RESUMEN
Application of polyethylene glycol (PEG) to a peripheral nerve injury at the time of primary neurorrhaphy is thought to prevent Wallerian degeneration via direct axolemma fusion. The molecular mechanisms of nerve fusion and recovery are unclear. Our study tested the hypothesis that PEG alters gene expression in neural and muscular environments as part of its restorative properties. Lewis rats underwent unilateral sciatic nerve transection with immediate primary repair. Subjects were randomly assigned to receive either PEG treatment or standard repair at the time of neurorrhaphy. Samples of sciatic nerve distal to the injury and tibialis muscle at the site of innervation were harvested at 24 hours and 4 weeks postoperatively. Total RNA sequencing and subsequent bioinformatics analyses were used to identify significant differences in differentially expressed genes (DEGs) and their related biological pathways (p<0.05) in PEG-treated subjects compared to non-PEG controls. No significant DEGs were identified in PEG-treated sciatic nerve compared to controls after 24 hours, but 1,480 DEGs were identified in PEG-treated tibialis compared to controls. At 4 weeks, 918 DEGs were identified in PEG-treated sciatic nerve, whereas only 3 DEGs remained in PEG-treated tibialis compared to controls. DEGs in sciatic were mostly upregulated (79%) and enriched in pathways present during nervous system development and growth, whereas DEGs in muscle were mostly downregulated (77%) and related to inflammation and tissue repair. Our findings indicate that PEG application during primary neurorrhaphy leads to significant differential gene regulation in the neural and muscular environment that is associated with improved functional recovery in animals treated with PEG compared to sham non-PEG controls. A detailed understanding of key molecules underlying PEG function in recovery after peripheral nerve repair may facilitate amplification of PEG effects through systemic or focal treatments at the time of neurotmesis.
Asunto(s)
Músculo Esquelético , Traumatismos de los Nervios Periféricos , Polietilenglicoles , Ratas Endogámicas Lew , Nervio Ciático , Animales , Ratas , Nervio Ciático/lesiones , Traumatismos de los Nervios Periféricos/genética , Polietilenglicoles/farmacología , Músculo Esquelético/metabolismo , Músculo Esquelético/inervación , Músculo Esquelético/efectos de los fármacos , Modelos Animales de Enfermedad , Análisis de Secuencia de ARN , Regeneración Nerviosa/efectos de los fármacos , Regeneración Nerviosa/genética , Masculino , Regulación de la Expresión Génica/efectos de los fármacos , Perfilación de la Expresión GénicaRESUMEN
Motoneuronal persistent inward currents (PICs) are facilitated by neuromodulatory inputs but are highly sensitive to local inhibitory circuits. Estimates of PICs are reduced by group Ia reciprocal inhibition, and increased with the diffuse actions of neuromodulators released during remote muscle contraction. However, it remains unknown how motoneurons function in the presence of simultaneous excitatory and inhibitory commands. To probe this topic, we investigated motor unit discharge patterns and estimated PICs during voluntary co-contraction of ankle muscles, which simultaneously demands the contraction of agonist-antagonist pairs. Twenty participants performed triangular ramps of both co-contraction (simultaneous dorsiflexion and plantar flexion) and isometric dorsiflexion to a peak of 30% of their maximum muscle activity from a maximal voluntary contraction. Motor unit spike trains were decomposed from high-density surface EMG activity recorded from tibialis anterior using blind source separation algorithms. Voluntary co-contraction altered motor unit discharge rate characteristics. Discharge rate at recruitment and peak discharge rate were modestly reduced (â¼6% change; P < 0.001; d = 0.22) and increased (â¼2% change; P = 0.001, d = -0.19), respectively, in the entire dataset but no changes were observed when motor units were tracked across conditions. The largest effects during co-contraction were that estimates of PICs (ΔF) were reduced by â¼20% (4.47 vs. 5.57 pulses per second during isometric dorsiflexion; P < 0.001, d = 0.641). These findings suggest that, during voluntary co-contraction, the inhibitory input from the antagonist muscle overcomes the additional excitatory and neuromodulatory drive that may occur due to the co-contraction of the antagonist muscle, which constrains PIC behaviour. KEY POINTS: Voluntary co-contraction is a unique motor behaviour that concurrently provides excitatory and inhibitory synaptic input to motoneurons. Co-contraction of agonist-antagonist pairs alters agonist motor unit discharge characteristics, consistent with reductions in persistent inward current magnitude.
Asunto(s)
Tobillo , Neuronas Motoras , Contracción Muscular , Músculo Esquelético , Humanos , Músculo Esquelético/fisiología , Músculo Esquelético/inervación , Neuronas Motoras/fisiología , Masculino , Adulto , Femenino , Contracción Muscular/fisiología , Tobillo/fisiología , Adulto Joven , Electromiografía , Potenciales de Acción/fisiología , Contracción Isométrica/fisiologíaRESUMEN
Preclinical studies are crucial for developing amyotrophic lateral sclerosis drugs. Current FDA-approved drugs have been created by monitoring limb muscle function and histological analysis of amyotrophic lateral sclerosis model animals. Drug candidates for this disease have yet to be tested for bulbar-onset type due to the limitations of traditional preclinical tools: excessive animal use and discrete detection of disease progress. Here, our study introduces an all-in-one, wireless, integrated wearable system for facilitating continuous drug efficacy assessment of dysphagia-related muscles in animals during natural eating behaviors. By incorporating a kirigami-based strain-isolation mechanism, this device mounted on the skin of animals mitigates electromyography signal contamination caused by unpredictable animal movements. Our findings indicate this system, measuring the progression of motor neuron denervation, offers high precision in monitoring drug effects on dysphagia-responsible bulbar muscles. This study paves the way for more humane and efficient approaches to developing treatment solutions for degenerative neuromuscular diseases.
Asunto(s)
Esclerosis Amiotrófica Lateral , Modelos Animales de Enfermedad , Electromiografía , Dispositivos Electrónicos Vestibles , Esclerosis Amiotrófica Lateral/fisiopatología , Esclerosis Amiotrófica Lateral/tratamiento farmacológico , Animales , Electromiografía/métodos , Evaluación Preclínica de Medicamentos , Trastornos de Deglución/fisiopatología , Trastornos de Deglución/etiología , Músculo Esquelético/efectos de los fármacos , Músculo Esquelético/fisiopatología , Músculo Esquelético/inervación , Humanos , Masculino , Neuronas Motoras/efectos de los fármacos , Neuronas Motoras/fisiología , RatasRESUMEN
Upper extremity amputation can lead to significant functional morbidity. The main goals after amputation are to minimize pain and maintain or improve functional status while optimizing the quality of life. Postamputation pain is common and can be addressed with regenerative peripheral nerve interface surgery or targeted muscle reinnervation surgery. Both modalities are effective in treating residual limb pain and phantom limb pain, as well as improving prosthetic use. Differences in surgical technique between the 2 approaches need to be weighed when deciding what strategy may be most appropriate for the patient.
Asunto(s)
Amputación Quirúrgica , Músculo Esquelético , Regeneración Nerviosa , Nervios Periféricos , Extremidad Superior , Humanos , Extremidad Superior/cirugía , Extremidad Superior/inervación , Regeneración Nerviosa/fisiología , Nervios Periféricos/cirugía , Músculo Esquelético/inervación , Músculo Esquelético/cirugía , Transferencia de Nervios/métodos , Miembro FantasmaRESUMEN
PURPOSE: The saphenous nerve is a predominantly sensory nerve. It is the longest nerve of the body which supplies the skin of the medial side of the leg and foot as far as the ball of the great toe. We present here an unusual motor branch of the saphenous nerve to the sartorius muscle. METHOD: Institutional guidelines for use of human cadaver were followed. Routine dissection of the lower limbs for undergraduate medical teaching was performed in a 67 years old female cadaver employing standard methods. Relevant gross features of the variations were photographed. H&E staining of relevant structure was done and photomicrographed. RESULTS: The unusual motor branch to Sartorius was observed in the right thigh. The branch was given off in the lower third of the thigh after the saphenous nerve exited the adductor canal. The branch was distinctly seen entering the substance of the sartorius. The structure was confirmed to be a peripheral nerve by histological examination. The saphenous nerve then descended between the sartorius and gracilis tendons, pierced the fascia lata and became cutaneous. CONCLUSION: The motor branch to the sartorius muscle is a very rare branch whose knowledge is important for clinicians as it can get damaged during arthroscopy and other knee surgery or during adductor canal block.
Asunto(s)
Variación Anatómica , Cadáver , Músculo Esquelético , Humanos , Femenino , Anciano , Músculo Esquelético/inervación , Músculo Esquelético/anatomía & histología , Disección , Muslo/inervación , Nervio Femoral/anatomía & histologíaRESUMEN
INTRODUCTION: Targeted muscle reinnervation (TMR) is an established modality for the surgical management of neuropathic pain. Although the preventive effect of primary (acute) TMR at the time of amputation has been demonstrated previously, it remains unclear how many and which patients benefit most. Therefore, this study investigated the proportion of patients achieving sustained pain prophylaxis following amputation, as well as factors associated with its efficacy. METHODS: Primary patients who underwent TMR with a minimum follow-up of 6 months between 2018 and 2023 were enrolled. Pain outcomes (numeric rating scale [NRS], 0-10), comorbidities, and surgical factors were collected from chart review. Patients achieving sustained pain prophylaxis (NRS of ≤3 for ≥3 months until final follow-up) were identified. Multilevel mixed-effect models and multivariable regression were used to visualize pain courses and identify associated factors. RESULTS: Seventy-five patients who underwent primary TMR were included (median follow-up: 2.0 years), of whom 57.3% achieved sustained pain prophylaxis whereas 26.7% reported pain disappearance. Distal amputation levels (p = 0.036), a lower Elixhauser Comorbidity Index (p = 0.001), and the absence of psychiatric comorbidities (p = 0.039) were associated with pain prophylaxis. CONCLUSION: This study demonstrates that more than half of all patients undergoing primary TMR achieved sustained pain prophylaxis, and approximately a quarter of patients achieved sustained pain disappearance. Several factors associated with these favorable outcomes are described. These results will aid in preoperative counseling, managing patient expectations, and selecting patients who may benefit most from primary TMR surgery. LEVEL OF EVIDENCE: IV - Therapeutic.
Asunto(s)
Amputación Quirúrgica , Neuralgia , Humanos , Masculino , Femenino , Amputación Quirúrgica/efectos adversos , Amputación Quirúrgica/métodos , Persona de Mediana Edad , Neuralgia/prevención & control , Neuralgia/etiología , Neuralgia/cirugía , Músculo Esquelético/inervación , Anciano , Estudios Retrospectivos , Dimensión del Dolor , Transferencia de Nervios/métodos , Adulto , Dolor Postoperatorio/prevención & control , Dolor Postoperatorio/etiologíaRESUMEN
PURPOSE: The brachioradialis muscle (BRM) belongs to the lateral group of forearm muscles and contributes to the elbow flexion. Accessory brachioradialis muscle (ABRM) or "brachioradialis accessorius" represents an uncommon BRM variant, not been enough studied. The present study investigates the prevalence of the ABRM, along with its origin, insertion, and innervation. MATERIALS: Eighty-three upper limbs were meticulously dissected at the arm, forearm, and cubital fossa to investigate the ABRM presence. When the variant muscle was identified, morphometric measurements were obtained. RESULTS: The ABRM was identified in two upper limbs (2/83, 2.4%), in a male cadaver, bilaterally. Its origin was located along with the typical BRM, and its insertion was identified into the anterior surface of the radius (proximal third). The ABRM was innervated by the radial nerve, coursing posteriorly (deeply). CONCLUSIONS: In the current study, the variant muscle was observed in 2.4%. Radial nerve compression, at the forearm, is not an uncommon entrapment neuropathy. The relationship between the radial nerve and the ABRM could precipitate radial neuropathy.
Asunto(s)
Variación Anatómica , Cadáver , Antebrazo , Músculo Esquelético , Humanos , Masculino , Músculo Esquelético/anomalías , Músculo Esquelético/anatomía & histología , Músculo Esquelético/inervación , Prevalencia , Antebrazo/inervación , Antebrazo/anomalías , Antebrazo/anatomía & histología , Femenino , Nervio Radial/anatomía & histología , Nervio Radial/anomalías , Anciano , Persona de Mediana Edad , Síndromes de Compresión Nerviosa/diagnóstico , Disección , Anciano de 80 o más AñosRESUMEN
Increasing evidence suggests that activation of muscle nerve afferents may inhibit central motor drive, affecting contractile performance of remote exercising muscles. Although these effects are well documented for metaboreceptors, very little is known about the activation of mechano- and mechanonociceptive afferents on performance fatigability. Therefore, the purpose of the present study was to examine the influence of mechanoreceptors and nociceptors on performance fatigability. Eight healthy young males undertook four randomized experimental sessions on separate occasions in which the experimental knee extensors were the following: 1) resting (CTRL), 2) passively stretched (ST), 3) resting with delayed onset muscle soreness (DOMS), or 4) passively stretched with DOMS (DOMS+ST), whereas the contralateral leg performed an isometric time to task failure (TTF). Changes in maximal voluntary contraction (ΔMVC), potentiated twitch force (ΔQtw,pot), and voluntary muscle activation (ΔVA) were also assessed. TTF was reduced in DOMS+ST (-43%) and ST (-29%) compared with CTRL. DOMS+ST also showed a greater reduction of VA (-25% vs. -8%, respectively) and MVC compared with CTRL (-28% vs. -45%, respectively). Rate of perceived exertion (RPE) was significantly increased at the initial stages (20-40-60%) of the TTF in DOMS+ST compared with all conditions. These findings indicate that activation of mechanosensitive and mechanonociceptive afferents of a muscle with DOMS reduces TTF of the contralateral homologous exercising limb, in part, by reducing VA, thereby accelerating mechanisms of central fatigue.NEW & NOTEWORTHY We found that activation of mechanosensitive and nociceptive nerve afferents of a rested muscle group experiencing delayed onset muscle soreness was associated with reduced exercise performance of the homologous exercising muscles of the contralateral limb. This occurred with lower muscle voluntary activation of the exercising muscle at the point of task failure.
Asunto(s)
Mecanorreceptores , Fatiga Muscular , Músculo Esquelético , Mialgia , Nociceptores , Humanos , Masculino , Músculo Esquelético/inervación , Músculo Esquelético/fisiología , Mecanorreceptores/fisiología , Mecanorreceptores/metabolismo , Adulto Joven , Nociceptores/fisiología , Mialgia/fisiopatología , Adulto , Ejercicio Físico/fisiología , Contracción Muscular , Contracción IsométricaRESUMEN
Objective: To observe the possibility of hyper selective neurectomy (HSN) of triceps branches combined with partial neurotomy of S 2 nerve root for relieving spastic equinus foot. Methods: Anatomical studies were performed on 12 adult cadaveric specimens. The S 2 nerve root and its branches were exposed through the posterior approach. Located the site where S 2 joined the sciatic nerve and measured the distance to the median line and the vertical distance to the posterior superior iliac spine plane, and the S 2 nerve root here was confirmed to have given off branches of the pelvic splanchnic nerve, the pudendal nerve, and the posterior femoral cutaneous nerve. Between February 2023 and November 2023, 4 patients with spastic equinus foot were treated with HSN of muscle branches of soleus, gastrocnemius medial head and lateral head, and cut the branch where S 2 joined the sciatic nerve. There were 3 males and 1 female, the age ranged from 5 to 46 years, with a median of 26 years. The causes included traumatic brain injury in 2 cases, cerebral hemorrhage in 1 case, and cerebral palsy in 1 case. The disease duration ranged from 15 to 84 months, with a median of 40 months. The triceps muscle tone measured by modified Ashworth scale (MAC) before operation was grade 3 in 2 cases and grade 4 in 2 cases. The muscle strength measured by Daniels-Worthingham manual muscle test (MMT) was grade 2 in 1 case, grade 3 in 1 case, and 2 cases could not be accurately measured due to grade 4 muscle tone. The Holden walking function grading was used to evaluate lower limb function and all 4 patients were grade 2. After operation, triceps muscle tone, muscle strength, and lower limb function were evaluated by the above grading. Results: The distance between the location where S 2 joined the sciatic nerve and median line was (5.71±0.53) cm and the vertical distance between the location and posterior superior iliac spine plane was (6.66±0.86) cm. Before joining the sciatic nerve, the S 2 nerve root had given off branches of the pelvic splanchnic nerve, the pudendal nerve, and the posterior femoral cutaneous nerve. All the 4 patients successfully completed the operation, and the follow-up time was 4-13 months, with a median of 7.5 months. At last follow-up, the muscle tone of the patients decreased by 2-3 grades when compared with that before operation, and the muscle strength did not decrease when compared with that before operation. Holden walking function grading improved by 1-2 grades, and there was no postoperative hypoesthesia in the lower limbs. Conclusion: HSN of triceps branches combined with partial neurotomy of S 2 nerve root can relieve spastic equinus foot without damaging other sacral plexus nerves.
Asunto(s)
Espasticidad Muscular , Músculo Esquelético , Nervio Ciático , Humanos , Masculino , Adulto , Femenino , Músculo Esquelético/inervación , Persona de Mediana Edad , Nervio Ciático/cirugía , Adulto Joven , Espasticidad Muscular/cirugía , Adolescente , Niño , Raíces Nerviosas Espinales/cirugía , Preescolar , Pie Equino/cirugía , Pie Equino/etiologíaRESUMEN
CASE: An overall healthy 48-year-old man suffered a left foot mangled crush injury resulting in a post-transmetatarsal amputation and subsequently developing a painful neuroma on the plantar surface of the foot. To avoid the zone of injury, targeted muscle reinnervation was used to treat the neuroma by coapting the tibial nerve to the motor point of the flexor hallucis longus (FHL) muscle. At 1-year follow-up, the patient reported no pain at rest, returned to work, and could ambulate with an orthosis for 30 minutes. CONCLUSION: Rare tibial nerve coaptations to the FHL could serve as a treatment option for patients with neuromas in traumatic postmetatarsal amputation.
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Neuroma , Humanos , Masculino , Persona de Mediana Edad , Neuroma/cirugía , Neuroma/etiología , Músculo Esquelético/cirugía , Músculo Esquelético/inervación , Músculo Esquelético/trasplante , Nervio Tibial/cirugía , Nervio Tibial/lesiones , Amputación Traumática/cirugíaRESUMEN
The present study investigated the impact of central α2-adrenergic mechanisms on sympathetic action potential (AP) discharge, recruitment and latency strategies. We used the microneurographic technique to record muscle sympathetic nerve activity and a continuous wavelet transform to investigate postganglionic sympathetic AP firing during a baseline condition and an infusion of a α2-adrenergic receptor agonist, dexmedetomidine (10 min loading infusion of 0.225 µg kg-1; maintenance infusion of 0.1-0.5 µg kg h-1) in eight healthy individuals (28 ± 7 years, five females). Dexmedetomidine reduced mean pressure (92 ± 7 to 80 ± 8 mmHg, P < 0.001) but did not alter heart rate (61 ± 13 to 60 ± 14 bpm; P = 0.748). Dexmedetomidine reduced sympathetic AP discharge (126 ± 73 to 27 ± 24 AP 100 beats-1, P = 0.003) most strongly for medium-sized APs (normalized cluster 2: 21 ± 10 to 5 ± 5 AP 100 beats-1; P < 0.001). Dexmedetomidine progressively de-recruited sympathetic APs beginning with the largest AP clusters (12 ± 3 to 7 ± 2 clusters, P = 0.002). Despite de-recruiting large AP clusters with shorter latencies, dexmedetomidine reduced AP latency across remaining clusters (1.18 ± 0.12 to 1.13 ± 0.13 s, P = 0.002). A subset of six participants performed a Valsalva manoeuvre (20 s, 40 mmHg) during baseline and the dexmedetomidine infusion. Compared to baseline, AP discharge (Δ 361 ± 292 to Δ 113 ± 155 AP 100 beats-1, P = 0.011) and AP cluster recruitment elicited by the Valsalva manoeuvre were lower during dexmedetomidine (Δ 2 ± 1 to Δ 0 ± 2 AP clusters, P = 0.041). The reduction in sympathetic AP latency elicited by the Valsalva manoeuvre was not affected by dexmedetomidine (Δ -0.09 ± 0.07 to Δ -0.07 ± 0.14 s, P = 0.606). Dexmedetomidine reduced baroreflex gain, most strongly for medium-sized APs (normalized cluster 2: -6.0 ± 5 to -1.6 ± 2 % mmHg-1; P = 0.008). These data suggest that α2-adrenergic mechanisms within the central nervous system modulate sympathetic postganglionic neuronal discharge, recruitment and latency strategies in humans. KEY POINTS: Sympathetic postganglionic neuronal subpopulations innervating the human circulation exhibit complex patterns of discharge, recruitment and latency. However, the central neural mechanisms governing sympathetic postganglionic discharge remain unclear. This microneurographic study investigated the impact of a dexmedetomidine infusion (α2-adrenergic receptor agonist) on muscle sympathetic postganglionic action potential (AP) discharge, recruitment and latency patterns. Dexmedetomidine infusion inhibited the recruitment of large and fast conducting sympathetic APs and attenuated the discharge of medium sized sympathetic APs that fired during resting conditions and the Valsalva manoeuvre. Dexmedetomidine infusion elicited shorter sympathetic AP latencies during resting conditions but did not affect the reductions in latency that occurred during the Valsalva manoeuvre. These data suggest that α2-adrenergic mechanisms within the central nervous system modulate sympathetic postganglionic neuronal discharge, recruitment and latency strategies in humans.
Asunto(s)
Potenciales de Acción , Agonistas de Receptores Adrenérgicos alfa 2 , Dexmedetomidina , Sistema Nervioso Simpático , Humanos , Dexmedetomidina/farmacología , Femenino , Adulto , Masculino , Agonistas de Receptores Adrenérgicos alfa 2/farmacología , Sistema Nervioso Simpático/fisiología , Sistema Nervioso Simpático/efectos de los fármacos , Potenciales de Acción/efectos de los fármacos , Potenciales de Acción/fisiología , Adulto Joven , Frecuencia Cardíaca/efectos de los fármacos , Frecuencia Cardíaca/fisiología , Presión Sanguínea/fisiología , Presión Sanguínea/efectos de los fármacos , Músculo Esquelético/fisiología , Músculo Esquelético/inervación , Músculo Esquelético/efectos de los fármacos , Receptores Adrenérgicos alfa 2/fisiología , Receptores Adrenérgicos alfa 2/metabolismoRESUMEN
Suprascapular nerve entrapment (SNE) syndrome is a commonly overlooked cause of shoulder weakness and pain. It frequently causes weakness over the posterior and lateral and posterior aspects of the shoulder, as well as pain of infraspinatus muscles. Therefore, we considered that the infraspinatus muscle cross-sectional area (IMCSA) might be a new morphological parameter to analyze SNE syndrome. We assumed that the IMCSA is an important morphologic parameter in SNE syndrome diagnosis. We acquired infraspinatus muscle data from 10 patients with SNE syndrome and from 10 healthy subjects who had undergone magnetic resonance imaging of the shoulder and who revealed no evidence of SNE syndrome. We analyzed the infraspinatus muscle thickness (IMT) and IMCSA at the shoulder on the imaging of the shoulder using our image analysis program. The IMCSA was measured as the whole infraspinatus muscle cross-sectional area that was most atrophied in the sagittal S-MR images. The IMT was measured as the thickest level of infraspinatus muscle. The mean IMT was 29.17â ±â 2.81 mm in the healthy subjects and 25.22â ±â 3.19 mm in the SNE syndrome group. The mean IMCSA was 1321.95â ±â 175.91 mm2 in the healthy group and 1048.38â ±â 259.94 mm2 in the SNE syndrome group. SNE syndrome patients had significantly lower IMT (Pâ <â .001) and IMCSA (Pâ <â .001) than the healthy group. The ROC curve shows that the optimal cutoff point of the IMT was 26.74 mm, with 70.0% sensitivity, 70.0% specificity, and an AUC of 0.83 (95% CI, 0.65-1.00). The best cutoff value of the IMCSA was 1151.02 mm2, with 80.0% sensitivity, 80.0% specificity, and AUC of 0.87 (95% CI, 0.69-1.00). The IMT and IMCSA were both significantly associated with SNE syndrome. And the IMCSA was a highly sensitive diagnostic tool.
Asunto(s)
Imagen por Resonancia Magnética , Síndromes de Compresión Nerviosa , Humanos , Masculino , Femenino , Imagen por Resonancia Magnética/métodos , Síndromes de Compresión Nerviosa/diagnóstico por imagen , Persona de Mediana Edad , Adulto , Músculo Esquelético/diagnóstico por imagen , Músculo Esquelético/inervación , Músculo Esquelético/patología , Hombro/diagnóstico por imagen , Hombro/inervación , Anciano , Estudios de Casos y ControlesRESUMEN
OBJECTIVE: MScanFit motor unit number estimation (MUNE) is a sensitive method for detecting motor unit loss and has demonstrated high reproducibility in various settings. In this study, our aim was to assess the outputs of this method when the nerve conduction distance is increased. METHODS: MScanFit recordings were obtained from the abductor digiti minimi muscle of 20 healthy volunteers. To evaluate the effect of nerve conduction distance, the ulnar nerve was stimulated from the wrist and elbow respectively. Reproducibility of MUNE, compound muscle action potential (CMAP), and other motor unit parameters were assessed using intraclass correlation coefficients (ICCs). RESULTS: Motor unit numbers obtained from stimulation at the wrist and elbow did not significantly differ and exhibited strong consistency in the ICC test (120.3 ± 23.7 vs. 118.5 ± 27.9, p > 0.05, ICC: 0.88). Similar repeatability values were noted for other parameters. However, the Largest Unit (%) displayed notable variability between the two regions and exhibited a negative correlation with nerve conduction distance. CONCLUSION: Our findings indicate that MScanFit can consistently calculate motor unit numbers and most of its outputs without substantial influence from nerve conduction distance. Exploring MScanFit's capabilities in various settings could enhance our understanding of its strengths and limitations for extensive use in clinical practice.
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Potenciales de Acción , Neuronas Motoras , Músculo Esquelético , Conducción Nerviosa , Nervio Cubital , Humanos , Conducción Nerviosa/fisiología , Adulto , Masculino , Femenino , Neuronas Motoras/fisiología , Potenciales de Acción/fisiología , Nervio Cubital/fisiología , Músculo Esquelético/fisiología , Músculo Esquelético/inervación , Electromiografía/métodos , Reproducibilidad de los Resultados , Adulto Joven , Persona de Mediana EdadRESUMEN
For centuries scientists and technologists have sought artificial leg replacements that fully capture the versatility of their intact biological counterparts. However, biological gait requires coordinated volitional and reflexive motor control by complex afferent and efferent neural interplay, making its neuroprosthetic emulation challenging after limb amputation. Here we hypothesize that continuous neural control of a bionic limb can restore biomimetic gait after below-knee amputation when residual muscle afferents are augmented. To test this hypothesis, we present a neuroprosthetic interface consisting of surgically connected, agonist-antagonist muscles including muscle-sensing electrodes. In a cohort of seven leg amputees, the interface is shown to augment residual muscle afferents by 18% of biologically intact values. Compared with a matched amputee cohort without the afferent augmentation, the maximum neuroprosthetic walking speed is increased by 41%, enabling equivalent peak speeds to persons without leg amputation. Further, this level of afferent augmentation enables biomimetic adaptation to various walking speeds and real-world environments, including slopes, stairs and obstructed pathways. Our results suggest that even a small augmentation of residual muscle afferents restores biomimetic gait under continuous neuromodulation in individuals with leg amputation.
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Amputación Quirúrgica , Amputados , Miembros Artificiales , Biomimética , Biónica , Marcha , Humanos , Marcha/fisiología , Biomimética/métodos , Masculino , Persona de Mediana Edad , Adulto , Femenino , Músculo Esquelético/inervación , Caminata , Pierna/cirugíaRESUMEN
PURPOSE: To evaluate the effects on peripheral neural regeneration of the end-to-side embracing repair technique compared to the autograft repair technique in Wistar rats. METHODS: Fifteen male Wistar rats were divided into three groups with five animals each: denervated group (GD), autograft group (GA), and embracing group (EG). For the evaluation, the grasping test, electroneuromyography (ENMG), and muscle weight assessment were used. RESULTS: Muscle weight assessment and ENMG did not show significant neural regeneration at the end of 12 weeks in the DG and GE groups, but only in GA. The grasping test showed an increase in strength between the surgery and the fourth week in all groups, and only the GA maintained this trend until the 12th week. CONCLUSIONS: The present study indicates that the neural regeneration observed in the end-to-side embracing neurorrhaphy technique, in the repair of segmental neural loss, is inferior to autograft repair in Wistar rats.
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Regeneración Nerviosa , Ratas Wistar , Animales , Masculino , Regeneración Nerviosa/fisiología , Electromiografía , Ratas , Procedimientos Neuroquirúrgicos/métodos , Músculo Esquelético/inervación , Traumatismos de los Nervios Periféricos/cirugía , Trasplante Autólogo/métodos , Factores de Tiempo , Reproducibilidad de los Resultados , Nervio Ciático/cirugía , Nervio Ciático/lesiones , Nervio Ciático/fisiologíaRESUMEN
The dystrophin protein has well-characterized roles in force transmission and maintaining membrane integrity during muscle contraction. Studies have reported decreased expression of dystrophin in atrophying muscles during wasting conditions, and that restoration of dystrophin can attenuate atrophy, suggesting a role in maintaining muscle mass. Phosphorylation of S3059 within the cysteine-rich region of dystrophin enhances binding between dystrophin and ß-dystroglycan, and mimicking phosphorylation at this site by site-directed mutagenesis attenuates myotube atrophy in vitro. To determine whether dystrophin phosphorylation can attenuate muscle wasting in vivo, CRISPR-Cas9 was used to generate mice with whole body mutations of S3059 to either alanine (DmdS3059A) or glutamate (DmdS3059E), to mimic a loss of, or constitutive phosphorylation of S3059, on all endogenous dystrophin isoforms, respectively. Sciatic nerve transection was performed on these mice to determine whether phosphorylation of dystrophin S3059 could attenuate denervation atrophy. At 14 days post denervation, atrophy of tibialis anterior (TA) but not gastrocnemius or soleus muscles, was partially attenuated in DmdS3059E mice relative to WT mice. Attenuation of atrophy was associated with increased expression of ß-dystroglycan in TA muscles of DmdS3059E mice. Dystrophin S3059 phosphorylation can partially attenuate denervation-induced atrophy, but may have more significant impact in less severe modes of muscle wasting.
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Distrofina , Músculo Esquelético , Atrofia Muscular , Animales , Fosforilación , Ratones , Atrofia Muscular/metabolismo , Atrofia Muscular/patología , Atrofia Muscular/genética , Músculo Esquelético/metabolismo , Músculo Esquelético/inervación , Músculo Esquelético/patología , Distrofina/metabolismo , Distrofina/genética , Masculino , Desnervación Muscular/métodos , Ratones Endogámicos C57BLRESUMEN
The response of spinal motoneurons to synaptic input greatly depends on the activation of persistent inward currents (PICs), the contribution of which can be estimated through the paired motor unit technique. Yet, the intra-session test-retest reliability of this measurement remains to be fully established. Twenty males performed isometric triangular dorsiflexion contractions to 20 and 50 % of maximal torque at baseline and after a 15-min resting period. High-density electromyographic signals (HD-EMG) of the tibialis anterior were recorded with a 64-electrode matrix. HD-EMG signals were decomposed, and motor units tracked across time points to estimate the contribution of PICs to motoneuron firing through quantification of motor unit recruitment-derecruitment hysteresis (ΔF). A good intraclass correlation coefficient (ICC = 0.75 [0.63, 0.83]) and a large repeated measures correlation coefficient (rrm = 0.65 [0.49, 0.77]; p < 0.001) were found between ΔF values obtained at both time points for 20 % MVC ramps. For 50 % MVC ramps, a good ICC (0.77 [0.65, 0.85]) and a very large repeated measures correlation coefficient (rrm = 0.73 [0.63, 0.80]; p < 0.001) were observed. Our data suggest that ΔF scores can be reliably investigated in tibialis anterior motor units during both low- and moderate-intensity contractions within a single experimental session.
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Electromiografía , Contracción Isométrica , Neuronas Motoras , Músculo Esquelético , Reclutamiento Neurofisiológico , Humanos , Masculino , Neuronas Motoras/fisiología , Músculo Esquelético/fisiología , Músculo Esquelético/inervación , Electromiografía/métodos , Reproducibilidad de los Resultados , Adulto , Reclutamiento Neurofisiológico/fisiología , Contracción Isométrica/fisiología , Adulto JovenRESUMEN
Objective.Peripheral nerve stimulation (PNS) has been demonstrated as an effective way to selectively activate muscles and to produce fine hand movements. However, sequential multi-joint upper limb movements, which are critical for paralysis rehabilitation, has not been tested with PNS. Here, we aimed to restore multiple upper limb joint movements through an intraneural interface with a single electrode, achieving coherent reach-grasp-pull movement tasks through sequential stimulation.Approach.A transverse intrafascicular multichannel electrode was implanted under the axilla of the rat's upper limb, traversing the musculocutaneous, radial, median, and ulnar nerves. Intramuscular electrodes were implanted into the biceps brachii (BB), triceps brachii (TB), flexor carpi radialis (FCR), and extensor carpi radialis (ECR) muscles to record electromyographic (EMG) activity and video recordings were used to capture the kinematics of elbow, wrist, and digit joints. Charge-balanced biphasic pulses were applied to different channels to recruit distinct upper limb muscles, with concurrent recording of EMG signals and joint kinematics to assess the efficacy of the stimulation. Finally, a sequential stimulation protocol was employed by generating coordinated pulses in different channels.Main results.BB, TB, FCR and ECR muscles were selectively activated and various upper limb movements, including elbow flexion, elbow extension, wrist flexion, wrist extension, digit flexion, and digit extension, were reliably generated. The modulation effects of stimulation parameters, including pulse width, amplitude, and frequency, on induced joint movements were investigated and reach-grasp-pull movement was elicited by sequential stimulation.Significance.Our results demonstrated the feasibility of sequential intraneural stimulation for functional multi-joint movement restoration, providing a new approach for clinical rehabilitation in paralyzed patients.
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Fuerza de la Mano , Movimiento , Nervios Periféricos , Ratas Sprague-Dawley , Animales , Ratas , Nervios Periféricos/fisiología , Movimiento/fisiología , Fuerza de la Mano/fisiología , Músculo Esquelético/fisiología , Músculo Esquelético/inervación , Masculino , Terapia por Estimulación Eléctrica/métodos , Electrodos Implantados , Electromiografía/métodosRESUMEN
Neuromuscular control of bionic arms has constantly improved over the past years, however, restoration of sensation remains elusive. Previous approaches to reestablish sensory feedback include tactile, electrical, and peripheral nerve stimulation, however, they cannot recreate natural, intuitive sensations. Here, we establish an experimental biological sensorimotor interface and demonstrate its potential use in neuroprosthetics. We transfer a mixed nerve to a skeletal muscle combined with glabrous dermal skin transplantation, thus forming a bi-directional communication unit in a rat model. Morphological analyses indicate reinnervation of the skin, mechanoreceptors, NMJs, and muscle spindles. Furthermore, sequential retrograde labeling reveals specific sensory reinnervation at the level of the dorsal root ganglia. Electrophysiological recordings show reproducible afferent signals upon tactile stimulation and tendon manipulation. The results demonstrate the possibility of surgically creating an interface for both decoding efferent motor control, as well as encoding afferent tactile and proprioceptive feedback, and may indicate the way forward regarding clinical translation of biological communication pathways for neuroprosthetic applications.
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Biónica , Músculo Esquelético , Animales , Ratas , Músculo Esquelético/inervación , Músculo Esquelético/fisiología , Retroalimentación Sensorial/fisiología , Propiocepción/fisiología , Ganglios Espinales/fisiología , Mecanorreceptores/fisiología , Husos Musculares/fisiología , Masculino , Femenino , Tacto/fisiología , Piel/inervaciónRESUMEN
The purpose of the present study was to clarify the impact of age on the sympathoinhibitory response to cardiopulmonary baroreceptor loading in females. Nine older females (mean ± SD, 70 ± 6 yr) and 11 younger females (20 ± 1 yr) completed the study. A passive leg raising (PLR) test was performed wherein the participants were positioned supine (baseline, 0°), and their lower limbs were passively lifted at 10°, 20°, 30°, and 40° (3 min at each angle). Muscle sympathetic nerve activity (MSNA) was recorded via microneurography of the left radial nerve. The central venous pressure was estimated based on peripheral venous pressure (eCVP), which was monitored using a cannula in the right large antecubital vein. Baseline MSNA was higher in older females than in younger females. MSNA burst frequency (BF) decreased during the PLR test in both older and younger females, but the magnitude of the decrease in MSNA BF was smaller in older females than in younger females (older, -3.5 ± 1.5 vs. younger, -6.3 ± 1.5 bursts/min at 40° from baseline, P = 0.014). The eCVP increased during the PLR in both groups, and there was no difference in the changes in eCVP between the two groups (older, +1.07 ± 0.37 vs. younger, +1.12 ± 0.33 mmHg at 40° from baseline, P = 0.941). These results suggest that inhibition of sympathetic vasomotor outflow during cardiopulmonary baroreceptor loading could be blunted with advancing age in females.NEW & NOTEWORTHY There were no available data concerning the effect of age on the sympathoinhibitory response to cardiopulmonary baroreceptor loading in females. The magnitude of the decrease in muscle sympathetic nerve activity during passive leg raising (10°-40°) was smaller in older females than in young females. In females, inhibition of sympathetic vasomotor outflow during cardiopulmonary baroreceptor loading could be blunted with advancing age.