Electroneurographic Evaluation of Neural Impulse Transmission in Patients after Ischemic Stroke Following Functional Electrical Stimulation of Antagonistic Muscles at Wrist and Ankle in Two-Month Follow-Up

The available data from electroneurography (ENG) studies on the transmission of neural impulses in the motor fibers of upper and lower extremity nerves following neuromuscular functional electrical stimulation (NMFES) combined with kinesiotherapy in post-stroke patients during sixty-day observation do not provide convincing results. This study aims to compare the effectiveness of an NMFES of antagonistic muscle groups at the wrist and ankle and kinesiotherapy based mainly on proprioceptive neuromuscular facilitation (PNF). An ENG was performed once in a group of 60 healthy volunteers and three times in 120 patients after stroke (T0, up to 7 days after the incident; T1, after 21 days of treatment; and T2, after 60 days of treatment); 60 subjects received personalized NMFES and PNF treatment (NMFES+K), while the other 60 received only PNF (K). An ENG studied peripheral (M-wave recordings), C8 and L5 ventral root (F-wave recordings) neural impulse transmission in the peroneal and the ulnar nerves on the hemiparetic side. Both groups statistically differed in their amplitudes of M-wave recording parameters after peroneal nerve stimulation performed at T0 and T2 compared with the control group. After 60 days of treatment, only the patients from the NMFES+K group showed significant improvement in M-wave recordings. The application of the proposed NMFES electrostimulation algorithm combined with PNF improved the peripheral neural transmission in peroneal but not ulnar motor nerve fibers in patients after ischemic stroke. Combined kinesiotherapy and safe, personalized, controlled electrotherapy after stroke give better results than kinesiotherapy alone.

Bolus formation from fission of nonlinear internal waves over a mild slope

Breaking nonlinear internal waves (NLIWs) of depression on boundary slopes drives mixing in the coastal ocean. Of the different breaker types, fission is most commonly observed on mild slopes of continental margins. However, fission on mild slopes has rarely been investigated in the laboratory owing to limitations on flume length. In the present work, a train of NLIWs of depression is generated in an 18.2 m wave flume and shoaled upon a mild uniform slope. During fission, each NLIW of depression scatters into one or two NLIWs of elevation, which transforms into a bolus at the bolus birth point, where shear instability occurs through the pycnocline. The bolus propagates upslope, decreasing in size until it degenerates by shear and lobe-cleft instability, while losing volume to a return flow along the bed. The location of the bolus birth point, bolus propagation length scale, initial size and the number of boluses from each incident wave are parameterized from the wave half-width and the wave Froude number associated with the incident NLIW. These are compared with the characteristics of boluses generated by other breaking mechanisms on steeper slopes. Some bolus characteristics (height to length ratio, change in size and velocity field) are similar for boluses generated by fission, collapsing sinusoidal waves and internal solitary waves of elevation; however, the number of boluses, their birth point and initial height differ. The boluses formed by fission have more initial energy and no reflection. Further research is required to better quantify bolus-driven mixing on continental margins.

Electrophysiological comparison study between effectiveness of the treatment modalities (Baclofen and Tizanidine drug) on spasticity management

Background: Baclofen and tizanidine are both used for the treatment of muscle spasticity of spinal origin. patients and methods: This study was conducted in Ibn Al-Quf hospital for spinal cord injuries from the period December 2011 to June 2012. All of the participants gave written consent to participate in the study. The patients were divided into 2 groups: Group (I): Baclofen with physiotherapy treatment group; and Group (II): Tizanidine with physiotherapy treatment groups .H-reflex measurements were performed. parameters were studied: H-reflex latency, M wave latency, H-reflex conduction velocity, H-reflex duration, H-reflex amplitude. Results: All the patients had symptoms of spasticity at any time during the day with a Modified Ashworth Scale (MAS) before performing the H-reflex study. highly significant improvement in the H/M ratio when comparing positive controls to the two groups while the H/M ratio in the negative controls shows no significant difference with group I and group II. A significant correlation was noticed between the height of control subjects & H-reflex latency (P= 0.002), significant positive correlation was also found (P=0.028) between the height & M wave latency in the control subjects, The results revealed that the type of treatment did not affect the H-reflex and F wave parameters except for the H/M ratio. conclusion: H-reflex can provide information regarding neural function after spinal cord injury and the H/M ratio can be used as a good indicator for both spasticity assessment and response to treatment. Tizanidine hydrochloride is useful in the management of spasticity caused by SCI and can be used as a routine drug treatment although liver function tests should be periodically monitored.

Contraction-Induced Loss of Plasmalemmal Electrophysiological Function Is Dependent on the Dystrophin Glycoprotein Complex

Weakness and atrophy are key features of Duchenne muscular dystrophy (DMD). Dystrophin is one of the many proteins within the dystrophin glycoprotein complex (DGC) that maintains plasmalemmal integrity and cellular homeostasis. The dystrophin-deficient mdx mouse is also predisposed to weakness, particularly when subjected to eccentric (ECC) contractions due to electrophysiological dysfunction of the plasmalemma. Here, we determined if maintenance of plasmalemmal excitability during and after a bout of ECC contractions is dependent on intact and functional DGCs rather than, solely, dystrophin expression. Wild-type (WT) and dystrophic mice (mdx, mL172H and Sgcb−/− mimicking Duchenne, Becker and Limb-girdle Type 2E muscular dystrophies, respectively) with varying levels of dystrophin and DGC functionality performed 50 maximal ECC contractions with simultaneous torque and electromyographic measurements (M-wave root-mean-square, M-wave RMS). ECC contractions caused all mouse lines to lose torque (p<0.001); however, deficits were greater in dystrophic mouse lines compared to WT mice (p<0.001). Loss of ECC torque did not correspond to a reduction in M-wave RMS in WT mice (p=0.080), while deficits in M-wave RMS exceeded 50% in all dystrophic mouse lines (p≤0.007). Moreover, reductions in ECC torque and M-wave RMS were greater in mdx mice compared to mL172H mice (p≤0.042). No differences were observed between mdx and Sgcb−/− mice (p≥0.337). Regression analysis revealed ≥98% of the variance in ECC torque loss could be explained by the variance in M-wave RMS in dystrophic mouse lines (p<0.001) but not within WT mice (R2=0.211; p=0.155). By comparing mouse lines that had varying amounts and functionality of dystrophin and other DGC proteins, we observed that (1) when all DGCs are intact, plasmalemmal action potential generation and conduction is maintained, (2) deficiency of the DGC protein β-sarcoglycan is as disruptive to plasmalemmal excitability as is dystrophin deficiency and, (3) some functionally intact DGCs are better than none. Our results highlight the significant role of the DGC plays in maintaining plasmalemmal excitability and that a collective synergism (via each DGC protein) is required for this complex to function properly during ECC contractions.

Headland Rip Modelling at a Natural Beach under High-Energy Wave Conditions

A XBeach surfbeat model is used to explore the dynamics of natural headland rip circulation under a broad range of incident wave conditions and tide level. The model was calibrated and extensively validated against measurements collected in the vicinity of a 500-m rocky headland. Modelled bulk hydrodynamic quantities were in good agreement with measurements for two wave events during which deflection rips were captured. In particular, the model was able to reproduce the tidal modulation and very-low-frequency fluctuations (≈1 h period) of the deflection rip during the 4-m wave event. For that event, the synoptic flow behaviour shows the large spatial coverage of the rip which extended 1600 m offshore at low tide, when the surf zone limit extends beyond the headland tip. These results emphasize a deflection mechanism different from conceptualised deflection mechanisms based on the boundary length to surf zone width ratio. Further simulations indicate that the adjacent embayment is responsible for the seaward extent of the rip under energetic wave conditions. The present study shows that the circulation patterns along natural rugged coastlines are strongly controlled by the natural variability of the coastal morphology, including headland shape and adjacent embayments, which has implications on headland bypassing expressions.

Overcoming Challenges of Mechanical Lifting Capabilities on Offshore Installation by Utilizing Coiled Tubing Boat Spooling Technique

Coiled tubing (CT) operations in the Norwegian continental shelf (NCS) often require a long and large-outside-diameter pipe due to big diameter completions, deep wells, and the need for high annular velocity during fluid circulation. However, getting the CT string onboard becomes a challenge when the crane lifting limit is 35 t, and using a standalone crane barge increases the cost of the operation. The alternative is spooling the CT from a vessel to the platform. Boat spooling is done by placing the CT string on a floating vessel with dynamic positioning while the standard CT injector head is secured at the edge of the platform to pull the pipe from the vessel to an empty CT reel on the platform. The boat is equipped with a CT guide; special tension clamps; and an emergency disconnect system, which consists of a standard CT shear-seal blowout preventer. The technique requires careful study of the platform structure for placement of the injector head support frame, metocean data of the field, and equipment placement on the vessel and platform. The boat spooling operation of a 7,700-m long, 58.7-t, 2.375-in.-outside-diameter CT string was successfully executed for a platform at 70-m height from mean sea level. The total operating time from hooking up the vessel to successfully spooling the string only took 12 hours. Historically for the region, the method has been attempted in sea state of up to 4-m wave height and 16 knots maximum wind speed. For this operation, the spooling was carried out during an average sea state of 2-m wave height and 15-knot wind speed. The continuous CT string allows a telemetry cable to be installed inside the pipe after the CT is spooled onto the platform reel, enabling real-time downhole measurements during the intervention. Such installation is not possible or presents high risk if the CT string is taken onboard by splicing two sections of pipe together with a spoolable connector or butt welding. From a cost perspective, the boat-spooling operation had up to 80% direct cost saving for the operator when compared to other methods of lifting a single CT string onboard, such as using a motion-compensated barge crane. The planning for the boat spooling included several essential contingency plans. Performing a CT boat spooling operation in a complex environment is possible and opens new opportunities to use longer and heavier CT strings, with lower mobilization costs. Such strings enable more advanced and efficient interventions, with the option of using real-time CT downhole measurements during the execution of a wide range of production startup work. This, in turn, is critical to support the drilling of more extended reach wells, which allow access to untapped reservoirs.

Sarcolemmal Excitability, M-Wave Changes, and Conduction Velocity During a Sustained Low-Force Contraction

This study was undertaken to investigate whether sarcolemmal excitability is impaired during a sustained low-force contraction [10% maximal voluntary contraction (MVC)] by assessing muscle conduction velocity and also by analyzing separately the first and second phases of the muscle compound action potential (M wave). Twenty-one participants sustained an isometric knee extension of 10% MVC for 3min. M waves were evoked by supramaximal single shocks to the femoral nerve given at 10-s intervals. The amplitude, duration, and area of the first and second M-wave phases were computed. Muscle fiber conduction velocity, voluntary surface electromyographic (EMG), perceived effort, MVC force, peak twitch force, and temperature were also recorded. The main findings were: (1) During the sustained contraction, conduction velocity remained unchanged. (2) The amplitude of the M-wave first phase decreased for the first ~30s (−7%, p<0.05) and stabilized thereafter, whereas the second phase amplitude increased for the initial ~30s (+7%, p<0.05), before stabilizing. (3) Both duration and area decreased steeply during the first ~30s, and then more gradually for the rest of the contraction. (4) During the sustained contraction, perceived effort increased fivefold, whereas knee extension EMG increased by ~10%. (5) Maximal voluntary force and peak twitch force decreased (respectively, −9% and −10%, p<0.05) after the low-force contraction. Collectively, the present results indicate that sarcolemmal excitability is well preserved during a sustained 10% MVC task. A depression of the M-wave first phase during a low-force contraction can occur even in the absence of changes in membrane excitability. The development of fatigue during a low-force contraction can occur without alteration of membrane excitability.

Neurophysiological Factors Affecting Muscle Innervation Zone Estimation Using Surface EMG: A Simulation Study

Surface electromyography (EMG) recorded by a linear or 2-dimensional electrode array can be used to estimate the location of muscle innervation zones (IZ). There are various neurophysiological factors that may influence surface EMG and thus potentially compromise muscle IZ estimation. The objective of this study was to evaluate how surface-EMG-based IZ estimation might be affected by different factors, including varying degrees of motor unit (MU) synchronization in the case of single or double IZs. The study was performed by implementing a model simulating surface EMG activity. Three different MU synchronization conditions were simulated, namely no synchronization, medium level synchronization, and complete synchronization analog to M wave. Surface EMG signals recorded by a 2-dimensional electrode array were simulated from a muscle with single and double IZs, respectively. For each situation, the IZ was estimated from surface EMG and compared with the one used in the model for performance evaluation. For the muscle with only one IZ, the estimated IZ location from surface EMG was consistent with the one used in the model for all the three MU synchronization conditions. For the muscle with double IZs, at least one IZ was appropriately estimated from interference surface EMG when there was no MU synchronization. However, the estimated IZ was different from either of the two IZ locations used in the model for the other two MU synchronization conditions. For muscles with a single IZ, MU synchronization has little effect on IZ estimation from electrode array surface EMG. However, caution is required for multiple IZ muscles since MU synchronization might lead to false IZ estimation.

Maximal strength training-induced increase in efferent neural drive is not reflected in relative protein expression of SERCA

Introduction Maximal strength training (MST), performed with heavy loads (~ 90% of one repetition maximum; 1RM) and few repetitions, yields large improvements in efferent neural drive, skeletal muscle force production, and skeletal muscle efficiency. However, it is elusive whether neural adaptations following such high intensity strength training may be accompanied by alterations in energy-demanding muscular factors. Methods Sixteen healthy young males (24 ± 4 years) were randomized to MST 3 times per week for 8 weeks (n = 8), or a control group (CG; n = 8). Measurements included 1RM and rate of force development (RFD), and evoked potentials recordings (V-wave and H-reflex normalized to M-wave (M) in the soleus muscle) applied to assess efferent neural drive to maximally contracting skeletal muscle. Biopsies were obtained from vastus lateralis and analyzed by western blots and real-time PCR to investigate the relative protein expression and mRNA expression of Sarcoplasmic Reticulum Ca2+ ATPase (SERCA) 1 and SERCA2. Results Significant improvements in 1RM (17 ± 9%; p < 0.001) and early (0–100 ms), late (0–200 ms) and maximal RFD (31–53%; p < 0.01) were observed after MST, accompanied by increased maximal Vmax/Msup-ratio (9 ± 14%; p = 0.046), with no change in H-reflex to M-wave ratio. No changes were observed in the CG. No pre- to post-training differences were found in mRNA or protein expressions of SERCA1 and SERCA2 in either group. Conclusion MST increased efferent neural drive to maximally contracting skeletal muscle, causing improved force production. No change was observed in SERCA expression, indicating that responses to high intensity strength training may predominantly be governed by neural adaptations.