Effective Diagnostic Screening Tests for Carpal Tunnel Syndrome
Continuous numbness and tingling of fingers is a sign of carpal tunnel syndrome.
In patients with carpal tunnel syndrome (CTS), the best sensitivity for a case definition of the disorder is a history of nocturnal awakenings with paresthesia in median nerve-served digits, and the specificity of continuous tingling/numbness is high, at 97.5%, according to the results of a cross-sectional analysis from a prospective cohort study. Findings from the analysis were published in the Journal of the American Academy of Orthopaedic Surgeons.
The investigators evaluated a cross-section of working adults, using standardized assessment of signs and symptoms of CTS, combined with nerve conduction velocity testing, to explore the relationship between symptoms and electrocardiographic abnormalities. The following 2 hypotheses were proposed: What is the prevalence of paresthesias and CTS in a large, multistate population? How do signs and symptoms used to diagnose CTS differ among those in 4 groups of patients (ie, patients with and without symptoms and patients with and without nerve conduction study abnormalities)?
Baseline analyses from a large, prospective cohort study conducted in Utah and Wisconsin were reported to evaluate the relative value of symptoms, the Phalen sign, the Hoffman-Tinel sign, and electrophysiologic studies in the assessment of CTS. The prevalence of symptoms, findings from physical examinations, and electrophysiologic abnormalities was also reported.
A total of 1194 patients participated in the analysis. Mean patient age was 42.2±11.4 years, and mean body mass index was 29.5±7.0 kg/m2. Specificity, sensitivity, and positive and negative predictive values (NPVs) were calculated. The prevalence of CTS was 8.9% according to a definition of tingling/numbness in ≥2 median nerve-served digits. The following findings were reported with respect to sensitivity: paresthesias with nocturnal awakening: 77.4%; the Phalen sign: 52.8%; and the Hoffman-Tinel sign: 37.7%.
In this study, the highest specificity (97.5%) was for continuous tingling/numbness. The Phalen sign had an NPV of 95%, which suggests that as a diagnostic tool, the use of NPVs is of particular diagnostic value. The Hoffman-Tinel sign had an NPV of 93.7%. The prevalence of right-hand median nerve conduction abnormalities was reported in 189 (15.8%) of 1194 participants.
Researchers noted that using positive results from either the Phalen or the Hoffman-Tinel sign over the median nerve at the wrist to verify the presence of CTS has the significant potential to be unreliable. Oftentimes, clinicians should ignore patient-reported positive findings because of their potential to be misleading.
Hegmann KT, Merryweather A, Thiese MS, et al. Median nerve symptoms, signs, and electrodiagnostic abnormalities among working adults. J Am Acad Orthop Surg. 2018;26:576-584.