The purpose of this research study is to investigate the effects of Transcranial Magnetic Stimulation on pain perception. TMS is a non - invasive technique that uses electromagnetic pulses to temporarily stimulate specific brain areas in awake people (without the need for surgery, anesthetic, or other invasive procedures)
To test whether rTMS over the left prefrontal cortex significantly reduces post-operative pain and PCA use following gastric-bypass surgery relative to sham and an active control, in a mood- independent manner. Note that the active control is still mentioned in the aims and hypotheses, but was apparently removed from the study design. To determine the effects of timing (one immediately following surgery and one 4 hours later) and dose of TMS (0, 1, or 2 sessions of active rTMS) on post-operative pain and PCA use; To determine the effects of TMS on post-surgical recovery time (time to discharge) and clinical outcomes at 1-month, 3- months and 6-months follow-up. Again an active control is mentioned, though this was removed from the design. It appears that this aspect of the proposal was not edited to reflect the new study design. In the new design, 108 participants received two 20 minute sessions of 10 Hz rTMS (110% of motor threshold) over the left dorsolateral prefrontal cortex (one immediately following surgery and one 4 hours later). Participants were randomly assigned to receive two sessions of real rTMS, two sessions of sham, 1 real then 1 sham, or 1 sham then 1 real rTMS treatments.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
SINGLE
Enrollment
108
Real TMS 45 minutes after surgery, first determined resting motor threshold (rMT) by starting with 40% of the machine output and 0.5 Hz stimulus frequency. The coil was positioned over the motor cortex and then adjusted until each pulse results in movement of the right thumb. The machine output was then adjusted to the lowest intensity that reliably produces thumb movement. Parameter estimation by sequential testing was used to determine the amount of machine energy necessary to visibly move the thumb 50% of the time. rMT was assessed before each rTMS treatment. The left prefrontal cortex was the cortical target for rTMS treatment. The EEG-10-20 system was used to locate the prefrontal cortex (F3).
Sham TMS 45 minutes after surgery used specifically designed rTMS coil that produces auditory signals identical to real (active) TMS coils but is shielded so that actual stimulation does not occur. The eSham system was used to mimic sensations of real rTMS. This system produces mild tingling on the scalp underneath the sham rTMS coil, making it difficult in differentiating between real and sham. The amount of electrical stimulation necessary to match real rTMS pulses was determined using an algorithm (parameter estimation by sequential testing). All subjects underwent the sham titration at the beginning of every rTMS session regardless of group assignment. The left prefrontal cortex was the cortical target for rTMS treatment, located using the EEG-10-20 system.
Institute of Psychiatry Brain Stimulation lab
Charleston, South Carolina, United States
Patient Controlled Analgesia (PCA) Hydromorphone Usage
PCA pump usage values were reported by concentration in mg/mL. Post operative PCA pump usage was tracked 0-48 hours after surgery. The PCA pump usage was downloaded from the PCA pump after discharge from the hospital and values were reported in mg/mL (concentration in mg/mL). The PCA pump data were averaged over Post-operative hours 0-48 (total PCA pump usage post-operatively) and the mean PCA pump usage was calculated and reported in mg/mL for all groups (4).
Time frame: Post-Op Hour 0 through 48
Sensory Dimension of McGill Pain Questionnaire
Participants completed the McGill Pain Questionnaire-short form (MPQ) at Check Up 1, Check Up 2, Check Up 3, and Check Up 4. Check Up 1 \& 2 occurred on Post-Op Day 1. Check Up 1 occurred immediately after surgery. Check Up 2 occurred 4 hours after Check Up 1. Check Up 3 \& 4 occurred on Post-Op Day 2, 4 hours apart. The MPQ has two pain dimensions: 1.Sensory subscale with 11 words, and 2.Affective subscale with 4 words from the original MPQ. The range of scores for the affective dimension of pain is 0-12. The range of scores for the sensory dimension of pain is 0-33. The maximum total score for the sensory dimension is 33. Higher scores are indicative of worse pain on the sensory dimension of pain.
Time frame: Check Up 1, Check Up 2, Check Up 3, and Check Up 4
Affective Dimension of McGill Pain Questionnaire
Participants completed the McGill Pain Questionnaire-short form (MPQ) at Check Up 1, Check Up 2, Check Up 3, and Check Up 4. Check Up 1 \& 2 occurred on Post-Op Day 1. Check Up 1 occurred immediately after surgery. Check Up 2 occurred 4 hours after Check Up 1. Check Up 3 \& 4 occurred on Post-Op Day 2, 4 hours apart. The MPQ has two pain dimensions: 1.Sensory subscale with 11 words, and 2.Affective subscale with 4 words from the original MPQ. The range of scores for the affective dimension of pain is 0-12. The maximum total score for the Affective dimension is 12. Higher scores are indicative of worse pain on the affective dimension of pain.
Time frame: Check Up 1, Check Up 2, Check Up 3, and Check Up 4
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Real TMS 4 hours after surgery, first determined resting motor threshold (rMT) by starting with 40% of the machine output and 0.5 Hz stimulus frequency. The coil was positioned over the motor cortex and then adjusted until each pulse results in movement of the right thumb. The machine output was then adjusted to the lowest intensity that reliably produces thumb movement. Parameter estimation by sequential testing was used to determine the amount of machine energy necessary to visibly move the thumb 50% of the time. rMT was assessed before each rTMS treatment. The left prefrontal cortex was the cortical target for rTMS treatment. The EEG-10-20 system was used to locate the prefrontal cortex (F3).
Sham TMS 4 hours after surgery used specifically designed rTMS coil that produces auditory signals identical to real (active) TMS coils but is shielded so that actual stimulation does not occur. The eSham system was used to mimic sensations of real rTMS. This system produces mild tingling on the scalp underneath the sham rTMS coil, making it difficult in differentiating between real and sham. The amount of electrical stimulation necessary to match real rTMS pulses was determined using an algorithm (parameter estimation by sequential testing). All subjects underwent the sham titration at the beginning of every rTMS session regardless of group assignment. The left prefrontal cortex was the cortical target for rTMS treatment, located using the EEG-10-20 system.
Correctly Guessed Assignment Condition at 4 Hours
Participants were asked to guess whether they received real or sham TMS after each rTMS session. The results below report the percentage or participants that correctly guessed TMS Condition after the second TMS treatment, 4 hours after surgery.
Time frame: After second TMS treatment (Check up 4)
Confidence Ratings of Guessing TMS Condition Assignment
After participants guessed their TMS condition; whether they received real or sham TMS, They were then asked to rate the confidence in their guess. Ratings were on a scale of 0-10 where 0=complete guess and 10=absolutely sure. Results below include the mean confidence ratings of those that guessed the TMS condition correctly and those that guessed incorrectly.
Time frame: After Second TMS Treatment (Check up 4)