Relationship between changes in gray matter volume in different brain regions in early postoperative period and development of chronic pain after radical mastectomy

Abstract

Objective To evaluate the relationship between the changes in gray matter volume (GMV) in different brain regions in the early postoperative period and the development of chronic pain after radical mastectomy. Methods Forty-four American Society of Anesthesiologists physical status Ⅰ or Ⅱ patients, aged 25-64 yr, scheduled for elective radical mastectomy, were divided into 3 groups according to the numeric rating scale (NRS) score within 3 months after surgery: severe chronic pain group (NRS score≥3, group SEP), slight chronic pain group (NRS score=1 or 2, group SLP) and no chronic pain group (NRS score=0, group NP). All the patients underwent whole brain MRI scan within 7 days after surgery.MRI data processing and analysis were carried out using SPM8-based VBM software package and REST 1.8 software. Results There were 17 cases in group SEP, 10 cases in group SLP and 17 cases in group NP.Compared with group NP, GMV in the right postcentral gyrus was significantly decreased, and GMV in the right superior frontal gyrus was increased in group SEP (P<0.01). Conclusion The changes in GMV in the right postcentral and superior frontal gyrus in the early postoperative period may be related to the development of chronic pain after radical mastectomy. Key words: Cerebrum; Postoperative period; Gray matter; Breast neoplasms; Pain, postoperative