Mirror-image sensory dysfunction (MISD) has been described in various medical conditions, but has not been systematically characterized following major surgery.
The presence of MISD was evaluated with standardized thermal and mechanical stimuli, in a group of preoperative patients scheduled for thoracotomy (n = 14) and in patients with post-thoracotomy pain syndrome (PTPS = 14). The primary outcome was areas with sensory dysfunction evaluated by dynamic sensory mapping with metal-rollers and a brush. The test procedures were repeated after 2 weeks in PTPS-patients.
The preoperative patients all had normal sensory mapping. In all PTPS-patients sensory dysfunction on the surgical side was observed, while in 12/14 patients MISD was demonstrated. In 5/12 patients, the spatial distribution of MISD areas corresponded to the sensory dysfunction on the surgical side. The total areas of sensory dysfunction (median, [25–75% interquartile range]) were Day 1, on the surgical side 500 cm2 (289–636) and on the non-surgical side 60cm2 (0–379 [P<0.005]), and on Day 2, 355cm2 (266–697) and 81 cm2 (0–202379 [P< 0.0002]), respectively. Area of sensory dysfunction on the surgical side, respectively on the non- surgical side, did not differ significantly between Day 1 and Day 2 (P >0.5).
Mirror-image sensory dysfunction is a prevalent finding in PTPS-patients. The sensory dysfunction does not seem related to the underlying lung neoplasm per se. The study demonstrated a high day-to-day variability both in sensory dysfunction areas in the surgical side and in MISD-areas. The pathophysiological mechanisms behind MISD in chronic post-surgery pain deserve further study.
© 2012 Scandinavian Association for the Study of Pain