Comparison between nerve conduction studies and current perception threshold test in carpal tunnel syndrome.Neurophysiol Clin. 2008 Apr; 38(2):127-31.NC
AIM OF STUDY
Nerve conduction studies (NCS) only test large myelinated A(alpha) or A(beta) nerve fibers, whereas the current perception threshold (CPT) test has been suggested to evaluate a wide range of nerve fibers (A(beta), A(delta) and C). This study was undertaken to compare CPT and the standard NCS test by Bland's severity scale with the patient-based measurement of symptoms and functional status of the hand by Boston CTS questionnaire assessment.
PATIENTS AND METHODS
We performed NCS and CPT on 31 patients (mean age 54.6+/-11.7 years; 31-79 years) with clinical diagnosis of CTS. NCS severity was classified according to Bland's scale and CPT was measured at 2000, 250 and 5 Hz and severity was graded between 0 and 12. Two-tailed Spearman's correlation analysis was performed to assess correlations between Boston questionnaire score and Bland's severity scale and CPT total score.
The results showed that Bland's scale, based on NCS, had more significant correlations with symptoms (Spearman's rho=0.402, p=0.002) and function (rho=0.400, p=0.001) than CPT total scores (rho=0.200, p=0.135; rho=0.234, p=0.069). In CPT, only score measure at 2000 Hz showed a significant correlation with Boston CTS questionnaire scores (with symptom rho=0.308, p=0.020; with function rho=0.302, p=0.018), whereas those measured at 250 Hz and 5 Hz did not (p>0.05).
Though CPT may have a supplementary role in the diagnosis of CTS, NCS better reflects patients' symptoms and functions than CPT on the patient's perspective.