Table 1.
Summary of brain stimulation techniques for pain improvement targeting the motor strip.
| Techniques | Pain type (example references) |
Electrodes/
modality |
Cortical target | Feasibility at home | Non-surgical | Non-significant risk | Bilateral bipolar M1 | Bilateral excitatory M1 | ||
|---|---|---|---|---|---|---|---|---|---|---|
| Invasive | MCS | Bipolar iMC | • Thalamic pain (19) | Permanent four array electrode |
Left motor cortex; Contralateral to pain | N | N | N | N | N |
| • Deafferentation pain (20) | ||||||||||
| Bilateral symmetric | • Dysesthetic pain (21) | Bilateral motor cortex | N | N | N | N | Y | |||
| • Deafferentation pain (22) | ||||||||||
| Non-Invasive | rTMS | High-frequency rTMS | • Migraine (23–26) | Figure-of-eight coil | Left motor cortex; Right motor cortex; Motor cortex contralateral to pain |
N | Y | N | N | N |
| • Chronic facial pain (27) | ||||||||||
| • Mild traumatic brain injury related headaches (28) | ||||||||||
| • Central Neuropathic Pain (29) | ||||||||||
| • Hemichorea—pain in left shoulder (30) | ||||||||||
| • Central pain in spinal cord injury (31) | ||||||||||
| • Fibromyalgia (32, 33) | ||||||||||
| • Central and phantom limb pain (34) | ||||||||||
| • Chronic neurogenic pain (35) | ||||||||||
| Low-frequency rTMS | • Phantom limb pain (36) | Figure-of- eight coil | Left motor cortex; Motor cortex contralateral to pain | N | Y | N | N | N | ||
| • Chronic neuropathic pain (37) | ||||||||||
| • Central pain (38, 39) | ||||||||||
| • Deafferentation pain (40) | ||||||||||
| Deep rTMS | • Diabetic neuropathy (41) | Hesed (H)-coil | Lower limb region of the motor cortex | N | Y | N | Y | N | ||
| • Neuropathic pain (42) | ||||||||||
| tDCS | Conventional 1 × 1 tDCS | • Central Pain in traumatic spinal cord injury (43) | Direct current electrodes with saline-soaked sponges | Left motor cortex (M1-SO montage); Left and right motor cortex for bilateral bipolar |
Y | Y | Y | Y | N | |
| • Knee osteoarthritis (44) | ||||||||||
| • Fibromyalgia (45) | ||||||||||
| • Migraine (46, 47) | ||||||||||
| • Post-stroke chronic limb pain (48) | ||||||||||
| 4 × 1 HD-tDCS | • Fibromyalgia (49, 50) | Ag/AgCl sintered ring electrodes |
Left motor cortex | N | Y | Y | N | N | ||
| 2 × 2 HD-tDCS | • Chronic myofascial TMD pain (17) | Right motor cortex | N | Y | Y | N | N | |||
| 2 × 2 Bilateral M1 HD-tDCS* | • Migraine | 4cm × 1cm strip electrodes | Left and right motor cortex | Y | Y | Y | Y | Y | ||
| • Widespread pain such as fibromyalgia | ||||||||||
HD, high-definition; iMC, ipsilateral motor cortex; MCS, motor cortex stimulation; M1-SO, primary motor cortex and contralateral supraorbital area; rTMS, repetitive transcranial magnetic stimulation; tDCS, transcranial direct current stimulation.
*
Proposed home-based non-invasive HD-tDCS montage for bilateral M1 stimulation.