First-In-Human Demonstration of High Frequency Electrical Motor Nerve Block: Case Report.

ABSTRACT: This feasibility study tested the capability of high frequency stimulation (HFS) to block muscle contractions elicited by electrical stimulation of the same nerve proximally. During a tendon lengthening surgery in the forearm, the anterior interosseous nerve (AIN) was exposed. A specialized nerve cuff electrode was placed around the nerve, and a stimulating probe held on the nerve 1 cm proximal to the cuff electrode delivered pulses of current causing the pronator quadratus muscle to contract. Through the cuff electrode, 20 kHz HFS was delivered to the nerve for 10 seconds during proximal stimulation. HFS amplitudes between 5 and 10 mA peak-to-peak were tested to determine which produced complete and partial block of the electrically induced contractions. The minimum HFS amplitude that produced complete block was 8 mA, with lower amplitudes producing partial block. In all trials, muscle contractions resumed immediately after HFS was turned off. This demonstration of high frequency electrical nerve block is a milestone in the road to clinical implementation of HFS mediated motor block for spasticity.

A review of prospective studies regarding percutaneous peripheral nerve stimulation treatment in the management of chronic pain.

Conventionally, peripheral nerve stimulation (PNS) for treatment of chronic pain has involved a two-stage process: a short-term (e.g., 7 days) trial and, if significant pain relief is achieved, a permanent PNS system is implanted. A percutaneous PNS treatment is now available where a coiled lead may be implanted for up to 60 days with the goal of producing sustained relief. In the present review, published prospective trials using percutaneous PNS treatment were identified and synthesized. The collected evidence indicates that percutaneous PNS treatment for up to 60 days provides durable clinically significant improvements in pain and pain interference. Similar efficacy across diverse targets and etiologies supports the broad applicability for use within the chronic pain population using this nonopioid technology.

What is this review about? This review looks at a drug-free way to treat chronic pain called percutaneous peripheral nerve stimulation (PNS). Percutaneous means it is placed through the skin. PNS applies small amounts of electricity to the nerves to reduce chronic pain. Most PNS systems involve a two-step process. A short trial is first performed to see if a patient has pain relief. A permanent system is then placed if the person had pain relief. Percutaneous PNS treatments are different. They use a thin wire called a lead placed in the body for up to 60 days. The lead is taken out at the end of the treatment period. Studies have shown that this type of PNS treatment can reduce chronic pain even after the treatment is over. No previous article has collected all these studies of percutaneous PNS in one place.What evidence was gathered? This review found evidence from studies on treatment of chronic pain. Pain types included shoulder pain, neuropathic pain and low back pain. It found that percutaneous PNS treatment for up to 60 days can reduce pain and how pain interferes with daily life.How can these data lead to better care for patients? These findings mean that percutaneous PNS treatments could be a useful, non-drug option for many types of chronic pain.

Innovations in Stroke Recovery and Rehabilitation: Poststroke Pain.

Pain can be a significant barrier to a stroke survivors' functional recovery and can also lead to a decreased quality of life. Common pain conditions after stroke include headache, musculoskeletal pain, spasticity-related pain, complex regional pain syndrome, and central poststroke pain. This review investigates the evidence of diagnostic and management guidelines for various pain syndromes after stroke and identifies opportunities for future research to advance the field of poststroke pain.

Reliability and minimal detectable difference of pressure pain thresholds in a pain-free population.

The objective of this work was to evaluate the inter-rater and intra-rater reliability and minimal detectable difference (MDD) of pressure pain thresholds (PPTs) in pain-free participants with two examiners over two consecutive days in a cross-sectional study design. Examiners used a standardized method to measure and locate a specific testing site over tibialis anterior for PPT testing with a hand-held algometer. The mean of each examiner's three PPT measurements was used to calculate the intraclass correlation coefficient, inter-rater reliability, and intra-rater reliability. The minimal detectable difference (MDD) was calculated. Eighteen participants were recruited (11 female). The inter-rater reliability was 0.94 and 0.96 on day 1 and day 2, respectively. Intra-rater reliability for the examiners was 0.96 and 0.92 on day 1 and day 2, respectively. The MDD on day 1 was 1.24 kg/cm2 (CI: 0.76-2.03) and the MDD on day 2 was 0.88 kg/cm2 (CI: 0.54-1.43). This study demonstrates high inter- and intra-rater reliability and the MDD values for this method of pressure algometry.

Adding Contralaterally Controlled Electrical Stimulation of the Triceps to Contralaterally Controlled Functional Electrical Stimulation of the Finger Extensors Reduces Upper Limb Impairment and Improves Reachable Workspace but not Dexterity: A Randomized Controlled Trial.

OBJECTIVE: Different methods of neuromuscular electrical stimulation may be used for poststroke upper limb rehabilitation. This study evaluated the effects of contralaterally controlled functional electrical stimulation of the triceps and finger extensors. DESIGN: This is a randomized controlled trial of 67 participants who were less than 2 yrs poststroke and assigned to the following: (a) arm + hand contralaterally controlled functional electrical stimulation, (b) hand contralaterally controlled functional electrical stimulation, or (c) arm + hand cyclic neuromuscular electrical stimulation. Participants were prescribed 10 sessions/week of assigned electrical stimulation at home plus 24 sessions of functional task practice in the laboratory for 12 wks. The primary outcome measure was the Box and Blocks Test. Secondary measures included reachable workspace, Upper Extremity Fugl-Meyer, Stroke Upper Limb Capacity Scale, Arm Motor Abilities Test, and Motor Activity Log. RESULTS: There were no significant between-group differences on the Box and Blocks Test. At 6 mos after treatment, arm + hand contralaterally controlled functional electrical stimulation improved reachable workspace more than hand contralaterally controlled functional electrical stimulation, between-group difference of 264 (95% confidence interval = 28-500) cm and more than arm + hand cyclic neuromuscular electrical stimulation, between-group difference of 281 (95% confidence interval = 22-540) cm. Arm + hand contralaterally controlled functional electrical stimulation improved Upper Extremity Fugl-Meyer score more than hand contralaterally controlled functional electrical stimulation, between-group difference of 6.7 (95% confidence interval = 0.6-12.7). The between-group differences on the Stroke Upper Limb Capacity Scale and Arm Motor Abilities Test were not significant. CONCLUSIONS: Adding contralaterally controlled elbow extension to hand contralaterally controlled functional electrical stimulation does not improve on gains in hand dexterity, but it further reduces upper limb impairment and improves reachable workspace measured in the laboratory. However, these additional benefits may not be large enough to be perceived by stroke survivors when they are performing activities of daily living at home.

The protocol for a multisite, double blind, randomized, placebo-controlled trial of axillary nerve stimulation for chronic shoulder pain.

BACKGROUND: Shoulder impingement syndrome is one of the most common causes of shoulder pain, accounting for approximately 30% of all shoulder pain. Approximately 35% of patients with shoulder impingement syndrome are refractory to conservative treatment. For patients who fail conservative treatment, there is no established treatment to successfully treat their chronic pain. Prior randomized control trials have demonstrated efficacy for the use of a single lead intramuscular peripheral nerve stimulation of the axillary nerve at the motor points of the deltoid muscle for treatment of hemiplegic shoulder pain. This is the first controlled trial to utilize the same novel technology to treat shoulder impingement syndrome outside of the stroke population. METHODS: This is a dual-site, placebo-controlled, double-blinded, randomized control trial. Participants will be randomized to two treatment groups. The intervention group will be treated with active peripheral nerve stimulation of the axillary nerve of the affected shoulder and the control group will be treated with sham peripheral nerve stimulation of the axillary nerve of the affected shoulder. Both groups will receive a standardized exercise therapy program directed by a licensed therapist. DISCUSSION: This study protocol will allow the investigators to determine if this novel, non-pharmacologic treatment of shoulder pain can demonstrate the same benefit in musculoskeletal patients which has been previously demonstrated in the stroke population. TRIAL REGISTRATION: Clinicaltrials.gov, NCT03752619. Registered on 26 November 2018.

Evaluation of an OSA risk stratifying and treatment protocol during inpatient rehabilitation of post-stroke patients.

PURPOSE: To evaluate outcomes, outside of a clinical trial setting, of a protocol utilizing overnight oximetry (NOx) to risk stratify post-stroke patients for obstructive sleep apnea (OSA) followed by autoadjusting continuous positive airway pressure (APAP) treatment in patients considered high risk for OSA. METHODS: Retrospective observational study of post-stroke patients at an academic inpatient stroke rehabilitation facility. Patients underwent NOx, and those at high risk for OSA (oxygen desaturation index 3% > 10 per hour) were attempted on a trial of APAP, and further stratified into high risk adherent with treatment (HRAT) or high-risk failed treatment (HRFT). Change in functional independence measure (FIM) was used to assess recovery. RESULTS: Two hundred twenty-four post-stroke patients underwent NOx, with 120 (53%) considered high risk for OSA. Twelve (10%) were compliant with APAP treatment (> 4 h/night on > 70% of nights). No difference in change in FIM scores was observed for HRAT versus HRFT [total FIM change - 5.8, 95% CI (- 13.9, 2.2); motor FIM change - 4.5, 95% CI (- 11.5, 2.4); cognitive FIM change - 1.3, 95% CI (-3.8, 1.2)]. A subgroup analysis matched 14 HRAT patients (using adherence criterion of APAP usage > 50% of nights) to 35 HRFT patients. A statistically significant, but clinically irrelevant, difference in total FIM change was observed (HRAT vs HRFT, difference between means - 5.2, p = 0.03). CONCLUSIONS: The use of APAP in high-risk patients was poorly tolerated and did not improve post-stroke recovery. Further studies with larger sample sizes are needed to determine the effect of APAP treatment on short-term recovery.

The effect of electrical stimulation on impairment of the painful post-stroke shoulder.

Background: Transcutaneous electrical nerve stimulation (TENS) and transcutaneous neuromuscular electrical stimulation (t-NMES) are commonly used therapies in the treatment of chronic hemiplegic shoulder pain. These treatments are often utilized during physical or occupational therapy sessions, yet research into the acute analgesic effects of TENS and t-NMES on hemiplegic shoulder pain and use during therapy is limited. Objective: To compare the acute effects of transcutaneous electrical nerve stimulation (TENS), transcutaneous neuromuscular electrical stimulation (t-NMES), and no stimulation on pain-free passive range of motion of the shoulder in subjects with hemiplegic shoulder pain. Methods: Prospective cohort study of 10 subjects randomly treated with t-NMES, TENS, and one non-stimulation experimental condition. Pain-free passive external rotation and abduction range of motion of the affected shoulder were measured during stimulation. Results: There was not a significant within-subject difference in pain-free range of motion for external rotation or abduction. Subject to subject differences explained the majority of the variability in pain-free range of motion. Conclusion: This pilot study is the first to measure pain-free passive range of motion during electrical stimulation. Our findings demonstrate the lack of an acute effect of TENS and t-NMES on pain reduction.

Neuromodulation for Functional Electrical Stimulation.

This article describes the application of neuromodulation in different ways to motor recovery, to replace lost function, or to improve function of organ systems for those who have experienced spinal cord injury or stroke. Multiple devices have been developed and are currently available for use whereas others are still in the experimental stage. Multiple uses of neuromodulation are described.

Percutaneous peripheral nerve stimulation for treatment of shoulder pain after spinal cord injury: A case report.

CONTEXT: This describes the first person with spinal cord injury (SCI) treated with percutaneous peripheral nerve stimulation for chronic shoulder pain. FINDINGS: From baseline to one-week after treatment, the subject's worst pain in the last week, rated on a 0-10 numerical rating scale (BPI-SF3), decreased by 44%. Pain interference decreased and remained below baseline 12 weeks after the end of treatment. There was an associated improvement in the mental component of quality of life. CONCLUSION: This case demonstrates the feasibility of treating shoulder pain in patients with SCI with percutaneous PNS. To demonstrate efficacy further studies are required.

Fully Implantable Peripheral Nerve Stimulation for Hemiplegic Shoulder Pain: A Multi-Site Case Series With Two-Year Follow-Up.

OBJECTIVE: To explore the feasibility and safety of a single-lead, fully implantable peripheral nerve stimulation system for the treatment of chronic shoulder pain in stroke survivors. PARTICIPANTS: Participants with moderate to severe shoulder pain not responsive to conservative therapies for six months. METHODS: During the trial phase, which included a blinded sham introductory period, a percutaneous single-lead peripheral nerve stimulation system was implanted to stimulate the axillary nerve of the affected shoulder. After a three-week successful trial, participants received an implantable pulse generator with an electrode placed to stimulate the axillary nerve of the affected shoulder. Outcomes included pain, pain interference, pain-free external rotation range of motion, quality of life, and safety. Participants were followed for 24 months. RESULTS: Twenty-eight participants underwent trial stimulation and five participants received an implantable pulse generator. The participants who received the implantable generator experienced an improvement in pain severity (p = 0.0002). All five participants experienced a 50% or greater pain reduction at 6 and 12 months, and four experienced at least a 50% reduction at 24 months. There was an improvement in pain interference (p < 0.0001). There was an improvement in pain-free external ROM (p = 0.003). There were no serious adverse events related to the device or to the procedure. CONCLUSIONS: This case series demonstrates the safety and efficacy of a fully implantable axillary PNS system for chronic HSP. Participants experienced reduction in pain, reduction in pain interference, and improved pain-free external rotation ROM. There were no serious adverse events associated with the system or the procedure.

The Effect of Peripheral Nerve Stimulation on Shoulder Biomechanics: A Randomized Controlled Trial in Comparison to Physical Therapy.

OBJECTIVE: To establish the effects on shoulder biomechanics from a peripheral nerve stimulation (PNS) treatment compared to physical therapy (PT) in stroke survivors with chronic hemiplegic shoulder pain. DESIGN: Single-site, pilot, randomized controlled trial for adults with chronic shoulder pain after stroke. Participants were randomized to receive a 3-week treatment of single-lead PNS or physical therapy (PT). The outcomes included isometric shoulder abduction strength, pain-free shoulder external rotation range of motion (ROM), delay in initiation and termination of shoulder abduction electromyogram (EMG) activity, and the Fugl-Meyer Motor Assessment (upper extremity section). Outcomes were measured at baseline, and at weeks 1, 4, 12, and 16. RESULTS: Twenty-five participants were recruited, 13 to PNS and 12 to PT. There were significant improvements for both PNS and PT in maximum isometric shoulder abduction strength, pain-free external rotation ROM, and Fugl-Meyer Motor Assessment. There were no significant changes in delay of initiation or termination of deltoid EMG with either treatment. CONCLUSIONS: Both PNS and PT are capable of improving shoulder biomechanics in those with HSP, though changes in biomechanics alone do not account for the greater pain relief associated with PNS than PT.

Neurostimulation for Postsurgical Analgesia: A Novel System Enabling Ultrasound-Guided Percutaneous Peripheral Nerve Stimulation.

While neurostimulation-stimulation of the nervous system using electrical current-has been used to treat chronic pain, its use treating postsurgical pain has been limited. Here, we report on the clinical application of a novel investigational lead to provide analgesia following total knee arthroplasty. In 5 subjects, leads were inserted percutaneously using ultrasound guidance within 0.5 to 3.0 cm of the femoral and/or sciatic nerve(s). With the delivery of current, pain decreased an average of 63% at rest, with 4 of 5 subjects having relief of > 50%. During passive and active knee flexion, pain decreased an average of 14% and 50%, with 0/3 and 1/2 subjects attaining > 50% relief, respectively. Ultrasound-guided percutaneous peripheral nerve stimulation may be a practical modality for the treatment of postsurgical pain.

Contralaterally Controlled Functional Electrical Stimulation Improves Hand Dexterity in Chronic Hemiparesis: A Randomized Trial.

BACKGROUND AND PURPOSE: It is unknown whether one method of neuromuscular electrical stimulation for poststroke upper limb rehabilitation is more effective than another. Our aim was to compare the effects of contralaterally controlled functional electrical stimulation (CCFES) with cyclic neuromuscular electrical stimulation (cNMES). METHODS: Stroke patients with chronic (>6 months) moderate to severe upper extremity hemiparesis (n=80) were randomized to receive 10 sessions/wk of CCFES- or cNMES-assisted hand opening exercise at home plus 20 sessions of functional task practice in the laboratory for 12 weeks. The task practice for the CCFES group was stimulation assisted. The primary outcome was change in Box and Block Test (BBT) score at 6 months post treatment. Upper extremity Fugl-Meyer and Arm Motor Abilities Test were also measured. RESULTS: At 6 months post treatment, the CCFES group had greater improvement on the BBT, 4.6 (95% confidence interval [CI], 2.2-7.0), than the cNMES group, 1.8 (95% CI, 0.6-3.0), between-group difference of 2.8 (95% CI, 0.1-5.5), P=0.045. No significant between-group difference was found for the upper extremity Fugl-Meyer (P=0.888) or Arm Motor Abilities Test (P=0.096). Participants who had the largest improvements on BBT were <2 years post stroke with moderate (ie, not severe) hand impairment at baseline. Among these, the 6-month post-treatment BBT gains of the CCFES group, 9.6 (95% CI, 5.6-13.6), were greater than those of the cNMES group, 4.1 (95% CI, 1.7-6.5), between-group difference of 5.5 (95% CI, 0.8-10.2), P=0.023. CONCLUSIONS: CCFES improved hand dexterity more than cNMES in chronic stroke survivors. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00891319.

Upper-Limb Recovery After Stroke: A Randomized Controlled Trial Comparing EMG-Triggered, Cyclic, and Sensory Electrical Stimulation.

BACKGROUND AND PURPOSE: This study compared the effect of cyclic neuromuscular electrical stimulation (NMES), electromyographically (EMG)-triggered NMES, and sensory stimulation on motor impairment and activity limitations in patients with upper-limb hemiplegia. METHODS: This was a multicenter, single-blind, multiarm parallel-group study of nonhospitalized hemiplegic stroke survivors within 6 months of stroke. A total of 122 individuals were randomized to receive either cyclic NMES, EMG-triggered NMES, or sensory stimulation twice every weekday in 40-minute sessions, over an 8 week-period. Patients were followed for 6 months after treatment concluded. RESULTS: There were significant increases in the Fugl-Meyer Assessment [F(1, 111) = 92.6, P < .001], FMA Wrist and Hand [F(1, 111) = 66.7, P < .001], and modified Arm Motor Ability Test [mAMAT; time effect: F(1, 111) = 91.0, P < .001] for all 3 groups. There was no significant difference in the improvement among groups in the FMA [F(2, 384) = 0.2, P = .83], FMA Wrist and Hand [F(2, 384) = 0.4, P = .70], or the mAMAT [F(2, 379) = 1.2, P = .31]. CONCLUSIONS: All groups exhibited significant improvement of impairment and functional limitation with electrical stimulation therapy applied within 6 months of stroke. Improvements were likely a result of spontaneous recovery. There was no difference based on the type of electrical stimulation that was administered.

Hemiplegic Shoulder Pain.

Hemiplegic shoulder pain is a common complaint for stroke survivors. Many pathologies are included in the diagnosis of hemiplegic shoulder pain, and many with shoulder pain have a multifactorial cause. This article provides rehabilitation specialists with an approach to evaluation and management of those with hemiplegic shoulder pain.

Percutaneous peripheral nerve stimulation for chronic pain in subacromial impingement syndrome: a case series.

OBJECTIVE: The objective of this study was to determine the effect of peripheral nerve stimulation (PNS) on pain reduction for those with refractory subacromial impingement syndrome (SIS) and to evaluate the association with reduced disability, impairment, and safety. Our hypotheses are that PNS will be associated with a reduction in pain, impairment and disability, and improvement in quality of life while demonstrating safety. MATERIAL AND METHODS: Adults with shoulder pain of at least six months duration were recruited for a three-week treatment of percutaneous PNS applied through a percutaneous electrode to the axillary motor points of the deltoid muscle. Subjects were followed for 12 weeks after treatment. The primary outcome was the worst pain in the last week, and secondary outcomes included pain interference, the Disabilities of the Arm, Shoulder, and Hand questionnaire, shoulder abduction range of motion, and safety. Analysis was with a linear mixed model. RESULTS: Ten subjects were recruited. Longitudinal analysis demonstrated significant reduction in pain relative to baseline (F(1, 66) = 12.9, p < 0.01). After correcting for multiple comparisons, there were significant reductions at explantation and all follow-up time points when compared with baseline. There were also significant improvements in pain interference (F(1,65) = 15.0, p < 0.01), the Disabilities of the Arm, Shoulder, and Hand questionnaire (F(1,35) = 7.0, p = 0.01), and shoulder abduction range of motion (F(1,35) = 6.3, p = 0.02). CONCLUSION: Intramuscular PNS for chronic shoulder pain due to SIS is a safe treatment associated with pain reduction, lower pain interference with activities of daily living, reduced disability, and improved shoulder abduction. Pain reduction is maintained for at least 12 weeks after treatment.