External Noninvasive Peripheral Nerve Stimulation Treatment of Neuropathic Pain: A Prospective Audit

doi:10.1111/ner.12244

Neuromodulation: Technology at the Neural Interface

Volume 18, Issue 5, July 2015, Pages 384-391

https://doi.org/10.1111/ner.12244 Get rights and content

Background

Peripheral nerve stimulation (PNS) is a neuromodulation technique in which electrical current is applied to the peripheral nerves to ameliorate chronic pain through preferential activation of myelinated fibres, inducing long-term depression of synaptic efficacy. External noninvasive peripheral nerve stimulation (EN-PNS) is a novel and simple form of PNS that involves stimulation via an external nerve-mapping probe that is placed on the skin and connected to a power source.

Objectives

We aimed to assess the clinical utility of EN-PNS in patients with refractory neuropathic pains referred to a tertiary pain treatment center.

Methods

We undertook a prospective audit of EN-PNS. Patients with a diagnosis of either complex regional pain syndrome or neuropathic pain after peripheral nerve injury who met inclusion criteria were included. Participants completed three stages of the audit: stage 1, six weekly outpatient treatment sessions; stage 2, six-week equipment home loan; stage 3, six weeks of no EN-PNS treatment. The primary outcome was the average post-treatment instantaneous pain intensity during the last week in stage 2 compared with baseline (11-point numerical rating scale).

Results

EN-PNS provided significant short-term pain relief (n = 20 patients, average reduction of 2.8 numerical rating scale points, 95% CI 1.6–4.0, p < 0.001, intention-to-treat analysis). Eight patients (40%) improved in several outcome parameters (“responders”), including quality of life and function.

Conclusion

In this first prospective report on the use of EN-PNS in neuropathic pain, this technology provided significant clinical benefit for some patients. Controlled studies are required to confirm our results and the place of EN-PNS in future neuromodulation treatment algorithms. Given the refractory nature of these conditions, these results are encouraging.

Section snippets

INTRODUCTION

Neuropathic pain is defined as “pain arising as a direct consequence of a lesion or disease affecting the somatosensory system” (1). It results from abnormal activation of pain pathways (2). Neuropathic pain can be debilitating for the sufferer and is frequently refractory to established treatments. Neuromodulation is a treatment modality for the management of chronic pain conditions that involves stimulation of the nervous system with electrical signals. One form of neuromodulation developed

Setting

The audit center was a specialist neurosciences hospital providing a pain management service. All referrals to this service are first seen by a pain consultant and may be referred on to pain-specialist physiotherapists. EN-PNS has been used since 2009 by the center’s physiotherapy staff to treat selected neuropathic pain conditions. The audit was designed to enable a systematic evaluation of current use of this treatment and was led by two senior physiotherapists. As this was not a research

Patient Referral, Inclusion, and Exclusion

Between January and October 2011, 34 patients were referred to the EN-PNS audit team (19 CRPS, 15 PNI). During this period, the referring consultants received 60 new CRPS referrals and 122 PNI referrals; that is, 32% and 12%, respectively, of all new patients with these conditions were felt appropriate for the audit. We included 20 of these 34 patients in the audit (12 CRPS, 8 PNI); patient demographics and baseline scores are outlined in Table 2. Fifty-five percent of this group did not

DISCUSSION

The audit results indicate that EN-PNS can provide significant immediate pain relief in mostly longstanding, refractory CRPS and PNI localized to the territory of 1–2 peripheral nerves. Approximately 40% of audit participants experienced meaningful improvements in four or more clinical outcome domains. For two patients, this effect was sustained for a period of six months beyond the audit completion, without ongoing treatment; one of these reported complete resolution of her pain.

In the group

CONCLUSIONS

On the basis of this audit, EN-PNS appears to be beneficial for some patients with CRPS or PNI localized to 1–2 major nerves. Given the refractory nature of these conditions, the results are encouraging. EN-PNS is noninvasive, relatively simple to administer, and reasonably well tolerated. Further controlled studies are needed to establish efficacy and determine the place of EN-PNS within routine care pathways for patients with regionally confined neuropathic pains.

Authorship Statement

All authors designed the study. Ms. Johnson and Ms. Ayling conducted the study, including patient data collection and data analysis. Ms. Johnson prepared the manuscript draft with important intellectual input from Dr. Goebel. All authors were involved in editing and approved the final manuscript. All authors had complete access to the study data.

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Effectiveness of Different Electrical Stimulation Modalities for Pain and Masticatory Function in Temporomandibular Disorders: A Systematic Review and Meta-Analysis
2023, Journal of Pain
Temporomandibular disorders comprise a set of conditions that include alterations of the temporomandibular joint and masticatory muscles. Although different modalities of electric currents are widely used for treating temporomandibular disorders, previous reviews have suggested these are ineffective. This systematic review and meta-analysis aimed to determine the effectiveness of different electrical stimulation modalities in patients with temporomandibular disorders for reducing musculoskeletal pain, increasing the range of movement, and improving muscle activity. An electronic search was conducted of randomized controlled trials published until March of 2022 that compared the application of an electrical stimulation therapy versus a sham or control group. The main outcome measure was pain intensity. Seven studies were included in the qualitative analysis and in the quantitative analysis (n = 184 subjects). The overall effect of electrical stimulation on pain reduction was statistically superior to sham/control (MD = −1.12 cm; CI 95%: −1.5 to −0.8), showing moderate heterogeneity of results (I² = 57%, P = .04). The overall effect on range of movement of the joint (MD = 0.97 mm; CI 95%: −0.3 to 2.2) and muscle activity (SMD = −2.9; CI 95%: −8.1 to 2.3) were not significant. Transcutaneous electrical nerve stimulation (TENS) and high-voltage current stimulation reduces pain intensity clinically in people with temporomandibular disorders with a moderate quality of evidence. On the other hand, there is no evidence of the effect of different electrical stimulation modalities on range of movement and muscle activity in people with temporomandibular disorders with a moderate and low quality of evidence respectively.
TENS and high voltage currents are valid options for the control of pain intensity in patients suffering from temporomandibular disorder. Data suggest clinically relevant changes compared to sham. Healthcare professionals should take this into account as it is inexpensive therapy, has no adverse effects and can be self-administered by patients.
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Only recently have technological improvements and scientific innovation previously accorded SCS addressed the shortcomings of using “borrowed” SCS equipment for PNS (3,18,20,37,38). The introduction of dedicated electrode designs, the development of micro-electrodes, and wireless technology facilitated by ultrasound (US) percutaneous implantation, has not only reduced the power requirement for PNS but also reduced the complication rate that is associated with surgically dependent systems (15,39–41). Suffice to say, this study and many other reports in which similar equipment was used during this time period more than justifies the use of this older generation PNS for treatment of CRPS 1 and 2 (2–4,39,42).
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This chart review describes the use of implantable PNS systems in the treatment of CRPS of the upper and lower extremities spanning nearly three decades.
A retrospective chart review was performed on 240 patients with PNS implanted between 1990 and 2017 at our institution. Of these, 165 patients were identified who had PNS systems implanted for a diagnosis of CRPS. Patient profile, including baseline characteristics, comorbidities, past/current interventions/medications and targeted nerves, was descriptively summarized through standard summary statistics. Patients' pain scores and opioid consumptions at baseline (preimplant), 1 month, 6 months, and 12 months were collected and compared. Device revisions and explants were summarized, and patient functional outcomes were described.
Pain scores at baseline and at 12-month follow-up were decreased from a mean of 7.4 ± 1.6 to 5.5 ± 2.4 and estimated to be 1.87 (95% CI: [1.29, 2.46], paired t-test p-value <0.001) lower at 12 months. At baseline, 62% of patients were on chronic opioid therapy, compared with 41% at 12 months. Of 126 patients who reported changes in functional status, 64 (51%) reported improvement, 27 (21%) reported worsening, and 35 (28%) did not report any meaningful change. Excluding end-of-life battery replacements, surgical revision occurred in 56 (34%) of patients. Thirteen patients (8%) underwent implantation of a second PNS because of symptomatic expansion outside of the original painful region. Device explant was performed in 32 (19%) of patients. Median length of follow-up was 74 [14, 147] months. Of the 36 patients who continue to follow-up at our institution, 29 (81%) continue to use their PNS.
We can conclude that PNS is a useful modality to improve function and reduce long-term pain in selected patients suffering from CRPS type I and type II.
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LFS attenuated somatosensory processing both during and after stimulation.
Results further our understanding of the attenuation of somatosensory processing both during and after LFS.
Percutaneous Versus Transcutaneous Electrical Nerve Stimulation for the Treatment of Musculoskeletal Pain. A Systematic Review and Meta-Analysis
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Sources of financial support: The audit was funded by internal sources (the Walton Centre NHS Trust). Machines and some additional funds were provided by Pajunk Medizintechnologie GmbH (Karl-Hall-Str. 1, D-78187 Geisingen, Germany). The funding sources had no role in the design, conduct, or analysis of the study, the writing of the manuscript, or the decision to publish. We notified Pajunk of the results of the study and provided them with a copy of the manuscript before submission.

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Basic ResearchExternal Noninvasive Peripheral Nerve Stimulation Treatment of Neuropathic Pain: A Prospective Audit

Background

Objectives

Methods

Results

Conclusion

Section snippets

INTRODUCTION

Setting

Patient Referral, Inclusion, and Exclusion

DISCUSSION

CONCLUSIONS

Authorship Statement

Pain

Eur J Pain

Reg Anesth Pain Med

Reg Anesth Pain Med

Neuromodulation

J Clin Neurosci

Pain

Pain

Clin Neurophysiol

J Pain

Pain

J Pain

Basic Research
External Noninvasive Peripheral Nerve Stimulation Treatment of Neuropathic Pain: A Prospective Audit