A longitudinal study of predictors of research-defined carpal tunnel syndrome in industrial workers: findings at 17 years.

In 1984, we initiated a prospective study of factors associated with research-defined carpal tunnel syndrome (CTS) in 471 industrial workers. Medical history, lifestyle factors and job tasks were assessed by questionnaire and CTS case status was based on both symptoms and electrophysiologic findings. Participants were re-examined in 1989, 1994 to 1995 and 2001 to 2002. This study reports both baseline and aggregated risk factors associated with increased risk of CTS by 2001 to 2002 for 166 participants successfully re-examined after 17 years. In analyses of baseline risk factors, fewer repetitive tasks at work, female gender and greater relative weight were associated with any occurrence of CTS during follow-up. In analyses of aggregate risk factor scores through 1994 to 1995, only greater relative weight and female gender were associated with CTS in 2001 to 2002. Although obesity and gender are consistent predictors of CTS, workplace demands appear to bear an uncertain relationship to CTS. These findings are also discussed in relation to the possible differences between research-defined CTS and medically referred CTS.

Intermediate and long-term outcomes following simple decompression of the ulnar nerve at the elbow.

INTRODUCTION: There is currently little consensus regarding the appropriate surgical approach to treatment of cubital tunnel syndrome (CubTS), and few studies have reported long-term follow-up of patients who have received surgical treatment for ulnar nerve compression at the elbow. METHOD: Seventy-four patients with a total of 102 cases of CubTS treated with simple decompression of the ulnar nerve were examined 1.0-12.4 years postoperatively. Ulnar nerve conduction studies (slowest conducting 5 cm segment of ulnar nerve motor fibers measured at the elbow) were performed both pre- and postoperatively. The primary clinical outcome was percentage relief of symptoms, divided into "excellent" outcome group or less (> or = 90% improvement or < 90% improvement). RESULTS: Ulnar nerve conduction improved pre- to postoperatively, but clinical improvement was not related to changes in velocity. Women reported greater clinical improvement than men, and weight gain in men (but not women) predicted less improvement. Relief of cubital tunnel symptoms was greatest for those arms receiving carpal tunnel release surgery simultaneous or subsequent to cubital tunnel release. DISCUSSION: Simple decompression may offer excellent intermediate and long-term relief of symptoms associated with CubTS. Although improvement in ulnar motor nerve conduction velocity occurs following treatment of CubTS, it may not be a consistent marker of perceived symptom relief. Finally, these findings suggest that less complete relief of symptoms following ulnar nerve decompression may be related to unrecognized carpal tunnel syndrome or weight gain.

Effects of an aerobic exercise program on median nerve conduction and symptoms associated with carpal tunnel syndrome.

Carpal tunnel syndrome is associated with greater body mass index and less physical activity. To determine the effect of aerobic exercise on median nerve conduction and symptoms suggestive of carpal tunnel syndrome, 30 symptomatic volunteers (30 to 64 years old) with abnormal median nerve conduction studies participated in a 10-month program of supervised aerobic exercise. Changes in percentage of body fat, body mass index, peak oxygen consumption, 14-cm median sensory latency, and hand/wrist symptoms were assessed. A decrease in 14-cm sensory median latency correlated with a decrease in percentage of body fat (R = 0.52, P = 0.004) and was predicted by an increase in peak oxygen utilization (partial R = 0.52, P = 0.005) and a decrease in body mass index (partial R = 0.47, P = 0.014). There was also a tendency for a set of symptoms sometimes associated with carpal tunnel syndrome (pain, tightness, and clumsiness) to be relieved by the exercise program. These results suggest that an aerobic exercise program can be beneficial to median nerve function and may be associated with a reduction in hand symptoms.

Neuromusculoskeletal conditions of the upper extremity: are they due to repetitive occupational trauma?

The significance of neuromusculoskeletal conditions in the workplace is the subject of much discussion among occupational medicine professionals. There are differing philosophies as to what constitutes appropriate diagnostic criteria for identification of these conditions. The traditional diagnostic model requires the presence of objective pathology. An emerging symptom-based model accepts that symptoms by themselves can constitute a diagnostic entity. The extent to which these conditions are considered to be associated with occupational activity depends greatly upon which of the two models is employed. This chapter presents an overview of each diagnostic model and a discussion of the impact each has on the prevalence of identified conditions and the manner in which the various diagnostic requirements can affect treatment, prevention, and disability rating protocols.

Natural history of median nerve sensory conduction in industry: relationship to symptoms and carpal tunnel syndrome in 558 hands over 11 years.

We evaluated the natural history of median nerve sensory conduction, hand/wrist symptoms, and carpal tunnel syndrome (CTS) in an 11-year longitudinal study of 289 workers from four industries. Twenty hands which had carpal tunnel release surgery were excluded, leaving 558 hands for the primary study group. Overall, the trend was for mean sensory latencies and prevalence of slowing to increase, the prevalence of symptoms to decrease, and the prevalence of CTS to remain unchanged. Among individual hands, nerve conduction abnormalities tended to persist (82% 11-year persistence), while symptoms fluctuated widely (13% 11-year persistence). There was a strong, direct linear correlation between initial severity of slowing and subsequent development of CTS; however, most workers who developed de novo slowing did not develop symptoms or CTS. We conclude that changes in conduction status of the median nerve occur naturally with increasing age and do not necessarily lead to symptoms and CTS.

Vitamin B6, vitamin C, and carpal tunnel syndrome. A cross-sectional study of 441 adults.

As part of an ongoing study of carpal tunnel syndrome (CTS) in industry, we measured plasma concentrations of pyridoxal 5'-phosphate (PLP, a measure of vitamin B6 status) and total ascorbate (ASC, a measure of vitamin C status) in 441 adult volunteers from six industries and a university exercise study. In the entire study group and in non-vitamin users (n = 218), there were no significant differences in mean plasma PLP or ASC concentrations between controls (neither symptoms nor slowing), subjects with symptoms only, subjects with median nerve slowing only, or subjects with CTS (symptoms + slowing). In male non-vitamin users (n = 137), there were significant inverse univariate associations between plasma PLP concentration and the prevalence of pain, the frequency of tingling and nocturnal awakening, and the Phalen test result. In this same subgroup, the ASC/PLP ratio was directly associated with the prevalence of pain and nocturnal awakening, and with the frequency of pain, tingling, and nocturnal awakening. In multivariate analyses, plasma ASC concentration predicted more median nerve slowing and confirmed CTS, and vitamin or vitamin interaction variables were independent predictors of 20 CTS-related outcomes. These multivariate relationships often occurred only after adjustment for age, gender, body mass index, serum alkaline phosphatase activity, or tobacco use. We conclude that there are significant relationships between plasma vitamin levels and both components of CTS (specific symptoms and median nerve slowing). The interaction between plasma PLP and ASC appears to be particularly important with respect to symptoms.