Misdiagnosis of Stiff Person Syndrome Spectrum Disorders: Identifying the Most Common Culprits
Shuvro Roy1, Yujie Wang2, Scott Newsome1
1Johns Hopkins University, 2UW Northwest
Objective:
To characterize common misdiagnoses in a cohort of patients with Stiff Person Syndrome Spectrum Disorders (SPSD) and identify clinical features associated with misdiagnosis.
Background:
SPSD are a group of rare, disabling neuroimmunological disorders that can take several years to diagnose, often secondary to clinicians’ lack of awareness of the associated signs and symptoms. The classic SPS phenotype is associated with insidious worsening of lower extremity stiffness/rigidity, while SPS-plus includes classic features with cerebellar and/or brainstem involvement.
Design/Methods:
The Johns Hopkins SPS center’s longitudinal observational database was used, which contains clinical characteristics of people with SPSD. Patient’s charts were also reviewed to identify prior misdiagnoses and tabulated. Similar conditions were combined into categories (e.g.,
“Cervical spondylosis” and “Myelopathy” into “Spondylotic myelopathy”). Demographic factors were evaluated via univariate analysis for association with prior misdiagnoses. Calculated odds ratios (OR) were performed for any clinical factors associated with misdiagnosis across the full cohort, and for both Classic SPS and SPS-plus phenotypes.
Results:
Of 240 patients diagnosed with SPSD, 145 (58%) had a prior misdiagnosis. The most common misdiagnoses were spondylotic myelopathy (22,16%), neuropathy (18,12%), movement disorder (12,8%), and conversion disorder (11,7%). Age, race/ethnicity, and sex were not associated with misdiagnosis. The clinical characteristics associated with misdiagnosis were upper extremity stiffness and/or spasms (OR 3.86, 95% CI 2.63-5.88), and this association was strongest for Classic SPS (OR 8.40, 95% CI 6.35-10.44). In SPS-plus patients, brainstem (OR 7.00, 95% CI 5.38-8.62) and cerebellar symptoms (OR 3.27, 95% CI 1.83-4.71) were associated with misdiagnosis.
Conclusions:
Most of our patients were found to have prior misdiagnoses. These misdiagnoses were associated with presentations involving the upper extremities and symptoms localizable to infratentorial regions. Increased awareness by clinicians of the signs and symptoms in SPSD may help prevent misdiagnoses and unnecessary procedures, and expediate initiation of treatment.