Comparison between nerve conduction studies and current perception threshold test in carpal tunnel syndrome

Area of Science:

• Neurology
• Neurophysiology
• Clinical Diagnostics

Background:

• Nerve conduction studies (NCS) primarily assess large myelinated nerve fibers (A(alpha), A(beta)).
• Current perception threshold (CPT) testing is proposed to evaluate a broader range of nerve fibers, including A(beta), A(delta), and C fibers.
• Carpal Tunnel Syndrome (CTS) diagnosis and severity assessment often rely on a combination of clinical evaluation and electrophysiological tests.

Purpose of the Study:

• To compare the efficacy of CPT and standard NCS using Bland's severity scale in assessing CTS.
• To correlate electrophysiological findings with patient-reported symptoms and functional status using the Boston CTS questionnaire.
• To determine which testing method better reflects the patient's perspective on CTS severity.

Main Methods:

• NCS and CPT were performed on 31 patients diagnosed with CTS.
• NCS severity was graded using Bland's scale; CPT was measured at 2000, 250, and 5 Hz.
• Spearman's correlation analysis assessed the relationship between the Boston CTS questionnaire scores and the severity scales from NCS and CPT.

Main Results:

• Bland's scale (NCS) showed significant correlations with both CTS symptoms (rho=0.402, p=0.002) and function (rho=0.400, p=0.001).
• CPT total scores did not significantly correlate with symptom or function scores (p>0.05).
• Only CPT at 2000 Hz showed significant correlation with symptom (rho=0.308, p=0.020) and function (rho=0.302, p=0.018) scores; lower frequencies (250 Hz, 5 Hz) did not.

Conclusions:

• Standard NCS, as assessed by Bland's scale, more accurately reflects patient-reported symptoms and functional status in CTS compared to CPT.
• CPT may serve as an adjunctive diagnostic tool for CTS.
• NCS provides a more relevant patient-centered assessment of CTS severity than CPT.