Operant Conditioning of Sensory Brain Responses to Reduce Phantom Limb Pain in People With Limb Amputation

Operant Conditioning of Sensory Evoked Potentials to Reduce Phantom Limb Pain

The study will investigate the application of a non-pharmacological operant conditioning approach to reduce phantom limb pain (PLP). PLP afflicts 60-90% people who have lost a limb. It can last for years and lead to drug dependence, job loss, and poor quality of life. Current non-pharmacological interventions are encouraging but limited, and their efficacy remains unclear. Limb amputation is known to lead to abnormal sensorimotor reorganization in the brain. Multiple studies have shown that PLP severity is correlated with the extent of this reorganization. The current study will train participants via realtime feedback of brain responses to promote more normal sensorimotor response, with the goal to reduce phantom limb pain.

The study will be recruiting people who have had a limb amputation (traumatic or atraumatic) and are experiencing chronic phantom limb pain (PLP). Participants will be asked to be seated during the study session. Non-painful peripheral stimulation will be applied to elicit an evoked response (from either muscle or brain). Electrodes will be placed on the muscles and or scalp to record these electrical brain responses during the study session. Visual feedback based on the response will be provided in pseudo realtime. The study will involve three 1-hour sessions per week for 8-9 weeks, followed by 2 follow-up sessions at 3 and 6 months after the last session. Assessments of pain intensity and quality, and neurophysiological sensorimotor response, will be performed before the first session, after the last session, and at follow-up sessions. Additional electroencephalography (EEG) based assessments will also be performed as exploratory measures, to assess inter- and intra- hemispheric functional connectivity and sensorimotor responses associated with amputation and operant conditioning training.

Inclusion Criteria:

• An upper (or lower limb) amputation more than 6 months ago, that has produced a moderate to severe hand/arm (or foot/leg) phantom limb pain,
• Male or female age 18 years or older,
• Medical clearance to participate,
• Reasonable expectation that ongoing medications, if any, will be maintained without change for at least 4 months from the start of the study,
• Able to provide informed consent and to understand the study instructions,
• Able to participate in the specific study procedures.

Exclusion Criteria:

• Presence of other medically unstable and/or infectious condition (e.g., uncontrolled diabetes with recent weight loss, diabetic coma, frequent insulin reactions),
• A cardiac condition (e.g., history of myocardial infarction or congestive heart failure),
• Cognitive and/or attention difficulties affecting participant's ability to follow study directions,
• Known skin disorders or damaged skin at the anticipated at the scalp for EEG recording (e.g., unhealed wounds, broken skin).
• Metal implants above the chest