RESUMEN
CONTEXT: The evaluation of quadriceps muscle inhibition with the interpolated twitch technique is usually performed by stimulating the femoral nerve (FN). However, there are some problems related to the use of this stimulation site, which may be partially overcome by delivering the stimulation over the motor point (MP). This study sought to compare MP to FN stimulation at different joint angles for the evaluation of quadriceps muscle inhibition, resting peak torque, and discomfort in healthy women. DESIGN: Cross-sectional study. METHODS: Sixteen healthy women (age: 28 [4] y; body mass: 60 [5] kg; height: 162 [5] cm) participated in this study. Supramaximal paired stimuli were delivered to the FN and to the rectus femoris MP before and during maximal voluntary contractions at different knee angles (15°, 30°, 45°, 60°, and 90° of knee flexion) to assess muscle inhibition and resting peak torque. Discomfort was also recorded for each stimulation site and knee angle. RESULTS: Muscle inhibition was similar between the 2 stimulation sites (P > .05) and was higher at 45° than at 90° (P = .03). MP stimulation evoked lower resting peak torque at 30° (P = .004), 60° (P = .006), and 90° (P = .006) and higher discomfort at 30° (P = .008) and 90° (P = .027) compared to FN stimulation. CONCLUSIONS: Despite lower resting peak torque and higher discomfort at some angles, MP stimulation provided similar muscle inhibition to FN stimulation at all knee angles and is therefore a valid method to evaluate quadriceps muscle inhibition in healthy women. MP stimulation can be used as an alternative to FN stimulation for the evaluation of quadriceps muscle inhibition with no added discomfort at the angles where muscle inhibition is the highest.
Asunto(s)
Nervio Femoral , Músculo Cuádriceps , Torque , Humanos , Femenino , Músculo Cuádriceps/fisiología , Adulto , Nervio Femoral/fisiología , Estudios Transversales , Estimulación Eléctrica/métodos , Adulto Joven , Contracción Muscular/fisiología , Articulación de la Rodilla/fisiología , Voluntarios SanosRESUMEN
PURPOSE: To investigate the relationship between the recovery of neuromuscular fatigue and the recovery of amount of work done above critical power (W´). METHODS: Ten healthy men performed, on different days, constant work rate exercises until task failure to determine critical power (CP) and W´. In the three following visits, participants performed two exhausting constant work rate exercises estimated to induce task failure within 6 min (P61 and P62), interspaced by 3, 6 or 15 min of recovery. Neuromuscular function was assessed before and periodically after the P61 using percutaneous electrical femoral nerve stimulation. The W´ recovery was measured from the total work performed above CP during the P62. RESULTS: The P61 induced a full use of W´ and a reduction in maximal voluntary contraction (MVC, - 19 ± 4%), voluntary activation (VA, - 6 ± 2%) and twitch force stimulated at 1 Hz (- 37 ± 11%), 10 Hz (- 50 ± 16%) and 100 Hz (- 32 ± 11%), when compared to baseline (P < 0.05). The time constant of VA recovery was significantly faster than the time constant of W´ recovery (P < 0.05), but there was no significant difference between the time constant of W´ recovery and the time constant of recovery of MVC or twitch force stimulated at 1, 10 and 100 Hz (P > 0.05). However, the time constant of W´ recovery was only associated to the time constant of MVC recovery (r = 0.73, P < 0.05). CONCLUSION: The W´ recovery is not associated to the recovery of peripheral or central fatigue alone. Rather, W´ seems to be associated to the recovery of the overall capacity to generate force.
Asunto(s)
Tolerancia al Ejercicio/fisiología , Ejercicio Físico/fisiología , Fatiga Muscular/fisiología , Recuperación de la Función/fisiología , Adulto , Estimulación Eléctrica , Electromiografía , Prueba de Esfuerzo , Nervio Femoral/fisiología , Humanos , Masculino , Músculo Esquelético/fisiología , Resistencia Física/fisiología , Adulto JovenRESUMEN
BACKGROUND: A new technique to obtain the sensory nerve action potential (SNAP) of the medial femoral cutaneous nerve is described. METHODS: SNAPs were recorded from 104 subjects with a bar recording electrode 10 cm proximal to the patella along an imaginary line drawn between the medial edge of the patella and the femoral pulse below the inguinal ligament. Stimulation was applied 14 cm proximal to the recording point. RESULTS: There were 104 healthy subjects. Onset latency of the SNAPs was 2.20 ± 0.16 ms (mean ± SD), peak latency was 2.70 ± 0.16 ms, peak-to-peak amplitude was 7.5 ± 3.0 µV, and conduction velocity was 51.5 ± 3.0 m/s. The side-to-side difference in the mean amplitude was 22.27 ± 13.6%. CONCLUSIONS: This new technique is easy, reliable, and reproducible, and should prove useful for the evaluation of neuropathies of the medial femoral cutaneous nerve.
Asunto(s)
Potenciales de Acción , Electrodiagnóstico/métodos , Nervio Femoral/fisiología , Conducción Nerviosa , Adolescente , Adulto , Anciano , Electrodos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Rótula , Adulto JovenRESUMEN
The objective of the present study was to analyze alterations of the femoral nerve of aged rats subjected to aerobic training. Wistar rats (12-mo of age) were divided in to two groups: S group (sedentary) and T group (trained). The exercise protocol were 16â¯weeks long. The groups were sacrificed at 16â¯months. Ultrafine sections of the femoral nerve have been used. There was no change in the body weight between the groups. T group showed a significant increase in myelinated fiber area, axon diameter, myelin sheath thickness and myelin fiber number compared with sedentary controls. In exercised trained animals, histograms of the frequency distribution of myelinated axons according to their areas showed increased number of medium and large fibers in relation to small fibers, which decreased in number. Aerobic training animals, showed the distribution of myelinated fiber population according to their area being bimodal, with the distribution shifted to the right, indicating increased fiber area. The T group showed a percent damage of large myelinated fibers significantly lower compared to controls. No significant difference was observed between the groups for the g-ratio. The T group also showed a significant increase in the number of microtubules and neurofilaments in myelinated fibers, which was not observed in S group. In conclusion, aerobic training improves nerve structure without evidence of nerve damage and produces an attenuation on the modifications in femoral nerve that develop in old age.
Asunto(s)
Envejecimiento/fisiología , Nervio Femoral/fisiología , Condicionamiento Físico Animal , Animales , Axones/fisiología , Masculino , Vaina de Mielina/fisiología , Fotomicrografía , Distribución Aleatoria , Ratas , Ratas WistarRESUMEN
PURPOSE: The aim of this study was to investigate whether hypnotic suggestions can alter knee extensor neuromuscular function at rest and during exercise. METHODS: Thirteen healthy volunteers (8 men and 5 women, 27 ± 3 years old) took part in this counterbalanced, crossover study including two experimental (hypnosis and control) sessions. Knee extensor neuromuscular function was tested before and after hypnosis suggestion by using a combination of voluntary contraction, transcutaneous femoral nerve electrical stimulation and transcranial magnetic stimulation (TMS). A fatiguing exercise (sustained submaximal contraction at 20% maximal voluntary contraction (MVC) force) was also performed to evaluate the potential influence of hypnosis on the extent and origin of neuromuscular adjustments. RESULTS: Hypnosis did not (p>0.05) alter MVC force or knee extensor neural properties. Corticospinal excitability, assessed with the amplitude of knee extensor motor evoked potentials, was also unchanged (p>0.05), as was the level of intracortical inhibition assessed with paired pulse TMS (short-interval intracortical inhibition, SICI). Time to task failure (~300 s) was not different (p>0.05) between the two sessions; accordingly, hypnosis did not influence neuromuscular adjustments measured during exercise and at task failure (p>0.05). CONCLUSION: Hypnotic suggestions did not alter neuromuscular properties of the knee extensor muscles under resting condition or during/after exercise, suggesting that hypnosis-induced improvement in exercise performance and enhanced corticospinal excitability might be limited to highly susceptible participants.
Asunto(s)
Ejercicio Físico/fisiología , Fatiga Muscular/fisiología , Músculo Esquelético/fisiología , Sugestión , Adulto , Estudios Cruzados , Potenciales Evocados Motores , Fatiga/fisiopatología , Fatiga/terapia , Femenino , Nervio Femoral/fisiología , Humanos , Rodilla , Articulación de la Rodilla , Masculino , Corteza Motora/fisiología , Contracción Muscular/fisiología , Tractos Piramidales/fisiología , Descanso , Estimulación Magnética Transcraneal , Estimulación Eléctrica Transcutánea del NervioRESUMEN
OBJECTIVES: This study was conducted to validate the dorsal approach for femoral nerve (FN) blockade in cats and to verify the efficacy of the sole use of peripheral nerve electrolocation (PNE) or ultrasound (US)-guided technique to achieve the block. METHODS: This study was carried out in two phases. In phase 1, five adult experimental cats were used to validate the approach. In each cat, one FN was located by US and the accuracy of this location confirmed by PNE. Then, 2 mg/kg lidocaine 2% (diluted in saline to a final volume of 1 ml) was injected around the target nerve and the success of the blockade was evaluated. In phase 2, four adult experimental cats were included in two groups to verify the reliability of this approach to block eight FNs by the sole use of PNE (group 1) or US-guided technique (group 2). Evidence of motor blockade, time required to perform the blockade, onset time and duration of the blockades were determined. RESULTS: The FN was successfully located by US in all cats enrolled in phase 1, as confirmed by PNE in all cases. The success rate was clinically higher in group 2 (87.5%) than in group 1 (75.0%). The US-guided technique required less time to perform and produced blocks of longer duration. Recovery was uneventful in all cases. CONCLUSIONS AND RELEVANCE: The combined use of PNE and US-guided technique enabled validation of the dorsal approach for the FN blockade as it provided a successful FN blockade in all cases. The sole use of a US-guided technique may offer some advantages over the use of a sole PNE-guided technique to perform these blocks.
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Nervio Femoral/diagnóstico por imagen , Nervio Femoral/fisiología , Bloqueo Nervioso/veterinaria , Ultrasonografía Intervencional/veterinaria , Animales , Gatos , Electrofisiología , Bloqueo Nervioso/métodos , Reproducibilidad de los ResultadosRESUMEN
BACKGROUND: We determined the sensitivity of motor responses evoked by stimulating catheters in determining catheter-nerve contact using ultrasonography as reference. METHODS: Femoral nerves were contacted using stimulating catheters under ultrasonography scanning in 25 patients. The output current was increased from its minimum until quadriceps muscle contraction occurred. The sensitivity of the motor response in determining catheter-nerve contact was calculated using 0.5 mA as current threshold. RESULTS: The current required for catheter stimulation to evoke a motor response ranged between 0.18 and 2.0 mA. Muscle contraction in response to 0.5 mA occurred in 16 of 25 subjects. The sensitivity of motor response for nerve stimulation was 64% (95% confidence interval: 0.43, 0.82). CONCLUSIONS: The absence of muscle responses at a stimulating current≤0.5 mA does not necessarily indicate the absence of catheter-nerve contact.
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Catéteres , Nervio Femoral/fisiología , Movimiento/fisiología , Bloqueo Nervioso/instrumentación , Adulto , Anestésicos Locales/administración & dosificación , Anestésicos Locales/farmacología , Bupivacaína/administración & dosificación , Bupivacaína/análogos & derivados , Bupivacaína/farmacología , Cateterismo/métodos , Estimulación Eléctrica , Femenino , Nervio Femoral/diagnóstico por imagen , Humanos , Rodilla/cirugía , Levobupivacaína , Masculino , Contracción Muscular/fisiología , Músculo Esquelético/fisiología , Agujas , Procedimientos Ortopédicos , UltrasonografíaRESUMEN
BACKGROUND AND OBJECTIVE: The latency times of midfemoral sciatic nerve blocks vary greatly. This study investigated the correlation between the type of motor response to nerve stimulation on the one hand and latency and block efficacy on the other. PATIENTS AND METHODS: We enrolled 215 consecutive patients (184 women) undergoing orthopedic foot surgery. A tourniquet was applied above the malleolus. The puncture location was found by palpating to locate the groove between the vastus lateralis and biceps femoris muscles, at the mid-point of the line between the posterior edge of the greater trochanter muscle and the insertion of the biceps femoris muscle in the popliteal fossa. A solution of equal proportions (1:1) of 1.5% mepivacaine (with bicarbonate 1:10) and 0.75% levobupivacaine was injected at a dose of 0.45 mL x kg(-1) (maximum 40 mL) using a 10-cm needle. Nerve stimulation was applied at 100-300 ms, 02-0.4 mA, and 2 Hz. Latency was classified as response in less than 15 minutes, in 15 to 30 minutes, or later than 30 minutes. RESULTS: The evoked motor response was inversion in 30 patients, flexion or extension in 38, plantar flexion in 101, dorsiflexion in 37, and eversion in 9. Shorter latencies (15 minutes) were observed in all patients with inversion or flexion/extension and in 84 (83%) of the 101 patients with plantar flexion. Mid-range latencies were observed in 13% of those with a plantar flexion response and in 29.7% of those with dorsiflexion. All 9 patients with eversion and 17 (45.9%) of the 37 patients with dorsiflexion had the longest latencies. The surgical block was complete for all patients. CONCLUSIONS: This approach provides an effective block with minimum latency in patients who have a flexion or extension motor response in the foot and/or fingers, inversion, or plantar flexion, which assumes that the injection has reached the common trunk of the sciatic or tibial nerve. However, a longer latency is associated with a peroneal motor response, particularly eversion.
Asunto(s)
Nervio Femoral/fisiología , Pie/cirugía , Bloqueo Nervioso/métodos , Adulto , Anciano , Anciano de 80 o más Años , Anestésicos Locales/farmacología , Bupivacaína/análogos & derivados , Bupivacaína/farmacología , Femenino , Nervio Femoral/anatomía & histología , Nervio Femoral/efectos de los fármacos , Pie/anatomía & histología , Pie/inervación , Humanos , Levobupivacaína , Masculino , Mepivacaína/farmacología , Persona de Mediana Edad , Movimiento , Procedimientos Ortopédicos , Estudios Prospectivos , Tiempo de Reacción/efectos de los fármacos , Tiempo de Reacción/fisiología , Adulto JovenRESUMEN
Ten canine cadavers were used to investigate the anatomy and ultrasonographic approaches to the sciatic (ScN) and femoral (FN) nerves and to assess the accuracy of an ultrasound (US) guided technique to locate and block these nerves in the dog. The nerves of four sedated dogs were sought using US, blocked with 1% lidocaine and successful location confirmed by peripheral neurostimulation. The ScN was identified by US in all cases whereas the FN was not located in all cases. This study validates the usefulness of the US-guided technique to locate and block the ScN at the midfemoral level but the acoustic window of the inguinal region was less successful for locating and blocking the FN.
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Nervio Femoral/diagnóstico por imagen , Bloqueo Nervioso/veterinaria , Nervio Ciático/diagnóstico por imagen , Ultrasonografía Intervencional/veterinaria , Anestésicos Locales/administración & dosificación , Animales , Cadáver , Perros , Estimulación Eléctrica , Nervio Femoral/fisiología , Lidocaína/administración & dosificación , Bloqueo Nervioso/métodos , Nervio Ciático/fisiologíaRESUMEN
The rat saphenous nerve contains only somato-sensory fibers and is used in investigations of neuropathic pain and its treatment. Due to its superficial anatomical path, the saphenous nerve is also widely used in electrophysiological studies. Nevertheless, morphologic and morphometric descriptions of the normal saphenous nerve are scanty in the literature and information on useful morphometric parameters of this nerve is still missing. Thus, the present study aimed to investigate the longitudinal and lateral symmetry of the saphenous nerve in young rats. Proximal and distal segments of the left and right saphenous nerves from female Wistar rats, aged 30 days (N=5) were morphometrically evaluated and comparisons were made between sides and segments. Our results show that the saphenous nerve is longitudinally and laterally symmetric since there were no morphometric differences between proximal and distal segments, as well as between right and left sides. This lateral symmetry is important in order to validate those experiments in which the contralateral nerve is used as the control. Also, the longitudinal symmetry information is fundamental to further studies involving the "dying back" neuropathy models. The present study adds to the literature new morphometric information on the rat saphenous nerve that might be useful for a better interpretation of further studies involving this nerve and experimental models of nerve diseases.
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Nervio Femoral/anatomía & histología , Animales , Animales Recién Nacidos , Femenino , Nervio Femoral/fisiología , Lateralidad Funcional , Fibras Nerviosas/clasificación , Fibras Nerviosas/fisiología , Ratas , Ratas WistarRESUMEN
Anatomical descriptions of the genitofemoral nerve (GFn) innervating the lower pelvic area are contradictory. Here we re-examine its origin and innervation by its various branches of principal target organs in the male rat. Using gross dissection, electrophysiological techniques and retrograde tracing of motoneurones with horseradish peroxidase, we confirm that the GFn originates from lumbar spinal nerves 1 and 2, and that at the level of the common iliac artery it divides into a lateral femoral and a medial genital branch. In contrast to previous studies, we report that the genital and not the femoral branch innervates the abdominal-inguinal skin, and not only the genital but also the femoral branch innervates the cremaster muscle (Cm) surrounding the testes. Motoneurones innervating the Cm proper are located in the ventral nucleus of L1 and L2, and those innervating the muscular transition region of the rostral Cm are located in the ventral nucleus in L1 and the ventrolateral nucleus in L2. The GFn may contribute to male reproductive performance by transmitting cutaneous information during copulation and, via contraction of the Cm to promote ejaculation, the protective displacement of the testes into the abdominal cavity during fighting and as a sperm-protecting thermoregulatory measure.
Asunto(s)
Nervio Femoral/anatomía & histología , Genitales Masculinos/inervación , Neuronas Motoras/citología , Vías Nerviosas , Abdomen , Animales , Electrofisiología , Nervio Femoral/fisiología , Histocitoquímica/métodos , Peroxidasa de Rábano Silvestre , Masculino , Neuronas Motoras/fisiología , Músculo Esquelético/inervación , Ratas , Ratas Wistar , Piel/inervación , TestículoRESUMEN
Selective transection of peripheral nerves that innervate the pelvic region results in the alteration of some aspects of copulatory behavior, including seminal plug weight. Both branches of the genitofemoral nerve primarily innervate the cremaster muscle although the genital branch has a wide distribution in the cremasteric sac. Thermoregulation of spermatogenesis and the mechanical event of ejaculation largely depend on cremaster contractility. In this study, we analyzed the effects of bilateral transection of the genitofemoral nerve on male copulatory behavior and on fertility. Sexually experienced adult male rats were submitted to sexual behavior tests before and after surgical transection of the genitofemoral nerve. Tests were made four times before and on Days 9, 12, 15, 18 and 21 after surgery, and seminal plug weight was also analyzed. In addition, fertility was tested using two different approaches: by allowing the male to ejaculate once in an estrous female or keeping the male with three females during 15 days. Results showed that there were no differences in any of the copulatory parameters, including seminal plug weight. Regarding fertility, both procedures showed that the ability to induce pregnancy was significantly diminished in the neurectomized males tested at different times after surgery. These results support the notion that genitofemoral nerve regulation of fertility via contraction of the male cremaster muscle is an important factor in reproduction in rats.