Quantitative vibrometry and electrophysiological assessment in screening for carpal tunnel syndrome among industrial workers: a comparison.

Vibrometry has been demonstrated to be an effective adjunct to electrophysiological evaluation of nerve integrity in diffuse peripheral neuropathies but there is controversy over its value in the diagnosis of isolated compression neuropathy such as carpal tunnel syndrome (CTS). One hundred thirty factory workers were screened for peripheral nerve impairment using both vibrometry and electrophysiologic testing of digits 2 and 5 in both hands. Vibrometry had a low sensitivity in identifying individuals with symptoms of CTS or a median mononeuropathy defined by nerve conduction studies (NCS). The correlation of vibratory and the sensory evoked latencies were modest in the median nerve distribution (r = 0.297 to 0.370, p = 0.001). Using a comparison between vibration thresholds from digit 2 to 5 was not helpful in identifying cases of CTS and the difference in thresholds did not correlate with the difference in sensory evoked latencies. CTS is primarily a demyelinating process and can be easily detected with NCS. Because vibration threshold sensation is related to axonal loss it is not as sensitive in early CTS. Our results do not support the use of quantitative vibrometry as a screening tool median nerve impairment among industrial workers.