Towards an optimized monothermal caloric screening test: comparing stimuli and thresholds.

Objectives: Monothermal caloric testing (MCT) shows potential as a screening method in vestibular assessment; however, the optimal stimulus modality and diagnostic threshold remain unclear. This study aimed to identify, within a single investigation, the most effective stimulus type (air or water; warm or cool) and the optimal cut-off threshold (15% or 25%) for maximising the diagnostic performance of MCT.

Design: Retrospective study.

Study sample: Bithermal caloric test (BCT) results from 202 adults (103 water, 99 air) were analysed. MCT results were assessed at 15% and 25% thresholds based on sensitivity, specificity, and overall diagnostic accuracy, using BCT as the reference standard.

Results: Warm stimuli demonstrated higher sensitivity, with warm air yielding the highest value (86.7%), while cool stimuli showed greater specificity, with cool water reaching the highest specificity (78.7%) at the 25% threshold. Warm air MCT resulted in the lowest false negative rate (6%) and highest diagnostic accuracy (94%), reducing the need for BCT to 57.6% of patients. Lowering the threshold to 15% slightly improved accuracy (95.9%) but increased BCT referrals (64.6%).

Conclusions: Warm air MCT appears to be an efficient screening tool for detecting unilateral vestibular weakness, offering high diagnostic accuracy while potentially reducing the need for comprehensive BCT.