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Shaped magnetic field pulses by multi-coil repetitive transcranial magnetic stimulation (rTMS) differentially modulate anterior cingulate cortex responses and pain in volunteers and fibromyalgia patients.

Tzabazis A, Aparici CM, Rowbotham MC, Schneider MB, Etkin A, Yeomans DC - Mol Pain (2013)

Bottom Line: The ability to affect activity in certain deep brain structures may however, allow for a better efficacy, safety, and tolerability.A single 30 minute session using one of 3 tested rTMS coil configurations operated at 1 Hz consistently produced robust reduction (mean 70% on NRS scale) in evoked pain in volunteers.In fibromyalgia patients, the 20 rTMS sessions also produced a significant pain inhibition (43% reduction in NRS pain over last 24 hours), but only when operated at 10 Hz.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: Repetitive transcranial magnetic stimulation (rTMS) has shown promise in the alleviation of acute and chronic pain by altering the activity of cortical areas involved in pain sensation. However, current single-coil rTMS technology only allows for effects in surface cortical structures. The ability to affect activity in certain deep brain structures may however, allow for a better efficacy, safety, and tolerability. This study used PET imaging to determine whether a novel multi-coil rTMS would allow for preferential targeting of the dorsal anterior cingulate cortex (dACC), an area always activated with pain, and to provide preliminary evidence as to whether this targeted approach would allow for efficacious, safe, and tolerable analgesia both in a volunteer/acute pain model as well as in fibromyalgia chronic pain patients.

Methods: Part 1: Different coil configurations were tested in a placebo-controlled crossover design in volunteers (N = 16). Tonic pain was induced using a capsaicin/thermal pain model and functional brain imaging was performed by means of H2(15)O positron emission tomography - computed tomography (PET/CT) scans. Differences in NRS pain ratings between TMS and sham treatment (NRS(TMS)-NRS(placebo)) which were recorded each minute during the 10 minute PET scans. Part 2: 16 fibromyalgia patients were subjected to 20 multi-coil rTMS treatments over 4 weeks and effects on standard pain scales (Brief Pain Inventory, item 5, i.e. average pain NRS over the last 24 hours) were recorded.

Results: A single 30 minute session using one of 3 tested rTMS coil configurations operated at 1 Hz consistently produced robust reduction (mean 70% on NRS scale) in evoked pain in volunteers. In fibromyalgia patients, the 20 rTMS sessions also produced a significant pain inhibition (43% reduction in NRS pain over last 24 hours), but only when operated at 10 Hz. This degree of pain control was maintained for at least 4 weeks after the final session.

Conclusion: Multi-coil rTMS may be a safe and effective treatment option for acute as well as for chronic pain, such as that accompanying fibromyalgia. Further studies are necessary to optimize configurations and settings as well as to elucidate the mechanisms that lead to the long-lasting pain control produced by these treatments.

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Representative PET scan images of one subject during noxious heat pain stimulation after sham (left side of the panel) and real (ride side of the panel) multi-coil rTMS treatment. The red arrow indicates the ACC region. After sham treatment activity in the ACC region seems to be increased by the noxious heat pain stimulus. After real multi-coil rTMS this activation was not observed.
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Figure 5: Representative PET scan images of one subject during noxious heat pain stimulation after sham (left side of the panel) and real (ride side of the panel) multi-coil rTMS treatment. The red arrow indicates the ACC region. After sham treatment activity in the ACC region seems to be increased by the noxious heat pain stimulus. After real multi-coil rTMS this activation was not observed.

Mentions: Each subject’s resting motor threshold (MT) was determined by TMS stimulation over the site of the motor cortex, with a positive response in the motor cortex indicated by the minimum power level that produced movement of the subject’s contralateral thumb. To insure subject comfort, maximal TMS power was set to be 110% of motor threshold. However, the subjects’ comfort was assessed throughout the stimulation – if, at any time the patient indicated significant discomfort from the stimulus, the power was decreased incrementally. Simultaneous stimuli produced by pulsed (1 Hz) magnetic fields generated by the four coils produced a composite field the shape of which is dependent on the placement of the four coils on the head as well as the polarity of the fields. The center of each of the coils was at least 4 cm from the center of each other coil, thereby insuring that superficial magnetic fields did not summate above the power of any one coil. The coil configurations tested, A, B and C, shown in Figure 5, were generated using mathematical modeling of the composite field generated by simultaneous activation of 4 coils. Each stimulation session was carried out for a period of 30 minutes and consisted of 1800 pulses.


Shaped magnetic field pulses by multi-coil repetitive transcranial magnetic stimulation (rTMS) differentially modulate anterior cingulate cortex responses and pain in volunteers and fibromyalgia patients.

Tzabazis A, Aparici CM, Rowbotham MC, Schneider MB, Etkin A, Yeomans DC - Mol Pain (2013)

Representative PET scan images of one subject during noxious heat pain stimulation after sham (left side of the panel) and real (ride side of the panel) multi-coil rTMS treatment. The red arrow indicates the ACC region. After sham treatment activity in the ACC region seems to be increased by the noxious heat pain stimulus. After real multi-coil rTMS this activation was not observed.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3750766&req=5

Figure 5: Representative PET scan images of one subject during noxious heat pain stimulation after sham (left side of the panel) and real (ride side of the panel) multi-coil rTMS treatment. The red arrow indicates the ACC region. After sham treatment activity in the ACC region seems to be increased by the noxious heat pain stimulus. After real multi-coil rTMS this activation was not observed.
Mentions: Each subject’s resting motor threshold (MT) was determined by TMS stimulation over the site of the motor cortex, with a positive response in the motor cortex indicated by the minimum power level that produced movement of the subject’s contralateral thumb. To insure subject comfort, maximal TMS power was set to be 110% of motor threshold. However, the subjects’ comfort was assessed throughout the stimulation – if, at any time the patient indicated significant discomfort from the stimulus, the power was decreased incrementally. Simultaneous stimuli produced by pulsed (1 Hz) magnetic fields generated by the four coils produced a composite field the shape of which is dependent on the placement of the four coils on the head as well as the polarity of the fields. The center of each of the coils was at least 4 cm from the center of each other coil, thereby insuring that superficial magnetic fields did not summate above the power of any one coil. The coil configurations tested, A, B and C, shown in Figure 5, were generated using mathematical modeling of the composite field generated by simultaneous activation of 4 coils. Each stimulation session was carried out for a period of 30 minutes and consisted of 1800 pulses.

Bottom Line: The ability to affect activity in certain deep brain structures may however, allow for a better efficacy, safety, and tolerability.A single 30 minute session using one of 3 tested rTMS coil configurations operated at 1 Hz consistently produced robust reduction (mean 70% on NRS scale) in evoked pain in volunteers.In fibromyalgia patients, the 20 rTMS sessions also produced a significant pain inhibition (43% reduction in NRS pain over last 24 hours), but only when operated at 10 Hz.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: Repetitive transcranial magnetic stimulation (rTMS) has shown promise in the alleviation of acute and chronic pain by altering the activity of cortical areas involved in pain sensation. However, current single-coil rTMS technology only allows for effects in surface cortical structures. The ability to affect activity in certain deep brain structures may however, allow for a better efficacy, safety, and tolerability. This study used PET imaging to determine whether a novel multi-coil rTMS would allow for preferential targeting of the dorsal anterior cingulate cortex (dACC), an area always activated with pain, and to provide preliminary evidence as to whether this targeted approach would allow for efficacious, safe, and tolerable analgesia both in a volunteer/acute pain model as well as in fibromyalgia chronic pain patients.

Methods: Part 1: Different coil configurations were tested in a placebo-controlled crossover design in volunteers (N = 16). Tonic pain was induced using a capsaicin/thermal pain model and functional brain imaging was performed by means of H2(15)O positron emission tomography - computed tomography (PET/CT) scans. Differences in NRS pain ratings between TMS and sham treatment (NRS(TMS)-NRS(placebo)) which were recorded each minute during the 10 minute PET scans. Part 2: 16 fibromyalgia patients were subjected to 20 multi-coil rTMS treatments over 4 weeks and effects on standard pain scales (Brief Pain Inventory, item 5, i.e. average pain NRS over the last 24 hours) were recorded.

Results: A single 30 minute session using one of 3 tested rTMS coil configurations operated at 1 Hz consistently produced robust reduction (mean 70% on NRS scale) in evoked pain in volunteers. In fibromyalgia patients, the 20 rTMS sessions also produced a significant pain inhibition (43% reduction in NRS pain over last 24 hours), but only when operated at 10 Hz. This degree of pain control was maintained for at least 4 weeks after the final session.

Conclusion: Multi-coil rTMS may be a safe and effective treatment option for acute as well as for chronic pain, such as that accompanying fibromyalgia. Further studies are necessary to optimize configurations and settings as well as to elucidate the mechanisms that lead to the long-lasting pain control produced by these treatments.

Show MeSH
Related in: MedlinePlus