Mechanisms of Electrode Induced Injury. Part 1: Theory

Utility and rationale for continuous EEG monitoring: a primer for the general intensivist

This review offers a comprehensive guide for general intensivists on the utility of continuous EEG (cEEG) monitoring for critically ill patients. Beyond the primary role of EEG in detecting seizures, this review explores its utility in neuroprognostication, monitoring neurological deterioration, assessing treatment responses, and aiding rehabilitation in patients with encephalopathy, coma, or other consciousness disorders. Most seizures and status epilepticus (SE) events in the intensive care unit (ICU) setting are nonconvulsive or subtle, making cEEG essential for identifying these otherwise silent events. Imaging and invasive approaches can add to the diagnosis of seizures for specific populations, given that scalp electrodes may fail to identify seizures that may be detected by depth electrodes or electroradiologic findings. When cEEG identifies SE, the risk of secondary neuronal injury related to the time-intensity "burden" often prompts treatment with anti-seizure medications. Similarly, treatment may be administered for seizure-spectrum activity, such as periodic discharges or lateralized rhythmic delta slowing on the ictal-interictal continuum (IIC), even when frank seizures are not evident on the scalp. In this setting, cEEG is utilized empirically to monitor treatment response. Separately, cEEG has other versatile uses for neurotelemetry, including identifying the level of sedation or consciousness. Specific conditions such as sepsis, traumatic brain injury, subarachnoid hemorrhage, and cardiac arrest may each be associated with a unique application of cEEG; for example, predicting impending events of delayed cerebral ischemia, a feared complication in the first two weeks after subarachnoid hemorrhage. After brief training, non-neurophysiologists can learn to interpret quantitative EEG trends that summarize elements of EEG activity, enhancing clinical responsiveness in collaboration with clinical neurophysiologists. Intensivists and other healthcare professionals also play crucial roles in facilitating timely cEEG setup, preventing electrode-related skin injuries, and maintaining patient mobility during monitoring.

Neonatal Electroencephalogram Electrode-Related Pressure Injury Prevention Quality Improvement Study

OBJECTIVE

To lengthen the days between electroencephalogram electrode-related pressure injury (EERPI) to 100 EERPI-free days in 6 months of study implementation with a goal to maintain 200 EERPI-free days thereafter (≤1 EERPI event/year).

METHODS

This quality improvement study took place in a level IV neonatal ICU over three epochs spanning 2 years: epoch 1 or baseline (January-June 2019), epoch 2 or implementation of intervention (July-December 2019), and epoch 3 or sustainment (January-December 2020). A daily electroencephalogram (EEG) skin assessment tool, introduction in practice of a flexible hydrogel EEG electrode, and successive rapid-cycle staff-education sessions were key interventions of the study.

RESULTS

Seventy-six infants were monitored for 214 continuous EEG (cEEG) days, of which six (13.2%) developed EERPI in epoch 1. Eighty infants were monitored for 193 cEEG days, of which two (2.5%) developed EERPI in epoch 2. One hundred thirty-nine infants were monitored for 338 cEEG days, and none developed EERPI in epoch 3. There was no statistical difference with respect to the median cEEG days among study epochs. A G-chart of EERPI-free days showed an increase in EERPI-free days from an average of 34 days in epoch 1 to 182 days in epoch 2 and 365 days (or zero harm) in epoch 3. Skin erythema from EEG electrodes was noted during the study.

CONCLUSIONS

The structured study interventions eliminated EERPI events in infants monitored with cEEG. Preventive intervention at the cEEG-electrode level coupled with skin assessment successfully reduced EERPIs in neonates.

Spatially controlled, bipolar, cortical stimulation with high-capacitance, mechanically flexible subdural surface microelectrode arrays

Most neuromodulation approaches rely on extracellular electrical stimulation with penetrating electrodes at the cost of cortical damage. Surface electrodes, in contrast, are much less invasive but are challenged by the lack of proximity to axonal processes, leading to poor resolution. Here, we demonstrate that high-density (40-μm pitch), high-capacitance (>1 nF), single neuronal resolution PEDOT:PSS electrodes can be programmed to shape the charge injection front selectively at depths approaching 300 micrometers with a lateral resolution better than 100 micrometers. These electrodes, patterned on thin-film parylene substrate, can be subdurally implanted and adhere to the pial surface in chronic settings. By leveraging surface arrays that are optically transparent with PEDOT:PSS local interconnects and integrated with depth electrodes, we are able to combine surface stimulation and recording with calcium imaging and depth recording to demonstrate these spatial limits of bidirectional communication with pyramidal neurons in mouse visual cortex both laterally and at depth from the surface.

A Hydrogel Ionic Circuit Based High-Intensity Iontophoresis Device for Intraocular Macromolecule and Nanoparticle Delivery

Iontophoresis is an electrical-current-based, noninvasive drug-delivery technology, which is particularly suitable for intraocular drug delivery. Current ocular iontophoresis devices use low current intensities that significantly limit macromolecule and nanoparticle (NP) delivery efficiency. Increasing current intensity leads to ocular tissue damage. Here, an iontophoresis device based on a hydrogel ionic circuit (HIC), for high-efficiency intraocular macromolecule and NP delivery, is described. The HIC-based device is capable of minimizing Joule heating, effectively buffering electrochemical (EC) reaction-generated pH changes, and absorbing electrode overpotential-induced heating. As a result, the device allows safe application of high current intensities (up to 87 mA cm-2 , more than 10 times higher than current ocular iontophoresis devices) to the eye with minimal ocular cell death and tissue damage. The high-intensity iontophoresis significantly enhances macromolecule and NP delivery to both the anterior and posterior segments by up to 300 times compared to the conventional iontophoresis. Therapeutically effective concentrations of bevacizumab and dexamethasone are delivered to target tissue compartments within 10-20 min of iontophoresis application. This study highlights the significant safety enhancement enabled by an HIC-based device design and the potential of the device to deliver therapeutic doses of macromolecule and NP ophthalmic drugs within a clinically relevant time frame.

Best Practices in Facial Nerve Monitoring

OBJECTIVES/HYPOTHESIS

Facial nerve monitoring (FNM) has evolved into a widely used adjunct for many surgical procedures along the course of the facial nerve. Even though majority opinion holds that FNM reduces the incidence of iatrogenic nerve injury, there are few if any studies yielding high-level evidence and no practice guidelines on which clinicians can rely. Instead, a review of the literature and medicolegal cases reveals significant variations in methodology, training, and clinical indications.

STUDY DESIGN

Literature review and expert opinion.

METHODS

Given the lack of standard references to serve as a resource for FNM, we assembled a multidisciplinary group of experts representing more than a century of combined monitoring experience to synthesize the literature and provide a rational basis to improve the quality of patient care during FNM.

RESULTS

Over the years, two models of monitoring have become well-established: 1) monitoring by the surgeon using a stand-alone device that provides auditory feedback of facial electromyography directly to the surgeon, and 2) a team, typically consisting of surgeon, technologist, and interpreting neurophysiologist. Regardless of the setting and the number of people involved, the reliability of monitoring depends on the integration of proper technical performance, accurate interpretation of responses, and their timely application to the surgical procedure. We describe critical steps in the technical set-up and provide a basis for context-appropriate interpretation and troubleshooting of recorded signals.

CONCLUSIONS

We trust this initial attempt to describe best practices will serve as a basis for improving the quality of patient care while reducing inappropriate variations.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:S1-S42, 2021.

Reducing EEG (Electroencephalogram) Electrode-induced Skin Injury among Ambulatory EEG Monitored Patients: A Non-randomized Interventional Study of Two Commonly Used Cream-based Products for Electrode Application

Ambulatory electroencephalography (AEEG) seeks to capture inter-ictal epileptiform activity or paroxysmal events when patients are not in the clinic. Skin inflammation is a common complication of prolonged EEG monitoring. This non-randomized study aimed to investigate the performance of two commonly used cream-based methods of electrode application in reducing electrode-induced skin injury among patients undergoing AEEG monitoring. A non-randomized interventional study was conducted from July to December 2019 in the Neurosciences Ambulatory Care Unit at Royal Prince Alfred Hospital, Australia. Patients were enrolled into two groups: i) Group T, which received Ten20® Conductive Paste with Tensive® Conductive Adhesive Gel as the primary approach to electrode application; ii). Group E, which received EC2⁺® Conductive Cream as the primary approach to electrode application. Patients in Group T were enrolled in the 1st and 3rd week of the month, and patients in Group E were enrolled in the 2nd and 4th week for each month of the study. A total of 152 patients participated in this study. Two sub-groups were established: those who were monitored for two days (Group T; n = 36, Group E; n = 30) and those who were monitored for four days (Group T; n = 43, Group E; n = 43). Significant (p < 0.05) differences indicating greater inflammation in the Group E were noted for both Day 2 and Day 4 participants. Skin injury/inflammation was significantly less using the standard method (Group T: Ten20® with Tensive® gel) when compared to EC2⁺® (Group E) as the conductive material at the electrode site.

Technical recommendations and interpretation guidelines for electroencephalography for premature and full-term newborns

Electroencephalography (EEG) of neonatal patients is amongst the most valuable diagnostic and prognostic tool. EEG recordings, acquired at the bedside of infants, evaluate brain function and the maturation of premature and extremely premature infants. Strict conditions of acquisition and interpretation must be respected to guarantee the quality of the EEG and ensure its safety for fragile children. This article provides guidance for EEG acquisition including: (1) the required equipment and devices, (2) the modalities of installation and asepsis precautions, and (3) the digital signal acquisition parameters to use during the recording. The fundamental role of a well-trained technician in supervising the EEG recording is emphasized. In parallel to the acquisition recommendations, we present a guideline for EEG interpretation and reporting. The successive steps of EEG interpretation, from reading the EEG to writing the report, are described. The complexity of the EEG signal in neonates makes artefact detection difficult. Thus, we provide an overview of certain characteristic artefacts and detail the methods for eliminating them.

Review of semi-dry electrodes for EEG recording

Developing reliable and user-friendly electroencephalography (EEG) electrodes remains a challenge for emerging real-world EEG applications. Classic wet electrodes are the gold standard for recording EEG; however, they are difficult to implement and make users uncomfortable, thus severely restricting their widespread application in real-life scenarios. An alternative is dry electrodes, which do not require conductive gels or skin preparation. Despite their quick setup and improved user-friendliness, dry electrodes still have some inherent problems (invasive, relatively poor signal quality, or sensitivity to motion artifacts), which limit their practical utilization. In recent years, semi-dry electrodes, which require only a small amount of electrolyte fluid, have been successfully developed, combining the advantages of both wet and dry electrodes while addressing their respective drawbacks. Semi-dry electrodes can collect reliable EEG signals comparable to wet electrodes. Moreover, their setup is as fast and convenient similar to that of dry electrodes. Hence, semi-dry electrodes have shown tremendous application prospects for real-world EEG acquisition. Herein, we systematically summarize the development, evaluation methods, and practical design considerations of semi-dry electrodes. Some feasible suggestions and new ideas for the development of semi-dry electrodes have been presented. This review provides valuable technical support for the development of semi-dry electrodes toward emerging practical applications.

EEG Electrode-induced Skin Injury among Adult Patients Undergoing Ambulatory EEG Monitoring

Introduction: Ambulatory electroencephalography technology has improved in the last 40 years. Many clinicians believe that some skin injury is an unavoidable complication of prolonged EEG monitoring. In this study, we examined potential risk factors associated with electrode-induced skin injury in adult patients with AEEG monitoring. Methods: A cross-sectional observational study was conducted from December 2017 to October 2018, in the outpatient clinic at a teaching hospital in Sydney, Australia. Patients were included if they were older than 16 years of age and had been referred for AEEG monitoring of two to five days duration. Trained neurophysiology nurses completed a pre-application skin assessment before they applied the EEG electrodes. Daily assessments of the skin condition were conducted. The patients completed a questionnaire to assess comfort levels at the completion of the testing. Results: A total of 251 patients participated in this study. Two groups were established - those who were monitored for 2-3 days (Group 1; n = 92) and those who were monitored for 4-5 days (Group 2; n = 159). There was a significant acceleration in inflammation which occurred between day 2 and day 4/5. Cross-sectional analyses of patient characteristics showed that increasing age, fair skin color, dry skin texture and fine hair texture were the prevailing risk factors for greater inflammation scores. Conclusion: The patient discomfort and inflammatory burden associated with this procedure were high. Inflammation was shown to increase with the duration of electrode application.

Volume Resuscitation in Patients With High-Voltage Electrical Injuries

Volume resuscitation of patients with high-voltage electrical injuries (>1000 V) is a more complex challenge than standard burn resuscitation. High voltages penetrate deep tissues. These deep injuries are not accounted for in resuscitation formulae dependent on percentage of cutaneous burn. Myonecrosis occurring from direct electrical injury and secondary compartment syndromes can result in rhabdomyolysis, compromising renal function and urine output. Urine output is the primary end point, with a goal of 1 mL/kg/h for adult patients with high-voltage electrical injuries. As such, secondary resuscitation end points of laboratory values, such as lactate, base deficit, hemoglobin, and creatinine, as well as hemodynamic monitoring, such as mean arterial pressure and thermodilution techniques, can become crucial in guiding optimum administration of resuscitation fluids. Mannitol and bicarbonates are available but have limited support in the literature. High-voltage electrical injury patients often develop acute kidney injury requiring dialysis and have increased risks of chronic kidney disease and mortality. Continuous venovenous hemofiltration is a well-supported adjunct to clear the myoglobin load that hemodialysis cannot from circulation.

Successful Reduction in Electrode-Related Pressure Ulcers During EEG Monitoring in Critically Ill Neonates

BACKGROUND

Neonates are at a high risk for pressure ulcers (PU) due to skin immaturity and exposure to various medical devices. The prevalence of PU in the neonatal intensive care unit is estimated to be 23%, with 80% of those being related to medical devices, including electroencephalographic (EEG) electrodes. Proposed mechanisms involve prolonged pressure to the electrodes and chemical reactions to conductive agents.

PURPOSE

The object of this quality improvement project was to reduce PU in neonates during continuous EEG (cEEG) monitoring by 50% within 12 months and 75% within 18 months. A secondary objective was to eliminate electrode-related infections by 12 months. Balancing measures included gestational age at the time of monitoring, integrity of the EEG setup, and cost effectiveness. The process measure was adherence to the skin-monitoring tool kit.

METHODS

A multiple Plan-Do-Study-Act cycle method was used. All neonates monitored with cEEG were included. The monitoring tool kit was used to document the condition of scalp and EEG electrodes before, during, and after cEEG.

RESULTS

In the preproject period, 8.5% (9/106) of monitored patients developed PU, and 22.2% (2/9) of those developed infections. During the project period, 3.5% (7/198) of monitored patients developed PU and no infections were observed. During monitoring, 21 patients showed skin irritation, and timely intervention resulted in resolution in more than 90% of the cases and prevented progression into PU. Silver/silver chloride-plated electrodes, when exposed to external heat sources, can cause burns, resembling PU.

IMPLICATIONS FOR PRACTICE

Intervention at the electrode level together with skin inspection successfully reduces PU in neonates. Silver/silver chloride-plated electrodes should be avoided in neonates.

IMPLICATIONS FOR RESEARCH

Further research is needed to identify the optimal electrode for neonatal EEG.

Acute Compartment Syndrome as a Complication of the Use of Intraoperative Neuromonitoring Needle Electrodes

BACKGROUND

The use of intraoperative neurophysiologic monitoring (IOM) has become commonplace in many neurosurgical procedures as a tool to reduce the risk of complications through the early identification of reversible neurologic compromise. Although complications related to IOM itself are exceedingly rare, recognizing their clinical presentation in the postoperative neurosurgical patient is essential for the early identification and implementation of appropriate treatment.

CASE DESCRIPTION

The authors present a case report of a patient who developed postoperative acute compartment syndrome in the right arm after placement of neuromonitoring needles for routine IOM during endovascular treatment of a left internal carotid artery aneurysm. Before the procedure, the patient received dual antiplatelet therapy and was noted to have a P2Y12 reaction unit value within therapeutic range. The patient had not received other anticoagulation therapy and had no family or personal history of hematologic or coagulopathic disorders. Immediately after an uncomplicated endovascular intervention, the patient began to develop symptoms of forearm swelling, tightness, and tenderness to palpation; pain with wrist flexion and extension; and paresthesias of the distal digits of the hand. She had eventual loss of a palpable radial pulse. The patient underwent emergent fasciotomies of multiple forearm compartments and had immediate return of a palpable radial pulse.

CONCLUSIONS

This case represents the first report of post-procedural compartment syndrome resulting from placement of neuromonitoring needles for routine IOM. Although it is a particularly rare complication of IOM, compartment syndrome represents a surgical emergency that carries significant morbidity if not immediately recognized and treated.

Perspectives on setting limits for RF contact currents: a commentary

BACKGROUND

Limits for exposure to radiofrequency (RF) contact currents are specified in the two dominant RF safety standards and guidelines developed by the Institute of Electrical and Electronics Engineers (IEEE) and the International Commission on Non-Ionizing Radiation Protection (ICNIRP). These limits are intended to prevent RF burns when contacting RF energized objects caused by high local tissue current densities. We explain what contact currents are and review some history of the relevant limits with an emphasis on so-called "touch" contacts, i.e., contact between a person and a contact current source during touch via a very small contact area.

RESULTS

Contact current limits were originally set on the basis of controlling the specific absorption rate resulting from the current flowing through regions of small conductive cross section within the body, such as the wrist or ankle. More recently, contact currents have been based on thresholds of perceived heating. In the latest standard from the IEEE developed for NATO, contact currents have been based on two research studies in which thresholds for perception of thermal warmth or thermal pain have been measured. Importantly, these studies maximized conductive contact between the subject and the contact current source. This factor was found to dominate the response to heating wherein high resistance contact, such as from dry skin, can result in local heating many times that from a highly conductive contact. Other factors such as electrode size and shape, frequency of the current and the physical force associated with contact are found to introduce uncertainty in threshold values when comparing data across multiple studies.

CONCLUSIONS

Relying on studies in which the contact current is minimized for a given threshold does not result in conservative protection limits. Future efforts to develop limits on contact currents should include consideration of (1) the basis for the limits (perception, pain, tissue damage); (2) understanding of the practical conditions of real world exposure for contact currents such as contact resistance, size and shape of the contact electrode and applied force at the point of contact; (3) consistency of how contact currents are applied in research studies across different researchers; (4) effects of frequency.

Case-study of a user-driven prosthetic arm design: bionic hand versus customized body-powered technology in a highly demanding work environment

BACKGROUND

Prosthetic arm research predominantly focuses on "bionic" but not body-powered arms. However, any research orientation along user needs requires sufficiently precise workplace specifications and sufficiently hard testing. Forensic medicine is a demanding environment, also physically, also for non-disabled people, on several dimensions (e.g., distances, weights, size, temperature, time).

METHODS

As unilateral below elbow amputee user, the first author is in a unique position to provide direct comparison of a "bionic" myoelectric iLimb Revolution (Touch Bionics) and a customized body-powered arm which contains a number of new developments initiated or developed by the user: (1) quick lock steel wrist unit; (2) cable mount modification; (3) cast shape modeled shoulder anchor; (4) suspension with a soft double layer liner (Ohio Willowwood) and tube gauze (Molnlycke) combination. The iLimb is mounted on an epoxy socket; a lanyard fixed liner (Ohio Willowwood) contains magnetic electrodes (Liberating Technologies). An on the job usage of five years was supplemented with dedicated and focused intensive two-week use tests at work for both systems.

RESULTS

The side-by-side comparison showed that the customized body-powered arm provides reliable, comfortable, effective, powerful as well as subtle service with minimal maintenance; most notably, grip reliability, grip force regulation, grip performance, center of balance, component wear down, sweat/temperature independence and skin state are good whereas the iLimb system exhibited a number of relevant serious constraints.

CONCLUSIONS

Research and development of functional prostheses may want to focus on body-powered technology as it already performs on manually demanding and heavy jobs whereas eliminating myoelectric technology's constraints seems out of reach. Relevant testing could be developed to help expediting this. This is relevant as Swiss disability insurance specifically supports prostheses that enable actual work integration. Myoelectric and cosmetic arm improvement may benefit from a less forgiving focus on perfecting anthropomorphic appearance.

Spinal Cord Stimulation for Treating Chronic Pain: Reviewing Preclinical and Clinical Data on Paresthesia-Free High-Frequency Therapy

BACKGROUND

Traditional spinal cord stimulation (SCS) requires that paresthesia overlaps chronic painful areas. However, the new paradigm high-frequency SCS (HF-SCS) does not rely on paresthesia.

STUDY DESIGN

A review of preclinical and clinical studies regarding the use of paresthesia-free HF-SCS for various chronic pain states.

METHODS

We reviewed available literatures on HF-SCS, including Nevro's paresthesia-free ultra high-frequency 10 kHz therapy (HF10-SCS). Data sources included relevant literature identified through searches of PubMed, MEDLINE/OVID, and SCOPUS, and manual searches of the bibliographies of known primary and review articles.

OUTCOME MEASURES

The primary goal is to describe the present developing conceptions of preclinical mechanisms of HF-SCS and to review clinical efficacy on paresthesia-free HF10-SCS for various chronic pain states.

RESULTS

HF10-SCS offers a novel pain reduction tool without paresthesia for failed back surgery syndrome and chronic axial back pain. Preclinical findings indicate that potential mechanisms of action for paresthesia-free HF-SCS differ from those of traditional SCS.

CONCLUSIONS

To fully understand and utilize paresthesia-free HF-SCS, mechanistic study and translational research will be very important, with increasing collaboration between basic science and clinical communities to design better trials and optimize the therapy based on mechanistic findings from effective preclinical models and approaches. Future research in these vital areas may include preclinical and clinical components conducted in parallel to optimize the potential of this technology.

Effectiveness of neuromuscular electrical stimulation for management of shoulder subluxation post-stroke: a systematic review with meta-analysis

Objectives:

To examine the effectiveness of neuromuscular electrical stimulation (NMES) for the management of shoulder subluxation after stroke including assessment of short (1 hour or less) and long (more than one hour) daily treatment duration.

Data sources:

MEDLINE, CENTRAL, CINAHL, WOS, KoreaMed, RISS and reference lists from inception to January 2017

Review methods:

We considered randomized controlled trials that reported neuromuscular electrical stimulation for the treatment of shoulder subluxation post-stroke. Two reviewers independently selected trials for inclusion, assessed trial quality, and extracted data.

Results:

Eleven studies were included (432 participants); seven studies were good quality, four were fair. There was a significant treatment effect of neuromuscular electrical stimulation for reduction of subluxation for persons with acute and subacute stroke (SMD:–1.11; 95% CI:–1.53, –0.68) with either short (SMD:–0.91; 95% CI:–1.43, –0.40) or long (SMD:–1.49; 95% CI:–2.31, –0.67) daily treatment duration. The effect for patients with chronic stroke was not significant (SMD:–1.25; 95% CI:–2.60, 0.11). There was no significant effect of neuromuscular electrical stimulation on arm function or shoulder pain.

Conclusion:

This meta-analysis suggests a beneficial effect of neuromuscular electrical stimulation, with either short or long daily treatment duration, for reducing shoulder subluxation in persons with acute and subacute stroke. No significant benefits were observed for persons with chronic stroke or for improving arm function or reducing shoulder pain.

cEEG electrode-related pressure ulcers in acutely hospitalized patients

BACKGROUND

Pressure ulcers resulting from continuous EEG (cEEG) monitoring in hospitalized patients have gained attention as a preventable medical complication. We measured their incidence and risk factors.

METHODS

We performed an observational investigation of cEEG-electrode-related pressure ulcers (EERPU) among acutely ill patients over a 22-month period. Variables analyzed included age, sex, monitoring duration, hospital location, application methods, vasopressor usage, nutritional status, skin allergies, fever, and presence/severity of EERPU. We examined risk for pressure ulcers vs monitoring duration using Kaplan-Meyer survival analysis, and performed multivariate risk assessment using Cox proportional hazard model.

RESULTS

Among 1,519 patients, EERPU occurred in 118 (7.8%). Most (n = 109, 92.3%) consisted of hyperemia only without skin breakdown. A major predictor was monitoring duration, with 3-, 5-, and 10-day risks of 16%, 32%, and 60%, respectively. Risk factors included older age (mean age 60.65 vs 50.3, p < 0.01), care in an intensive care unit (9.37% vs 5.32%, p < 0.01), lack of a head wrap (8.31% vs 27.3%, p = 0.02), use of vasopressors (16.7% vs 9.64%, p < 0.01), enteral feeding (11.7% vs 5.45%, p = 0.04), and fever (18.4% vs 9.3%, p < 0.01). Elderly patients (71-80 years) were at higher risk (hazard ratio 6.84 [1.95-24], p < 0.01), even after accounting for monitoring time and other pertinent variables in multivariate analysis.

CONCLUSIONS

EERPU are uncommon and generally mild. Elderly patients and those with more severe illness have higher risk of developing EERPU, and the risk increases as a function of monitoring duration.

The effects of ultrasound and alternating current on the laser penetration in the tissue

The visible (VIS) and near-infrared (NIR) lasers are now widely used in therapeutic and other medical applications. Some of these applications require to deliver the laser energy deep toward the desired tissue target or organ. The aim of this in vitro study is to investigate practically whether the modulation of laser energy by employing the therapeutic ultrasound or electrical energies can increase the penetration depth of the laser light inside the tissue. Such modulation was implemented in this study by coupling the (c.w.) diode and Nd:YAG laser energies with the ultrasound or AC current simultaneously as they pass through preprepared ex vivo bovine muscular tissue strips. Two wavelengths of diode lasers were used, 637 and 808 nm beside the 1064-nm Nd:YAG laser. The results showed a noticeable decrease of these laser attenuation factors as they pass through the tissue strips in the presence of the ultrasound or AC energies. By using this coupling modulation, the capability of increasing the laser penetration depths inside the tissue was confirmed without having to increase their applied power.

Optimizing stimulation parameters in functional electrical stimulation of denervated muscles: a cross-sectional study

Background

To counteract denervation atrophy long-term electrical stimulation with a high number of muscle contractions has to be applied. This may lead to discomfort of the patient and negative side effects like burns. A functional effective muscle contraction induced by the lowest possible stimulation intensity is desirable. In clinical practice a selective stimulation of denervated muscles with triangular pulses is used.

The aim of the study was to evaluate the influence of polarity and pulse duration on the stimulation intensity of triangular pulses in denervated muscles in patients with peripheral nerve lesions.

Methods

Twenty-four patients with denervated extensor digitorum communis muscle and twenty-four patients with denervated tibialis anterior muscle due to peripheral nerve lesions were included. Four different combinations of triangular pulses with various duration and polarity were delivered randomly to the denervated muscles. The threshold intensity to induce a functional effective muscle contraction was noted. One-way within subject ANOVA was used to assess changes in intensity. An alpha level of p less than or equal to 0.05 was the criterion for statistical significance.

Results

Patients with a denervated tibialis anterior muscle presented significant lower intensities inducing a functional effective muscle contraction in favor of the stimulation with a duration of 200 ms and a polarity with the cathode proximally applied. No significant differences could be shown between the different stimulation protocols in case of denervated extensor digitorum communis muscle.

Conclusions

We recommend electrical stimulation of the denervated tibialis anterior muscle with triangular current with a duration of 200 ms and a polarity with the cathode proximally applied.

10-kHz High-Frequency SCS Therapy: A Clinical Summary

Objective

Chronic pain remains a serious public health problem worldwide. A spinal cord stimulation (SCS) therapy called HF10 SCS uses 10-kHz high-frequency stimulation to provide pain relief without paresthesia. In this article, we describe the therapy, device, and the methods of implant and then review the safety and effectiveness data for this therapy.

Results

HF10 SCS uses a charge-balanced stimulation waveform that has been shown to be safe in both animal and human studies. Data from a multicenter, prospective clinical trial shows that the therapy provides substantial back and leg pain relief. Numerous additional reports suggest improved pain relief in other body areas and for complex pain patterns, even for patients who have previously failed other neuromodulation therapies.

Conclusions

The clinical experience reported in this article supports the efficacy and pain relief provided by HF10 SCS therapy. Clinical studies have also concluded that HF10 SCS does not generate paresthesia nor was it necessary to provide adequate coverage for pain relief. As clinical evidence accumulates and technological innovation improves patient outcomes, neuromodulatory techniques will be sought earlier in the treatment continuum to reduce the suffering for the many with otherwise intractable chronic pain.

Effects of pH on the response of peripheral nerve to anoxia

PURPOSE/AIM

Changes in pH are not infrequently encountered in clinical situations and can be associated with significant effects on ion channels, mitochondria and axon function. The purpose of this paper is to study the modulatory effects of pH on the anoxic response in peripheral nerve.

MATERIALS AND METHODS

A total of 48 rat sciatic nerves were studied in vitro in a perfusion apparatus. Experiments were carried out at 6 pH levels from 6.0 to 7.8.

RESULTS

The amplitude of the nerve action potential (NAP) drops more dramatically with repetitive periods of anoxia when the pH is reduced below 6.5. In addition, velocity decreases and duration increases more with each cycle of anoxia at low pH values. Despite these effects of pH on recovery after anoxia, there was no significant effect of pH on the time course of changes during anoxia. During recovery from anoxia, the NAP recovered more slowly when the pH was lowered.

CONCLUSIONS

The pattern of changes in amplitude, velocity and duration suggest that they may be due to interference of high hydrogen ion concentrations with sodium and potassium channel function.

Third-degree burns incurred as a result of interferential current therapy

As an ancillary part of physical therapy, ice, heat, transcutaneous electrical nerve stimulation, and interferential currents are often used as nonpharmacological modalities to treat pain and reduce edema. Although medical electrical stimulation devices are touted as having few side effects, cutaneous irritation, contact dermatitis, and burns have been noted. The following article describes a patient who incurred third-degree burns in an area treated with interferential currents.