Definition of Implanted Neurological Device Abandonment: A Systematic Review and Consensus Statement

Importance

Establishing a formal definition for neurological device abandonment has the potential to reduce or to prevent the occurrence of this abandonment.

Objective

To perform a systematic review of the literature and develop an expert consensus definition for neurological device abandonment.

Evidence Review

After a Royal Society Summit on Neural Interfaces (September 13-14, 2023), a systematic English language review using PubMed was undertaken to investigate extant definitions of neurological device abandonment. Articles were reviewed for relevance to neurological device abandonment in the setting of deep brain, vagal nerve, and spinal cord stimulation. This review was followed by the convening of an expert consensus group of physicians, scientists, ethicists, and stakeholders. The group summarized findings, added subject matter experience, and applied relevant ethics concepts to propose a current operational definition of neurological device abandonment. Data collection, study, and consensus development were done between September 13, 2023, and February 1, 2024.

Findings

The PubMed search revealed 734 total articles, and after review, 7 articles were found to address neurological device abandonment. The expert consensus group addressed findings as germane to neurological device abandonment and added personal experience and additional relevant peer-reviewed articles, addressed stakeholders' respective responsibilities, and operationally defined abandonment in the context of implantable neurotechnological devices. The group further addressed whether clinical trial failure or shelving of devices would constitute or be associated with abandonment as defined. Referential to these domains and dimensions, the group proposed a standardized definition for abandonment of active implantable neurotechnological devices.

Conclusions and Relevance

This study's consensus statement suggests that the definition for neurological device abandonment should entail failure to provide fundamental aspects of patient consent; fulfill reasonable responsibility for medical, technical, or financial support prior to the end of the device's labeled lifetime; and address any or all immediate needs that may result in safety concerns or device ineffectiveness and that the definition of abandonment associated with the failure of a research trial should be contingent on specific circumstances.

OC-087 PAIN AND INFLAMMATORY SIGNALLING IN TACKOMESH TRIAL PARTICIPANTS FOLLOWING ELECTIVE LAPAROSCOPIC INCISIONAL HERNIA REPAIR WITH INTRAPERITONEAL ONLAY MESH (IPOM) AND SPIRAL-TACK MESH FIXATION

Background

The aim of this study was to investigate for links between reported pain and inflammation within a sub-cohort of patients undergoing the IPOM plus repair through the measurement of serum/plasma levels of established inflammatory biomarkers in trial participants across 1-year follow up.

Methods

22 patients (12 Protack™ and 10 Reliatack™) within the TACKoMesh randomised controlled trial underwent serial blood sampling as part of their follow up. A panel of pro- and anti-inflammatory biomarkers were assayed using Luminex multiplex assays and ELISAs. Circulating biomarker concentrations were described and compared in the context of clinical and patient reported outcome data that was obtained within the trial.

Results

An increase in the serum concentration of pro- (IL-6 and CRP) and anti- (IL-10) inflammatory biomarkers was seen following IPOM plus repair. Serum IL-6 and CRP were significantly raised compared to baseline at post-operative Days 1, 6 and 30 (p < 0.05). Markers of onward signalling (Cortisol and TNF-alpha) and tissue repair (PDGF-AA and VEGF) showed a trend towards an elevation at similar timepoints (notably at post-op Day 6) but were not significantly different from baseline levels. There were no observed correlations between inflammatory signal and reported pain, treatment allocation within the trial, burden of implanted prosthetic material, or hernia recurrence.

Discussion

This study demonstrates the novel finding of a pro-inflammatory signal at post-operative Day 30 following the IPOM plus repair.

OC-088 CAN PROCOLLAGEN I AND PROCOLLAGEN III SERVE AS PREDICTIVE BIOMARKERS FOR INCISIONAL HERNIA RECURRENCE?

Background

The aim of this study was to determine the temporal evolution of extracellular matrix (ECM) remodelling and collagen biomarkers and their influence on incisional hernia recurrence after the IPOM plus repair.

Methods

A sub-cohort of patients (n=25) undergoing laparoscopic incisional hernia repair within the TACKoMesh randomised controlled trial were bled at serial timepoints up to 1-year following surgery. Serum/plasma concentration of biomarkers (Procollagen I, Procollagen III, Fibronectin, TGF-beta, MMP-2, MMP-9, TIMP-1, and TIMP-2) were quantified using ELISA and Luminex multiplex techniques. Data were described and compared between groups that developed and remained free from recurrence using R statistical software.

Results

Procollagen I was reduced relative to baseline on post-op Day 1 but increased at Days 6 and 30 (p<0.05). Procollagen III showed an elevation at Day 30. Lower levels of Procollagen I were detected at Day 0, Day 1 and Day 6 (p<0.05) and higher levels of Procollagen III at Day 0, Day 1, Day 6 and Day 30 (p<0.05) in patients with a recurrence.

Fibronectin was reduced at Day 1 and 6 (p<0.05) whilst TGF-β was increased at Day 30 (p<0.05). MMP-2 and its inhibitor TIMP-2 were reduced at post-operative Day 1 (p<0.05). MMP-9 was persistently higher than baseline (p<0.05) at all timepoints. TIMP-1 was elevated at post-op Days 6 and 30. No differences were found in the circulating concentrations of these biomarkers to predict a recurrence.

Conclusion

In patients that developed incisional hernia recurrence, low levels of Procollagen I and high levels of Procollagen III were detected.

P-112 PRE-OPERATIVE PAIN AND REDUCED QUALITY OF LIFE SCORES IN PATIENTS THAT REPORT PERSISTENT PAIN AT 365 DAYS FOLLOWING LAPAROSCOPIC INCISIONAL HERNIA REPAIR

Background

​The use of patient reported outcome measures (PROMs) for incisional hernia has been established. This study aims to explore relationships between persistent pain at Day365 post laparoscopic-IPOM repair and other clinical and patient-reported data for patients within the TACKoMESH randomised trial.

Methods

Clinical, operative and PROMs data were collected pre-operatively and at four post-operative time points up to one year. Pain scores were measured using a visual analogue scale (VAS). Quality of life (QoL) data were measured using the short-form 36 (SF-36) and Carolina Comfort Score (CCS). Patients reporting pain ‘at rest’ at Day365 were compared with those reporting no pain. Statistical analysis was undertaken in R studio.

Results

54/63 trial participants attended followed up at Day365; 36 were male, and mean age was 59.1.

10 patients reported persistent pain at Day365 ranging from 1–9 on VAS. Patients were found to have reported higher pre-operative pain scores ‘at rest’ (5 [2–7] vs 0 [0–3] p=0.0181) and ‘on activity’ (8.5 [5–10] vs 4 [2–8] p=0.0181). They reported lower QoL scores in every domain on the SF-36, with significantly lower score for social function (50 [31–50] vs 75 [63–100] p=0.006).

Those reporting persistent pain at Day365 were more likely to have developed hernia recurrence (4 vs 3 p=0.0171). There were no significant differences in baseline characteristics, operative variables, and other complication rates between the groups.

Conclusion

Patients that report persistent pain at Day365 following laparoscopic-IPOM repair are more likely to have reported higher pain and lower QoL scores at pre-operative assessment.

OC-086 COMPARISON OF MESH-FIXATION TECHNIQUES IN LAPAROSCOPIC REPAIR OF INCISIONAL HERNIA, RELIATACK™ V PROTACK™ (TACKOMESH) NCT 03434301

Background

A study examining post-op pain, comparing permanent versus absorbable tack fixation devices, Protack™ versus Reliatack™, in IPOM plus repair.

Methods

TACKoMesh is a single-centre double-blind RCT conducted from 2017–2020 with 1-year follow up. Patients were randomised to either Protack™ (titanium tacks) or Reliatack™ (an articulating-arm with dissolvable tacks). Primary outcome was reported pain on activity at Day30. Secondary outcomes include recurrence and quality of life measures (SF-36 & Carolina Comfort Score).

Results

67 patients randomised: 36 with Protack™, 27 with Reliatack™, with 4 conversions. No significant difference in reported pain ‘on activity’ (post-operative Day 1, 6, 30 and 365). There was significantly reduced pain ‘at rest’ on Day1 with Reliatack™ (Protack™ 6 [4 to 9] vs Reliatack™ 4 [3 to 5], p = 0.020) and reduced pain at all other points with Reliatack™.

Operation (p = 0.001) & mesh-fixation (p = 0.001) times were longer, with more knots (p = 0.001) & tacks (p = 0.001) used with Reliatack™.

Entire cohort hernia recurrence, seroma formation, SSI & Clavien-Dindo Grade III-V complication were 8/63 (12.7%), 33/63 (52.4%), 7/63 (11.1%), and 12/63 (19.1%) respectively. There were no significant differences in these outcomes between the treatment groups. CCS showed improvement from post-op Day30 to 365. SF36 showed a reduction in baseline scores at post-op Day30.

Conclusion

There is no difference in reported pain ‘on activity’ following elective IPOM plus hernia repair when choosing either Protack™ or Reliatack™. There is a trend towards improved post-op pain ‘at rest’ with Reliatack™.

Positive genetic correlation between parasite resistance and body size in a free-living ungulate population

Parasite resistance and body size are subject to directional natural selection in a population of feral Soay sheep (Ovis aries) on the island of St. Kilda, Scotland. Classical evolutionary theory predicts that directional selection should erode additive genetic variation and favor the maintenance of alleles that have negative pleiotropic effects on other traits associated with fitness. Contrary to these predictions, in this study we show that there is considerable additive genetic variation for both parasite resistance, measured as fecal egg count (FEC), and body size, measured as weight and hindleg length, and that there are positive genetic correlations between parasite resistance and body size in both sexes. Body size traits had higher heritabilities than parasite resistance. This was not due to low levels of additive genetic variation for parasite resistance, but was a consequence of high levels of residual variance in FEC. Measured as coefficients of variation, levels of additive genetic variation for FEC were actually higher than for weight or hindleg length. High levels of additive genetic variation for parasite resistance may be maintained by a number of mechanisms including high mutational input, balancing selection, antagonistic pleiotropy, and host-parasite coevolution. The positive genetic correlation between parasite resistance and body size, a trait also subject to sexual selection in males, suggests that parasite resistance and growth are not traded off in Soay sheep, but rather that genetically resistant individuals also experience superior growth.

Density-dependent variation in lifetime breeding success and natural and sexual selection in Soay rams

Variation in male lifetime breeding success (LBS) is central to understanding selection, yet it has rarely been measured in natural populations of large mammals. Here, we first describe variation in the opportunity for selection in cohorts of Soay rams (Ovis aries) on the archipelago of St. Kilda, Scotland, that were born during years of varying population density. Variation in LBS is closely coupled with demography, as rams born in years of low density following population crashes enjoy greater LBS than do those born in high-density years. Paradoxically, the opportunity for selection was greatest in the largest cohorts, those born in years of high population density, owing to low juvenile breeding success and overwinter survival. Variation in longevity and the contribution of nonbreeders were the most important components of the total variance in LBS in cohorts born in years of high density, while variation in fecundity was more important in cohorts born in low-density years. The opportunity for sexual selection is thus stronger in cohorts born in low-density years, as many rams in these cohorts survive to compete for mates as adults in subsequent ruts. Variation in population density in the year of birth also influenced the intensity of selection. Individuals born in years of high population density underwent strong natural selection in favor of longer hindlimbs over their first winter. In contrast, in cohorts born in low-density years, there was no natural selection on hindlimb in the first year of life. Longer hindlimbs were associated with increased fecundity over the entire lifetime of individuals born in low-density years. Natural and sexual selection thus act on the same trait in the same direction at different life-history stages in Soay rams, depending on the population density experienced in the year of birth.

Long-term efficacy of continuing hepatitis B vaccination in infancy in two Gambian villages

In 1984, all non-immune children under the age of 5 years in the Gambian villages of Keneba and Manduar were vaccinated against hepatitis B virus (HBV). All children born in these villages since 1984 have been vaccinated in infancy. Despite a rapid fall in antibody concentrations, vaccine efficacy against HBV infection and chronic carriage of HBsAg has increased with time. Overall, vaccine efficacies in 1993 against HBV infection and chronic HBsAg carriage were 94.7% (95% Cl 93.0-96.0) and 95.3% (91.0-97.5), respectively. Breakthrough infections in vaccinated children largely originate from chronic HBsAg carriers. Thus, we tested 261 chronic carriers for HBV DNA and e antigen. The prevalence of these markers of infectivity, and the amount of HBV DNA, decreased greatly with age. Detailed studies of breakthrough infections over two 4-year periods revealed that in the second period there were fewer than half the expected numbers of infections. Our findings suggest that in Keneba and Manduar long-term vaccination is progressively decreasing HBV transmission by chronic carriers, since their infectivity diminishes with time.

Further evidence for the long distance dispersal of taeniid eggs

Autopsy of Soay Sheep on St. Kilda revealed the presence of cysticerci of Taenia hydatigena despite the absence of the definitive host on the island. Both the intensity of infection and the prevalence increased with age implying that the sheep did not acquire immunity to reinfection or superinfection. The sheep on average ingested approximately 2.4 eggs per annum. This is far below that expected if an infected dog had visited the island even on a single occasion. The data provide evidence that taeniid eggs are being transported against the prevailing wind by wildlife from at least the nearest inhabited land mass to St Kilda some 60 km distant.

Unification using a distributed representation

In the neural network and artificial intelligence research communities at the moment there is an ongoing debate about the representational adequacy of neural networks versus that of classical symbolic systems. Supporters of the classical symbolic AI paradigm argue that systems such as neural networks using a distributed representation do not have the compositionality required to perform structure-sensitive logical tasks. Supporters of the neural network paradigm point to the difficulty symbolic systems have in generalising to novel inputs. We have investigated performing variable binding with a distributed representation by using a neural network to perform unification. The successful performance of this task adds further evidence to the assertion that neural networks using distributed representations can be used to perform complex structure-sensitive tasks.

Glucocorticoid stimulation of tetrahydrobiopterin levels and phenylalanine hydroxylase activity in rat hepatoma cells

Incubation of H4-II-E-C3 rat hepatoma cells with either hydrocortisone or dexamethasone resulted in 3- to 5-fold increases in the levels of both phenylalanine hydroxylase and its essential cofactor, tetrahydrobiopterin. Maximum elevation of phenylalanine hydroxylase was noted after 24 h of incubation, whereas significant increases in tetrahydrobiopterin were found only after 48 h exposure of the cells to glucocorticoids. Removal of hormone from the culture medium resulted in rapid loss of cell tetrahydrobiopterin, but a much slower decline in the level of phenylalanine hydroxylase. Thus, although the levels of both phenylalanine hydroxylase and tetrahydrobiopterin in rat hepatoma cells are regulated by glucocorticoids, this regulation is apparently not strictly coordinated. Nevertheless, control of cellular tetrahydrobiopterin levels may be an important regulator of hepatic phenylalanine catabolism since significant increases in the ability of intact rat liver cells to hydroxylate phenylalanine were observed only after 48 h exposure to glucocorticoids, in correlation with increases in cell tetrahydrobiopterin content.