Practical use of electromyography in veterinary medicine – A review

Electromyography (EMG) is a sophisticated electrodiagnostic-neurophysiological method, which serves to diagnose neuromuscular system diseases. It is based on the measurement of the electrical potentials created by the skeletal muscle activity. For this technique, surface electrodes and needle electrodes can be used, which read the action potential of a large number of motor units and read a small number of motor units, respectively. The wide-spectrum application of this method extends our diagnostic possibilities of the clinical examination in veterinary practice. Together with a clinical neurological examination and imaging methods, EMG forms a part of the diagnosis of nervous system diseases and it is a useful diagnostic technique for differentiating neuropathies, junctionopathies, and myopathies. The results of the neurophysiological examination inform us about the functional state of the peripheral and central nervous system; it can demonstrate subclinical diseases and monitor the dynamics of changes in the functional state of individual nervous systems over time. In this article, we review the electromyographic method and its use in veterinary practice.

An Electrical Stimulation Method to Control Deep Muscle Contraction using Surface Electrodes

Conventional EMS technology cannot stimulate deep muscles to induce muscle contraction using surface electrodes. Several treatments use electrical stimulation for various neurological conditions, including stroke and spinal cord injury. One such treatment is functional electrical stimulation (FES), a form of rehabilitation in which electrical muscle stimulation (EMS) is provided while the muscles are being moved. Here, we show whether two interfering electrical stimulation pulses could stimulate the deep muscles of the forearm to control muscle contraction. The results showed that the strongest torques were generated across the subjects when the reference frequency was mid-frequency (4,000 Hz) and the beat frequencies were low (20 Hz, 40 Hz, 80 Hz, 160 Hz and 320 Hz). This study is the first counterexample to demonstrate that it is possible to control muscle contraction in the deep muscles of the forearm using surface electrodes, which was previously thought to be impossible.

Superficial Peroneal Neuromodulation of Nonobstructive Urinary Retention Induced by Prolonged Pudendal Afferent Activity in Cats

The purpose of this study is to determine if superficial peroneal nerve stimulation (SPNS) can improve nonobstructive urinary retention (NOUR) induced by prolonged pudendal nerve stimulation (PNS). In this exploratory acute study using 8 cats under anesthesia, PNS and SPNS were applied by nerve cuff electrodes. Skin surface electrodes were also used for SPNS. A double lumen catheter was inserted via the bladder dome for bladder infusion and pressure measurement and to allow voiding without a physical urethral outlet obstruction. The voided and postvoid residual (PVR) volumes were also recorded. NOUR induced by repetitive (4-13 times) application of 30-min PNS significantly (p<0.05) reduced voiding efficiency by 49.5±16.8% of control (78.3±7.9%) with a large PVR volume at 208.2±82.6% of control bladder capacity. SPNS (1 Hz, 0.2 ms) at 1.5 to 2 times threshold intensity (T) for inducing posterior thigh muscle contractions was applied either continuously (SPNSc) or intermittently (SPNSi) during cystometrograms to improve the PNS-induced NOUR. SPNSc and SPNSi applied by nerve cuff electrodes significantly (p<0.05) increased voiding efficiency to 74.5±18.9% and 67.0±15.3%, respectively, and reduced PVR volume to 54.5±39.0% and 88.3±56.0%, respectively. SPNSc and SPNSi applied non-invasively by skin surface electrodes also improved NOUR similar to the stimulation applied by a cuff electrode. This study indicates that abnormal pudendal afferent activity could be a pathophysiological cause for the NOUR occurring in Fowler's syndrome and a noninvasive superficial peroneal neuromodulation therapy might be developed to treat NOUR in patients with Fowler's syndrome.

Augmented Transcutaneous Stimulation Using an Injectable Electrode: A Computational Study

Minimally invasive neuromodulation technologies seek to marry the neural selectivity of implantable devices with the low-cost and non-invasive nature of transcutaneous electrical stimulation (TES). The Injectrode® is a needle-delivered electrode that is injected onto neural structures under image guidance. Power is then transcutaneously delivered to the Injectrode using surface electrodes. The Injectrode serves as a low-impedance conduit to guide current to the deep on-target nerve, reducing activation thresholds by an order of magnitude compared to using only surface stimulation electrodes. To minimize off-target recruitment of cutaneous fibers, the energy transfer efficiency from the surface electrodes to the Injectrode must be optimized. TES energy is transferred to the Injectrode through both capacitive and resistive mechanisms. Electrostatic finite element models generally used in TES research consider only the resistive means of energy transfer by defining tissue conductivities. Here, we present an electroquasistatic model, taking into consideration both the conductivity and permittivity of tissue, to understand transcutaneous power delivery to the Injectrode. The model was validated with measurements taken from (n = 4) swine cadavers. We used the validated model to investigate system and anatomic parameters that influence the coupling efficiency of the Injectrode energy delivery system. Our work suggests the relevance of electroquasistatic models to account for capacitive charge transfer mechanisms when studying TES, particularly when high-frequency voltage components are present, such as those used for voltage-controlled pulses and sinusoidal nerve blocks.

Probabilistic comparison of gray and white matter coverage between depth and surface intracranial electrodes in epilepsy

In this study, we quantified the coverage of gray and white matter during intracranial electroencephalography in a cohort of epilepsy patients with surface and depth electrodes. We included 65 patients with strip electrodes (n = 12), strip and grid electrodes (n = 24), strip, grid, and depth electrodes (n = 7), or depth electrodes only (n = 22). Patient-specific imaging was used to generate probabilistic gray and white matter maps and atlas segmentations. Gray and white matter coverage was quantified using spherical volumes centered on electrode centroids, with radii ranging from 1 to 15 mm, along with detailed finite element models of local electric fields. Gray matter coverage was highly dependent on the chosen radius of influence (RoI). Using a 2.5 mm RoI, depth electrodes covered more gray matter than surface electrodes; however, surface electrodes covered more gray matter at RoI larger than 4 mm. White matter coverage and amygdala and hippocampal coverage was greatest for depth electrodes at all RoIs. This study provides the first probabilistic analysis to quantify coverage for different intracranial recording configurations. Depth electrodes offer increased coverage of gray matter over other recording strategies if the desired signals are local, while subdural grids and strips sample more gray matter if the desired signals are diffuse.

Prototipe Elektrokardiograf Tiga Lead Berbasis Komputer Jinjing

Penyakit jantung masih menjadi ancaman di Indonesia, menurut Kementerian Kesehatan, pada tahun 2014 penyakit jantung koroner (PJK) merupakan penyebab kematian tertinggi setelah stroke. Persentase terbesar penyakit kardiovaskuler adalah pada gangguan irama jantung. Instrumentasi medik elektrokardiograf (EKG) digunakan untuk mendeteksi sinyal biopotensial yang dihasilkan jantung sehingga dapat didiagnosis oleh dokter spesialis jantung. Penelitian ini mengusulkan sebuah prototipe sistem rekam jantung EKG yang ekonomis, dengan memanfaatkan suatu program aplikasi menggunakan bahasa pemrograman C Sharp. Sistem menggunakan 3 buah surface electrodes, modul AD8232, dan modul Arduino Uno sebagai komponen pembentuk instrument elektrokardiograf. Surface electrodes berfungsi menangkap sinyal aktivitas listrik pada jantung yang dikondisikan oleh modul AD8232 dan diubah menjadi sinyal digital pada Arduino. Tampilan pada layar komputer memperlihatkan jumlah denyut jantung per menit (BPM) dan grafik gelombang EKG yang dapat dibaca nilai amplitudo dan lebar waktu gelombangnya. Berdasarkan hasil perbandingan pengujian antara prototype EKG terhadap Portable Easy ECG Monitor PC-08B didapati kesalahan rata-rata parameter gelombang jantung yaitu pada denyut jantung per menit 1,19%, pada interval R-R 2.44%, pada interval P-R 2,05 %, pada interval Q-T 1,16 %, pada interval waktu gelombang P 2,58 %, pada interval waktu gelombang QRS 2,07 %, pada interval waktu gelombang T 3,26 %, pada nilai amplitudo QRS 3,40 %, pada nilai amplitudo gelombang P 4 %, dan pada nilai amplitudo gelombang T 4,10 %. Heart disease was a threat in Indonesia, according to the Ministry of Health in 2014 coronary heart disease (CHD) was the highest cause of death after stroke. The largest percentage of cardiovascular disease was in heart rhythm disorders. Electrocardiograph (ECG) was used to detect biopotential signals generated by the heart. This research proposed a low cost electrocardiograph (ECG) prototype by utilizing an application using C Sharp. The system consisted of three surface electrodes, an AD8232 module, and an Arduino Uno module. Surface electrodes detected the electrical activity signal from the heart that was conditioned using AD8232 module and converted to digital signal in Arduino Uno. The bit per minute (BPM) of the heart and the ECG graph are displayed on the laptop screen with graticule to measure the amplitude and the width of the wave. Based on the test results of the ECG prototype compare to the Portable Easy ECG Monitor PC-08B, it is found that the average error of heartbeat per minute is 1.19 %, the R-R time interval is 2.44 %, the P-R time interval is 2.05 %, the Q-T time interval is 1.16 %, the P wave time interval is 2.58 %, the QRS time interval is 2.07 %, T wave time interval is 3.26 %, the QRS amplitude is 3.40 %, the P amplitude is 4 %, and the T amplitude is 4.10 %.

New Developments in Anterior Laryngeal Recording Technique During Neuromonitored Thyroid and Parathyroid Surgery

A recurrent laryngeal nerve (RLN) injury resulting in vocal fold paralysis and dysphonia remains a major source of morbidity after thyroid and parathyroid surgeries. Intraoperative neural monitoring (IONM) is increasingly accepted as an adjunct to the standard practice of visual RLN identification. Endotracheal tube (ET) surface recording electrode systems are now widely used for IONM; however, the major limitation of the clinical use of ET-based surface electrodes is the need to maintain constant contact between the electrodes and vocal folds during surgery to obtain a high-quality recording. An ET that is malpositioned during intubation or displaced during surgical manipulation can cause a false decrease or loss of electromyography (EMG) signal. Since it may be difficult to distinguish from an EMG change caused by a true RLN injury, a false loss or decrease in EMG signal may contribute to inappropriate surgical decision making. Therefore, researchers have investigated alternative electrode systems that circumvent common causes of poor accuracy in ET-based neuromonitoring. Recent experimental and clinical studies have confirmed the hypothesis that needle or adhesive surface recording electrodes attached to the thyroid cartilage (transcartilage and percutaneous recording) or attached to the overlying neck skin (transcutaneous recording) can provide functionality similar to that of ET-based electrodes, and these recording methods enable access to the EMG response of the vocalis muscle that originates from the inner surface of the thyroid cartilage. Studies also indicate that, during surgical manipulation of the trachea, transcartilage, percutaneous, and transcutaneous anterior laryngeal (AL) recording electrodes could be more stable than ET-based surface electrodes and could be equally accurate in depicting RLN stress during IONM. These findings show that these AL electrodes have potential applications in future designs of recording electrodes and support the use of IONM as a high-quality quantitative tool in thyroid and parathyroid surgery. This article reviews the major recent developments of newly emerging transcartilage, percutaneous, and transcutaneous AL recording techniques used in IONM and evaluates their contribution to improved voice outcomes in modern thyroid surgery.

New Stimulation Device to Drive Multiple Transverse Intrafascicular Electrodes and Achieve Highly Selective and Rich Neural Responses

Peripheral Nerve Stimulation (PNS) is a promising approach in functional restoration following neural impairments. Although it proves to be advantageous in the number of implantation sites provided compared with intramuscular or epimysial stimulation and the fact that it does not require daily placement, as is the case with surface electrodes, the further advancement of PNS paradigms is hampered by the limitation of spatial selectivity due to the current spread and variations of nerve physiology. New electrode designs such as the Transverse Intrafascicular Multichannel Electrode (TIME) were proposed to resolve this issue, but their use was limited by a lack of innovative multichannel stimulation devices. In this study, we introduce a new portable multichannel stimulator—called STIMEP—and implement different stimulation protocols in rats to test its versatility and unveil the potential of its combined use with TIME electrodes in rehabilitation protocols. We developed and tested various stimulation paradigms in a single fascicle and thereafter implanted two TIMEs. We also tested its stimulation using two different waveforms. The results highlighted the versatility of this new stimulation device and advocated for the parameterizing of a hyperpolarizing phase before depolarization as well as the use of small pulse widths when stimulating with multiple electrodes.

The Use of Electrocardiographic Imaging in Localising the Origin of Arrhythmias During Catheter Ablation of Ventricular Tachycardia

Non-invasive electrocardiographic imaging (ECGI) is a novel clinical tool for mapping ventricular arrhythmia. Using multiple body surface electrodes to collect unipolar electrograms and conventional medical imaging of the heart, an epicardial shell can be created to display calculated electrograms. This calculation is achieved by solving the inverse problem and allows activation times to be calculated from a single beat. The technology was initially pioneered in the US using an experimental torso-shaped tank. Accuracy from studies in humans has varied. Early data was promising, with more recent work suggesting only moderate accuracy when reproducing cardiac activation. Despite these limitations, the system has been successfully used in pioneering work with non-invasive cardiac radioablation to treat ventricular arrhythmia. This suggests that the resolution may be sufficient for treatment of large target areas. Although untested in a well conducted clinical study it is likely that it would not be accurate enough to guide more discreet radiofrequency ablation.