Serial electrodiagnostic studies in acute partial conduction block from cyclist's palsy.

INTRODUCTION/AIMS: To date, there is minimal literature in following resolution of partial conduction block (PCB) in compression neuropathy. We investigated a case of cyclist's palsy with PCB from compression using serial nerve conduction studies to monitor recovery. METHODS: Clinical recovery was monitored concomitant with compound muscle action potential (CMAP) amplitudes that were recorded from 3 ulnar-innervated muscles (first dorsal interosseous [FDI] 6 days post-onset, palmar interosseus [PI] 16 days post-onset, and abductor digiti minimi [ADM]) in both limbs. Sensory nerve conduction studies and needle electromyography were also performed. RESULTS: PCB was demonstrated in the FDI and PI with recordings done proximal and distal to the site of injury. Recovery in the FDI and PI occurred between week 2 and 3 post-onset but continued to improve until about 14 wk post-onset when the CMAP values on the affected side approximated the contralateral side. Sensory conduction studies were normal and symmetric. Needle EMG at 21 days post-injury showed no active denervation and a reduced number of normal-appearing motor unit potentials firing >16 Hz that reverted to a normal pattern on final study at 99 days post-onset. DISCUSSION: This study shows how rapidly PCB may initially resolve although full recovery takes longer. Criteria for defining PCB may be misleading when doing nerve conductions and comparing only the evoked responses below and above the block. To fully characterize PCB, it is important to optimize the position of the active recording electrode (E1) as well as compare results with the unaffected side.

Optimization of Intraoperative Neural Monitoring of the Recurrent Laryngeal Nerve in Thyroid Surgery.

The application of intraoperative neural monitoring (IONM) has been widely accepted to improve surgical outcomes after thyroid surgery. The malfunction of an IONM system might interfere with surgical procedures. Thus, the development of anesthesia modalities aimed at ensuring functional neuromonitoring is essential. Two key issues should be taken into consideration for anesthetic management. Firstly, most patients undergo recurrent laryngeal nerve monitoring via surface electrodes embedded in an endotracheal tube. Thus, advanced video-assisted devices might optimize surface electrode positioning for improved neuromonitoring signaling accuracy. Secondly, neuromuscular blocking agents are routinely used during thyroid surgery. The ideal neuromuscular block should be deep enough for surgical relaxation at excision and recovered enough for an adequate signal f nerve stimulation. Proper neuromuscular block management could be achieved by titration doses of muscle relaxants and reversal agents.

Efficacy of transcutaneous perineal electrostimulation versus intracavitary anal electrostimulation in the treatment of urinary incontinence after a radical prostatectomy: Randomized controlled trial.

AIM: To compare the efficacy of the treatment with transcutaneous perineal electrostimulation versus intracavitary electrostimulation to reduce the frequency of urinary incontinence after radical prostatectomy and the impact on the quality of life (QoL). METHODS: This single-blind equivalence-randomized controlled trial equally (1:1) randomly allocated men with urinary incontinence post radical prostatectomy into surface electrodes perineal group (intervention group, IG) and intra-anal probe group (control group, CG). Outcomes included changes in the 24h-Pad Test (main variable), and ICIQ-SF (International Consultation on Incontinence Questionnaire Short-Form), SF-12 (Short Form Health Survey), and I-QOL (incontinence quality of life questionnaire) questionnaires. Clinical data were collected at baseline, 6 and 10 weeks. For the comparisons between variables, χ2 test and Student's t test were used. Equivalence was analyzed by estimating the mean change (90% confidence interval) of urinary incontinence based on the Pad Test. The analysis was performed for the per-protocol and the intention-to-treat populations. Statistical significance level was set at p < 0.05. RESULTS: Seventy patients were included, mean age 62.8 (SD 9.4) years. Mean baseline 24h-Pad Test was 328.3 g (SD 426.1) and a significant decrease (p < 0.001) in the grams of urine loss at 5 weeks (159.1 g in the IG and 121.7 g in the CG), and at 10 weeks of treatment (248.5 g in the IG and 235.8 g in the CG) was observed. However, the final difference in the grams of urine loss between both treatments showed the absence of statistical significance (p = 0.874). In both groups, the ICIQ-SF, I-QOL, and SF-12 questionnaires revealed a significant improvement in QoL. CONCLUSION: Surface and intra-anal electrostimulation treatments reduced significantly losses of urine, but differences in grams of urine loss throughout the therapy between groups were not significant, suggesting that the efficacy of the two treatments is not statistically different. Nonetheless, the improvement observed in both groups was statistically significant and clinically relevant.

Efficacy of transcutaneous perineal electrostimulation versus intracavitary anal electrostimulation in the treatment of urinary incontinence after a radical prostatectomy: randomized controlled trial study protocol.

BACKGROUND: Radical prostatectomy is the gold standard treatment for men with localized prostate cancer. This technique is associated with post-operative urinary incontinence. Pelvic floor physiotherapy is a conservative, painless and economical treatment for this specific situation. Kegel exercises and perineal electrostimulation are common techniques to train pelvic floor muscles. The perineal electrostimulation can be applied to the patient with surface electrodes or by an intra-cavitary anal probe. This study proposes that transcutaneous perineal electrostimulation is as effective as intra-cavitary electrostimulation in reducing urinary incontinence secondary to radical prostatectomy. The main objective is to compare the efficacy of the treatment with transcutaneous perineal electrostimulation versus the same intra-cavitary treatment to reduce the magnitude of urinary incontinence after radical prostatectomy, and the impact on the quality of life. METHODS: This single-blind equivalence randomized controlled trial will include 70 man who suffer urinary incontinence post radical prostatectomy. Participants will be randomized into surface electrodes group and intra-anal probe group. The groups will receive treatment for 10 consecutive weeks. Outcomes include changes in the 24-h Pad Test, and ICIQ-SF, SF-12 and I-QoL questionnaires. Clinical data will be collected at baseline, 6 and 10 weeks after the first session, and 6 months after the end of treatment. DISCUSSION: The results will allow us to prescribe the most beneficial perineal electrostimulation technique in the treatment of urinary incontinence derived from radical prostatectomy. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03587402. 27/06/2018.

Phonotactic steering and representation of directional information in the ascending auditory pathway of a cricket.

Directional hearing is crucial for animals depending on acoustic signals to locate a mate. We focused on crickets to explore the reliability of directional information forwarded to the brain by the ascending auditory interneuron AN1, which is crucial for phonotactic behavior. We presented calling song from -45° to +45° in steps of 3° and compared the phonotactic steering of females walking on a trackball with the directional responses of AN1. Forty percent of females showed good steering behavior and changed their walking direction when the speaker passed the body's longitudinal axis. The bilateral latency difference between right and left AN1 responses was small and may not be reliable for auditory steering. In respect to spike count, all AN1 recordings presented significant bilateral differences for angles larger than ±18°, yet 35% showed a mean significant difference of 1-3 action potentials per chirp when the frontal stimulus deviated by 3° from their length axis. For small angles, some females had a very similar AN1 activity forwarded to the brain, but the accuracy of their steering behavior was substantially different. Our results indicate a correlation between directional steering and the response strength of AN1, especially for large angles. The reliable steering of animals at small angles would have to be based on small bilateral differences of AN1 activity, if AN1 is the only source providing directional information. We discuss whether such bilateral response difference at small angles can provide a reliable measure to generate auditory steering commands descending from the brain, as pattern recognition is intensity independent.NEW & NOTEWORTHY The ascending auditory interneuron AN1 has been implicated in cricket auditory steering, but at small acoustic stimulation angles, it does not provide reliable directional information. We conclude that either the small bilateral auditory activity differences of the AN1 neurons are enhanced to generate reliable descending steering commands or, more likely, directional auditory steering is mediated via a thoracic pathway, as indicated by the reactive steering hypothesis.

Adhesive surface electrodes versus needle-based neuromonitoring in lumbar spinal surgery.

Background: The relative safety and more widespread utility of an adhesive surface electrode-based neuromonitoring (ABM) system may reduce the time and cost of traditional needle-based neuromonitoring (NBM). Methods: This retrospective cohort review included one- and two-level transforaminal lumbar interbody fusion procedures (2019-2023). The primary variables studied included were time (in minutes) from patient entry into the operating room (OR) to incision, time from patient entry into the OR to closure, and time from incision to closure. Univariate and bivariate analyses were performed to compare the outcomes between the ABM (31 patients) and NBM (51 patients) modalities. Results: We found no significant differences in the time from patient entry into the OR to incision (ABM: 71.8, NBM: 70.3, P = 0.70), time from patient entry into the OR to closure (ABM: 284.2, NBM: 301.7, P = 0.27), or time from incision to closure (ABM: 212.4, NBM: 231.4, P = 0.17) between the two groups. Further, no patients from either group required reoperation for mal-positioned instrumentation, and none sustained a new postoperative neurological deficit. The ABM approach did, however, allow for a reduction in neurophysiologist-workforce and neuromonitoring costs. Conclusion: The introduction of the ABM system did not lower surgical time but did demonstrate similar efficacy and clinical outcomes, with reduced clinical invasiveness, neurophysiologist-associated workforce, and overall neuromonitoring cost compared to NBM.

Characterization of Benchtop-Fabricated Arrays of Nanowrinkled Surface Electrodes as a Nitric Oxide Electrochemical Sensor.

In this work, we present an accessible benchtop fabrication technique to obtain a planar array of gold nanowrinkled surface electrodes (ANSE) for the construction of electrochemical cells, specifically to monitor soluble biomarkers of interest in cell culture environments. We present a complete characterization of the array and its response as an electrochemical cell. To validate our sensor, we evaluated the device sensitivity to detect nitric oxide (NO), an important molecule produced by endothelial cells as a response to environmental signals such as mechanics and growth factors. While testing measurements of nitric oxide in aqueous solutions with isotonic salt concentrations, we evidenced the influence of the environmental conditions for such electrochemical measurements, showing that the aqueous medium, usually not accounted for, significantly impacts the outcome. Finally, we present the application of the electrochemical sensor for the detection of nitric oxide released from stimulated endothelial cells as a proof of concept.

Pain-related evoked potentials with concentric surface electrodes in patients and healthy subjects: a systematic review.

Pain-related evoked potentials with concentric surface electrodes (PREP with CE) have been increasingly used in the diagnostics of polyneuropathies as well as in pain research. However, the study results are partly inconsistent regarding their utility to distinguish between normal and abnormal findings. The present systematic review aimed to summarise and compare study results, where PREP with CE were used in healthy subjects or patients and to identify possible influencing factors. We found 36 research articles, of which 21 investigated disorders in patients compared to healthy controls, while the other 15 focussed on basic research in healthy subjects. Patients with polyneuropathies showed the most consistent PREP results with similar prolonged latencies and reduced amplitude values. Findings in other patient groups or in healthy subjects were more heterogeneous. There was evidence for an influence by age and height as well as by central effects like emotions, which should be considered in further studies. Further systematic research analysing PREP results depending on individual and disease-specific factors is needed to develop optimal normative values.

Selective zygomaticus muscle activation by ball electrodes in synkinetically reinnervated patients after facial paralysis.

Introduction: Although many different treatments were developed for facial palsy, only a few therapeutic options are available for facial synkinesis. Electrical stimulation of specific muscles via implants could be useful in restoring facial symmetry in synkinetic patients. A challenge in developing stimulation devices is finding the right stimulation location, type, and amplitude. This work assesses the ability to selectively stimulate the zygomaticus muscle (ZYG) in patients with oral-ocular synkinesis to elicit a visually detectable response of the ipsilateral corner of the mouth (COM), without causing a reaction of the orbicularis oculi muscle (OOM). We aimed to assess how close to the COM the stimulation should be delivered in order to be selective. Methods: A total of 10 patients (eight females, two males) were enrolled. Facial function was graded according to the Sunnybrook facial grading system. Needle EMG was used to test the activities of the muscles, during volitional and "unintended" movements, and the degree of synkinesis of the ZYG and OOM. Two ball electrodes connected to an external stimulator were placed on the paretic ZYG, as close as possible to the COM. Results: Independent of the waveform with which the stimulation was presented, a selective ZYG response was observed within 4.5 cm of the horizontal plane and 3 cm of the vertical plane of the COM. When the distance between the electrodes was kept to ≤2 cm, the amplitude necessary to trigger a response ranged between 3 and 6 mA when the stimulation was delivered with triangular pulses and between 2.5 and 3.5 mA for rectangular pulses. The required amplitude did not seem to be dependent on the applied phase duration (PD), as long as the PD was ≥5 ms. Conclusion: Our results show that selective stimulation of the ZYG presenting synkinetic ZYG-OOM reinnervation can be achieved using a broad PD range (25-1,000 ms) and an average amplitude ≤6 mA, which may be further decreased to 3.5 mA if the stimulation is delivered via rectangular rather than triangular waves. The most comfortable and effective results were observed with PDs between 50 and 250 ms, suggesting that this range should be selected in future studies. Clinical Trial Registration: [https://drks.de/search/de/trial/DRKS00019992], identifier (DRKS00019992).

MUNIX repeatability evaluation method based on FastICA demixing.

To enhance the reproducibility of motor unit number index (MUNIX) for evaluating neurological disease progression, this paper proposes a negative entropy-based fast independent component analysis (FastICA) demixing method to assess MUNIX reproducibility in the presence of inter-channel mixing of electromyography (EMG) signals acquired by high-density electrodes. First, composite surface EMG (sEMG) signals were obtained using high-density surface electrodes. Second, the FastICA algorithm based on negative entropy was employed to determine the orthogonal projection matrix that minimizes the negative entropy of the projected signal and effectively separates mixed sEMG signals. Finally, the proposed experimental approach was validated by introducing an interrelationship criterion to quantify independence between adjacent channel EMG signals, measuring MUNIX repeatability using coefficient of variation (CV), and determining motor unit number and size through MUNIX. Results analysis shows that the inclusion of the full (128) channel sEMG information leads to a reduction in CV value by $1.5 \pm 0.1$ and a linear decline in CV value with an increase in the number of channels. The correlation between adjacent channels in participants decreases by $0.12 \pm 0.05$ as the number of channels gradually increases. The results demonstrate a significant reduction in the number of interrelationships between sEMG signals following negative entropy-based FastICA processing, compared to the mixed sEMG signals. Moreover, this decrease in interrelationships becomes more pronounced with an increasing number of channels. Additionally, the CV of MUNIX gradually decreases with an increase in the number of channels, thereby optimizing the issue of abnormal MUNIX repeatability patterns and further enhancing the reproducibility of MUNIX based on high-density surface EMG signals.

The use of thyroid cartilage needle electrodes in intraoperative neuromonitoring during thyroidectomy: Case-control study.

BACKGROUND: The most commonly used recording-side method in intraoperative neural monitoring (IONM) detects the stimulus with the endotracheal tube surface (ETS) electrodes placed in the endotracheal tube during thyroidectomy. The thyroid cartilage needle (TCN) electrode method is an alternative recording-side system in IONM. This study compared two recording-side techniques in IONM. METHODS: Data were retrospectively analyzed from 885 patients who underwent thyroidectomy between January 2012 and December 2020, with 110 ETS and 775 TCN electrodes. Patients' demographics, diagnosis, surgery type, and amplitudes of all stimulation steps were compared. Costs per patient were calculated. RESULTS: No significant differences were found in the demographic data between the two groups. All amplitudes were higher in the IONM system where TCN electrodes were used than that with ETS electrodes (all stimulation steps p < 0.001, except left-V2 p = 0.007). Further, TCN electrodes were 20 times cheaper than the ETS electrodes. CONCLUSION: TCN electrodes are an inexpensive and efficient alternative to ETS electrodes in IONM.

Selective Surface Electrostimulation of the Denervated Zygomaticus Muscle.

This article describes a first attempt to generate a standardized and safe selective surface electrostimulation (SES) protocol, including detailed instructions on electrode placement and stimulation parameter choice to obtain a selective stimulation of the denervated zygomaticus muscle (ZYG), without unwanted simultaneous activation of other ipsilateral or contralateral facial muscles. METHODS: Single pulse stimulation with biphasic triangular and rectangular waveforms and pulse widths (PW) of 1000, 500, 250, 100, 50, 25, 15, 10, 5, 2, 1 ms, at increasing amplitudes between 0.1 and 20 mA was performed. Stimulations delivered in trains were assessed at a PW of 50 ms only. The stimulation was considered successful exclusively if it drew the ipsilateral corner of the mouth upwards and outwards, without the simultaneous activation of other ipsilateral or contralateral facial muscles. I/t curves, accommodation quotient, rheobase, and chronaxie were regularly assessed over 1-year follow-up. RESULTS: 5 facial paralysis patients were assessed. Selective ZYG response in absence of discomfort and unselective contraction of other facial muscle was reproducibly obtained for all the assessed patients. The most effective results with single pulses were observed with PW ≥ 50 ms. The required amplitude was remarkably lower (≤5 mA vs. up to 15 mA) in freshly diagnosed (≤3 months) than in long-term facial paralysis patients (>5 years). Triangular was more effective than rectangular waveform, mostly because of the lower discomfort threshold of the latter. Delivery of trains of stimulation showed similar results to the single pulse setting, though lower amplitudes were necessary to achieve the selective ZYG response. Initial reinnervation signs could be detected effectively by needle-electromyography (n-EMG). CONCLUSION: It is possible to define stimulation parameters able to elicit an effective selective stimulation of a specific facial muscle, in our case, of the ZYG, without causing discomfort to the patient and without causing unwanted unspecific reactions of other ipsilateral and/or contralateral facial muscles. We observed that the SES success is strongly conditioned by the correct electrode placement, which ideally should exclusively interest the area of the target muscles and its immediate proximity.

Extramuscular Recording of Spontaneous EMG Activity and Transcranial Electrical Elicited Motor Potentials in Horses: Characteristics of Different Subcutaneous and Surface Electrode Types and Practical Guidelines.

INTRODUCTION: Adhesive surface electrodes are worthwhile to explore in detail as alternative to subcutaneous needle electrodes to assess myogenic evoked potentials (MEP) in human and horses. Extramuscular characteristics of both electrode types and different brands are compared in simultaneous recordings by also considering electrode impedances and background noise under not mechanically secured (not taped) and taped conditions. METHODS: In five ataxic and one non-ataxic horses, transcranial electrical MEPs, myographic activity, and noise were simultaneously recorded from subcutaneous needle (three brands) together with pre-gelled surface electrodes (five brands) on four extremities. In three horses, the impedances of four adjacent-placed surface-electrode pairs of different brands were measured and compared. The similarity between needle and surface EMGs was assessed by cross-correlation functions, pairwise comparison of motor latency times (MLT), and amplitudes. The influence of electrode noise and impedance on the signal quality was assessed by a failure rate (FR) function. Geometric means and impedance ranges under not taped and taped conditions were derived for each brand. RESULTS: High coherencies between EMGs of needle-surface pairs degraded to 0.7 at moderate and disappeared at strong noise. MLTs showed sub-millisecond simultaneous differences while sequential variations were several milliseconds. Subcutaneous MEP amplitudes were somewhat lower than epidermal. The impedances of subcutaneous needle electrodes were below 900 Ω and FR = 0. For four brands, the FR for surface electrodes was between 0 and 80% and declined to below 25% after taping. A remaining brand (27G DSN2260 Medtronic) revealed impedances over 100 kΩ and FR = 100% under not taped and taped conditions. CONCLUSION: Subcutaneous needle and surface electrodes yield highly coherent EMGs and TES-MEP signals. When taped and allowing sufficient settling time, adhesive surface-electrode signals may approach the signal quality of subcutaneous needle electrodes but still depend on unpredictable conditions of the skin. The study provides a new valuable practical guidance for selection of extramuscular EMG electrodes. This study on horses shares common principles for the choice of adhesive surface or sc needle electrodes in human applications such as in intraoperative neurophysiological monitoring of motor functions of the brain and spinal cord.

Comparison of nerve conduction parameters in canine studies using recording needle and surface electrodes.

Surface electrodes have been used in electromyography and nerve conduction studies in human and veterinary medicine, but comparisons have not been made between surface and needle electrode recordings in dogs. Our aim in this method comparison study was to determine whether surface electrodes captured larger compound motor action potentials (CMAP) than needle electrodes. Tibial nerve CMAP from 25 dogs with normal limb function was acquired using both surface and needle recording electrodes; the stimulus was elicited with monopolar concentric needles. Paired Wilcoxon signed rank test (if data was not normally distributed) or a paired two tailed t-test was used if data were normally distributed; significance was set at P<0.05. Mean CMAP amplitude (P=0.009), area (P=0.045) and latency (P=0.02) recorded with needle electrodes were larger compared with surface recording. CMAP duration was not significantly longer when recorded with surface electrodes (P=0.898). Needle electrode recordings are suitable for canine studies, although surface electrodes could also be considered. Low CMAP amplitudes recorded with surface electrodes should be verified with needle electrodes.

Safety and reliability of a handheld stimulator for neural monitoring during thyroid surgery.

OBJECTIVE: The Checkpoint nerve stimulator (Checkpoint Surgical, Cleveland, OH) is a U.S. Food and Drug Administration-approved device for neural localization and monitoring during surgery. Its safety, efficacy, and reliability for neural monitoring during thyroid and parathyroid surgery have not been compared to more standard formats of neural monitoring. STUDY DESIGN: Retrospective review. METHODS: Vagal, recurrent, and superior laryngeal nerve monitoring were performed using both the Checkpoint stimulator and Medtronic NIM 3.0 laryngeal electromyography endotracheal tube (Medtronic, Jacksonville, FL) during thyroid and parathyroid surgery. A total of 21 operated sides in 15 patients were included for analysis. Latency and amplitude data for the Checkpoint stimulator were recorded using the NIM monitor and compared to normative endotracheal tube surface electrode data. RESULTS: Mean amplitude using the Checkpoint stimulator was 574.6 microvolts (µV), 1060.6 µV, and 182.8 µV for the vagus, recurrent laryngeal, and superior laryngeal nerves, respectively. Mean amplitude using standard laryngeal electromyography was 709 µV, 1077.0 µV, and 183.7 µV for the same nerves. Mean latency was significantly shorter with stimulation of the recurrent laryngeal nerve compared to the vagus nerve with both stimulators (P < 0.001). No neural injuries occurred during the study. CONCLUSION: The Checkpoint stimulator is a safe and reliable alternative to traditional laryngeal electromyography providing equivalent induced electromyography of the vocalis for neural monitoring during thyroid and parathyroid surgery. LEVEL OF EVIDENCE: 4 Laryngoscope, 130:561-565, 2020.

Natural Sensations Evoked in Distal Extremities Using Surface Electrical Stimulation.

BACKGROUND: Electrical stimulation is increasingly relevant in a variety of medical treatments. In this study, surface electrical stimulation was evaluated as a method to non-invasively target a neural function, specifically natural sensation in the distal limbs. METHOD: Electrodes were placed over the median and ulnar nerves at the elbow and the common peroneal and lateral sural cutaneous nerves at the knee. Strength-duration curves for sensation were compared between nerves. The location, modality, and intensity of each sensation were also analyzed. In an effort to evoke natural sensations, several patterned waveforms were evaluated. RESULTS: Distal sensation was obtained in all but one of the 48 nerves tested in able-bodied subjects and in the two nerves from subjects with an amputation. Increasing the pulse amplitude of the stimulus caused an increase in the area and magnitude of the sensation in a majority of subjects. A low frequency waveform evoked a tapping or tapping-like sensation in 29 out of the 31 able-bodied subjects and a sensation that could be considered natural in two subjects with an amputation. This waveform performed better than other patterned waveforms that had proven effective during implanted extra-neural stimulation. CONCLUSION: Surface electrical stimulation has the potential to be a powerful, non-invasive tool for activation of the nervous system. These results suggest that a tapping sensation in the distal extremity can be evoked in most able-bodied individuals and that targeting the nerve trunk from the surface is a valid method to evoke sensation in the phantom limb of individuals with an amputation for short term applications.

Electrotonic potentials in Aloe vera L.: Effects of intercellular and external electrodes arrangement.

Electrostimulation of plants can induce plant movements, activation of ion channels, ion transport, gene expression, enzymatic systems activation, electrical signaling, plant-cell damage, enhanced wound healing, and influence plant growth. Here we found that electrical networks in plant tissues have electrical differentiators. The amplitude of electrical responses decreases along a leaf and increases by decreasing the distance between polarizing Pt-electrodes. Intercellular Ag/AgCl electrodes inserted in a leaf and extracellular Ag/AgCl electrodes attached to the leaf surface were used to detect the electrotonic potential propagation along a leaf of Aloe vera. There is a difference in duration and amplitude of electrical potentials measured by electrodes inserted in a leaf and those attached to a leaf's surface. If the external reference electrode is located in the soil near the root, it changes the amplitude and duration of electrotonic potentials due to existence of additional resistance, capacitance, ion channels and ion pumps in the root. The information gained from this study can be used to elucidate extracellular and intercellular communication in the form of electrical signals within plants.

Non-invasive, home-based electroencephalography hypoglycaemia warning system for personal monitoring using skin surface electrodes: a single-case feasibility study.

AIMS: Hypoglycaemia unawareness is a common condition associated with increased risk of severe hypoglycaemia. The purpose of the authors' study was to develop a simple to use, home-based and non-invasive hypoglycaemia warning system based on electroencephalography (EEG), and to demonstrate its use in a single-case feasibility study. METHODS: A participant with type 1 diabetes forms a single-person case study where blood sugar levels and EEG were recorded. EEG was recorded using skin surface electrodes placed behind the ear located within the T3 region by the participant in the home. EEG was analysed retrospectively to develop an algorithm which would trigger a warning if EEG changes associated with hypoglycaemia onset were detected. RESULTS: All hypoglycaemia events were detected by the EEG hypoglycaemia warning algorithm. Warnings were triggered with blood glucose concentration levels at or below 4.2 mmol/l in this participant and no warnings were issued when in euglycaemia. CONCLUSION: The feasibility of a non-invasive EEG-based hypoglycaemia warning system for personal monitoring in the home has been demonstrated in a single case study. The results suggest that further studies are warranted to evaluate the system prospectively in a larger group of participants.

Resonances and energy trapping in AT-cut quartz resonators operating with fast shear modes driven by lateral electric fields produced by surface electrodes.

We analyze coupled thickness-shear and extensional vibrations of a piezoelectric resonator of AT-cut quartz. Different from most of the AT-cut quartz resonators studied in the literature which are based on the slow shear mode excited by a thickness electric field, the resonator in this paper operates with the fast shear mode driven by a lateral electric field produced by a pair of electrodes on the top surface of the resonator. Mindlin's first-order theory of piezoelectric plates is used. Dispersion relations of the relevant waves in unelectroded and electroded plates are presented and compared. The motional capacitance, resonant frequencies and mode shapes near resonances are obtained from an electrically forced vibration analysis. Trapped modes without vibration near the resonator edges are identified. The effects of various structural parameters on energy trapping are examined and the mechanisms are discussed. The results can provide important bases for the parameters design of new resonators operating with the fast shear mode with new excitation schemes.

Surface electrical stimulation to evoke referred sensation.

Surface electrical stimulation (SES) is being investigated as a noninvasive method to evoke natural sensations distal to electrode location. This may improve treatment for phantom limb pain as well as provide an alternative method to deliver sensory feedback. The median and/or ulnar nerves of 35 subjects were stimulated at the elbow using surface electrodes. Strength-duration curves of hand sensation were found for each subject. All subjects experienced sensation in their hand, which was mostly described as a paresthesia-like sensation. The rheobase and chronaxie values were found to be lower for the median nerve than the ulnar nerve, with no significant difference between sexes. Repeated sessions with the same subject resulted in sufficient variability to suggest that recalculating the strength-duration curve for each electrode placement is necessary. Most of the recruitment curves in this study were generated with 28 to 36 data points. To quickly reproduce these curves with limited increase in error, we recommend 10 data points. Future studies will focus on obtaining different sensations using SES with the strength-duration curve defining the threshold of the effective parameter space.