Phantom Limb
Conditions
Keywords
Phantom Limb, Upper Amputee, Electrodes, Implant, Pain
Brief summary
Individuals with upper-limb amputation usually have intact nerves within the residual limb, and studies have demonstrated that electrical stimulation of those nerves can produce sensations that appear to emanate from the amputated limb. In this study, investigators will examine the sensations that are produced by electrical stimulation of these nerves at the location where they exit the spinal cord. Stimulation of the spinal cord is commonly used to treat intractable back and limb pain, and the procedure includes a test phase in which electrodes are temporarily placed under the skin near the spinal cord and removed at the end of testing. Similarly, in this study, electrodes will be placed near the spinal cord in the upper back and neck, and stimulation will be applied over the course of multiple testing sessions, lasting less than 30 days. The electrodes will be removed at the last day of testing. During each testing session, electrical stimulation will be applied through the electrodes and a series of tests will be performed to determine the types of sensations produced by stimulation. In addition to producing meaningful sensations with electrical stimulation, this study will also test the effect of stimulation on phantom limb sensations and phantom limb pain.
Detailed description
The purpose of this research study is to characterize the types of sensations that can be produced by stimulating the spinal nerves in upper-limb amputees, as well as the effects of that stimulation on phantom limb pain. The study involves a medical procedure to temporarily place one to three stimulation electrodes in the space near the spinal cord. This medical procedure will be performed under local anesthesia, and will take approximately one to two hours. Afterwards, the electrodes will be connected to an external stimulator and a series of experiments will be performed to characterize the types of sensations generated by electrical stimulation of the spinal cord and spinal nerves, as well as to measure the effect of stimulation on phantom limb sensations and phantom limb pain. Over the course of less than 30 days, there will be up to 20 of these experimental sessions. At the end of the final experimental session, the stimulation electrodes will be removed by gently pulling on them. The investigators are inviting participants to consider participating in this research because they have an upper-limb amputation. Participants must be between the ages of 18 and 70 and at least one year post-amputation. Participants must be willing to travel to the University of Pittsburgh at least twice per week for 30 days. Participants cannot have any serious diseases or disorders that affect your ability to participate in this study. Women who are pregnant or plan to become pregnant during the study cannot be included. The investigators will ask females of child-bearing potential to undergo a urine pregnancy test prior to any procedures (such as MRI, x-ray, fluoroscopy) that may disrupt the healthy development of an unborn child. If participants are currently taking any medications that thin their blood, participants will not be eligible for this study. Participants will have to meet other criteria to be eligible, which will be reviewed with participants upon their consent. The investigators will screen up to 15 people and expect that up to 10 individuals will complete this study.
Interventions
DEVICEBoston Scientific Stimulator Lead
A Boston Scientific (PMA P030017) spinal cord stimulator lead will be placed in the cervical epidural space of ten upper-limb amputees and steered laterally towards the dorsal spinal roots under fluoroscopic guidance.
Sponsors
Lee Fisher, PhD
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 70 Years
Healthy volunteers
No
Inclusion criteria
* have an upper-limb amputation * must be between the ages of 18 and 70 * be at least one year post-amputation * be willing to travel to the University of Pittsburgh at least twice per week for 29 days
Exclusion criteria
* women who are pregnant or plan to become pregnant during the study * all participants cannot have any serious diseases or disorders that affect your ability to participate in this study * must not be currently taking any medications that thin your blood
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Week 4 Average Stimulus Charge for All Subjects | During days 22-28 of implant | The average stimulus (nC) required to evoke sensation during week 4 of implant duration. |
| Stimulation Thresholds to a Variety of Stimulus Parameters | 30 days | Quantify the threshold (minimum charge) stimulus required to evoke sensation and neurophysiological responses during epidural spinal nerve stimulation, and monitor changes in those percepts and responses over time. |
| Week 1 Average Stimulus Charge for All Subjects | first 7 days of implant | The average stimulus (nC) required to evoke sensation during week 1 of implant duration. |
| Week 2 Average Stimulus Charge for All Subjects | During days 7-14 of implant | The average stimulus (nC) required to evoke sensation during week 2 of implant duration. |
| Week 3 Average Stimulus Charge for All Subjects | During days 15 to 21 of implant | The average stimulus (nC) required to evoke sensation during week 3 of implant duration. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Number of Participants Who Were Able to Discern Specific Regions of the Spinal Cord That Evoked Sensations | 30 days | Evaluate the relationship between stimulation parameters and the modality and naturalness of perceived sensations. |
| Qualitative Self-report of Evoked Sensations | 30 days | Document the subjective perception of cervical epidural spinal nerve stimulation for restoration of sensation. The investigators will ask each subject to provide subjective feedback on their perceived utility of the sensory feedback provided by the device. |
| Change in Pain Ratings After Study Completion | 30 days | Participants were asked to complete the McGill pain questionnaire at baseline, and weekly throughout implant. We expected to see a decrease in the pain level due to electrical stimulation. A positive score indicates a decrease in level of pain (baseline - study end). Minimum score is 0. Maximum score is 80. The higher the number, the greater the pain. This outcome measure suntracts the baseline pain score from the final pain score. A positive score indicates a reduction in pain from baseline. |
| Success Rate During Control of Prosthetic Hand to Identify Object Size | 30 days | Investigators will test the subject's ability to use a myoelectric prosthetic hand with and without sensory feedback provided by electrical stimulation of the spinal roots. Using either a virtual prosthetic limb or an instrumented prosthesis, stimulation of the spinal roots will be modulated based on signals recorded from the limb such as pressure at the finger tips or joint angles. In both the presence and absence of stimulation, subjects will be asked to perform tasks such as manipulating blocks, opening a jar, or identifying the stiffness and size of various objects. |
| Success Rate During Control of Prosthetic Hand to Identify Object Compliance (Soft, Medium, Hard) | 30 days | Investigators tested the subject's ability to use a myoelectric prosthetic hand with and without sensory feedback provided by electrical stimulation of the spinal roots. Using either a virtual prosthetic limb or an instrumented prosthesis, stimulation of the spinal roots was modulated based on signals recorded from the limb such as pressure at the finger tips or joint angles. In both the presence and absence of stimulation, subjects were asked to perform tasks such as manipulating blocks, opening a jar, or identifying the stiffness (soft, medium, hard) and size of various objects. |
Countries
United States
Participant flow
Recruitment details
Participants were met in amputee clinics, referred by prosthetics representatives, or responded to advertisements posted at amputee support groups. The study team spoke with approximately 25 interested patients. Of these, four completed the consent process.
Pre-assignment details
Eligibility checking ruled out participants due to congenital missing limb (not amputation), taking prescription blood thinners, or unable to refrain from physical exertion during the duration of the experiment. These individuals were either excluded, or withdrew. Others declined the surgery.
Participants by arm
| Arm | Count |
|---|---|
| Boston Scientific Cord Stimulator Lead A Boston Scientific Stimulator Lead (PMA P030017) will be placed in the cervical epidural space of ten upper-limb amputees and steered laterally towards the dorsal spinal roots under fluoroscopic guidance.
Boston Scientific Stimulator Lead: A Boston Scientific (PMA P030017) spinal cord stimulator lead will be placed in the cervical epidural space of ten upper-limb amputees and steered laterally towards the dorsal spinal roots under fluoroscopic guidance. | 4 |
| Total | 4 |
Baseline characteristics
| Characteristic | Boston Scientific Cord Stimulator Lead |
|---|---|
| Age, Categorical <=18 years | 0 Participants |
| Age, Categorical >=65 years | 1 Participants |
| Age, Categorical Between 18 and 65 years | 3 Participants |
| Ethnicity (NIH/OMB) Hispanic or Latino | 0 Participants |
| Ethnicity (NIH/OMB) Not Hispanic or Latino | 4 Participants |
| Ethnicity (NIH/OMB) Unknown or Not Reported | 0 Participants |
| Participants with phantom limb pain | 3 Participants |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants |
| Race (NIH/OMB) Asian | 0 Participants |
| Race (NIH/OMB) Black or African American | 1 Participants |
| Race (NIH/OMB) More than one race | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants |
| Race (NIH/OMB) White | 3 Participants |
| Region of Enrollment United States | 4 participants |
| Sex: Female, Male Female | 3 Participants |
| Sex: Female, Male Male | 1 Participants |
Adverse events
| Event type | EG000 affected / at risk |
|---|---|
| deaths Total, all-cause mortality | 0 / 4 |
| other Total, other adverse events | 2 / 4 |
| serious Total, serious adverse events | 0 / 4 |
Outcome results
Primary
Stimulation Thresholds to a Variety of Stimulus Parameters
Quantify the threshold (minimum charge) stimulus required to evoke sensation and neurophysiological responses during epidural spinal nerve stimulation, and monitor changes in those percepts and responses over time.
Time frame: 30 days
Population: Participants implanted with stimulator leads
| Arm | Measure | Value (MEAN) |
|---|---|---|
| Boston Scientific Cord Stimulator Lead | Stimulation Thresholds to a Variety of Stimulus Parameters | 2.13 milliamps |
Primary
Week 1 Average Stimulus Charge for All Subjects
The average stimulus (nC) required to evoke sensation during week 1 of implant duration.
Time frame: first 7 days of implant
| Arm | Measure | Value (MEAN) |
|---|---|---|
| Boston Scientific Cord Stimulator Lead | Week 1 Average Stimulus Charge for All Subjects | 647 nC |
Primary
Week 2 Average Stimulus Charge for All Subjects
The average stimulus (nC) required to evoke sensation during week 2 of implant duration.
Time frame: During days 7-14 of implant
| Arm | Measure | Value (MEAN) |
|---|---|---|
| Boston Scientific Cord Stimulator Lead | Week 2 Average Stimulus Charge for All Subjects | 807 nC |
Primary
Week 3 Average Stimulus Charge for All Subjects
The average stimulus (nC) required to evoke sensation during week 3 of implant duration.
Time frame: During days 15 to 21 of implant
Population: Participant 2 had the stimulator removed before week 3. Participants 1, 3, and 4 were included in this analysis.
| Arm | Measure | Value (MEAN) |
|---|---|---|
| Boston Scientific Cord Stimulator Lead | Week 3 Average Stimulus Charge for All Subjects | 1115 nC |
Primary
Week 4 Average Stimulus Charge for All Subjects
The average stimulus (nC) required to evoke sensation during week 4 of implant duration.
Time frame: During days 22-28 of implant
Population: Participant 2 had the stimulator removed before week 3. Participants 1, 3, and 4 were included in this analysis.
| Arm | Measure | Value (MEAN) |
|---|---|---|
| Boston Scientific Cord Stimulator Lead | Week 4 Average Stimulus Charge for All Subjects | 902 nC |
Secondary
Change in Pain Ratings After Study Completion
Participants were asked to complete the McGill pain questionnaire at baseline, and weekly throughout implant. We expected to see a decrease in the pain level due to electrical stimulation. A positive score indicates a decrease in level of pain (baseline - study end). Minimum score is 0. Maximum score is 80. The higher the number, the greater the pain. This outcome measure suntracts the baseline pain score from the final pain score. A positive score indicates a reduction in pain from baseline.
Time frame: 30 days
Population: Participants were asked to complete the McGill pain questionnaire at baseline, and weekly throughout implant. We expected to see a decrease in the pain level due to electrical stimulation. A positive score indicates a decrease in level of pain (baseline - study end). Three participants reported having phantom limb pain prior to the study.
| Arm | Measure | Group | Value (MEAN) |
|---|---|---|---|
| Boston Scientific Cord Stimulator Lead | Change in Pain Ratings After Study Completion | Change in Pain Score (baseline - final) | 14.3 score on a scale |
| Boston Scientific Cord Stimulator Lead | Change in Pain Ratings After Study Completion | Baseline Pain Score | 32.3 score on a scale |
| Boston Scientific Cord Stimulator Lead | Change in Pain Ratings After Study Completion | Final Pain Score | 18 score on a scale |
Secondary
Number of Participants Who Were Able to Discern Specific Regions of the Spinal Cord That Evoked Sensations
Evaluate the relationship between stimulation parameters and the modality and naturalness of perceived sensations.
Time frame: 30 days
Population: Participants with implanted spinal cord stimulator who were able to discern specific regions of the spinal cord that evoked sensations
| Arm | Measure | Group | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|
| Boston Scientific Cord Stimulator Lead | Number of Participants Who Were Able to Discern Specific Regions of the Spinal Cord That Evoked Sensations | Felt stimulation | 4 Participants |
| Boston Scientific Cord Stimulator Lead | Number of Participants Who Were Able to Discern Specific Regions of the Spinal Cord That Evoked Sensations | Felt stim in hand | 4 Participants |
| Boston Scientific Cord Stimulator Lead | Number of Participants Who Were Able to Discern Specific Regions of the Spinal Cord That Evoked Sensations | Felt stim in elbow | 3 Participants |
| Boston Scientific Cord Stimulator Lead | Number of Participants Who Were Able to Discern Specific Regions of the Spinal Cord That Evoked Sensations | Felt stim in shoulder | 2 Participants |
| Boston Scientific Cord Stimulator Lead | Number of Participants Who Were Able to Discern Specific Regions of the Spinal Cord That Evoked Sensations | Felt stim in fingers | 4 Participants |
| Boston Scientific Cord Stimulator Lead | Number of Participants Who Were Able to Discern Specific Regions of the Spinal Cord That Evoked Sensations | C6 evoked stim | 3 Participants |
| Boston Scientific Cord Stimulator Lead | Number of Participants Who Were Able to Discern Specific Regions of the Spinal Cord That Evoked Sensations | C7 evoked stim | 3 Participants |
| Boston Scientific Cord Stimulator Lead | Number of Participants Who Were Able to Discern Specific Regions of the Spinal Cord That Evoked Sensations | C8 evoked stim | 4 Participants |
| Boston Scientific Cord Stimulator Lead | Number of Participants Who Were Able to Discern Specific Regions of the Spinal Cord That Evoked Sensations | T1 evoked stim | 4 Participants |
| Boston Scientific Cord Stimulator Lead | Number of Participants Who Were Able to Discern Specific Regions of the Spinal Cord That Evoked Sensations | T2 evoked stim | 2 Participants |
Secondary
Qualitative Self-report of Evoked Sensations
Document the subjective perception of cervical epidural spinal nerve stimulation for restoration of sensation. The investigators will ask each subject to provide subjective feedback on their perceived utility of the sensory feedback provided by the device.
Time frame: 30 days
Population: Participants implanted with spinal cord stimulator who reported sensations felt
| Arm | Measure | Group | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|
| Boston Scientific Cord Stimulator Lead | Qualitative Self-report of Evoked Sensations | Paresthetic sensation (primarily) | 1 Participants |
| Boston Scientific Cord Stimulator Lead | Qualitative Self-report of Evoked Sensations | Mixed Modality (paresthetic and naturalistic) | 2 Participants |
| Boston Scientific Cord Stimulator Lead | Qualitative Self-report of Evoked Sensations | Naturalistic (primarily) | 1 Participants |
Secondary
Success Rate During Control of Prosthetic Hand to Identify Object Compliance (Soft, Medium, Hard)
Investigators tested the subject's ability to use a myoelectric prosthetic hand with and without sensory feedback provided by electrical stimulation of the spinal roots. Using either a virtual prosthetic limb or an instrumented prosthesis, stimulation of the spinal roots was modulated based on signals recorded from the limb such as pressure at the finger tips or joint angles. In both the presence and absence of stimulation, subjects were asked to perform tasks such as manipulating blocks, opening a jar, or identifying the stiffness (soft, medium, hard) and size of various objects.
Time frame: 30 days
Population: Person with upper limb amputation for over two years. This subject had difficulty achieving reliable prosthesis control, even with simple control schemes such as parallel dual-site control. As such, a highly simplified control scheme was implemented, in which the subject was instructed to attempt a hand grasp, and when this signal crossed a manually defined threshold, the DEKA hand was commanded to close at a constant velocity of 15 degrees/second.
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Boston Scientific Cord Stimulator Lead | Success Rate During Control of Prosthetic Hand to Identify Object Compliance (Soft, Medium, Hard) | 60 percentage of success identifying compli |
Secondary
Success Rate During Control of Prosthetic Hand to Identify Object Size
Investigators will test the subject's ability to use a myoelectric prosthetic hand with and without sensory feedback provided by electrical stimulation of the spinal roots. Using either a virtual prosthetic limb or an instrumented prosthesis, stimulation of the spinal roots will be modulated based on signals recorded from the limb such as pressure at the finger tips or joint angles. In both the presence and absence of stimulation, subjects will be asked to perform tasks such as manipulating blocks, opening a jar, or identifying the stiffness and size of various objects.
Time frame: 30 days
Population: Person with upper limb amputation for over two years. This subject had a high trans-humeral amputation and did not have sufficient musculature in the residual limb to achieve reliable myoelectric control of the prosthesis. Instead, she wore a Data Glove (Fifth Dimension Technologies, 5 DT) on her contralateral, intact hand, and the grasp aperature from the Data Glove was used to proportionally control the aperture of the real and cirtual DEKA hand.
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Boston Scientific Cord Stimulator Lead | Success Rate During Control of Prosthetic Hand to Identify Object Size | 74 percentage of success identifying size |