A technique for electrically inserting electrode arrays into peripheral nerves

The authors developed a system based on high-frequency cutting methods to facilitate the insertion of multi-dimensional electrode arrays into peripheral nerves. The system incorporates a feedback loop for controlling arc intensity. This should reduce the risk of damage to electrode array and nerve. The high-frequency insertion system (HFIS) was used in a limited number of pilot experiments to insert wire electrodes into the peroneal nerve of the rat. Electrode coating and moistness of the nerve mere found to be very important factors for proper insertion. Recruitment curves obtained with an electrode inserted with the HFIS generally had lower maximum forces and higher threshold currents than curves obtained with a manually inserted electrod

Efficiency of endoneural stimulation with 5- to 24-fold multielectrodes

Optimal selective stimulation of nerve with endoneurally (intrafascicularly) inserted multi-microelectrodes means that each electrode activates, with its own threshold stimulation current, as few distinct motoneurons as possible, preferably only one, If the latter is the case, the efficiency of a multi-electrode is 100%. However, neighbouring electrodes may control the same motor fiber(s), as there are generally more fibers than electrodes and because the position of fibers is largely unknown. In that case, efficiency is less than 100%. This paper reports on experiments in rat peroneal nerve with 5- and 24-fold wire multi-microelectrode arrays, The threshold force of the twitch recruitment curve of the corresponding EDL muscle was used to monitor nerve activation, It was found that on average the threshold force efficiency was 0.48=48%, After re-inspection of the data, taking into account that neighbouring electrodes have a higher probability to activate the same motor units, in contrast to distant electrodes, the average efficiency even rises to 81%. For several reasons, threshold forces do not correspond to motor unit forces, implying that the threshold-force-efficiency can not be regarded as motor-unit-efficienc

Intraneural stimulation using 2D wire-microelectrode arrays: II. Comparison with single-wire electrode results

A two-dimensional wire-microelectrode array was inserted into the peroneal nerve of the rat through an incision. For each of the electrodes in the array the corresponding twitch-force recruitment curve was recorded from the extensor digitorum longus muscle (EDL). The mean value and standard deviation of the threshold current were found to be not significantly different from those for single wire electrodes. This suggests that the incision does not introduce significant (additional) current leakag

Intraneural stimulation using 2D wire-microelectrode arrays: I. Experimental results

A two-dimensional 24-channel wire-microelectrode array was inserted into the peroneal nerve of the rat during acute experiments. The electrodes in the array are on a regular grid of 6 by 4 electrodes; inter-electrode spacing is 120 ¿m. For each of the electrodes in the array the corresponding twitch-force recruitment curve was recorded from the extensor digitorum longus muscle (EDL). A complete set of 24 recruitment curves is presented The shape of the recruitment curves varies among the electrodes in the array. This supports previous findings which suggest a different motor unit recruitment order for stimulating electrodes at different intraneural position

Population Impact of Girls-Only Human Papillomavirus 16/18 Vaccination in the Netherlands: Cross-Protective and Second-Order Herd Effects

Background: Human papillomavirus (HPV) vaccination programs achieve substantial population-level impact, with effects extending beyond protection of vaccinated individuals. We assessed trends in HPV prevalence up to 8 years postvaccination among men and women in the Netherlands, where bivalent HPV vaccination, targeting HPV types 16/18, has been offered to (pre)adolescent girls since 2009 with moderate vaccination coverage. Methods: We used data from the PASSYON study, a survey initiated in 2009 (prevaccination) and repeated biennially among 16-to 24-year-old visitors of sexual health centers. We studied genital HPV positivity from 2009 to 2017 among women, heterosexual men, and unvaccinated women using Poisson generalized estimating equation models, adjusted for individual-and population-level confounders. Trends were studied for 25 HPV types detected by the SPF10-LiPA25 platform. Results: A total of 6354 women (64.7% self-reported unvaccinated) and 2414 heterosexual men were included. Percentual declines in vaccine types HPV-16/18 were observed for all women (12.6% per year [95% confidence interval {CI}, 10.6-14.5]), heterosexual men (13.0% per year [95% CI, 8.3-17.5]), and unvaccinated women (5.4% per year [95% CI, 2.9-7.8]). We observed significant declines in HPV-31 (all women and heterosexual men), HPV-45 (all women), and in all high-risk HPV types pooled (all women and heterosexual men). Significant increases were observed for HPV-56 (all women) and HPV-52 (unvaccinated women). Conclusions: Our results provide evidence for first-order herd effects among heterosexual men against HPV-16/18 and cross-protective types. Additionally, we show second-order herd effects against vaccine types among unvaccinated women. These results are promising regarding population-level and clinical impact of girls-only bivalent HPV vaccination in a country with moderate vaccine uptake