POSTOPERATIVE PAIN AND SUPERFICIAL ABDOMINAL REFLEXES AFTER POSTEROLATERAL THORACOTOMY

Background. Posterolateral thoracotomy can produce stretching of/or da mage to the intercostal nerves and their branches. To assess intercost al nerve impairment after operation, we measured the superficial abdom inal reflexes, which are mediated, at least in part, by the most infer ior intercostal nerves. Methods. Using electrophysiologic techniques, we made recordings from the left and right abdominal walls to study th e responses evoked by mechanical stimulation of the skin after operati on. In addition, we assessed postoperative pain intensity according to a numeric rating scale and recorded postoperative opioid dose. Result s. We found that the patients with complete disappearance of the super ficial abdominal reflexes experienced more severe postoperative pain t han those in whom the reflexes were maintained. Moreover, opioid treat ment was less effective in the patients with no reflexes postoperative ly. Conclusions. Our findings show a strict correlation between pain i ntensity after posterolateral thoracotomy and absence of abdominal ref lexes. We suggest that the higher pain intensity together with the abs ence of reflexes mag be due to intercostal nerve impairment, be it ana tomic or functional, and thus to a larger neuropathic component of pos toperative pain. This finding may be used as a predictor of patients w ith high analgesic requirements. (C) 1997 by The Society of Thoracic S urgeons.