Welcome to the e-INS 2023 Interactive Program

Introduction

Psychologists in Pain Neuromodulation (PiPiN) is a network of clinical psychologists working in UK neuromodulation services. The group meets regularly to discuss developments in the field of neuromodulation, psychological aspects of surgical care and to share good practice.

A multidisciplinary assessment, including a psychological assessment, is recommended for all patients under consideration for neuromodulation yet there are no existing guidelines to inform these assessments. Furthermore, access to psychological intervention prior to or after surgery can be variable.

This paper makes recommendations for good practice when conducting pre-operative assessments, planning pre or post-surgical psychological intervention and considers some of the professional challenges for psychologists working in neuromodulation services.

Materials / Methods

In light of the lack of standardised criteria for psychologists working in neuromodulation, one of the goals of the guideline development group was to map the arrangements for delivering psychological input within UK neuromodulation services. The mapping exercise was conducted using a short survey circulated to the PIPIN email distribution list.

A systematic review of the literature was conducted to establish the existing evidence regarding psychological predictors of outcome from neuromodulation for pain.

Extensive discussion within the professional network was undertaken to differentiate between factors that were amenable to treatment/intervention and could therefore be considered cautions for neuromodulation, and those that should be exclusions for the same.

Results

Survey data from the professionals invovled in PiPiN showed that, of the 17 centres which responded to the survey, 67% confirmed psychologists were routinely involved in preoperative assessment, whilst 33% had ad-hoc or variable provision. 54% of the centres included psychological input within their prehabilitation programmes, whilst 13% did not offer such a programme. In regard to postoperative care the results were more mixed. 40% of psychologists were routinely involved in following up patients after surgery, 30% offered no routine follow up, 10% made other arrangements and 20% services were unclear whether postoperative support was provided.

The systematic review hightlighted a range of psychological factors that are associated with poorer outcome from neuromodulation. A traffic light system was established that can aid clinical decision making with regards to the psychological appropriateness of neuromodulation. The wider role of psychologists in contributing to the neuromodulation team is also outlined.

Discussion

These guidelines provide a consensus agreement on the role of psychology within neuromodulation services for new and existing services in the UK and beyond.

Conclusions

These guidelines provide a consensus agreement on the role of psychology within neuromodulation services.

References

None

Learning Objectives

1. Outlining the role of psychology within neuromodulation services

2. Providing consenus on the psychological factors that may be identified during preoperative assessment

3. Identifying areas for research and development in the field of psychology and neuromodulation

Introduction

During the last century, a considerable number of ethics codes have emerged, sometimes embedding legally binding instruments, sometimes encoding good clinical practice for the first time. Apart from the general ethical considerations in use of neuromodulatory devices, specific ethical standards should be applied in clinical trials using neuromodulation as treatment option for chronic pain. The specific, but sometimes debatable place of neuromodulation in the treatment algorithm in chronic, refractory pain, makes the inclusion of such vulnerable populations in trials unique, but requires a solid framework to concur the ethical concerns.

Adding to the ethics guidelines, regulators have tried to keep up in protecting the patient, user and society of possible risks related to such devices, namely in the protection of the patient's privacy and ensuring manufacturer responsibility during the whole lifecycle of the device. This area of research with medical devices has become a regulatory minefield that the suggestion has been made to create an academic discipline of ‘medical device science’.

This review aims to demonstrate the limits of ethics guidelines, the personal responsibility of the researcher and the usefulness of the legal, ethics and deontology frameworks for clinical investigations in neuromodulation.

Materials / Methods

In this narrative review, the authors take the reader thought the full research cycle for clinical investigations in neuromodulation; from the initiation of the research towards execution of the research and publication. In each topic the authors provide practical advices building on a multidisciplinary experience in clinical neuromodulation practice, social researchers and legal and ethics advisors.

Results

The article focusses on common hurdles, namely patient centered study designs, obtaining true informed consent, clear contracts between sponsors and research partners, fees to the patient and post-trial accessibility and support of the device, usefulness of standards, including placebo and sham interventions, expectations with respect to institutional review boards or ethics committees, and publication hygiene.

Discussion

This review clearly demonstrated that general ethical guidelines and legislation need an additional translation towards specific fields to be useful for clinicians and researchers with a background in medical device science.

Conclusions

Due to the increased number of guidelines with respect to medical devices, awarness of these regulations should be increased, whereby legal experts could provide valuable input in the future developments of clinical trials in the field of neuromodulation.

References

None.

Learning Objectives

1. To create awarness about the set of regulations (legal and ethical) with respect to medical devices.

2. To learn about all aspects of medical ethics, and to know how to safeguard these principles in every step in clinical research from initiating an idea, over execution a study to reporting results.

3. To be able to point out the gaps in current legislation.

Introduction

Cluster headache (CH) is described to be one of the most painful conditions known to humans and affects about one in every 1000 adults (1,2). CH is a primary headache disorder characterized by an excruciating unilateral temporal or periorbital pain, sometimes accompanied by autonomic symptoms (3). Though its exact pathophysiology remains unknown, disturbed nociceptive signaling within the occipital and trigeminal nerve circuits are considered major causes of CH (4). Occipital nerve stimulation (ONS) is recognized as a promising treatment for CH patients refractory to standard pharmacological approaches. Despite its effectiveness in many patients, adequate pain relief is not reached in a subset of CH patients undergoing ONS (5). Reasons for failure of ONS are wrong diagnosis, indication and anatomical variations combined with different surgical approaches. The current study provides a clear analysis including elaborate visualization on literature regarding the technique of ONS with regard to the anatomy. Additionally, cadaveric experimentation is combined with our clinical experience to provide a standardized proposal for ONS.

Materials / Methods

Data from 65 articles were analyzed. For the cadaveric experimentation (N=1), two electrodes were inserted in various directions from the region of C2 and foramen magnum and projected towards the mastoid process. Thereafter, the GON was dissected, and x-ray imaging was performed from different angles.

Results

Inconsistencies in anatomical location and landmarks of the occipital nerve were found in literature. Upon the current analysis, deviations in surgical aspects including electrode placement, imaging technique and patient positioning were also found, with a clinical efficacy ranging from 35-90%.

Discussion

The absence of a standardized protocol was confirmed in this analysis due to the existence of multiple approaches and variations in ONS. Deviations in surgical approaches are likely to be responsible for the broad efficacy range reported for ONS. Implementation of a universal approach to ONS can therefore improve management for all patients with refractory CH. Hence, we propose a standardized protocol for ONS. In this proposal, electrodes should be placed higher upon the occipital area. This approach is expected to hold great potential to optimize clinical benefit of ONS due to increased electric field coverage. Even though current observations are promising, follow-up studies are required to confirm the efficacy of the current proposal.

Conclusions

There is no standardized surgical protocol for ONS. The presence of such a protocol allows for better comparison of data and outcome between different institutions and physicians and is hence necessary to optimize treatment for CH.

References

1) Wei DY, Yuan Ong JJ, Goadsby PJ. Cluster Headache: Epidemiology, Pathophysiology, Clinical Features, and Diagnosis. Ann Indian Acad Neurol. 2018;21(Suppl 1):S3-s8.

2) Weaver-Agostoni J. Cluster headache. Am Fam Physician. 2013;88(2):122-8.

3) May A, Schwedt TJ, Magis D, Pozo-Rosich P, Evers S, Wang SJ. Cluster headache. Nat Rev Dis Primers. 2018;4:18006.

4) Eskilsson A, Ageberg E, Ericson H, Marklund N, Anderberg L. Decompression of the greater occipital nerve improves outcome in patients with chronic headache and neck pain—a retrospective cohort study. Acta Neurochirurgica. 2021;163(9):2425-33.

5) Eghtesadi M, Leroux E, Fournier-Gosselin M-P, Lespérance P, Marchand L, Pim H, et al. Neurostimulation for refractory cervicogenic headache: a three-year retrospective study. Neuromodulation: Technology at the Neural Interface. 2018;21(3):302-9.

Learning Objectives

1) There is a wide variety in the use of anatomical landmarks, patient positioning, imaging, electrode placement in the technique of occipital neurostimulation

2) There is a need for a standardized surgical protocol in occipital nerve stimulation

3) Such a protocol enables comparison of data between physicians who treat patients suffering from intractable cluster headache with occipital nerve stimulation

Introduction

The increasing average age of our population results in a high incidence of chronic degenerative knee pathologies. Thereby knee surgery is a frequently performed elective procedure to treat chronic degenerative knee pain that is refractory to conservative treatment. However, the amount of patients with chronic postsurgical knee pain is estimated with 16-20%. Neuromodulation techniques like SCS and Dorsal Root Ganglion Stimulation have already been used to treat chronic knee pain. The evidence of selective treatment due to peripheral nerve stimulation (PNS) is very low so far because of the absence of suitable neuromodulation systems for the distal part of the lower limbs. The aim of this study was to show the effectiveness and safety of a wireless PNS system to treat chronic intractable knee pain via saphenous nerve stimulation.

Materials / Methods

Patients with chronic intractable postsurgical knee pain have been tested via landmark-guided PNS of the branches of the saphenous nerve. All implantations were performed with a wireless PNS system and external batterie to avoid lead migration due to cross-joint lead positions. Data was collected prospectively. Ethic was approved (EA2/093/13). Outcome scores and pain medication were followed in outpatient visits scheduled 0, 3, 6, 12 and 24 months after permanent implantation.

Results

All patients (n = 34) benefited significantly from PNS testing and a permanent device was implanted. 3 patients reported no benefit at the 3 month follow-up and system was explanted after the visit. The mean NRS (_NRSpreop =7.72 +/- 0.8) was reduced significantly (p<0.05) at the three (NRS_{3 months}= 2.5 +/- 0.6), six (NRS_6months= 2.8 +/- 0.7) and twelve months follow-up (NRS_12months= 2.5 +/- 0,4). Additionally, patients were able to reduce their opioid medication from 85 Morphine Milligram Equivalents (MME) preoperatively to 20 MME one year after the surgery. Further long-term follow-up appointments are pending.

Discussion

Wireless PNS of the branches of the saphenous nerve is a simple, selective and elegant technique for patients with chronic knee pain. The land-mark guided implantation is less invasive than classical neuromodulation techniques like Spinal Cord or DRG-stimulation. Complication rates are low and durations of surgeries are short. The patient reported outcome results and the reduction concerning their opioid medication are very promising within the first year of therapy. However, long-term results are pending.

Conclusions

Wireless peripheral nerve stimulation of branches of the saphenous nerve is a safe technique to treat chronic postsurgical knee pain. Current results are promising and show considerable pain and opioid reduction.

References

none

Learning Objectives

(1) Postsurgical knee pain is an important pathology --> 20% after surgery

(2) PNS is suitable therapy option --> NRS + Moprhine intakte

(3) PNS is a safe technique --> no complicaionts described

Introduction

The innovative technology of this neurostimulator has been developed to meet today's challenges in neuromodulation. First, MRI safety, offering potential for personalized therapy, is achieved through its optoelectronic technology. Optical pulses generated by an implantable pulse generator (IPG) are carried through optical fibers and converted into electrical stimuli at the electrode by ultra-miniature photovoltaic cells. Second, the potential for energy-intensive integrated biomarkers is made possible by its fast rechargeable battery. Third, ease of placement during surgery is provided by an innovative self-sizing spiral cuff electrode design. This study evaluates the performance, usability and safety of this new neurostimulator in sheep.

Materials / Methods

The neurostimulator and the cuff electrode were implanted in a total of thirty healthy sheep. Device usability was evaluated by experienced VNS neurosurgeons during implantation. Device performance was assessed by weekly interrogations of the device (IPG communication and recharge) and recording of the laryngeal motor evocation potential (LMEP) response to VNS through recurrent laryngeal nerve activation. Device safety was assessed by detailed histology reports, as well as daily clinical examination, behavior assessment, blood samples, and weight measurement.

Results

Each step of the implant surgery was rated as "very easy" by experienced VNS neurosurgeons. Mean device implantation time was 13.8 min and electrode cuff placement was 1.5 min. Weekly IPG communication and recharging was successful in all sheep. Full weekly charge time was between 2 and 5 minutes, except for one sheep (5-10 minutes). Usual clinical VNS pulse width parameters were applied, and cough used as a biomarker of the accepted upper stimulation threshold.

Discussion

Nerve stimulation, identified by LMEP recording, was impaired in 2 sheep. For one sheep, it was impossible to record LMEP data or manually feel laryngeal muscle contractions from week 3 to week 14 over the 26 weeks of implantation. In one animal with insufficient stimulation, the electrode was dislodged. Mild swelling of the implantation site without major inflammation was observed in 13/30 sheep. No other stimulation- or device-related adverse events were observed.

Conclusions

This pre-clinical study in 30 sheep has proven the performance, ease of use and safety of this novel VNS neurostimulator. Its innovative will make it possible to respond to the current challenges of neuromodulation by offering MRI safety, energy-intensive embedded biomarkers and greater ease of placement during surgery.

Learning Objectives

* Development of a new biomarker (LMEP) to understand the stimulatiion.

* Creation of a new technology (optoelectronic) to improve the safety in MRI

* Accessibility to a biomarker (fMRI) to understand the stimulationt thanks to the technology optoelectronic of the implant.

Introduction

Intrathecal drug delivery systems are approved with different analgesics in chronic refractory pain as well as baclofen in severe spasticity. In this retrospective analysis the clinical data of long-term ITT patients, which received pump exchanges between January 2008 and June 2020, were evaluated.

Materials / Methods

Overall, 116 pump devices were implanted in 71 patients (37 male, 34 female). ITT was used to treat chronic (non-malignant) pain in 36 patients and severe spasticity in 34 patients. In one patient, both indications coexisted. The follow-up period on average was 86 months (range: 12 to 147 months). 9 patients were excluded because of missing data. Any changes of intrathecal medication or application mode and the appearance of adverse events were collected.

Results

During the observation time, 30 patients received the first pump implantation and 41 patients had already been implanted before (27 battery-driven, 14 gas-driven devices). Pump exchanges were necessary in 56 patients for the first, in 15 patients for the second or more times. The most common cause for an exchange after a running period of approximately 6 years was battery depletion (n=51) of battery-driven pump devices.

Chronic pain was initially treated as intrathecal monotherapy with morphine in 26, ziconotide in six patients and hydromorphone in one patient. In three patients, morphine was combined with clonidine (n=2) or ziconotide (n=1) and in one case with baclofen for pain and spasticity treatment. All other patients (n=34) with spastic symptoms received baclofen monotherapy. After initial implantation a continuous application mode of the daily dosage was programmed. A flexible mode of drug delivery was used in three, a personal therapy manager in four patients. Adverse drug reactions were averted by dosage adjustments or a change of the intrathecal drug.

Complications were documented in 20 patients as follows: pump dysfunction/dislocation (n=18), spinal catheter disconnection/occlusion (n=14), wound healing disorder (n=5) or drug induced events (n=4).

Discussion

The long-term ITT was effective in controlling pain and spasticity, even over the lifetime of a pump device. Any exchanges were indicated, necessary and desired by the patients. The average time up to pump exchange is comparable to data from other publications. Occurrence of adverse events is usually managed by dosage adjustments or surgical revisions.

Conclusions

The evaluation of this single-center cohort demonstrates that the long-term ITT of chronic pain and severe spasticity is appropriate, safe and efficient. Although, continuous follow-ups are mandatory for warranting a successful management of ITT and troubleshooting in case of adverse events.

References

None

Learning Objectives

1. Long-term intrathecal therapy of chronic pain and severe spasticity is appropriate, safe and efficient.

2. Pump exchanges due to battery depletion should be performed after 6 years.

3. Continuous follow-ups are mandatory for warranting a successful management of ITT and troubleshooting in case of adverse events.