Abstract
Background Clinical diagnosis of sensory disturbances is extremely challenging, partly because
the utility of sensory tests is questionable. Transection of C7 nerve root provides
an objective assessment model to determine the diagnostic accuracy of sensory tests.
The purpose of this study was to investigate the diagnostic accuracy of Semmes-Weinstein
Monofilaments (SWM; Sammons Preston, Bolingbrook, IL), static two-point discrimination
(s2PD), and current perception threshold (CPT) tests in patients with contralateral
C7 nerve root transfer.
Methods The contralateral index finger of patients was tested preoperatively and 6 weeks
postoperatively, including the Revised Short-Form McGill Pain Questionnaire (SF-MPQ-2),
SWM, s2PD, and CPT tests. The SF-MPQ-2 was used as a gold standard for sensory disturbances.
Results A total of 38 patients were included in the study. The likelihood probability ratio
of SWM and CPT tests generated small shifts in probability, whereas the s2PD test
did not show any capacity to detect sensory disturbances. The areas under the curves
(AUC) for SWM and CPT tests were 0.724 and 0.697, respectively. Based on different
positive test standards, the AUCs for s2PD (≥ 6 mm) and s2PD (≥ 7 mm) tests were 0.632
and 0.658, respectively. When CPT and SWM tests were combined as a measure, the AUC
increased to 0.763.
Conclusion The SWM and CPT tests show a small capacity to detect sensory disturbances, whereas
the s2PD test does not show any diagnostic capacity. To better understand sensory
disturbances, a comprehensive testing protocol including valid measures of physical
impairment and symptom-specific measurement tools should be adopted.
Keywords
sensory disturbances - contralateral C7 nerve root transfer - sensory test
