Investigation of the temporal and spatial dynamics of muscular action potentials through optically pumped magnetometers

ABSTRACTAimThis study aims to simultaneously record the magnetic and electric components of the propagating muscular action potential.MethodA single-subject study of the monosynaptic stretch reflex of the musculus rectus femoris was performed; the magnetic field generated by the muscular activity was recorded in all three spatial directions by five optically pumped magnetometers. In addition, the electric field was recorded by four invasive fine-wire needle electrodes. The magnetic and electric fields were compared, and modelling and simulations were performed to compare the magnetic field vectors with the underlying muscular anatomy of the rectus femoris muscle.ResultsThe magnetomyography (MMG) signal can reliably be recorded following the stimulation of the monosynaptic stretch reflex. The MMG signal shows several phases of activity inside the muscle, the first of which is the propagating muscular action potential. As predicted by the finite wire model, the magnetic field vectors of the propagating muscular action potential are generated by the current flowing longitudinal to the muscle fiber. Based on the magnetic field vectors, it was possible to reconstruct the pinnation angle in the muscle. The later magnetic components are linked to the activated contractile apparatus.InterpretationMMG allows to analyze the muscle physiology from the propagating muscular action potential to the initiation of the contractile apparatus. At the same time this methods reveal information about muscle fiber direction and extend. With the development of high-resolution magnetic cameras, it will be possible to image the function and structure of any skeletal muscle with high precision. This method could be used in clinical medicine but also in sports and training science.What this paper adds-A robust technique for triggering a muscular action potential that can be recorded by MMG and needle EMG simultaneously-The correlation of the MMG signal with the needle EMG signal-A method for detecting the direction of the propagating muscular action potential-A method for correlating the magnetic field vectors with the pinnation angle of the examined muscle

Pode o kinesio taping alterar a inclinação pélvica de mulheres jovens saudáveis?

Introduction: The pelvis is a key structure for the alignment of the body and its misalignment can cause pain. Weakness of the gluteus maximus (GM) muscle can increase the pelvic tilt angle (PTA). Kinesio Taping (KT) is a technique used to stimulate muscular action, by applying a bandage over the muscle with a longitudinal tension of 25% to 35%. Objectives: To assess the immediate effects of the KT stimulating technique over the GM on the PTA of healthy women and verify if the 60% tension would lead to better results. Methods: Twenty-six healthy women, with a mean age of 23.3±2.8 years, had their PTA bilaterally assessed by means of computerized photogrammetry before and immediately after received KT application with 30 and 60% tensions. Repeated measure ANOVA (2x2) was used to assess the main and interaction effects between the applied tensions and time. The standard error of the measurement (SEM) was also calculated to evaluate the clinical impact of the techniques. Results: The analysis revealed that both KT tensions reduced the PTA. Although no significant differences were observed between the two employed tensions, the clinical effects were higher for the 60% tension. Conclusion: Both applied KT tensions reduced the PTA in the standing position of healthy young women, but the tension of 60% led to more clinically significant results.

Influence of the local anesthetics solutions’ temperature on muscular action potential amplitude decrease at brachial plexus block

Aim. To study influence of temperature of local anesthetics solutions on effectiveness of brachial plexus block using axillary access. Methods. Patients who underwent arm and hand surgeries were randomized either to the main group (n=25) or to the control group (n=25). In the main group, 1% lidocaine (20 ml) and 0.25% ropivacaine (40 ml - males, 30 ml - females) at 38 °C were used for brachial plexus block using axillary access. In the control group, anesthetics at room temperature were used. Brachial plexus block was performed using the axillary access at m. pectoralis major margin above the a. axillaris pulsation point. To register provoked muscular action potentials, a portative neurodiagnostic system «Nicolet One» was used. The percentage of provoked muscular action potential amplitude decrease was counted with results of a measurement before the block as a baseline. For additional analgesia and sedation phentanylum 0.005% was used until Ramsay sedation score II was achieved. «EZSAT-E» software package was used for data analysis. Results. In the main group brachial plexus block was achieved 14.2±3.4 minutes earlier than in the control group. Phentanylum dose required to provide psychic and emotional comfort was 45.4% lower in the main group (3.0±0.9 μg/kg per hour) compared to the control group (5.5±1.7 μg/kg per hour). Conclusion. The use of local anesthetics solutions at body temperature increases the efficiency of brachial plexus block and reduces the time of it’s achievement, increases it’s analgesic potential and decreases the need for narcotic analgesics to provide psychic and emotional comfort for the patient.

Electrodiagnostic Examination of the Tibial Nerve in Clinically Normal Ferrets

Tibial nerves of 10 normal domestic ferrets (Mustela putorius furo) were evaluated by means of electrodiagnostic tests: motor nerve conduction studies (MNCSs), supramaximal repetitive nerve stimulation (SRNS),Fwaves, and cord dorsum potentials (CDPs). Values of conduction velocity, proximal and distal compound muscular action potentials, and amplitudes of MNCS were, respectively, 63.25 7.56 m/sec, 10.79 2.75 mV, and 13.02 3.41 mV. Mean decrements in amplitude and area of compound muscular action potentials of wave 9 with low frequency SRNS were 0.3 3.83% and 0.1 3.51%. The minimum latency of theFwaves and theFratio were, respectively, 8.49 0.65 ms and 1.92 0.17. Onset latency of CDP was 1.99 0.03 ms. These tests may help in diagnosing neuromuscular disorders and in better characterizing the hindlimb paresis reported in many ferrets with systemic illnesses.