Objective:

To evaluate the sensitivity and specificity of clinical and paraclinical features of stiff person syndrome spectrum disorders (SPSD) to help aid in their diagnosis.

Background:

SPSD are a group of rare, disabling neuroimmunological disorders. SPSD is often challenging to diagnose since it can be insidious in nature and hallmark symptoms and signs are not readily identified by clinicians. Moreover, there is limited data on which clinical feature(s) and diagnostic test(s) are most helpful in making a diagnosis of SPSD.

Design/Methods:

The Johns Hopkins SPS center’s longitudinal observational database was used, which contains clinical characteristics, and diagnostic studies of people with SPSD. Patients with a diagnosis of either Classic SPS or SPS-plus phenotypes were compared to patients who were evaluated for SPSD but received an alternative diagnosis (control group). Each clinical and paraclinical feature important for a diagnosis of SPSD was evaluated for its sensitivity and specificity, and used to define its diagnostic odds ratio.

Results:

A total of 161 Classic SPS cases, 45 SPS-plus cases, and 66 controls were included. The most sensitive findings for classic SPS included clinical involvement of the lower extremities (98.1%), stress as a trigger for physical symptoms (96.8%), paravertebral stiffness/tightness (95.7%), and abnormal gait (91.4%). The most specific findings for SPS included characteristic EMG findings (98.3%), a high GAD65 antibody titer defined as >1000IU/mL and/or >20nmol/L (98.2%), and the presence of hyperlordosis on examination (87.1%). For SPS-plus, cerebellar and brainstem involvement were also highly specific (98.5% and 100%, respectively) as were the aforementioned paraclinical tests. Analyses are ongoing to assess whether major and minor criterion can be developed for a more accurate diagnosis leveraging the above data.

Conclusions: