Genetic and environmental influences on non-specific neck pain in early adolescence: a classical twin study.

BACKGROUND: Prevalence of neck pain has increased among adolescents. The origins of adult chronic neck pain may lie in late childhood, but for early prevention, more information is needed about its aetiology. We investigated the relative roles of genetic and environmental factors in early adolescent neck pain with a classic twin study. METHODS: Frequency of neck pain was assessed with a validated pain questionnaire in a population-based sample of nearly 1800 pairs of 11-12-year-old Finnish twins. Twin pair similarity for neck pain was quantified by polychoric correlations, and variance components were estimated with biometric structural equation modelling. RESULTS: Prevalence of neck pain reported at least once monthly was 38% and at least once weekly 16%, with no significant differences between gender and zygosity. A greater polychoric correlation in liability to neck pain was found in monozygotic (0.67) than for dizygotic pairs (0.38), suggesting strong genetic influences. Model fitting indicated that 68% (95% confidence interval 62-74) of the variation in liability to neck pain could be attributed to genetic effects, with the remainder attributed to unshared environmental effects. No evidence for sex-specific genetic effects or for sex differences in the magnitude of genetic effects was found. CONCLUSIONS: Genetic and unique environmental factors seem to play the most important roles in liability to neck pain in early adolescence. Future research should be directed to identifying pathways for genetic influences on neck pain and in exploring effectiveness of interventions that target already identified environmental risk factors.

Effectiveness of different cryotherapies on pain and disease activity in active rheumatoid arthritis. A randomised single blinded controlled trial.

OBJECTIVE: Local cryotherapy is used to relieve pain and inflammation in injuries and inflammatory conditions. Whole-body cryotherapy is an extreme method administered at -110 degrees C for 2 to 3 minutes. The aim of the study was to compare the effect of cryotherapies on pain and inflammation in patients with rheumatoid arthritis (RA). METHODS: Sixty patients with active seropositive RA were recruited in a randomised controlled single-blinded study to receive whole-body cryotherapy at -110 degrees C, whole-body cryotherapy at -60 degrees C, application of local cold air at -30 degrees C and the use of cold packs locally. In the final analysis, the last 2 groups were pooled. The patients had 2-3 cryotherapy sessions daily for one week plus conventional physiotherapy. Clinical and laboratory variables and patient's and physician's global assessments were used to assess the outcome. Disease activity was calculated by DAS. RESULTS: Pain decreased in all treatment groups, most markedly in the whole-body cryotherapy (-110 degrees C) group. DAS decreased slightly with no statistically significant differences between the groups. No serious or permanent adverse effects were detected. Six of 40 patients (15%) discontinued the whole-body cryotherapy. CONCLUSION: Pain seemed to decrease more in patients in the whole-body cryotherapy at -110 degrees C than during other cryotherapies, but there were no significant differences in the disease activity between the groups. However, cryotherapy at -110 degrees C is expensive and available only in special centres and may have minor adverse effects. Based on our results, whole-body cryotherapy at -110 degrees C is not superior to local cryotherapy commonly used in RA patients for pain relief and as an adjunct to physiotherapy.