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Journal of Neural Engineering Jun 2024. We intend to chronically restore somatosensation and provide high-fidelity myoelectric control for those with limb loss via a novel, distributed, high-channel-count,...
. We intend to chronically restore somatosensation and provide high-fidelity myoelectric control for those with limb loss via a novel, distributed, high-channel-count, implanted system.We have developed the implanted Somatosensory Electrical Neurostimulation and Sensing (iSens®) system to support peripheral nerve stimulation through up to 64, 96, or 128 electrode contacts with myoelectric recording from 16, 8, or 0 bipolar sites, respectively. The rechargeable central device has Bluetooth® wireless telemetry to communicate to external devices and wired connections for up to four implanted satellite stimulation or recording devices. We characterized the stimulation, recording, battery runtime, and wireless performance and completed safety testing to support its use in human trials.The stimulator operates as expected across a range of parameters and can schedule multiple asynchronous, interleaved pulse trains subject to total charge delivery limits. Recorded signals in saline show negligible stimulus artifact when 10 cm from a 1 mA stimulating source. The wireless telemetry range exceeds 1 m (direction and orientation dependent) in a saline torso phantom. The bandwidth supports 100 Hz bidirectional update rates of stimulation commands and data features or streaming select full bandwidth myoelectric signals. Preliminary first-in-human data validates the bench testing result.We developed, tested, and clinically implemented an advanced, modular, fully implanted peripheral stimulation and sensing system for somatosensory restoration and myoelectric control. The modularity in electrode type and number, including distributed sensing and stimulation, supports a wide variety of applications; iSens® is a flexible platform to bring peripheral neuromodulation applications to clinical reality. ClinicalTrials.gov ID NCT04430218.
Topics: Humans; Electromyography; Electrodes, Implanted; Wireless Technology; Telemetry; Equipment Design; Muscle, Skeletal
PubMed: 38861967
DOI: 10.1088/1741-2552/ad56c9 -
Journal of Pain Research 2024This multicenter, randomized, double-blinded, active sham-controlled pivotal study was designed to assess the efficacy and safety of high-frequency nerve block treatment... (Clinical Trial)
Clinical Trial
Primary 3-Month Outcomes of a Double-Blind Randomized Prospective Study (The QUEST Study) Assessing Effectiveness and Safety of Novel High-Frequency Electric Nerve Block System for Treatment of Post-Amputation Pain.
PURPOSE
This multicenter, randomized, double-blinded, active sham-controlled pivotal study was designed to assess the efficacy and safety of high-frequency nerve block treatment for chronic post-amputation and phantom limb pain.
PATIENTS AND METHODS
QUEST enrolled 180 unilateral lower-limb amputees with severe post-amputation pain, 170 of whom were implanted with the Altius device, were randomized 1:1 to active-sham or treatment groups and reached the primary endpoint. Responders were those subjects who received ≥50% pain relief 30 min after treatment in ≥50% of their self-initiated treatment sessions within the 3-month randomized period. Differences between the active treatment and sham control groups as well as numerous secondary outcomes were determined.
RESULTS
At 30-min, (primary outcome), 24.7% of the treatment group were responders compared to 7.1% of the control group (p=0.002). At 120-minutes following treatment, responder rates were 46.8% in the Treatment group and 22.2% in the Control group (p=0.001). Improvement in Brief Pain Inventory interference score of 2.3 ± 0.29 was significantly greater in treatment group than the 1.3 ± 0.26-point change in the Control group (p = 0.01). Opioid usage, although not significantly different, trended towards a greater reduction in the treatment group than in the control group. The incidence of adverse events did not differ significantly between the treatment and control groups.
CONCLUSION
The primary outcomes of the study were met, and the majority of Treatment patients experienced a substantial improvement in PAP (regardless of meeting the study definition of a responder). The significant in PAP was associated with significantly improved QOL metrics, and a trend towards reduced opioid utilization compared to Control. These data indicate that Altius treatment represents a significant therapeutic advancement for lower-limb amputees suffering from chronic PAP.
PubMed: 38860215
DOI: 10.2147/JPR.S463727 -
Plastic and Reconstructive Surgery Jun 2024Residual limb pain (RLP) and phantom pain can arise following amputation and may require additional treatment or surgery. This study aimed to determine the prevalence of...
BACKGROUND OBJECTIVE
Residual limb pain (RLP) and phantom pain can arise following amputation and may require additional treatment or surgery. This study aimed to determine the prevalence of neuropathic RLP following limb amputation and identify prognostic factors for the development of neuropathic RLP.
METHODS
A cross-sectional study was performed of patients who underwent upper or lower extremity amputation between 1990 and 2021 with a minimum of twelve months follow-up. The primary outcome was the prevalence of neuropathic RLP, defined as a 0-10 NRS pain score in the residual limb of ≥4, in combination with a score ≥4 on the short form DN4 questionnaire (s-DN4), validated for discriminating between nociceptive and neuropathic pain. The secondary outcome was quality of life for amputees with and without (neuropathic) RLP. A multivariable linear regression model was used to identify prognostic factors for neuropathic RLP development.
RESULTS
A total of 121 patients were included: 87 with lower extremity amputations, 29 with upper extremity amputations, and 5 with both. Neuropathic RLP was experienced by 21.5%, while 10.7% reported non-neuropathic RLP. Smoking status and Complex Regional Pain Syndrome as indication for limb amputation were associated with more severe neuropathic pain symptoms. Patients experiencing neuropathic RLP reported a significantly lower quality of life compared to patients without neuropathic RLP.
CONCLUSIONS
This study demonstrates that neuropathic RLP is common after limb amputation and impacts daily functioning. The absence of numerous manageable prognostic factors associated with neuropathic pain development emphasizes the importance of the consideration of prophylactic interventions at the time of amputation.
PubMed: 38857429
DOI: 10.1097/PRS.0000000000011568 -
Neurological Sciences : Official... Jun 2024Phantom Limb Syndrome (PLS) can be defined as the disabling or painful sensation of the presence of a body part that is no longer present after its amputation.... (Review)
Review
Phantom Limb Syndrome (PLS) can be defined as the disabling or painful sensation of the presence of a body part that is no longer present after its amputation. Anatomical changes involved in Phantom Limb Syndrome, occurring at peripheral, spinal and brain levels and include the formation of neuromas and scars, dorsal horn sensitization and plasticity, short-term and long-term modifications at molecular and topographical levels. The molecular reorganization processes of Phantom Limb Syndrome include NMDA receptors hyperactivation in the dorsal horn of the spinal column leading to inflammatory mechanisms both at a peripheral and central level. At the brain level, a central role has been recognized for sodium channels, BDNF and adenosine triphosphate receptors. In the paper we discuss current available pharmacological options with a final overview on non-pharmacological options in the pipeline.
PubMed: 38853232
DOI: 10.1007/s10072-024-07634-1 -
PM & R : the Journal of Injury,... Jun 2024Prescription medications are an essential element of military amputation care programs.
BACKGROUND
Prescription medications are an essential element of military amputation care programs.
OBJECTIVES
To analyze (1) outpatient prescription medications following combat-related amputations, (2) longitudinal changes in prescription activity during the first year postinjury, and (3) patient characteristics associated with prescription medications.
DESIGN
Retrospective study of military casualty records and outpatient prescription medications. Clinicians identified 13 medication categories based on American Hospital Formulary Service classifications.
SETTING
Military amputation rehabilitation program.
PATIENTS
1651 service members who sustained major limb amputations during 2001-2017.
MAIN OUTCOMES MEASURES
Prescription medication category, days' supply, opioid dosage.
RESULTS
During the first year postinjury, patients averaged 65 outpatient prescriptions (new or refills, SD = 43.3) and 8 (SD = 1.9) of 13 medication categories. Nearly all patients (99%) had opioid prescriptions averaging high dosages with variation by patient characteristics and postinjury time. At least 84% of patients had prescriptions for one or more central nervous system, gastrointestinal, psychotherapeutic, immune/anti-infective and/or nonopioid analgesic medications. Prescriptions declined from the first (92%) to fourth (73%) quarter postinjury. Many patients had prescription opioids (51%), central nervous system medications (43%), or psychotherapeutic medications (32%) during the fourth quarter. In regression models, multiple factors including White race/ethnicity (relative risk [RR] = 1.16; 95% confidence interval [CI]: [1.06-1.28], p = .001), injury severity, traumatic brain injury, upper limb amputation (RR = 0.90; CI: [0.83-0.99], p = .020), multiple amputation (RR = 1.12 CI: [1.03-1.22], p = .008), phantom limb syndrome, chronic pain, and posttraumatic stress disorder were significantly associated with prescriptions (p's < .05).
CONCLUSIONS
Amputation care providers manage a high volume and wide range of prescription medications including multiple central nervous system drugs. The results show significant variation in prescription practices by patient characteristics and time postinjury. These findings can help optimize the benefits and reduce the risks of prescription medications and indicate areas for future research.
PubMed: 38845483
DOI: 10.1002/pmrj.13192 -
Acta Medica Philippina 2024Phantom limb pain (PLP) is difficult to control, and patients frequently exhibit inadequate relief from medications or encounter unbearable side effects. We present here...
Phantom limb pain (PLP) is difficult to control, and patients frequently exhibit inadequate relief from medications or encounter unbearable side effects. We present here a novel application of erector spinae plane (ESP) block to manage PLP. Our patient is a 23-year-old, college student, diagnosed with high-grade osteosarcoma of the right humerus who underwent a right shoulder disarticulation. He reported PLP despite multimodal analgesia postoperatively. An ESP block using a high-frequency linear probe ultrasound was performed. A G23 spinal needle was advanced in-plane toward the right T3 transverse process. After negative aspiration, 20 mL of therapeutic solution containing bupivacaine 0.25%, lidocaine 1%, epinephrine 5 mcg/ml, and 40 mg methylprednisolone was injected. After the procedure, the patient reported that his PLP went down to NRS 1/10. He consistently reported to have an NRS score of 0-1/10 on succeeding consultations despite discontinuation of opioid and pregabalin. In literature, ESP block has been used as a regional technique for shoulder disarticulation surgery and other neuropathic pain conditions, but no account has shown its use for PLP treatment. The procedure was successfully done to alleviate the upper extremity phantom limb pain, significantly reduce analgesic requirements, and improve tolerance of physical therapy and overall quality of life.
PubMed: 38836080
DOI: 10.47895/amp.v58i9.8821 -
PM & R : the Journal of Injury,... Jun 2024This report explores and summarizes perspectives from end users on unmet needs in achieving optimal and effective phantom pain management through a human-centered design...
BACKGROUND
This report explores and summarizes perspectives from end users on unmet needs in achieving optimal and effective phantom pain management through a human-centered design approach.
OBJECTIVE
To examine current strategies, pharmacological, nonpharmacological, surgical procedures, virtual reality, and mirror therapy, and the evidence supporting them, in the management of phantom limb pain.
DESIGN
This study reviewed and analyzed transcripts acquired in nonresearch contexts from the Veterans Affairs Translational Education and Mentoring Center's commercialization training program and from a Veteran Engagement Panel. Key themes were extracted using quasi-qualitative analysis of one-on-one interviews.
RESULTS
Clinicians and patients report that early patient intervention and education will yield improved management of phantom limb pain, which aligns with the growing recognition of the impact of patient-centered care on overall treatment outcomes. Mirror therapy is viewed as an effective and low-risk therapy, though compliance and buy-in may be barriers to clinical practice. Patient engagement can contribute to better treatment adherence and outcomes.
CONCLUSION
The study highlights implementation barriers, importance of end-user input, and the role of the Veteran Engagement Panel in providing feedback to pain researchers. The findings help explain unaddressed challenges and areas requiring further research to direct phantom pain management.
PubMed: 38828635
DOI: 10.1002/pmrj.13198 -
Journal of Plastic, Reconstructive &... Jul 2024Targeted muscle reinnervation (TMR) has been shown to reduce phantom limb pain (PLP) and residual limb pain (RLP) after major limb amputation. However, the effect of the... (Comparative Study)
Comparative Study
BACKGROUND
Targeted muscle reinnervation (TMR) has been shown to reduce phantom limb pain (PLP) and residual limb pain (RLP) after major limb amputation. However, the effect of the timing of surgery on pain control and quality of life outcomes is controversial. We conducted a retrospective study to compare the outcomes of acute TMR for pain prevention with non-acute TMR for the treatment of established pain.
METHODS
All patients treated with TMR in our institution between January 2018 and December 2021 were evaluated at 6, 12, 18 and 24 months post-operatively. Pain intensity and quality of life outcomes were assessed using the Brief Pain Inventory (Pain Severity and Pain Interference scales) and Pain Catastrophizing Scale. Outcomes were compared between acute and non-acute TMR using the Wilcoxon ranked-sum test or Fisher's exact test as appropriate. Multilevel mixed-effects linear regression was used to account for repeat measures and potential pain confounders.
RESULTS
Thirty-two patients with 38 major limb amputations were included. Acute TMR patients reported significantly lower RLP and PLP scores, pain interference and pain catastrophisation at all time points (p < 0.05). Acute TMR was significantly associated with lower pain severity and pain interference in a linear mixed-effects model accounting for patient age, gender, amputation indication, amputation site, time post-TMR and repeated surveys (p < 0.05). There was no significant difference in the complication rate (p = 0.51).
CONCLUSION
Acute TMR was associated with clinically and statistically significant pain outcomes that were better than that in non-acute TMR. This suggests that TMR should be performed with preventative intent, when possible, as part of a multidisciplinary approach to pain management, rather than deferred until the development of chronic pain.
Topics: Humans; Male; Female; Amputation, Surgical; Middle Aged; Retrospective Studies; Phantom Limb; Pain Measurement; Muscle, Skeletal; Quality of Life; Pain, Postoperative; Aged; Nerve Transfer; Adult; Pain Management
PubMed: 38823079
DOI: 10.1016/j.bjps.2024.05.011 -
Disability and Rehabilitation May 2024Phantom limb pain (PLP) is treated with medications and non-drug treatments. Best clinical practices for measuring treatment outcomes have not been defined. The...
PURPOSE
Phantom limb pain (PLP) is treated with medications and non-drug treatments. Best clinical practices for measuring treatment outcomes have not been defined. The objective of this study was to evaluate the internal consistency of patient-reported outcomes measures (PROMs) in a sample of Veterans with lower limb amputation.
MATERIALS AND METHODS
The Veteran phone survey included administering PROMs [1) PLP numeric rating scale (NRS), 2) general pain NRS, 3) Pain, Enjoyment, and General Activity (PEG) scale, 4) Patient-Reported Outcomes Measurement Information System (PROMIS) Pain Interference Short Form 6b Replacement, 5) PROMIS Short Form Depression 4a and 6) PROMIS Short Form Anxiety 4a].
RESULTS
Fifty Veterans (48 male, 2 female; average age: 66 years) completed PROMs. In our sample, 40 Veterans (80%) experienced PLP with an average PLP NRS of 5 (±3.4). Internal consistency of each measure was good to excellent based on Cronbach's alpha co-efficient of >0.80. Correlations were moderate between PLP NRS and all other measures (≤0.32). Although many Veterans expressed bothersome PLP, the scores reflecting pain interference and impact on function were lower than pain intensity. Consistent use of outcome measures is needed to determine the effect of interventions for amputation-related pain.
PubMed: 38813752
DOI: 10.1080/09638288.2024.2356017 -
Ultrasonic Imaging May 2024Given its real-time capability to quantify mechanical tissue properties, ultrasound shear wave elastography holds significant promise in clinical musculoskeletal...
Given its real-time capability to quantify mechanical tissue properties, ultrasound shear wave elastography holds significant promise in clinical musculoskeletal imaging. However, existing shear wave elastography methods fall short in enabling full-limb analysis of 3D anatomical structures under diverse loading conditions, and may introduce measurement bias due to sonographer-applied force on the transducer. These limitations pose numerous challenges, particularly for 3D computational biomechanical tissue modeling in areas like prosthetic socket design. In this feasibility study, a clinical linear ultrasound transducer system with integrated shear wave elastography capabilities was utilized to scan both a calibrated phantom and human limbs in a water tank imaging setup. By conducting 2D and 3D scans under varying compressive loads, this study demonstrates the feasibility of volumetric ultrasound shear wave elastography of human limbs. Our preliminary results showcase a potential method for evaluating 3D spatially varying tissue properties, offering future extensions to computational biomechanical modeling of tissue for various clinical scenarios.
PubMed: 38770999
DOI: 10.1177/01617346241253798