Transcutaneous sacral nerve stimulation for intraoperative verification of internal anal sphincter innervation.

BACKGROUND: The current standard for pelvic intraoperative neuromonitoring (pIONM) is based on intermittent direct nerve stimulation. This study investigated the potential use of transcutaneous sacral nerve stimulation for non-invasive verification of pelvic autonomic nerves. METHODS: A consecutive series of six pigs underwent low anterior rectal resection. For transcutaneous sacral nerve stimulation, an array of ten electrodes (cathodes) was placed over the sacral foramina (S2 to S4). Anodes were applied on the back, right and left thigh, lower abdomen, and intra-anally. Stimulation using the novel method and current standard were performed at different phases of the experiments under electromyography of the autonomic innervated internal anal sphincter (IAS). KEY RESULTS: Transcutaneous stimulation induced increase of IAS activity could be observed in each animal under specific cathode-anode configurations. Out of 300 tested configurations, 18 exhibited a change in the IAS activity correlated with intentional autonomic nerve damage. The damage resulted in a significant decrease of the relative area under the curve of the IAS frequency spectrum (P<.001). Comparison of the IAS spectra under transcutaneous and direct stimulation revealed no significant difference (after rectal resection: median 5.99 µV•Hz vs 7.78 µV•Hz, P=.12; after intentional nerve damage: median -0.27 µV•Hz vs 3.35 µV•Hz, P=.29). CONCLUSIONS AND INFERENCES: Non-invasive selective transcutaneous sacral nerve stimulation could be used for verification of IAS innervation.

Consensus statement on prevention and management of adverse effects following rejuvenation procedures with hyaluronic acid-based fillers.

Facial fillers play an important role in the correction of facial changes associated with ageing. They offer quick treatments in the outpatient setting with minimal subsequent downtime that provide predictable, natural-looking, long-lasting results. Adverse reactions after hyaluronic acid injections tend to be mild or moderate and rather temporary. However, as with all injected or implanted biomaterials, severe adverse events can occur and patients must be fully informed of potential risks prior to undergoing treatment. A panel of experts from Germany (D), Austria (A) and Switzerland (CH) developed recommendations, and this study provides the 'DACH Consensus Recommendations' from this group specifically on the use of hyaluronic acid fillers. The aim is to help clinicians recognize potential risks and to provide guidance on how best to treat adverse events if they arise. Contraindications to hyaluronic acid fillers are also detailed, and ways to prevent adverse events occurring are discussed. Hyaluronic acid-based products are claimed to be very close to an ideal tissue augmentation agent; nevertheless, profound medical, anatomical and product knowledge are of paramount importance to minimize the occurrence of adverse reactions.

Precaution for volume conduction in rodent cortical electroencephalography using high-density polyimide-based microelectrode arrays on the skull.

In humans, significant progress has been made to link spatial changes in electroencephalographic (EEG) spectral density, connectivity strength, and phase-amplitude modulation to neurological, physiological, and psychological correlates. In contrast, standard rodent EEG techniques employ only few electrodes, which results in poor spatial resolution. Recently, a technique was developed to overcome this limitation in mice. This technique was based on a polyimide-based microelectrode (PBM) array applied on the mouse skull, maintaining a significant number of electrodes with consistent contact, electrode impedance, and mechanical stability. The present study built on this technique by extending it to rats. Therefore, a similar PBM array, but adapted to rats, was designed and fabricated. In addition, this array was connected to a wireless EEG headstage, allowing recording in untethered, freely moving rats. The advantage of a high-density array relies on the assumption that the signal recorded from the different electrodes is generated from distinct sources, i.e., not volume-conducted. Therefore, the utility and validity of the array were evaluated by determining the level of synchrony between channels due to true synchrony or volume conduction during basal vigilance states and following a subanesthetic dose of ketamine. Although the PBM array allowed recording with high signal quality, under both drug and drug-free conditions, high synchronization existed due to volume conduction between the electrodes even in the higher spectral frequency range. Discrimination existed only between frontally and centrally/distally grouped electrode pairs. Therefore, caution should be used in interpreting spatial data obtained from high-density PBM arrays in rodents.

Is intraoperative neuromonitoring associated with better functional outcome in patients undergoing open TME? Results of a case-control study.

AIMS: Intraoperative neuromonitoring (IONM) aims to control nerve-sparing total mesorectal excision (TME) for rectal cancer in order to improve patients' functional outcome. This study was designed to compare the urogenital and anorectal functional outcome of TME with and without IONM of innervation to the bladder and the internal anal sphincter. METHODS: A consecutive series of 150 patients with primary rectal cancer were analysed. Fifteen match pairs with open TME and combined urogenital and anorectal functional assessment at follow up were established identical regarding gender, tumour site, tumour stage, neoadjuvant radiotherapy and type of surgery. Urogenital and anorectal function was evaluated prospectively on the basis of self-administered standardized questionnaires, measurement of residual urine volume and longterm-catheterization rate. RESULTS: Newly developed urinary dysfunction after surgery was reported by 1 of 15 patients in the IONM group and by 6 of 15 in the control group (p = 0.031). Postoperative residual urine volume was significantly higher in the control group. At follow up impaired anorectal function was present in 1 of 15 patients undergoing TME with IONM and in 6 of 15 without IONM (p = 0.031). The IONM group showed a trend towards a lower rate of sexual dysfunction after surgery. CONCLUSIONS: In this study TME with IONM was associated with significant lower rates of urinary and anorectal dysfunction. Prospective randomized trials are mandatory to evaluate the definite role of IONM in rectal cancer surgery.

Connections of the superior colliculus to shoulder muscles of the rat: a dual tracing study.

Previous investigations indicate that the superior colliculus (SC) is involved in the initiation and execution of forelimb movements. In the present study we investigated the tectofugal, in particular the tecto-reticulo-spinal projections to the shoulder and arm muscles in the rat. We simultaneously retrogradely labeled the premotor neurons in the brainstem by injection of the pseudorabies virus PrV Bartha 614 into the m. rhomboideus minor and m. acromiodeltoideus, and anterogradely visualized the tectofugal projections by intracollicular injection of the tracer FITC dextrane. Our results demonstrate that the connection of the SC to the skeletal muscles of the forelimb is at least trisynaptic. This was confirmed by long survival times after virus injections into the muscles (98-101 h) after which numerous neurons in the deep layers of the SC were labeled. Transsynaptically retrogradely labeled brainstem neurons connected disynaptically to the injected muscles with adjacent tectal terminals were predominantly located in the gigantocellular nuclear complex of the reticular formation. In addition, putative relay neurons were found in the caudal part of the pontine reticular nucleus. Both tectal projections to the nucleus gigantocellularis and the pontine reticular nucleus were bilateral but ipsilaterally biased. We suggest this projection to be involved in more global functions in motivated behavior like general arousal allowing fast voluntary motor activity.

Evaluation of two-dimensional intraoperative neuromonitoring for predicting urinary and anorectal function after rectal cancer surgery.

PURPOSE: The aim of this study was to compare the results of two-dimensional intraoperative neuromonitoring (IONM) with the postoperative urinary and anorectal function of rectal cancer patients. METHODS: A consecutive series of 35 patients undergoing low anterior resection were investigated prospectively. IONM was performed with electric stimulations of the pelvic splanchnic nerves under simultaneous manometry of the bladder and electromyography (EMG) of the internal anal sphincter (IAS). Urinary and anorectal function were evaluated preoperatively and at follow-up by standardized questionnaires, digital rectal examination scoring system, and long-term catheterization rate. RESULTS: The rate of postoperative newly developed bladder dysfunction was 17 %. IONM with bladder manometry had a sensitivity of 100 %, specificity of 96 %, positive predictive value of 83 %, negative predictive value of 100 %, and overall accuracy of 97 %, respectively. The proportion of patients with severely impaired anorectal function at follow-up was 8 %. The sensitivity, specificity, and positive and negative predictive values for IONM with EMG of the IAS were, respectively, 100, 96, 67, and 100 % with an accuracy of 96 %. The degree of agreement for IONM with EMG of the IAS was good for anorectal function (к = 0.780) and poor for urinary function (к = 0.119). IONM with bladder manometry yielded a very good degree of agreement for urinary function (к = 0.891) and a fair agreement for anorectal function (к = 0.336). CONCLUSIONS: The two-dimensional IONM method is suitable for verification of bladder and IAS innervation. Accurate prediction of urinary and anorectal function necessitates both bladder manometry and EMG of the IAS.

Continuous intraoperative monitoring of autonomic nerves during low anterior rectal resection: an innovative approach for observation of functional nerve integrity in pelvic surgery.

PURPOSE: The aim of this study was to develop a methodological setup for continuous intraoperative neuromonitoring with intent to improve nerve-sparing pelvic surgery. METHODS: Fourteen pigs underwent low anterior rectal resection. Continuous stimulation of pelvic autonomic nerves was carried out with a newly developed tripolar surface electrode during lateral, anterolateral, and anterior mesorectal dissection. Neuromonitoring was performed under electromyography of the autonomic innervated internal anal sphincter. RESULTS: Continuous neuromonitoring resulted in significantly increased electromyographic amplitudes of the internal anal sphincter, confirming intact innervation throughout the whole dissection in each animal (median 0.9 µV, interquartile range 0.5; 1.5 vs. median 3.4 µV, interquartile range 2.1; 4.7) (p < 0.001). The median dissection time in each animal was 10 min within a median number of ten (range 8-13) tripolar electric stimulations. CONCLUSION: The present study is the first to demonstrate that continuous intraoperative monitoring of pelvic autonomic nerves during low anterior rectal resection is feasible.

Effect of feature-selective attention on neuronal responses in macaque area MT.

Attention influences visual processing in striate and extrastriate cortex, which has been extensively studied for spatial-, object-, and feature-based attention. Most studies exploring neural signatures of feature-based attention have trained animals to attend to an object identified by a certain feature and ignore objects/displays identified by a different feature. Little is known about the effects of feature-selective attention, where subjects attend to one stimulus feature domain (e.g., color) of an object while features from different domains (e.g., direction of motion) of the same object are ignored. To study this type of feature-selective attention in area MT in the middle temporal sulcus, we trained macaque monkeys to either attend to and report the direction of motion of a moving sine wave grating (a feature for which MT neurons display strong selectivity) or attend to and report its color (a feature for which MT neurons have very limited selectivity). We hypothesized that neurons would upregulate their firing rate during attend-direction conditions compared with attend-color conditions. We found that feature-selective attention significantly affected 22% of MT neurons. Contrary to our hypothesis, these neurons did not necessarily increase firing rate when animals attended to direction of motion but fell into one of two classes. In one class, attention to color increased the gain of stimulus-induced responses compared with attend-direction conditions. The other class displayed the opposite effects. Feature-selective activity modulations occurred earlier in neurons modulated by attention to color compared with neurons modulated by attention to motion direction. Thus feature-selective attention influences neuronal processing in macaque area MT but often exhibited a mismatch between the preferred stimulus dimension (direction of motion) and the preferred attention dimension (attention to color).

Selective pelvic autonomic nerve stimulation with simultaneous intraoperative monitoring of internal anal sphincter and bladder innervation.

BACKGROUND: Pelvic autonomic nerve preservation avoids postoperative functional disturbances. The aim of this feasibility study was to develop a neuromonitoring system with simultaneous intraoperative verification of internal anal sphincter (IAS) activity and intravesical pressure. METHODS: 14 pigs underwent low anterior rectal resection. During intermittent bipolar electric stimulation of the inferior hypogastric plexus (IHP) and the pelvic splanchnic nerves (PSN), electromyographic signals of the IAS and manometry of the urinary bladder were observed simultaneously. RESULTS: Stimulation of IHP and PSN as well as simultaneous intraoperative monitoring could be realized with an adapted neuromonitoring device. Neurostimulation resulted in either bladder or IAS activation or concerted activation of both. Intravesical pressure increase as well as amplitude increase of the IAS neuromonitoring signal did not differ significantly between stimulation of IHP and PSN [6.0 cm H(2)O (interquartile range [IQR] 3.5-9.0) vs. 6.0 cm H(2)O (IQR 3.0-10.0) and 12.1 µV (IQR 3.0-36.7) vs. 40.1 µV (IQR 9.0-64.3)] (p > 0.05). CONCLUSIONS: Pelvic autonomic nerve stimulation with simultaneous intraoperative monitoring of IAS and bladder innervation is feasible. The method may enable neuromonitoring with increasing selectivity for pelvic autonomic nerve preservation.

Online signal processing of internal anal sphincter activity during pelvic autonomic nerve stimulation: a new method to improve the reliability of intra-operative neuromonitoring signals.

AIM: Intra-operative neuromonitoring is increasingly applied in several surgical disciplines and has been introduced to facilitate pelvic autonomic nerve preservation. Nevertheless, it has been considered a questionable tool for the minimization of risk, as the results are variable and might be misleading. The aim of the present experimental study was to develop an intra-operative neuromonitoring system with improved reliability for monitoring pelvic autonomic nerve function. METHOD: Fifteen pigs underwent low anterior rectal resection with pelvic autonomic nerve preservation. Intra-operative neuromonitoring was performed under autonomic nerve stimulation with observation of electromyographic signals of the internal anal sphincter and bladder manometry. As the internal anal sphincter frequency spectrum during stimulation was found to be mainly in the range of 5-20 Hz, intra-operative neuromonitoring signals were postoperatively processed by implementation of matching band pass filters. RESULTS: In 10 preliminary experiments, signal processing was performed offline in the postoperative analysis. Of 163 stimulations intra-operatively assessed by the surgeon as positive responses, 135 (83%) were confirmed after signal processing. In the following five consecutive experiments intra-operative online signal processing was realized and demonstrated reliable intra-operative neuromonitoring signals of internal anal sphincter activity with significant increase during pelvic autonomic nerve stimulation [0.5 µV (interquartile range = 0.3-0.7) vs 4.8 µV (interquartile range = 2.5-7.5); P < 0.001]. CONCLUSION: Online signal processing of internal anal sphincter activity aids reliable identification of pelvic autonomic nerves with potential for improvement of intra-operative neuromonitoring in pelvic surgery.

Design and realization of a wireless sensor gateway for health monitoring.

This paper describes the design and realization of a wireless sensor gateway (WSG) within a wireless sensor network (WSN) for health monitoring. The WSN allows recording and wireless transmission of biosignals, namely the electrocardiogram, pulse wave and body weight, which are important parameters for cardiovascular monitoring. These can be displayed, analysed, and saved on the WSG through a user interface based on a touch screen. The proposed WSG has the distinctive feature of using two different radio transceivers, exploiting the advantages of each device. Currently, most personal computers and handhelds have standardized Bluetooth interfaces (IEEE 802.15.1) but not ZigBee interfaces (IEEE 802.15.4). Hence, the proposed gateway is designed to receive data from wireless sensors through its ZigBee interface and to forward them to a personal computer via its Bluetooth interface. This feature, combined with simple touch screen menu navigation will reach increased patient compliance and consequently increased benefit for patient in terms of healthcare and safety.

Low power wireless acquisition module for wearable health monitoring systems.

This paper presents a low power wireless acquisition module for use within wearable health monitoring systems and Ambient Assisted Living applications. The acquisition module provides continuous monitoring of the user's electrocardiogram (ECG) and activity, as well as the local temperature at the module. The module is placed on the chest of the user, and its wearability is achieved due to its fabrication based on a flexible PCB, and by the complete absence of connecting wires, as a result of the integration of flexible and dry ECG monitoring electrodes on the acquisition module, which do not require preparation with electrolyte gel. The design of the acquisition module also aimed for the minimization of power consumption to enable long-term continuous monitoring, namely concerning the wireless link, for which a proprietary low power solution was adopted. A low power analog frontend was custom designed for single-lead ECG monitoring, achieving a current consumption of 220 εA. The wireless acquisition module has a current consumption down to 1.3 mA while processing the acquisition of sensor data, and 4 mA when the wireless transceiver is active.

Intrafascicular thin-film multichannel electrodes for sensory feedback: Evidences on a human amputee.

The performance of motor neuroprostheses or robotic arm prostheses can be significantly improved by delivering sensory feed-back related to the ongoing motor task (e.g. the slippage of an object during grasping). Microfabricated neural electrodes implantable in peripheral nervous system seem a promising approach to this aim. New generation of thin-film intrafascicular electrodes longitudinally implantable in peripheral nerves (tf-LIFE4) has been developed and tested for afferent stimulation in human amputee case study.

On the control of a robot hand by extracting neural signals from the PNS: preliminary results from a human implantation.

The development of hybrid neuroprosthetic systems (HBSs) linking the human nervous system with artificial devices is an important area of research that is currently addressed by several groups to restore sensorimotor function in people affected by different disabilities. It is particularly important to establish a fast, intuitive, bidirectional flow of information between the nervous system of the user and the smart robotic device. Among the possible solutions to achieve this goal, interfaces with the peripheral nervous system and in particular intraneural electrodes can represent an interesting choice. In the present study, thin-film longitudinal intra-fascicular electrodes were implanted in the median and ulnar nerves of an amputee. The possibility of restoring the bidirectional link between the subject and the external world was investigated during a 4 week trial. The result showed that both the extraction of motor information and the restoration of sensory function are possible.

Visual response properties of neurons in cortical areas MT and MST projecting to the dorsolateral pontine nucleus or the nucleus of the optic tract in macaque monkeys.

Neurons in cortical medial temporal area (MT) and medial superior temporal area (MST) projecting to the dorsolateral pontine nucleus (DLPN) and/or to the nucleus of the optic tract and dorsal terminal nucleus (NOT-DTN) were identified by antidromic electrical stimulation in five macaque monkeys. Neurons projecting to either target were located in close proximity to each other, and in all subregions of MT and MST sampled. Only a small percentage of the antidromically identified projection neurons (4.4%) sent branches to both the NOT-DTN and the DLPN. Antidromic latencies of neurons projecting to the NOT-DTN (0.9-6 ms, median 2.1 ms) and to the DLPN (0.8-5 ms, median 2.0 ms) did not differ significantly. Visual response properties of the neurons antidromically activated from either site did not differ significantly from those of cells that were not so activated. On the population level only neurons activated from the NOT-DTN had a clear preference for ipsiversive stimulus movement, whereas the neurons activated from the DLPN and neurons not antidromically activated from either target had no common directional preference. These results are discussed in terms of specification of cortico-subcortical connections and with regard to pathways underlying slow eye movements in different visuomotor behaviours.