Determinants of pain in patients with carpal tunnel syndrome.

BACKGROUND: Carpal tunnel syndrome causes numbness, weakness, and atrophy. Pain without numbness is not characteristic of this disease. QUESTIONS/PURPOSES: We tested the hypothesis that among patients with carpal tunnel syndrome confirmed by electrophysiologic testing, pain catastrophizing and/or depression would be good predictors of pain intensity at the time of diagnosis, whereas nerve conduction velocity would not. PATIENTS AND METHODS: Fifty-four patients completed a measure of tendency to misinterpret pain, a measure of depressive symptoms, anxiety about pain, self-efficacy in response to pain, and a five-point Likert measure of pain intensity. One-tailed Spearman correlation was performed to find a correlation between pain and continuous variables. One-way ANOVA was performed to assess differences between categorical variables. For each group, all variables with significant correlations with pain intensity were included in a multiple linear regression analysis.
RESULTS: Sex, age, and electrophysiologic measures did not correlate with pain intensity. All measures of illness behavior correlated with pain intensity and were entered in a multiple linear regression model; only misinterpretation of nociception and depression were significantly associated and accounted for 39% of the variation in pain intensity.
CONCLUSIONS: Illness behavior (specifically depression and misinterpretation of nociception) predicts pain intensity in patients with carpal tunnel syndrome.