers. In other autoimmune disorders, later-onset disease has different outcomes, but there is no information  regarding late-onset SPS.

Design/Methods: Charts of 8 GAD-positive patients with symptom onset above age 60, examined, treated and followed-up by the same neurology experts, were reviewed . Clinical presentation, misdiagnoses, response and tolerance to therapies and evolving disability were examined.

Results: Median current age of all patients was 75 years with median age of symptom onset above 60.5 years and median time to diagnosis 3 years. Appropriate treatment was  delayed In all patients due to misdiagnoses; 5 patients were treated for lumbosacral radiculopathy and osteoarthritis, 2 for Parkinson’s disease and 1 with steroids for multiple sclerosis. One underwent laminectomy and detethering surgery at age 79 because symptoms were attributed to worsening spina bifida occulta. Tolerance and response to treatment were variable; 2 patients did not respond to IVIg, 2 discontinued IVIg despite early response due to comorbidities (cardiac disease, thrombosis), and one could not tolerate oral anti-spasmodics due to somnolence. Progressive clinical decline occurred rapidly in all patients; at time of diagnosis, 5 patients were using a cane or walker and 2 were wheelchair-bound. 

Conclusions: SPS with onset above age 60 or 70 is frequently misdiagnosed for other conditions commonly seen in elderly populations. Patients with late-onset SPS decline quickly to clinically severe disease because of delayed treatment and suboptimal therapeutic response due to other comorbidities and poor tolerance. Increased awareness of late-onset SPS is important for early treatment initiation to prevent faster-evolving severe disability.