Laboratory for
Magnetic
Brain
Stimulation
Felipe Fregni, MD, PhD
Assistant Professor
Harvard Medical School
Neuromodulatio...
• Why neuromodulation for the
treatment of chronic pain?
• What do we know about
chronic pain?
• Chronic pain has a different
pathophysiology as compared to acute
pain syndromes
• It is associated with plastic changes...
Development of spontaneous activity in primary afferents
Increase of mechanosensitiviy
Activation of protein kinase C faci...
• In chronic pain, usually, there is no (or
little) peripheral damage, injury or
inflammation - it is a result of nervous
...
Clinical examples
• Clinical conditions of chronic pain in which
the pathophysiology is maladaptive plastic
mechanisms
- P...
How to revert
nervous system
dysfunction
associated with
chronic pain?
TENS
Melzack and
Wall - gate
theory
Spinal cord
sti...
Cortical Stimulation for the
treatment of pain
• Initial experience with invasive stimulation - epidural
stimulation of mo...
PET scan after MCS
M1 stimulation for chronic pain
Noninvasive techniques of
cortical stimulation
• Repetitive transcranial magnetic
stimulation
• Transcranial direct curren...
Transcranial magnetic stimulationTranscranial magnetic stimulation
basic principlesbasic principles
Magnetic field
TMS coi...
Transcranial Direct Current
Stimulation
tDCS model
Wagner & Fregni, 2007
Clinical studies
Initial experience - rTMS
• Cross-over study in which
60 patients with
neuropathic pain received
a single session of activ...
Khedr et al. - JNNP - 2005
Long-lasting effects
• 48 patients - post-
stroke pain and
trigeminal
neuralgia
• 20Hz rTMS of ...
rTMS for chronic visceral pain
• Initial study - site and
parameters of stimulation
(1Hz - right and left SII
(secondary s...
18 100
19 100
20 100
21 100
22 200
23 200
24 200
25 200
26 200
27 200
28 100
29 100
30 200
31 200
32 200
33 200
34 200
35 ...
2 weeks of rTMS for chronic
visceral pain
Other strategies
• rTMS for migraine - site of stimulation (left
DLPFC ) - preliminary studies with
significant reduction ...
Pooled analysis - meta-analysis
• Studies
investigating M1
stimulation for
chronic pain (rTMS
and tDCS)
• 12 studies using...
Invasive vs. noninvasive brain
stimulation
• 12 studies using non-invasive brain
stimulation and 22 for invasive brain
sti...
Find a marker for pain changes
- glutamate levels?
0
1
2
3
4
5
6
7
8
9
10
Right SII Left SII
Glutamate (mmol/l)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Before rTMS After rTMS
Glutam...
Study design
• 17 patients with spinal cord injury and refractory chronic
pain
• Randomized (1:2) to receive sham and acti...
Site of stimulation
tDCS of the primary motor cortex for the treatment of central pain due
to spinal cord injury - Fregni et al., Pain, 2006
0...
Pain_changes(VAS)
Fitted values Duration_disease
tDCS and fibromyalgia
• Extensive evidence suggests that fibromyalgia is associated with a central
nervous system dysfunct...
Methods
• Thirty-two patients (females only – mean age of 53.4 ±
8.9 years) participated in this study.
• The following as...
Results - main outcome (pain)
The type 3 test of fixed effects revealed a significant effect of time
(p<0.0001), group (p=...
Results - sleep (1)
Results - sleep (2)
Questions
• Long-lasting effect?
• Efficacy of stimulation to other, non-
sensorimotor cortical targets?
• Optimum timing ...
What we don’t know about
chronic pain?
• Individual variability - why some
individuals develop chronic pain - nature
vs. n...
Is it the perfect therapy for
chronic pain?
• Far from it…
• Effects sizes are still modest
• Adverse effects associated w...
Challenges for the future
Redesigning TMS technology
• Coils that can induce an electric current in deep areas -
e.g. cone coils
• Changing pulse co...
Methods of monitoring TMS treatment
• Neuroimaging techniques (SPECT, PET,
fMRI) - “on-line”
Bestmann et al., Neuroimage. ...
EEG-guided TMS system
EEG system to control TMS parameters Analysis of the TMS response - comparison
between motor vs. pre...
Enhancing rTMS effects
- Effects of rTMS might be due to
synaptic strengthening
(LTP/LTD).
- Baseline cortical activity wo...
Preconditioning rTMS with tDCS
Siebner et al., Journal of Neuroscience, 2004
Theta burst stimulation
Theta burst stimulation of the motor cortex produces a long-lasting and powerful effect
on motor c...
Maintenance therapy - what to do after
the induction phase?
• Recent studies showing that rTMS if applied once every
1 or ...
Brain stimulation for the
treatment of pain is not new…
• Although there are some encouraging
results, neuromodulation for chronic pain
is still a relatively unexplored field and...
ffregni@bidmc.harvard.edu
Thank you
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  1. 1. Laboratory for Magnetic Brain Stimulation Felipe Fregni, MD, PhD Assistant Professor Harvard Medical School Neuromodulation for chronic pain
  2. 2. • Why neuromodulation for the treatment of chronic pain? • What do we know about chronic pain?
  3. 3. • Chronic pain has a different pathophysiology as compared to acute pain syndromes • It is associated with plastic changes in the nervous system - leading to the phenomenon of central and peripheral sensitization
  4. 4. Development of spontaneous activity in primary afferents Increase of mechanosensitiviy Activation of protein kinase C facilitates the response to sensory neurons to capsaicin Inflammation - production of multiple mediators - bind to G-protein receptors - activation of second messengers (alterations in gene expression and receptors Primary nociceptors mostly terminate in the spinal cord - second-order neurons exhibit plasticity dependent activity - repetitive activity induces long- lasting facilitation in the output system Brain activation - SI, SII - discrimation and intensity of pain; anterior cingulate cortex, insula and frontal cortex - emotional aspects of pain
  5. 5. • In chronic pain, usually, there is no (or little) peripheral damage, injury or inflammation - it is a result of nervous system dysfunction • Chronic pain is a result of maladaptive plasticity
  6. 6. Clinical examples • Clinical conditions of chronic pain in which the pathophysiology is maladaptive plastic mechanisms - Phantom limb pain - Fybromyalgia - Pain in spinal cord injury - Pain in stroke
  7. 7. How to revert nervous system dysfunction associated with chronic pain? TENS Melzack and Wall - gate theory Spinal cord stimulation Vagal nerve stimulation? Deep Brain Stimulation Cortical stimulation - noninvasive and invasive techniques
  8. 8. Cortical Stimulation for the treatment of pain • Initial experience with invasive stimulation - epidural stimulation of motor cortex is effective to reduce chronic pain (Tsubokawa, 1993) • Animal study - the spinal cord was transected - hyperactivity in the thalamus that was decreased by motor cortex stimulation, but not sensory stimulation (Tsubokawa, 1991) • Neuroimaging study - thalamic modulation associated with M1 stimulation (Garcia-Larrea, 1999)
  9. 9. PET scan after MCS
  10. 10. M1 stimulation for chronic pain
  11. 11. Noninvasive techniques of cortical stimulation • Repetitive transcranial magnetic stimulation • Transcranial direct current stimulation
  12. 12. Transcranial magnetic stimulationTranscranial magnetic stimulation basic principlesbasic principles Magnetic field TMS coil Electric current
  13. 13. Transcranial Direct Current Stimulation
  14. 14. tDCS model Wagner & Fregni, 2007
  15. 15. Clinical studies
  16. 16. Initial experience - rTMS • Cross-over study in which 60 patients with neuropathic pain received a single session of active and sham rTMS • 10Hz (1000 pulses) rTMS of the primary motor cortex - single session Lefaucheur et al., JNNP, 2004
  17. 17. Khedr et al. - JNNP - 2005 Long-lasting effects • 48 patients - post- stroke pain and trigeminal neuralgia • 20Hz rTMS of the primary motor cortex - 5 consecutive sessions
  18. 18. rTMS for chronic visceral pain • Initial study - site and parameters of stimulation (1Hz - right and left SII (secondary somatosensory area; 20 Hz - right and left SII; sham rTMS) • Main outcome = %VAS reduction + % Medication reduction Fregni et al., Annals of Neurology, 2005 1-Hz vs. 20-Hz -100 -80 -60 -40 -20 0 20 40 60 Pain changes (%) from baseline 1-Hz 20-Hz Right vs. Left -100 -80 -60 -40 -20 0 20 40 60 1 Pain changes (%) from baseline Right Left
  19. 19. 18 100 19 100 20 100 21 100 22 200 23 200 24 200 25 200 26 200 27 200 28 100 29 100 30 200 31 200 32 200 33 200 34 200 35 200 36 200 37 200 38 200 39 200 40 200 41 200 42 200 Mean Fentanyl use (mcg) 0 50 100 150 200 250 -7 -5 -3 -1 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 Days Mean fentanyl use (mcg) Baseline L-1Hz R-1Hz R-Sham L-20Hz L-sham R-20Hz Opioid use during treatment
  20. 20. 2 weeks of rTMS for chronic visceral pain
  21. 21. Other strategies • rTMS for migraine - site of stimulation (left DLPFC ) - preliminary studies with significant reduction of migraine attacks and medication use (Brighina, 2004) • Other sites of stimulation - comparison of M1, SI, SMA and PM - pain reduction only after M1 stimulation (Hirayama, 2006) • Prediction tool for epidural stimulation (Andre-Obadia, 2006)
  22. 22. Pooled analysis - meta-analysis • Studies investigating M1 stimulation for chronic pain (rTMS and tDCS) • 12 studies using nonivasive brain stimulation risk ratio noninvasive studies .1 1 10 Combined Fregni_2006 (tdcs 2) Fregni_2006 (tdcs 1) Hirayama_2006 André-Obadia_2_2006 André-Obadia_1_2006 Khedr_2005 Pleger_2004 Lefaucheur_2004 Canavero_2002 Rollnik_2002 Lefaucheur_2_2001 Lefaucheur_1_2001 Lefaucheur_2001 Risk ratio (responders rate) - active vs. sham rTMS - 2.64, 95% C.I., 1.63 – 4.30
  23. 23. Invasive vs. noninvasive brain stimulation • 12 studies using non-invasive brain stimulation and 22 for invasive brain stimulation (open studies) • Weighted responders rate: – 72.6% (95% C.I., 67.7 – 77.4) invasive stimulation studies – 45.3% (95% C.I., 39.2 – 51.4) noninvasive stimulation studies (36.8% (95% C.I., 30.5 – 43.0) for the rTMS studies and 71.4% (95% C.I., 52.1– 90.7) for tDCS studies)
  24. 24. Find a marker for pain changes - glutamate levels?
  25. 25. 0 1 2 3 4 5 6 7 8 9 10 Right SII Left SII Glutamate (mmol/l) 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 Before rTMS After rTMS Glutamate (mmol/l)
  26. 26. Study design • 17 patients with spinal cord injury and refractory chronic pain • Randomized (1:2) to receive sham and active tDCS • Baseline evaluation (2 weeks before) • Treatment (5 days of treatment) • Follow-up evaluation (after 2 weeks of treatment)
  27. 27. Site of stimulation
  28. 28. tDCS of the primary motor cortex for the treatment of central pain due to spinal cord injury - Fregni et al., Pain, 2006 0 1 2 3 4 5 6 7 8 9 Baseline Day 1 Day 2 Day 3 Day 4 Day 5 Follow-up Mean pain scores (VAS) Active tDCS Sham tDCS * * * ** * * *
  29. 29. Pain_changes(VAS) Fitted values Duration_disease
  30. 30. tDCS and fibromyalgia • Extensive evidence suggests that fibromyalgia is associated with a central nervous system dysfunction: • Recent evidence has shown that fibromyalgia is associated with specific brain activity changes. In a recent SPECT study, patients with fibromyalgia as compared to healthy controls showed a decrease in the regional cerebral blood flow in the thalamus, caudate nucleus and pontine tegmentum (1). I • In addition it has long been demonstrated that antidepressants, such as tricyclics, improve pain in fibromyalgia (2) and recent studies suggest that centrally acting drugs such as dopaminergic drugs are effective in alleviating the symptoms of fibromyalgia as compared with placebo (3). • Finally, this disorder is extremely refractroctory to peripheral treatments such as non-steroidal anti-inflamatory drugs 31
  31. 31. Methods • Thirty-two patients (females only – mean age of 53.4 ± 8.9 years) participated in this study. • The following assessments were made: pain measurement, quality-of-life/other domains of fibromyalgia, psychiatric symptoms, cognitive and safety evaluation and adverse events. • Sleep assessment - polysomnography • Stimulation - a constant current of 2mA intensity for 20 minutes - 3 groups: • Anodal M1 • Anodal DLPFC • Sham tDCS 32
  32. 32. Results - main outcome (pain) The type 3 test of fixed effects revealed a significant effect of time (p<0.0001), group (p=0.007) and interaction term time vs. group (p<0.0001)
  33. 33. Results - sleep (1)
  34. 34. Results - sleep (2)
  35. 35. Questions • Long-lasting effect? • Efficacy of stimulation to other, non- sensorimotor cortical targets? • Optimum timing of the brain stimulation? • Brain stimulation for acute pain?
  36. 36. What we don’t know about chronic pain? • Individual variability - why some individuals develop chronic pain - nature vs. nurture • Is there specific neural circuits associated with different chronic pain syndromes - resolution of neuroimaging tools are not suficient • Is it possible to cure chronic pain
  37. 37. Is it the perfect therapy for chronic pain? • Far from it… • Effects sizes are still modest • Adverse effects associated with long-term use • Loss of efficacy • Is there a tolerability for brain stimulation?
  38. 38. Challenges for the future
  39. 39. Redesigning TMS technology • Coils that can induce an electric current in deep areas - e.g. cone coils • Changing pulse configuration - unidirectional square pulse might improve the efficacy of this method • Continuous vs. variable frequency • Modeling the electrical current
  40. 40. Methods of monitoring TMS treatment • Neuroimaging techniques (SPECT, PET, fMRI) - “on-line” Bestmann et al., Neuroimage. 2005 • “off-line” (immediate response or long- term treatments such as depression treatment) Fregni et al. Neurology. 2006 (in press) • Spectroscopy to measure metabolite changes
  41. 41. EEG-guided TMS system EEG system to control TMS parameters Analysis of the TMS response - comparison between motor vs. prefrontal cortex (Kahkonen et al., Psychopharmacology (Berl), 2005) Klimesch et al showed that stimulation at alpha +1Hz frequency induces a larger cognitive performance gain
  42. 42. Enhancing rTMS effects - Effects of rTMS might be due to synaptic strengthening (LTP/LTD). - Baseline cortical activity would be an important predictor of the subsequent effects of rTMS Iyer et al., J Neurosci. 2003
  43. 43. Preconditioning rTMS with tDCS Siebner et al., Journal of Neuroscience, 2004
  44. 44. Theta burst stimulation Theta burst stimulation of the motor cortex produces a long-lasting and powerful effect on motor cortex physiology Huang et al., Neuron, 2005
  45. 45. Maintenance therapy - what to do after the induction phase? • Recent studies showing that rTMS if applied once every 1 or 2 weeks is effective to maintain the beneficial therapeutic effects O'Reardon JP, Blumner KH, Peshek AD, Pradilla RR, Pimiento PC. Long-term maintenance therapy for major depressive disorder with rTMS.J Clin Psychiatry. 2005 Dec;66(12):1524-8. Li X, Nahas Z, Anderson B, Kozel FA, George MS. Can left prefrontal rTMS be used as a maintenance treatment for bipolardepression?Depress Anxiety. 2004;20(2):98-100. • Our experience shows that it is possible to maintain patients in remission for several years using rTMS
  46. 46. Brain stimulation for the treatment of pain is not new…
  47. 47. • Although there are some encouraging results, neuromodulation for chronic pain is still a relatively unexplored field and conclusions regarding its clinical effects at this stage are not yet possible.
  48. 48. ffregni@bidmc.harvard.edu Thank you
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