Quantitative sensory testing and human surgery: effects of analgesic management
on postoperative neuroplasticity.
Author(s): Wilder-Smith OH, Tassonyi E, Crul BJ, Arendt-Nielsen L.
Affiliation(s): The Pain Centre, Department of Anaesthesiology, University Medical Centre St.
Radboud, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
o.wildersmith@anes.umcn.nl
Publication date & source: 2003, Anesthesiology. , 98(5):1214-22
BACKGROUND: Altered central nervous system sensory processing (neuroplasticity)
is a basic mechanism underlying postoperative pain that can be made visible using
quantitative sensory testing. Using quantitative sensory testing, the authors
investigated how perioperative analgesia affects postoperative neuroplasticity
and how this relates to clinical pain measures.
METHODS: Patients undergoing back surgery received placebo, fentanyl, or
ketorolac (n = 15 per group) before isoflurane-nitrous oxide anesthesia.
Preoperatively to 5 days postoperatively, we measured thresholds to electrical
skin stimulation at the incision site, arm, and leg; pain scores; and morphine
patient-controlled analgesia consumption.
RESULTS: Decreased pain thresholds versus preoperatively were seen 5 days
postoperatively, with decreases greater for ketorolac (-63%; P = 0.00005 vs.
preoperatively) than placebo (-45%; P = 0.008 vs. preoperatively) but
nonsignificant for fentanyl (-36%; P = 0.9 vs. preoperatively). Mainly
nonnociceptive thresholds were increased up to 24 h postoperatively.
Postoperative clinical pain measures were similar across drug groups.
Postoperative pain tolerance threshold changes did not correlate with
preoperative clinical pain measures but were inversely related to preoperative
thresholds for placebo and ketorolac but not fentanyl.
CONCLUSIONS: Without analgesia, neuroplasticity after surgery was inhibitory the
first 24 h and followed at 5 days by excitation. Fentanyl efficiently preempted
this hyperalgesia, but hyperalgesia was greater with ketorolac than with placebo.
Clinical pain measures neither reflected the different effects of ketorolac and
fentanyl on postoperative neuroplasticity nor permitted prediction of
postoperative neuroplasticity. The information obtained by perioperative
quantitative sensory testing is separate from and additional to that from
clinical pain measures and may enable more mechanism-based approaches to surgical
analgesia management in the future.
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