Median and ulnar nerve conduction studies among workers: Normative values

Abstract

To determine normative values for nerve conduction studies among workers, we selected a subset of 326 workers from 955 subjects who participated in medical surveys in the workplace. The reference cohort was composed exclusively of active workers, in contrast to the typical convenience samples. Nerve conduction measures included bilateral median and ulnar sensory amplitude and latency (onset and peak). Workers with upper extremity symptoms, medical conditions that could adversely affect peripheral nerve function, low hand temperature, or highly repetitive jobs were excluded from the “normal” cohort. Linear regression models explained between 21% and 51% of the variance in nerve function, with covariates of age, sex, hand temperature, and anthropometric factors. The most robust models were fitted for sensory amplitudes in the median and ulnar nerves for dominant and nondominant hands. The median–ulnar difference was least sensitive to adjustment, indicating it is the best measure to use if corrections are not made to account for relevant covariates. A key point was that the magnitude of variance increased with age and anthropometric factors. These findings provide strong evidence that to improve diagnostic accuracy, electrodiagnostic testing should control for relevant covariates, particularly age, sex, hand temperature, and anthropometric factors. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21:999–1005, 1998.

Prospective Comparison of the Six-Item Carpal Tunnel Symptoms Scale and Portable Nerve Conduction Testing in Measuring the Outcomes of Treatment of Carpal Tunnel Syndrome with Steroid Injection

“…In our study, the most consistent parameter was the median-ulnar difference. The median-ulnar difference acts as an internal control for differences in skin temperature and other factors and was therefore felt to be a useful measure in our portable setting [32].…”

Agreement between symptom surveys, physical examination procedures and electrodiagnostic findings for the carpal tunnel syndrome

“…Electrodiagnostic findings can also be influenced by other factors, such as obesity, age, height, finger circumference and wrist ratio (33,34). However, the use of the median minus ulnar peak latency difference, as employed in this study, has been shown to be the least sensitive measure to such covariates (35). Moreover, the results are directly applicable to epidemiologic studies of CTS among workers, with minimal, if any, spectrum bias, since the subjects were all active workers in a variety of employment settings that incorporated a broad range of job activities and potential ergonomic exposures (36).…”

Influence of age, height, gender on median and ulnar nerve conduction study

“…For this reason, proper normative data are critical for valid interpretation. [1] Physiological factors such as age, temperature, height, and gender are known to affect the NCV. It is stated that fixing absolute thresholds without adjustment for age, sex, temperature, and height may result in false positive and false negative results.…”