Oxidative stress and heat shock protein response in human paraspinal muscles during retraction.
OBJECTIVE
The need for wide dissection and forceful retraction of paraspinal muscles often required for posterolateral lumbar fusion and fixation may severely jeopardize the muscles, structurally and functionally. The underlying pathophysiology of muscle damage may involve both mechanical and ischemic mechanisms. On the other hand, the surgery-related stress may trigger certain protective responses within the insulted paraspinal muscles. This study was conducted to assess the relationship between the oxidative stress and the stress response mediated by heat shock protein 70 (HSP70) induction within paraspinal muscles being retracted.


METHODS
Multifidus muscle specimens were surgically obtained before, during, and after retraction in patients with lumbar spondylolisthesis undergoing posterolateral lumbar fusion, pedicle fixation, and laminectomy. Muscle samples were analyzed to determine HSP70 and malondialdehyde (MDA) levels. Both HSP70 expression and MDA production within multifidus muscle cells were increased significantly by retraction. Expression of HSP70 then decreased after a peak at 1.5 hours of retraction, whereas MDA levels remained elevated even after release of retractors for reperfusion of the muscles. Analysis of histopathological and immunohistochemical evidence indicated that the decline of HSP70 synthesis within muscle cells after prolonged retraction was the result of severe muscle damage.


CONCLUSIONS
Results of this study highlight the deleterious effect of intraoperative retraction on human paraspinal muscles at the cellular and molecular levels. The authors also found that intraoperative maneuvers aimed at reducing the oxidative stress within the paraspinal muscles may help to attenuate surgery-related paraspinal muscle damage.
Lu
Kang
K
Department of Neurosurgery, Chang Gung Memorial Hospital, Kaohsiung Medical Center, Kaohsiung Hsien, Taiwan. kang.lu@msa.hinet.net
Liang
Cheng-Loong
CL
Cho
Chung-Lung
CL
Chen
Han-Jung
HJ
Hsu
Huan-Chen
HC
Yiin
Shuenn-Jiun
SJ
Chern
Chi-Liang
CL
Chen
Yun-Ching
YC
Lee
Tao-Chen
TC
D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D007432:Intraoperative Period; D008159:Lumbar Vertebrae / Q000601:surgery; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology; D018384:Oxidative Stress; D013123:Spinal Fusion / Q000009:adverse effects* / Q000379:methods*; D013131:Spine; D013168:Spondylolisthesis / Q000601:surgery
D018840:HSP70 Heat-Shock Proteins; D008315:Malondialdehyde