Abstract Details

Title What Features Are Most Important for the Diagnosis of Stiff Person Syndrome?

Topic Autoimmune Neurology

Presentation(s) S18 - Paraneoplastic Neurological Disorders, irAE, Stiff Person, IGLON5 (2:00 PM-2:12 PM)

Poster/Presentation
Number 006

Background SPSD are rare neuroimmunological disorders that can be difficult to diagnose due to the lack of validated diagnostic criteria and awareness of non-classical symptoms or atypical presentations.

Objective To identify key features that are critical for helping aid in the diagnosis of Stiff Person Syndrome Spectrum Disorders (SPSD) and highlight characteristics associated with misdiagnosis.

Design/Methods We conducted a retrospective review of patients seen at a large academic center from 1997 to 2021. Clinical characteristics, examination findings, and diagnostic studies were analyzed to compare patients with SPSD to those receiving alternative diagnoses (controls). Sensitivity, specificity, and diagnostic odds ratios were calculated for key clinical features. Logistic regression helped define key diagnostic features for classic SPS and SPS-plus phenotypes.

Results We included 154 classic SPS cases, 45 SPS-plus cases, and 66 controls. The most sensitive findings (>80%) for classic SPS were torso and lower extremity involvement, stress and noise as symptom triggers, paravertebral stiffness, and gait dysfunction. The most specific findings included characteristic EMG results, high GAD65 antibody titers (>1000 IU/mL via ELISA or >20 nmol/L via RIA), GAD65 positivity in cerebrospinal fluid, agoraphobia, and hyperlordosis. For SPS-plus, cerebellar and brainstem involvement were highly specific (>95%). In univariate analysis, high GAD65 antibody titers, stress as a trigger, and paravertebral stiffness were most associated with SPSD. In multivariate analysis, the presence of high-titer GAD65 antibodies was the strongest independent feature for diagnosis. Misdiagnosis was more likely with upper extremity or brainstem/cerebellar involvement.

Conclusions This study highlights important clinical and paraclinical features in SPSD that can help clinicians make accurate and timely diagnoses. Further studies are needed to validate these findings.

Authors/Disclosures
Shuvro Roy, MD (University of Washington) PRESENTER	Dr. Roy has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Amgen. Dr. Roy has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Genentech.
Yujie Wang, MD (UW Northwest)	Dr. Wang has received personal compensation in the range of $500-$4,999 for serving as a Consultant for TG Therapeutics. The institution of Dr. Wang has received research support from Genentech. The institution of Dr. Wang has received research support from uniQure. The institution of Dr. Wang has received research support from NIH/NINDS.
Yishang Huang, research data anlayst	Miss Huang has nothing to disclose.
Chen Hu (University of Pittsburgh)	Chen Hu has nothing to disclose.
Kathryn Fitzgerald, PhD (Johns Hopkins University)	The institution of Dr. Fitzgerald has received research support from NIH. The institution of Dr. Fitzgerald has received research support from National MS Society.
Scott D. Newsome, DO, FAAN (Johns Hopkins Hospital)	Dr. Newsome has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Biogen. Dr. Newsome has received personal compensation in the range of $10,000-$49,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Genentech. Dr. Newsome has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Novartis. Dr. Newsome has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Bristol Myers Squibb. Dr. Newsome has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for TG Therapeutics. The institution of Dr. Newsome has received research support from Biogen. The institution of Dr. Newsome has received research support from Genentech/Roche. The institution of Dr. Newsome has received research support from Department of Defense. The institution of Dr. Newsome has received research support from Patient Centered Outcomes Research Institute. The institution of Dr. Newsome has received research support from National MS Society. The institution of Dr. Newsome has received research support from The Stiff Person Syndrome Research Foundation. The institution of Dr. Newsome has received research support from Lundbeck. The institution of Dr. Newsome has received research support from Sanofi. Dr. Newsome has received personal compensation in the range of $10,000-$49,999 for serving as a Lead PI for Clinical Trial with Roche.

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