Effects Of Electrode Placement Research Articles

Effects of electrode placement on symptoms, memory, and sustainment of results after electroconvulsive therapy- A comparative study

ABSTRACT Background: The memory-related side-effects rank among the strongest reasons for hostility against Modified Electroconvulsive Therapy (MECT). Most of the studies comparing the Unilateral v/s Bilateral Electrode placements on memory have been conducted on patients with depression while very few studies have been conducted on patients with psychosis in the Indian population. Aim: To compare the effects of right unilateral (RU/L) and bilateral (B/L) MECT on the severity of symptoms as well as memory in patients with psychosis after the fourth session and two weeks after the final session of the MECT. Materials and Methods: One hundred patients having a psychotic illness were randomized into either RU/L or B/L group. Comprehensive psychopathological rating scale (CPRS), clinical global impressions scale (CGI-S), and PGI-memory scale were applied before starting of MECT, after four sessions of MECT and two weeks after the last session of ECT. Results: The results show similar symptomatic improvement in patients receiving RU/L and B/L MECT and the results persisted beyond the therapy sessions. But, in the case of RU/L-MECT group, the deterioration in memory was less as compared to the B/L-MECT group. Both groups had no significant difference in psychopathology and its severity (CPRS and CGI). Both groups were significantly different in memory side effects after the fourth session and two weeks after the last session. Both groups showed a consistent downward trend in psychopathology and its severity. The consistent fall in the total PGI scores remained even after two weeks of the final session in the B/L group (total of six points as compared to baseline) while it came to baseline levels in the RU/L group. Both groups differed significantly in total PGI scores after the fourth session and two weeks after the final session. Conclusion: This study points toward a favorable outcome in the case of therapeutic response with MECT without any significant difference between both types of electrode placements and even after stopping MECT, the improvement appears to be stable over time. Although, there was a side-effect of memory impairment, it appears to be for a shorter duration and it improves with time. The side-effect profile of RU/L electrode placement is lower as compared to bilateral placement. In the post-MECT period, the patients receiving MECT with RU/L electrode placement showed better improvement in memory functions.

Transcutaneous spinal stimulation in people with and without spinal cord injury: Effect of electrode placement and trains of stimulation on threshold intensity.

Transcutaneous spinal cord stimulation (TSS) is purported to improve motor function in people after spinal cord injury (SCI). However, several methodology aspects are yet to be explored. We investigated whether stimulation configuration affected the intensity needed to elicit spinally evoked motor responses (sEMR) in four lower limb muscles bilaterally. Also, since stimulation intensity for therapeutic TSS (i.e., trains of stimulation, typically delivered at 15-50 Hz) is sometimes based on the single-pulse threshold intensity, we compared these two stimulation types. In non-SCI participants (n = 9) and participants with a SCI (n = 9), three different electrode configurations (cathode-anode); L1-midline (below the umbilicus), T11-midline and L1-ASIS (anterior superior iliac spine; non-SCI only) were compared for the sEMR threshold intensity using single pulses or trains of stimulation which were recorded in the vastus medialis, medial hamstring, tibialis anterior, medial gastrocnemius muscles. In non-SCI participants, the L1-midline configuration showed lower sEMR thresholds compared to T11-midline (p = 0.002) and L1-ASIS (p < 0.001). There was no difference between T11-midline and L1-midline for participants with SCI (p = 0.245). Spinally evoked motor response thresholds were ~13% lower during trains of stimulation compared to single pulses in non-SCI participants (p < 0.001), but not in participants with SCI (p = 0.101). With trains of stimulation, threshold intensities were slightly lower and the incidence of sEMR was considerably lower. Overall, stimulation threshold intensities were generally lower with the L1-midline electrode configuration and is therefore preferred. While single-pulse threshold intensities may overestimate threshold intensities for therapeutic TSS, tolerance to trains of stimulation will be the limiting factor in most cases.

The Effects of Electrode Placement on Analgesia Using Transcutaneous Electrical Nerve Stimulation for Primary Dysmenorrhea: A Single-Blind Randomized Controlled Clinical Trial.

Background Primary dysmenorrhea (PD) refers to the occurrence of painful menstrual crampswithout pathological involvement of the pelvic organs, with considerable morbidity and high prevalence among females of reproductive age. Objective The objective of this study is to present and test the efficacy of an innovative method of interactive transcutaneous electrical nerve stimulation (iTENS) for PD. Methods and materials This study is a single-blind controlled clinical trial. This was conducted at the outpatient clinic of the faculty of physical therapy. Females with PD (n=124) were divided into the treated group (transcutaneous electrical nerve stimulation {TENS} group {TG}, n=62) and the placebo group (PG, n=62). A single session of either iTENS or placebo intervention was used for 35 minutes. Pain, the duration of analgesia, and the use of pain medication were assessed before and after the intervention. Data from before and after the treatment were compared between groups (Student's t-test). The level of significance was set at 5%. Results A significant decrease in pain (p<0.001) was observed after the intervention for the TG, with a more long-lasting analgesia (p<0.001) and decreased need for pain medication (p<0.001). Conclusions The proposed method of transcutaneous electrical nerve stimulation (TENS) application showed positive results for pain management on females with PD, with no reported adverse effects. The new proposed TENS application takes into account the preferences of the patient regarding positioning and the number of channels needed to cause analgesia. This application was able to promote almost complete analgesia in females with primary dysmenorrhea, and the analgesia persisted for more than one menstrual cycle.

Preliminary Analysis of a Wireless and Wearable Electronic-Textile EASI-Based Electrocardiogram

Background: With cardiovascular disease continuing to be the leading cause of death and the primary reason for hospitalization worldwide, there is an increased burden on healthcare facilities. Electronic-textile (e-textile)-based cardiac monitoring offers a viable option to allow cardiac rehabilitation programs to be conducted outside of the hospital.Objectives: This study aimed to determine whether signals produced by an e-textile ECG monitor with textile electrodes in an EASI configuration are of sufficient quality to be used for cardiac monitoring. Specific objectives were to investigate the effect of the textile electrode characteristics, placement, and condition on signal quality, and finally to compare results to a reference ECG obtained from a current clinical standard the Holter monitor.Methods: ECGs during different body movements (yawning, deep-breathing, coughing, sideways, and up movement) and activities of daily living (sitting, sitting/standing from a chair, and climbing stairs) were collected from a baseline standard of normal healthy adult male using a novel e-textile ECG and a reference Holter monitor. Each movement or activity was recorded for 5 min with 2-min intervals between each recording. Three different textile area electrodes (40, 60, and 70 mm2) and electrode thicknesses (3, 5, and 10 mm) were considered in the experiment. The effect of electrode placement within the EASI configuration was also studied. Different signal quality parameters, including signal to noise ratio, approximate entropy, baseline power signal quality index, and QRS duration and QT intervals, were used to evaluate the accuracy and reliability of the textile-based ECG monitor.Results: The overall signal quality from the 70 mm2 textile electrodes was higher compared to the smaller area electrodes. Results showed that the ECGs from 3 and 5 mm textile electrodes showed good quality. Regarding location, placing the “A” and “I” electrodes on the left and right anterior axillary points, respectively, showed higher signal quality compared to the standard EASI electrode placement. Wet textile electrodes showed better signal quality compared to their dry counterparts. When compared to the traditional Holter monitor, there was no significant difference in signal quality, which indicated textile monitoring was as good as current clinical standards (non-inferior).Conclusion: The e-textile EASI ECG monitor could be a viable option for real-time monitoring of cardiac activities. A clinical trial in a larger sample is recommended to validate the results in a clinical population.

Effect of electrode placement on speed of response to ECT

ObjectiveElectroconvulsive therapy (ECT) can be rapidly effective in treating severe depression. Right unilateral (RUL) or bitemporal (BT) electrode placement may affect the speed of ECT effectiveness although our current understanding of demographic and clinical factors for predicting predict speed of response and remission with ECT is limited. We investigated differences in improvement speed and also time to achieving response and remission criteria between brief-pulse moderate-dose (1.5 x seizure threshold) BT ECT and high-dose (6 x seizure threshold) RUL ECT. Additionally, we explored the influence of demographic and clinical characteristics.MethodsSe analysed weekly 24-item Hamilton Depression Rating Scale scores obtained from severely depressed patients participating in the EFFECT-Dep trial (ISRCTN23577151). Improvement speeds in patients treated randomly with a course of either BT (n = 69) or RUL ECT (n = 69) were compared using independent sample t-tests. Weekly proportions of responders and remitters were compared using chi-square tests. Cox regression analyses were used to explore predictors of speed to achieve response and remission status.ResultsSe found no differences between RUL and BT ECT in speed of improvement or time to achieve response or remission. Exploratory analyses indicated that a wide variety of demographic and clinical features did not serve to predict speed of response and remission to ECT.ConclusionElectrode placement did not substantially influence speed of improvement, response and remission with twice-weekly brief-pulse ECT. Minimising the cognitive side-effects of ECT may be of more relevance when choosing between BT and RUL electrode placement for ECT.DisclosureDeclan M. McLoughlin has received speaker’s honoraria from Mecta and Otsuka and an honorarium from Janssen for participating in an esketamine advisory board meeting. The other author reports no conflicts of interest. This work was supported by awards from

Speed of electroconvulsive therapy for depression: Effects of electrode placement.

Electroconvulsive therapy (ECT) is a rapidly effective treatment for severe depression. Treatment with right unilateral (RUL) or bitemporal (BT) ECT may explain individual differences in speed of ECT effectiveness. There is limited evidence for demographic and clinical factors that predict speed of response and remission with ECT. We aimed to investigate differences in speed of improvement as well as achieving response and remission between twice-weekly brief-pulse high-dose (6 × seizure threshold) RUL ECT and moderate-dose (1.5 × seizure threshold) BT ECT. We also explored demographic and clinical characteristics that predict speed of response and remission. Weekly 24-item Hamilton Depression Rating Scale scores were assessed among patients with severe depression who participated in the EFFECT-Dep trial (ISRCTN23577151). Speed of improvement in patients randomised to RUL ECT (n=69) or BT ECT (n=69) was compared using independent sample t tests. Pearson's chi-square and Fisher's exact tests compared proportions of responders and remitters at each weekly assessment. Predictors of speed of response and remission were explored using Cox regression analyses. There were no significant differences between RUL and BT ECT in speed of improvement, response or remission. Exploratory analyses indicated that speed of response and remission were not predicted by a wide variety of demographic and clinical characteristics. ECT electrode placement did not have predictive value when determining speed of improvement, response and remission with ECT. Other clinical factors, such as cognitive side-effects, may be more relevant when making the clinical choice between RUL and BT ECT.

Computational Microfluidic Channel for Separation of Escherichia coli from Blood-Cells

Microfluidic channels play a vital role in separation of analytes of interest such as bacteria and platelet cells, etc., in various biochemical diagnosis procedures including urinary tract infections (UTI) and bloodstream infections. This paper presents the multi physics computational model specifically designed to study the effects of design parameters of a microfluidics channel for the separation of Escherichia coli (E. coli) from various blood constituents including red blood cells (RBC) and platelets. A standard two inlet and a two outlet microchannel of length 805 m with a channel width of 40 m is simulated. The effect of electrode potentials and the effect of electrode placement along the channel length and also the levitation of electrodes from the channel wall are studied to optimize the selective particle separation throughput. Simulated results show the efficient separation of E-coli with a mean diameter 0.68 m is achieved at low voltages (less than 20 V) when electrodes placed near to the micro channel and also noticed that the applied electric potential is inversely proportional to the number of electrodes placed along the microfluidic channel. The computer aided multi physics simulations with multiple governing parameters could be advantage in design optimization of microfluidics channels and support precise bioparticle separation for better diagnosis.

Speech recognition with cochlear implants as a function of the number of channels: Effects of electrode placement

This study investigated the effects of cochlear implant (CI) electrode array type and scalar location on the number of channels available to CI recipients for maximum speech understanding and sound quality. Eighteen post-lingually deafened adult CI recipients participated, including 11 recipients with straight electrode arrays entirely in scala tympani and 7 recipients with translocated precurved electrode arrays. Computerized tomography was used to determine electrode placement and scalar location. In each condition, the number of channels varied from 4 to 22 with equal spatial distribution across the array. Speech recognition (monosyllables, sentences in quiet and in noise), subjective speech sound quality, and closed-set auditory tasks (vowels, consonants, and spectral modulation detection) were measured acutely. Recipients with well-placed straight electrode arrays and translocated precurved electrode arrays performed similarly, demonstrating asymptotic speech recognition scores with 8-10 channels, consistent with the classic literature. This finding contrasts with recent work [Berg, Noble, Dawant, Dwyer, Labadie, and Gifford. (2019). J. Acoust. Soc. Am. 145, 1556-1564] that found precurved electrode arrays well-placed in scala tympani demonstrate continuous performance gains beyond 8-10 channels. Given these results, straight and translocated precurved electrode arrays are theorized to have less channel independence secondary to their placement farther away from neural targets.

Effects of expiratory muscle activation via high-frequency spinal cord stimulation.

In persons with spinal cord injury, lower thoracic low-frequency spinal cord stimulation (LF-SCS; 50 Hz, 15 mA) is a useful method to restore an effective cough. Unfortunately, the high-stimulus-amplitude requirements and potential activation of pain fibers significantly limit this application in persons with intact sensation. In this study, the mechanism of the expiratory muscle activation, via high-frequency SCS (HF-SCS; 500 Hz, 1 mA) was evaluated in dogs. In group 1, the effects of electrode placement on airway pressure generation (P) was evaluated. Maximal P occurred at the T9-T10 level with progressive decrements in P at more rostral and caudal levels for both LF-SCS and HF-SCS. In group 2, electromyographic (EMG) latencies of internal intercostal muscle (II) activation were evaluated before and after spinal root section and during direct motor root stimulation. Onset time of II EMG activity during HF-SCS was significantly longer (3.84 ± 1.16 ms) than obtained during direct motor root activation (1.61 ± 0.10 ms). In group 3, P and external oblique (EO) EMG activity, before and after sequential spinal section at the T11-T12 level, were evaluated. Bilateral dorsal column section significantly reduced EO EMG activity below the section and resulted in a substantial fall in P. Subsequent lateral funiculi section completely abolished those activities and resulted in further reductions in P. We conclude that 1) activation of the expiratory muscles via HF-SCS is dependent entirely on synaptic spinal cord pathways, and 2) HF-SCS at the T9 level produces a comparable level of muscle activation with that achieved with LF-SCS but with much lower stimulus amplitudes. NEW & NOTEWORTHY The findings in the present study suggest that lower thoracic high-frequency spinal cord stimulation with low stimulus currents results in sufficient activation of the expiratory muscles via spinal circuitry to produce large positive airway pressures sufficient to generate an effective cough mechanism. This method, therefore, may be applied in patient populations with intact sensation such as stroke and amyotrophic lateral sclerosis to restore an effective cough.

The Physiological Basis and Clinical Use of the Binaural Interaction Component of the Auditory Brainstem Response.

The auditory brainstem response (ABR) is a sound-evoked noninvasively measured electrical potential representing the sum of neuronal activity in the auditory brainstem and midbrain. ABR peak amplitudes and latencies are widely used in human and animal auditory research and for clinical screening. The binaural interaction component (BIC) of the ABR stands for the difference between the sum of the monaural ABRs and the ABR obtained with binaural stimulation. The BIC comprises a series of distinct waves, the largest of which (DN1) has been used for evaluating binaural hearing in both normal hearing and hearing-impaired listeners. Based on data from animal and human studies, the authors discuss the possible anatomical and physiological bases of the BIC (DN1 in particular). The effects of electrode placement and stimulus characteristics on the binaurally evoked ABR are evaluated. The authors review how interaural time and intensity differences affect the BIC and, analyzing these dependencies, draw conclusion about the mechanism underlying the generation of the BIC. Finally, the utility of the BIC for clinical diagnoses are summarized.

Effects of Electrode Placement and Measurement Time on Electrochemical Signal of Redox Species Flowing through Porous Material

Effects of Electrode Placement and Measurement Time on Electrochemical Signal of Redox Species Flowing through Porous Material

Evaluation of in-channel amperometric detection using a dual-channel microchip electrophoresis device and a two-electrode potentiostat for reverse polarity separations.

In-channel amperometric detection combined with dual-channel microchip electrophoresis is evaluated using a two-electrode isolated potentiostat for reverse polarity separations. The device consists of two separate channels with the working and reference electrodes placed at identical positions relative to the end of the channel, enabling noise subtraction. In previous reports of this configuration, normal polarity and a three-electrode detection system were used. In the two-electrode detection system described here, the electrode in the reference channel acts as both the counter and reference. The effect of electrode placement in the channels on noise and detector response was investigated using nitrite, tyrosine, and hydrogen peroxide as model compounds. The effects of electrode material and size and type of reference electrode on noise and the potential shift of hydrodynamic voltammograms for the model compounds were determined. In addition, the performance of two- and three-electrode configurations using Pt and Ag/AgCl reference electrodes was compared. Although the signal was attenuated with the Pt reference, the noise was also significantly reduced. It was found that lower LOD were obtained for all three compounds with the dual-channel configuration compared to single-channel, in-channel detection. The dual-channel method was then used for the detection of nitrite in a dermal microdialysis sample obtained from a sheep following nitroglycerin administration.

The effect of electrode placement and interphase interval on force production during stimulation of the dorsiflexor muscles.

The aims of this study were to investigate whether introducing an interphase interval (IPI) to biphasic pulses during stimulation of the dorsiflexor muscles would affect force production and to determine whether the IPI effect is dependent on electrode position. Twelve healthy volunteers participated in the study. Each subject participated in one session during which electrically induced contraction (EIC) forces of the ankle dorsiflexors were measured with five different IPI settings ranging from 0 to 400 μs. Forces of EICs were assessed with the electrodes placed either with the proximal electrode positioned over the common peroneal nerve and the second electrode over the dorsiflexor muscles or with both electrodes located over the dorsiflexor muscles. The order of electrode placements and of the different IPI settings was randomized across subjects. The results indicated that the introduction of a 100-μs-long IPI may enhance force production when one electrode is located over the common peroneal nerve. However, increasing the duration of the IPI beyond 100 μs did not result in further increase in force production. In contrast, the introduction of an IPI did not increase force production when both electrodes were located over the dorsiflexor muscles. These findings may help to optimize stimulation settings during functional electrical stimulation to prevent foot-drop.

Applying Research to the Clinical Use of ECT in Geriatric Mood Disorders

Applying Research to the Clinical Use of ECT in Geriatric Mood Disorders

The effect of electrode placement and pulsewidth on asystole and bradycardia during the electroconvulsive therapy stimulus

Electroconvulsive therapy (ECT) is the most effective treatment for severe depression, and different forms are increasingly used in clinical practice. This study investigated the acute cardiac effects of different forms of ECT: bitemporal and bifrontal (1.5 times seizure threshold), and right unilateral (RUL) (five times seizure threshold). For RUL ECT, the effect of stimulus pulsewidth (1.0 or 0.3 ms) was also examined. Electrocardiograms recorded just prior to and during the ECT stimulus in 476 ECT treatments in 114 patients were examined. The degree of bradycardia (any slowing of heart rate) and incidence of asystole (absence of heart beats for ≥5 s) during the ECT stimulus were measured from these traces. Regression analyses estimated the contribution of patient and ECT treatment factors to the risk of bradycardia and asystole. Bifrontal ECT was associated with less severe bradycardia than bitemporal or RUL ECT (p<0.001). Modelling showed, for a mean pre-ECT heart rate of 85 beats per minute (bpm), expected heart rates during the stimulus were 78 bpm (bifrontal), 46 bpm (bitemporal) and 35 bpm (RUL). Bifrontal ECT was also associated with a lower incidence of asystole than RUL ECT (corrected odds ratio 1:207) and bitemporal ECT (corrected odds ratio 1:24). Ultrabrief pulsewidth stimulation resulted in lesser bradycardia and asystole than standard pulsewidth stimulation for RUL ECT. Modelling showed, for a mean pre-ECT heart rate of 86 bpm, expected heart rates were 43 bpm (ultrabrief RUL) and 26 bpm (RUL). Bradycardia and asystole were relatively common side-effects during the ECT stimulus. Bifrontal ECT was associated with the lowest risk of bradycardia and asystole during ECT and should be considered for patients at risk of arrhythmias and prolonged asystole during ECT.

Unilateral brief-pulse electroconvulsive therapy and cognition: Effects of electrode placement, stimulus dosage and time

To clarify advantages of unilateral electrode placement as an optimisation technique for electroconvulsive therapy (ECT) for depression, aims were to meta-analyse unilateral ECT effects on cognitive performance relative to: (1) bitemporal electrode placement, (2) electrical dosage, and (3) time interval between final treatment and cognitive reassessment.Relevant electronic databases were systematically searched through May 2009, using the terms: "electroconvulsive therapy" and ["cogniti∗", "neuropsycholog∗", "memory", "attention", "executive", "spatial", or "intellectual"]. Inclusion criteria were: independent study of depressed patients receiving unilateral or bitemporal brief-pulse ECT; within-subjects design; use of objective cognitive assessments; available mean electrical dosage for unilateral samples. Standardized pre-post ECT weighted effect sizes were computed and pooled within 16 cognitive domains by a mixed-effects model.Thirty-nine studies (1415 patients) were meta-analysed. Up to three days after final treatment, unilateral ECT was associated with significantly smaller decreases in global cognition, delayed verbal memory retrieval, and autobiographical memory, compared to bitemporal ECT. Significant publication bias was found for autobiographical memory, favouring reporting of larger percentage loss. Higher unilateral ECT electrical dosage predicted larger decreases in verbal learning, delayed verbal memory retrieval, visual recognition, and semantic memory retrieval. When retested more than three days after completing ECT, no significant differences remained between the two electrode placements; for unilateral ECT, electrical dosage no longer predicted cognitive performance whereas increasing interval between final treatment and retesting predicted growing improvement in some variables. This interval is a more useful long-term predictor of cognitive function than electrode placement or electrical dosage following unilateral ECT.

Effects of sweep VEP parameters on visual acuity and contrast thresholds in children and adults

There are many parameters that may impact the thresholds obtained with sweep visually evoked potentials (sVEP), yet a number of these parameters have not been systematically studied, and there is no recognised standard for sVEP recording. In this study, the effects of electrode placement, temporal frequency, sweep direction, presence of a fixation target, stimulus area, and sweep duration on visual acuity (VA) and contrast thresholds of the sVEP were investigated. Additionally, the effect of these parameters on the number of viable threshold readings obtained from five active electrodes was investigated. Participants were six children (aged 6-8 years) and six adults (aged 17-30 years) with normal vision. Binocular sVEP VA and contrast thresholds were measured for two electrode placements (ISCEV and PowerDiva) of five active electrodes, three temporal frequencies (6, 7.5, and 10 Hz), two sweep directions (low to high and high to low), presence or absence of a fixation target, three stimulus areas, and three sweep durations. There were differences between adults and children with respect to visual acuity, the adults having better VA than the children (p = 0.033 in experiment 2). Overall, there were more viable readings at 7.5 Hz than at either 10 or 6 Hz (p = 0.0014 for VA and 0.001 for contrast thresholds). The adults performed better (in terms of viable readings) with the fixation target than without it (p = 0.04). The smallest stimulus size used gave rise to fewer viable readings in both adults and children (p = 0.022 for VA and 0.0001 for contrast thresholds). The other parameters (electrode placement, sweep direction and sweep duration) did not give rise to significant differences. A temporal frequency of 7.5 Hz, a stimulus area of 4° or larger for VA and 10° or larger for contrast thresholds, and the use of a fixation target gave more viable readings, and may be indicated for future application. Consideration of the number of viable readings showed more differences between parameters than the actual thresholds, and it is suggested that more readings presumably would yield more reliable threshold measurements.

P.1.g.008 Cognitive effects of electrode placement and stimulus dose in brief-pulse electroconvulsive therapy for depression

P.1.g.008 Cognitive effects of electrode placement and stimulus dose in brief-pulse electroconvulsive therapy for depression

Electrically Evoked Auditory Brainstem Responses in Adults and Children

Previous electrophysiologic studies of electrode placement within the scala tympani in both animals and humans have shown effects on neural responses to electrical stimulation. The specific effects, however, may be dependent on electrode design, the location of an electrode along the array, and the method of perimodiolar positioning. The present study compares the effects of lateral and medial positioning of the Nucleus Contour electrode array on electrophysiologic responses in adult and pediatric subjects. Prospective clinical study. Comprehensive Cochlear Implant Program/Tertiary Referral Center. Subjects were adults (n = 15) and children (n = 20) who were consecutively implanted at our center with the Nucleus 24 Contour device. Rehabilitative. Intraoperative electrically evoked auditory brainstem responses (EABRs) were recorded within subjects for lateral and medial placement of the electrode array. Effects of electrode placement on EABR Wave V threshold and suprathreshold amplitude were measured. Group analyses showed significant decreases in EABR threshold and significant increases in EABR amplitude across all electrodes with medial electrode placement. The effects differed across electrode locations for the adult and pediatric subjects. No significant changes in Wave V input/output function slope were found. Medial electrode placement from stylet removal with the Nucleus 24 Contour array results in an increased neural response compared with the lateral condition as demonstrated by lower threshold and larger suprathreshold amplitude of the EABR. Possible clinical implications of these findings are lower psychophysical threshold and comfortable levels with medial cochlear electrode position.

Electrode Placement and Ictal EEG Indices in Electroconvulsive Therapy

The authors determine whether quantitative electroencephalography (EEG) indices in electroconvulsive therapy (ECT) seizures correlate with stimulus electrode placement. The authors analyzed data from ECT seizures involving three electrode placements on 37 different quantitative EEG measures. Though there were a few statistically significant comparisons, no consistent pattern of differences was discerned among the three electrode placements. Though many different EEG analytical indices are available on modern ECT machines, the clinical or neurophysiologic relevance has yet to be established. These data provide a groundwork for future research on the neurophysiological aspects of ECT.