Background
In a recent preliminary trial in 20 patients after gastric bypass surgery, 20 minutes
of repetitive transcranial magnetic stimulation (TMS) over the left prefrontal cortex
was associated with a 40% reduction in postoperative patient-controlled morphine use.
As is the case with all novel scientific findings, and especially those that might
have an impact on clinical practice, replicability is paramount. This study sought
to test this finding for replication and to more accurately estimate the effect size
of this brief intervention on postoperative morphine use and postoperative pain and
mood ratings.
Methods
Twenty participants who underwent gastric bypass surgery completed this replication
and extension study. Beck Depression Inventory and Center for Epidemiological Studies
Depression scale scores were collected befor surgery and at the time of discharge
from the hospital. Immediately after surgery, participants were randomly assigned
to receive 20 minutes of real or sham repetitive TMS (rTMS) (10 Hz, 10 seconds-ON,
20 seconds-OFF for a total of 4000 pulses). Patient-controlled morphine pump usage
was tracked throughout each participant's postoperative hospital stay. In addition,
pain and mood ratings were collected via visual analogue scales twice per day.
Results
Findings from the original postoperative TMS trial were replicated, as cumulative
morphine usage curves were significantly steeper among patients receiving sham TMS,
and participants receiving real TMS had used 35% less morphine at the time of discharge
than participants receiving sham TMS. At the time of discharge, subjects who had received
real TMS had used 42.50 mg of morphine, whereas subjects receiving sham TMS had used
an average of 64.88 mg. When the data from the original preliminary trial were combined
with the data from this replication trial, a significant difference in cumulative
morphine usage was observed between subjects receiving real and sham TMS. Overall,
participants who received real TMS used 36% less morphine and had significantly lower
ratings of postoperative pain-on-average, and pain-at-its-worst than participants
receiving sham. In addition, participants who received real TMS rated their mood-at-its-worst
as significantly better than participants receiving sham. The effect of a single 20-minute
session of TMS on postoperative pain and morphine use appears to be large (Cohen's
d = 0.70) and clinically meaningful. Lastly, cross-lag correlational analyses indicate
that improvements in mood follow improvements in pain by approximately12 hours, supporting
the notion that postoperative analgesic TMS effects are not driven by antidepressant
effects.
Conclusions
Although more research is needed to verify these observed effects independently, findings
from the original postoperative TMS trial were replicated. TMS may have the potential
to significantly improve current standards of postoperative care among gastric bypass
patients, and further studies may be warranted on other surgical populations. Future
investigations should use methodology that permits more definitive conclusions about
causal effects of TMS on postoperative pain (for example, double-blinding, sham stimulation
that is matched with real TMS with respect to scalp discomfort).
Keywords
To read this article in full you will need to make a payment
Purchase one-time access:
Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online accessOne-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:
Subscribe to Brain Stimulation: Basic, Translational, and Clinical Research in NeuromodulationAlready a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
References
- Keeping pain out of mind: the role of the dorsolateral prefrontal cortex in pain modulation.Brain. 2003; 126: 1079-1091
- Chronic back pain is associated with decreased prefrontal and thalamic gray matter density.J Neurosci. 2004; 24: 10410-10415
- Determining anatomical connectivities between cortical and brainstem pain processing regions in humans: a diffusion tensor imaging study in healthy controls.Pain. 2006; 123: 169-178
- Improvement in chronic pain with transcranial magnetic stimulation.Aust N Z J Psychiatry. 2001; 35: 252
- Repetitive transcranial magnetic stimulation of dorsolateral prefrontal cortex increases tolerance to human experimental pain.Brain Res Cogn Brain Res. 2005; 25: 153-160
- Slow-frequency rTMS reduces fibromyalgia pain.Pain Med. 2005; 7: 115-118
- Transcranial magnetic stimulation reduces pain in patients with major depression: a sham-controlled study.J Nerv Ment Dis. 2007; 195: 378-381
- New insights into the therapeutic potential of non-invasive transcranial cortical stimulation in chronic neuropathic pain.Pain. 2006; 122: 11-13
- Neuropathic pain controlled for more than a year by monthly sessions of repetitive transcranial magnetic cortical stimulation.Neurophysiol Clin. 2004; 34: 91-95
- Post-operative left prefrontal repetitive transcranial magnetic stimulation reduces patient-controlled analgesia use.Anesthesiology. 2006; 105: 1-6
- Estimating resting motor thresholds in tms research and practice: a computer simulation evaluation of best methods.J ECT. 2006; 22: 169-175
- Using SAS PROC MIXED to fit multilevel models, hierarchical models and individual growth curves.J Educ Behav Stat. 1998; 24: 323-355
- Acute left prefrontal transcranial magnetic stimulation in depressed patients is associated with immediately increased activity in prefrontal cortical as well as subcortical regions.Biol Psychiatry. 2004; 55: 882-890
- Placebo effects mediated by endogenous opioid activity on μ-opioid receptors.J Neurosci. 2005; 25: 7754-7762
- Pain catastrophizing and neural responses to pain among persons with fibromyalgia.Brain. 2004; 127: 835-843
- Motor cortex stimulation for neuropathic paub:from phenomenology to mechanisms.Neuroimage. 2007; 37: S71-S79
- Reducing pain and unpleasantness during repetitive transcranial magnetic stimulation.J ECT. 2006; 22: 259-264
Article info
Publication history
Published online: May 12, 2008
Accepted:
April 14,
2008
Received in revised form:
April 10,
2008
Received:
January 25,
2008
Footnotes
The work was supported by funding from the National Institute for Neurological Disorders and Stroke at the National Institutes of Health (NIH), Cyberonics Inc, and the Neurosciences Institute at MUSC (JJB); the National Institute for Mental Health, NIDA, and NIAAA at NIH, Jazz Pharmaceuticals, GlaxoSmithKline, and Cyberonics Inc (MSG); the National Institute for Mental Health at NIH, and Cyberonics In (ZN); and the National Institute for Mental Health at NIH and the US Department of Defense (AK).
MUSC has filed 6 patents or invention disclosures in one or more of the authors' names regarding brain imaging and stimulation.
Dr. George is a consultant for Aspect Biomedical, Argolyn, Aventis, Abbott, Bristol-Meyers Squibb, Cephos, Cyberonics, and Neuropace; however, he has no equity ownership in any device or pharmaceutical company.
Dr. Nahas is a consultant for Neuropace.
The views expressed herein are those of the authors and do not necessarily reflect the views of the National Institutes of Health or the US Department of Defense.
Identification
Copyright
© 2008 Elsevier Inc. Published by Elsevier Inc. All rights reserved.
