Restoration of sensory feedback from the foot and reduction of phantom limb pain via closed-loop spinal cord stimulation.

Restoring somatosensory feedback in individuals with lower-limb amputations would reduce the risk of falls and alleviate phantom limb pain. Here we show, in three individuals with transtibial amputation (one traumatic and two owing to diabetic peripheral neuropathy), that sensations from the missing foot, with control over their location and intensity, can be evoked via lateral lumbosacral spinal cord stimulation with commercially available electrodes and by modulating the intensity of stimulation in real time on the basis of signals from a wireless pressure-sensitive shoe insole. The restored somatosensation via closed-loop stimulation improved balance control (with a 19-point improvement in the composite score of the Sensory Organization Test in one individual) and gait stability (with a 5-point improvement in the Functional Gait Assessment in one individual). And over the implantation period of the stimulation leads, the three individuals experienced a clinically meaningful decrease in phantom limb pain (with an average reduction of nearly 70% on a visual analogue scale). Our findings support the further clinical assessment of lower-limb neuroprostheses providing somatosensory feedback.

Closed-loop stimulation of lateral cervical spinal cord in upper-limb amputees to enable sensory discrimination: a case study.

Modern myoelectric prosthetic hands have multiple independently controllable degrees of freedom, but require constant visual attention to use effectively. Somatosensory feedback provides information not available through vision alone and is essential for fine motor control of our limbs. Similarly, stimulation of the nervous system can potentially provide artificial somatosensory feedback to reduce the reliance on visual cues to efficiently operate prosthetic devices. We have shown previously that epidural stimulation of the lateral cervical spinal cord can evoke tactile sensations perceived as emanating from the missing arm and hand in people with upper-limb amputation. In this case study, two subjects with upper-limb amputation used this somatotopically-matched tactile feedback to discriminate object size and compliance while controlling a prosthetic hand. With less than 30 min of practice each day, both subjects were able to use artificial somatosensory feedback to perform a subset of the discrimination tasks at a success level well above chance. Subject 1 was consistently more adept at determining object size (74% accuracy; chance: 33%) while Subject 2 achieved a higher accuracy level in determining object compliance (60% accuracy; chance 33%). In each subject, discrimination of the other object property was only slightly above or at chance level suggesting that the task design and stimulation encoding scheme are important determinants of which object property could be reliably identified. Our observations suggest that changes in the intensity of artificial somatosensory feedback provided via spinal cord stimulation can be readily used to infer information about object properties with minimal training.

Integrated Meditation and Exercise Therapy: A Randomized Controlled Pilot of a Combined Nonpharmacological Intervention Focused on Reducing Disability and Pain in Patients with Chronic Low Back Pain.

OBJECTIVE: This pilot trial examined the effects of a combined intervention of mindfulness meditation followed by aerobic walking exercise compared with a control condition in chronic low back pain patients. We hypothesized that meditation before exercise would reduce disability, pain, and anxiety by increasing mindfulness prior to physical activity compared with an audiobook control group. PARTICIPANTS: Thirty-eight adults completed either meditation and exercise treatment (MedExT) (n=18) or an audiobook control condition (n=20). SETTING: Duquesne University Exercise Physiology Laboratory. DESIGN: A pilot, assessor-blinded, randomized controlled trial. METHODS: Over a 4-week period, participants in the MedExT group performed 12-17 minutes of guided meditation followed by 30 minutes of moderate-intensity walking exercise 5 days per week. Measures of disability, pain, mindfulness, and anxiety were taken at baseline and postintervention. Pain perception measurements were taken daily. RESULTS: Compared with the control group, we observed larger improvements in disability in the MedExT intervention, although the changes were modest and not statistically significant (mean between-group difference, -1.24; 95% confidence interval [CI], -3.1 to 0.6). For secondary outcome measures, MedExT increased mindfulness (within-group) from pre-intervention to postintervention (P=0.0141). Additionally, mean ratings of low back pain intensity and unpleasantness significantly improved with time for the MedExT group compared with that of the control group, respectively (intensity P=0.0008; unpleasantness P=0.0022). CONCLUSION: . Overall, 4 weeks of MedExT produced suggestive between-group trends for disability, significant between-group differences for measures of pain, and significant within-group increases in mindfulness.

Sensory restoration by epidural stimulation of the lateral spinal cord in upper-limb amputees.

Restoring somatosensory feedback to people with limb amputations is crucial to improve prosthetic control. Multiple studies have demonstrated that peripheral nerve stimulation and targeted reinnervation can provide somatotopically relevant sensory feedback. While effective, the surgical procedures required for these techniques remain a major barrier to translatability. Here, we demonstrate in four people with upper-limb amputation that epidural spinal cord stimulation (SCS), a common clinical technique to treat pain, evoked somatosensory percepts that were perceived as emanating from the missing arm and hand. Over up to 29 days, stimulation evoked sensory percepts in consistent locations in the missing hand regardless of time since amputation or level of amputation. Evoked sensations were occasionally described as naturalistic (e.g. touch or pressure), but were often paresthesias. Increasing stimulus amplitude increased the perceived intensity linearly, without increasing area of the sensations. These results demonstrate the potential of SCS as a tool to restore somatosensation after amputations.

Even some of the most advanced prosthetic arms lack an important feature: the ability to relay information about touch or pressure to the wearer. In fact, many people prefer to use simpler prostheses whose cables and harnesses pass on information about tension. However, recent studies suggest that electrical stimulation might give prosthesis users more sensation and better control. After an amputation, the nerves that used to deliver sensory information from the hand still exist above the injury. Stimulating these nerves can help to recreate sensations in the missing limb and improve the control of the prosthesis. Still, this stimulation requires complicated surgical interventions to implant electrodes in or around the nerves. Spinal cord stimulation ­ a technique where a small electrical device is inserted near the spinal cord to stimulate nerves ­ may be an easier alternative. This approach only requires a simple outpatient procedure, and it is routinely used to treat chronic pain conditions. Now, Chandrasekaran, Nanivadekar et al. show that spinal cord stimulation can produce the feeling of sensations in a person's missing hand or arm. In the experiments, four people who had an arm amputation underwent spinal cord stimulation over 29 days. During the stimulation, the participants reported feeling electrical buzzing, vibration, or pressure in their missing limb. Changing the strength of the electric signals delivered to the spinal cord altered the intensity of these sensations. The experiments are a step toward developing better prosthetics that restore some sensation. Further studies are now needed to determine whether spinal cord stimulation would allow people to perform sensory tasks with a prosthetic, for example handling an object that they cannot see.

Effects of Anesthetic Fluid Injectates on Lesion Sizes in Cooled Radiofrequency Ablation.

STUDY DESIGN: Nonrandomized trial. OBJECTIVE: This is an ex vivo study using pork chops to simulate human vertebra to determine the effects of various anesthetic fluids injectates and concentrations on lesion size and shape created when using cooled radiofrequency ablation. Secondary objective is to determine the effects of various time durations of applied lesion on lesion size created. Our final objective is to determine the effects of fluid injectates on tissue temperature and impedance. SUMMARY OF BACKGROUND DATA: Radiofrequency neurotomy is a therapeutic procedure involving ablation of sensory afferent nerves to the vertebral zygapophyseal joints. Larger lesions increase the likelihood the target nerve is ablated. METHODS: Before cooled radiofrequency ablation, tissue was injected with either 0.9% normal saline, 1% lidocaine, 2% lidocaine, 0.25% bupivacaine, 0.5% bupivacaine, 0.75% bupivacaine, 0.2% ropivacaine, 0.5% ropivacaine, or 1% ropivacaine. Duration of cooled radiofrequency was either 45, 90, or 150 seconds. RESULTS: There was no significant difference in the size of the lesion created when using different injectates and concentrations. There was no significant difference in the size of the lesion created when applying a 90 seconds duration lesion compared with a 150 seconds duration lesion. CONCLUSION: Applying a 90 seconds duration lesion can be considered in clinical use for cooled radiofrequency ablation. The use of an injectate did not significantly alter the size or desired spherical shape of the lesion created, did not significantly alter the time required to create the lesion, and did not significantly lower the temperature threshold. The study is limited by the use of ex vivo tissue which does not account for the effects of tissue perfusion. The use of an injectate before cooled radiofrequency ablation can be made at the interventionalist's discretion. LEVEL OF EVIDENCE: N/A.

Multicenter survey of attitudes and perceptions of pain medicine fellows toward the use of lateral versus contralateral-oblique fluoroscopic view for interlaminar cervical epidural injection.

OBJECTIVE: For interlaminar cervical epidural steroid injections (CESI) the lateral fluoroscopic view (LAT) is often considered to improve needle localization. However, the contralateral-oblique view (CLO) is a useful alternative with potential advantages to improve identification of cervical anatomy and needle depth assessment. The authors explored the attitudes and perceptions of pain medicine fellows currently training in two ACGME-accredited pain medicine fellowship programs regarding the use of these two types of fluoroscopic views. METHODS: The survey was conducted online following a request by e-mail. Of a total of 20 fellows who were contacted, there were 17 respondents who had experience with both techniques, and they were included for analysis. RESULTS: The response rate for participation was 95%. Whereas 70.6% respondents reported they were very certain about the assessment of anatomy with the CLO view, only 17.6% felt very certain with the LAT view. Compared with learning to perform interlaminar CESI using the LAT view only, the majority of fellows thought that using the CLO technique was easier to learn (P < 0.01) and offered better visualization of contrast dye spread pattern to confirm the cervical epidural space (P = 0.013). All respondents perceived that the likelihood of interlaminar CESI complications would be lower with CLO technique. Overall, 82.4% of respondents considered CLO visualization as a preferred technique for interlaminar CESI. Respondents stated that the likelihood of using the CLO technique as an independent physician was significantly higher than using only the LAT technique (P < 0.001), particularly for patients who are obese and have short necks. CONCLUSIONS: For interlaminar CESI, using the CLO is perceived to provide better definition of anatomy and yet is easier to learn. Trainees may become more confident in performing interlaminar CESI with the CLO. We encourage all fellowship programs to include the CLO technique for interlaminar CESI as part of the training.