Distal upper extremity neuropathy was prevalent among 13 percent of engineers who perform computer activities at least 15 hours per week in a cross-sectional study by Conlon and Rempel. An increased risk of neuropathy was associated with number of computer use hours per week (with a threshold effect occurring above 28 hours), body mass index, and the use of blood pressure medication. A break time of 20 minutes per day was seen as protective.
202 engineers completed two surveys: a work-health questionnaire that gathered computer activity and recent symptom information and a personal questionnaire that obtained demographic and health condition/personal risk factor data. The subjects underwent electronic bilateral median and ulnar nerve function testing to determine distal motor latency. Control was applied for medical conditions associated with peripheral neuropathies. Subjects were classified as having a neuropathy if they reported regional discomfort in the distal upper extremity and an abnormal distal motor latency.
Prevalence of right median, left median, right ulnar, and left ulnar neuropathy was 10.3, 3.4, 1.8, and 2.9 percent respectively. Right distal upper extremity discomfort (discomfort of greater than 1 on a scale of 0 to 10) was reported by 57.2 percent of the subjects while 46.2 percent described left distal upper extremity discomfort.
Increased driving time was associated with a decreased risk of neuropathy which was difficult for the authors to explain other than stating those with hand complaints may drive less to avoid symptoms. Faster typing speed was also associated with a decreased risk of neuropathy. It was felt that those with symptoms would likely have a decreased estimate of typing speed.
Of the 441 eligible subjects, only 202 (47 percent) volunteered for the study. The authors described a potential selection bias – a survey of all eligible subjects disclosed that those who participated had an increased prevalence of upper extremity symptoms compared to those who did not participate. According to Conlon and Rempel, this would increase the study prevalence rate but likely not effect identified risk factors.
Article Title: Upper Extremity Mononeuropathy Among Engineers
Publication: Journal of Occupational and Environmental Medicine 47: 1276-1284, 2005
Authors: C F Conlon and D M Rempel
This article originally appeared in The Ergonomics Report™ on 2006-03-08.