Assessment of a Neurophysiological Model of the Mandibular Branch of the Facial Nerve in Rats by Electromyography

Objectives: Our objective was to develop an experimental model for the noninvasive and objective evaluation of facial nerve regeneration in rats using a motor nerve conduction test (electromyography). Methods: Twenty-two rats were submitted to neurophysiological evaluation using motor nerve conduction of the mandibular branch of the facial nerve to obtain the compound muscle action potentials (CMAPs). To record the CM APs, we used two needle electrodes that were inserted into the lower lip muscle of the rat. A supramaximal electrical stimulus was applied, and the values of CMAP latency, amplitude, length, area, and stimulus intensity obtained from each side were compared by use of the Wilcoxon test. Results: There was no significant difference (all p > 0.05) in latency, amplitude, duration, area, or intensity of stimuli between the two sides. The amplitudes ranged between 1.61 and 8.30 mV, the latencies between 1.03 and 1.97 ms, and the stimulus intensities between 1.50 and 2.90 mA. Conclusions: This is a noninvasive, easy, and highly reproducible method that contributes to an improvement of the techniques previously described and may contribute to future studies of the degeneration and regeneration of the facial nerve.

Ultrasound-guided block of sciatic and femoral nerves: an anatomical study

The sheep is a popular animal model for human biomechanical research involving invasive surgery on the hind limb. These painful procedures can only be ethically justified with the application of adequate analgesia protocols. Regional anaesthesia as an adjunct to general anaesthesia may markedly improve well-being of these experimental animals during the postoperative period due to a higher analgesic efficacy when compared with systemic drugs, and may therefore reduce stress and consequently the severity of such studies. As a first step 14 sheep cadavers were used to establish a new technique for the peripheral blockade of the sciatic and the femoral nerves under sonographic guidance and to evaluate the success rate by determination of the colorization of both nerves after an injection of 0.5 mL of a 0.1% methylene blue solution. First, both nerves were visualized sonographically. Then, methylene blue solution was injected and subsequently the length of colorization was measured by gross anatomical dissection of the target nerves. Twenty-four sciatic nerves were identified sonographically in 12 out of 13 cadavers. In one animal, the nerve could not be ascertained unequivocally and, consequently, nerve colorization failed. Twenty femoral nerves were located by ultrasound in 10 out of 13 cadavers. In three cadavers, signs of autolysis impeded the scan. This study provides a detailed anatomical description of the localization of the sciatic and the femoral nerves and presents an effective and safe yet simple and rapid technique for performing peripheral nerve blocks with a high success rate.

Rapid Atrophy of the Lumbar Multifidus Follows Experimental Disc or Nerve Root Injury.

Study Design. Experimental study of muscle changes after lumbar spinal injury. Objectives. To investigate effects of intervertebral disc and nerve root lesions on cross-sectional area, histology and chemistry of porcine lumbar multifidus. Summary of Background Data. The multifidus cross-sectional area is reduced in acute and chronic low back pain. Although chronic changes are widespread, acute changes at 1 segment are identified within days of injury. It is uncertain whether changes precede or follow injury, or what is the mechanism. Methods. The multifidus cross-sectional area was measured in 21 pigs from L1 to S1 with ultrasound before and 3 or 6 days after lesions: incision into L3 - L4 disc, medial branch transection of the L3 dorsal ramus, and a sham procedure. Samples from L3 to L5 were studied histologically and chemically. Results. The multifidus cross-sectional area was reduced at L4 ipsilateral to disc lesion but at L4 - L6 after nerve lesion. There was no change after sham or on the opposite side. Water and lactate were reduced bilaterally after disc lesion and ipsilateral to nerve lesion. Histology revealed enlargement of adipocytes and clustering of myofibers at multiple levels after disc and nerve lesions. Conclusions. These data resolve the controversy that the multifidus cross-sectional area reduces rapidly after lumbar injury. Changes after disc lesion affect 1 level with a different distribution to denervation. Such changes may be due to disuse following reflex inhibitory mechanisms.

Fracture Of Distal Humerus: Mipo Technique With Visualization Of The Radial Nerve.

To evaluate the outcomes in patients treated for humerus distal third fractures with MIPO technique and visualization of the radial nerve by an accessory approach, in those without radial palsy before surgery. The patients were treated with MIPO technique. The visualization and isolation of the radial nerve was done by an approach between the brachialis and the brachiorradialis, with an oblique incision, in the lateral side of the arm. MEPS was used to evaluate the elbow function. Seven patients were evaluated with a mean age of 29.8 years old. The average follow up was 29.85 months. The radial neuropraxis after surgery occurred in three patients. The sensorial recovery occurred after 3.16 months on average and also of the motor function, after 5.33 months on average, in all patients. We achieved fracture consolidation in all patients (M=4.22 months). The averages for flexion-extension and prono-supination were 112.85° and 145°, respectively. The MEPS average score was 86.42. There was no case of infection. This approach allowed excluding a radial nerve interposition on site of the fracture and/or under the plate, showing a high level of consolidation of the fracture and a good evolution of the range of movement of the elbow. Level of Evidence IV, Case Series.

Effects Of Misalignments In The Retinal Nerve Fiber Layer Thickness Measurements With Spectral Domain Optical Coherence Tomography.

Purpose. To investigate misalignments (MAs) on retinal nerve fiber layer thickness (RNFLT) measurements obtained with Cirrus(©) SD-OCT. Methods. This was a retrospective, observational, cross-sectional study. Twenty-seven healthy and 29 glaucomatous eyes of 56 individuals with one normal exam and another showing MA were included. MAs were defined as an improper alignment of vertical vessels in the en face image. MAs were classified in complete MA (CMA) and partial MA (PMA), according to their site: 1 (superior, outside the measurement ring (MR)), 2 (superior, within MR), 3 (inferior, within MR), and 4 (inferior, outside MR). We compared RNFLT measurements of aligned versus misaligned exams in all 4 sectors, in the superior area (sectors 1 + 2), inferior area (sectors 3 + 4), and within the measurement ring (sectors 2 + 3). Results. RNFLT measurements at 12 clock-hour of eyes with MAs in the superior area (sectors 1 + 2) were significantly lower than those obtained in the same eyes without MAs (P = 0.043). No significant difference was found in other areas (sectors 1 + 2 + 3 + 4, sectors 3 + 4, and sectors 2 + 3). Conclusion. SD-OCT scans with superior MAs may present lower superior RNFLT measurements compared to aligned exams.

Transcutaneous Tibial Nerve Stimulation In The Treatment Of Lower Urinary Tract Symptoms And Its Impact On Health-related Quality Of Life In Patients With Parkinson Disease: A Randomized Controlled Trial.

A randomized controlled trial study was performed to evaluate the efficacy of transcutaneous tibial nerve stimulation (TTNS) and sham TTNS, in patients with Parkinson disease (PD) with lower urinary tract symptoms (LUTS). Randomized controlled trial. Thirteen patients with a diagnosis of PD and bothersome LUTS were randomly allocated to one of the following groups: Group I: TTNS group (n = 8) and group II: Sham group (n = 5). Both groups attended twice a week during 5 weeks; each session lasted 30 minutes. Eight patients received TTNS treatment and 5 subjects allocated to group II were managed with sham surface electrodes that delivered no electrical stimulation. Assessments were performed before and after the treatment; they included a 3-day bladder diary, Overactive Bladder Questionnaire (OAB-V8), and the International Consultation on Incontinence Quality of Life Questionnaire Short Form (ICIQ-SF), and urodynamic evaluation. Following 5 weeks of treatment, patients allocated to TTNS demonstrated statistically significant reductions in the number of urgency episodes (P = .004) and reductions in nocturia episodes (P < .01). Participants allocated to active treatment also showed better results after treatment in the OAB-V8 and ICIQ-SF scores (P < .01, respectively). Urodynamic testing revealed that patients in the active treatment group showed improvements in intravesical volume at strong desire to void (P < .05) and volume at urgency (P < .01) when compared to subjects in the sham treatment group. These findings suggest that TTNS is effective in the treatment of LUTS in patients with PD, reducing urgency and nocturia episodes and improving urodynamic parameters as well as symptom scores measured by the OAB-V8 and health-related quality-of-life scores measured by the ICIQ-SF.

Effect Of Low-level Laser Therapy (lllt) On Peripheral Nerve Regeneration Using Fibrin Glue Derived From Snake Venom.

The purpose of this study was to assess whether the adhesive permits the collateral repair of axons originating from a vagus nerve to the interior of a sural nerve graft, and whether low-level laser therapy (LLLT) assists in the regeneration process. Study sample consisted of 32 rats randomly separated into three groups: Control Group (CG; n=8), from which the intact sural nerve was collected; Experimental Group (EG; n=12), in which one of the ends of the sural nerve graft was coapted to the vagus nerve using the fibrin glue; and Experimental Group Laser (EGL; n=12), in which the animals underwent the same procedures as those in EG with the addition of LLLT. Ten weeks after surgery, the animals were euthanized. Morphological analysis by means of optical and electron microscopy, and morphometry of the regenerated fibers were employed to evaluate the results. Collateral regeneration of axons was observed from the vagus nerve to the interior of the autologous graft in EG and EGL, and in CG all dimensions measured were greater and presented a significant difference in relation to EG and EGL, except for the area and thickness of the myelin sheath, that showed significant difference only in relation to the EG. The present study demonstrated that the fibrin glue makes axonal regeneration feasible and is an efficient method to recover injured peripheral nerves, and the use of low-level laser therapy enhances nerve regeneration.

Contribution of skin immunohistochemistry in the evaluation of nerve fibers in diabetes mellitus type 2

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Nerve endings of filliform, fungiform and vallate papillae of dorsal tongue mucosa of White-lipped peccary (Tayassu pecari): Neurohistological observations

The neurohistologic observations were performed using the specimens prepared by Winkelmann and Schmitt silver impregnation method. The tissues were fixed in 10% formalin solution and sections of 40µm thickness were obtained by Leica Cryostat at -30ºC. The sections of dorsal mucosa of White-lipped peccary tongue showed numerous filliform and fungiform papillae, and two vallate papillae on the caudal part. The epithelial layer revealed queratinized epithelial cells and the connective tissue papillae of different sizes and shapes. Thick nerve fiber bundles are noted into the subepithelial connective tissue of the papillae. The connective tissue of fungiform and vallate papillae contained numerous sensitive nerves fibers bundles forming a complex nerve plexus.

Motor Nerve-Conduction Studies in Obstetric Brachial Plexopathy for a Selection of Patients with a Poor Outcome

Background: The criteria and timing for nerve surgery in infants with obstetric brachial plexopathy remain controversial. Our aim was to develop a new method for early prognostic assessment to assist this decision process. Methods: Fifty-four patients with unilateral obstetric brachial plexopathy who were ten to sixty days old underwent bilateral motor-nerve-conduction studies of the axillary, musculocutaneous, proximal radial, distal radial, median, and ulnar nerves. The ratio between the amplitude of the compound muscle action potential of the affected limb and that of the healthy side was called the axonal viability index. The patients were followed and classified in three groups according to the clinical outcome. We analyzed the receiver operating characteristic curve of each index to define the best cutoff point to detect patients with a poor recovery. Results: The best cutoff points on the axonal viability index for each nerve (and its sensitivity and specificity) were <10% (88% and 89%, respectively) for the axillary nerve, 0% (88% and 73%) for the musculocutaneous nerve, <20% (82% and 97%) for the proximal radial nerve, <50% (82% and 97%) for the distal radial nerve, and <50% (59% and 97%) for the ulnar nerve. The indices from the proximal radial, distal radial, and ulnar nerves had better specificities compared with the most frequently used clinical criterion: absence of biceps function at three months of age. Conclusions: The axonal viability index yields an earlier and more specific prognostic estimation of obstetric brachial plexopathy than does the clinical criterion of biceps function, and we believe it may be useful in determining surgical indications in these patients.

Relationship between median nerve somatosensory evoked potentials and spinal cord injury levels in patients with quadriplegia

Study design: Cross-sectional study. Objectives: To observe if there is a relationship between the level of injury by the American Spinal Cord Injury Association (ASIA) and cortical somatosensory evoked potential (SSEP) recordings of the median nerve in patients with quadriplegia. Setting: Rehabilitation Outpatient Clinic at the university hospital in Brazil. Methods: Fourteen individuals with quadriplegia and 8 healthy individuals were evaluated. Electrophysiological assessment of the median nerve was performed by evoked potential equipment. The injury level was obtained by ASIA. N(9), N(13) and N(20) were analyzed based on the presence or absence of responses. The parameters used for analyzing these responses were the latency and the amplitude. Data were analyzed using mixed-effect models. Results: N(9) responses were found in all patients with quadriplegia with a similar latency and amplitude observed in healthy individuals; N(13) responses were not found in any patients with quadriplegia. N(20) responses were not found in C5 patients with quadriplegia but it was present in C6 and C7 patients. Their latencies were similar to healthy individuals (P > 0.05) but the amplitudes were decreased (P < 0.05). Conclusion: This study suggests that the SSEP responses depend on the injury level, considering that the individuals with C6 and C7 injury levels, both complete and incomplete, presented SSEP recordings in the cortical area. It also showed a relationship between the level of spinal cord injury assessed by ASIA and the median nerve SSEP responses, through the latency and amplitude recordings. Spinal Cord (2009) 47, 372-378; doi:10.1038/sc.2008.147; published online 20 January 2009

Relaxation evoked by extracellular Ca(2+) in rat aorta is nerve-independent and involves sarcoplasmic reticulum and L-type Ca(2+) channell

The perivascular nerve network expresses a Ca(2+) receptor that is activated by high extracellular Ca(2+) concentrations and causes vasorelaxation in resistance arteries. We have verified the influence of perivascular nerve fibers on the Ca(2+)-induced relaxation in aortic rings. To test our hypothesis, either pre-contracted aortas isolated from rats after sensory denervation with capsaicin or aortic rings acutely denervated with phenol were stimulated to relax with increasing extracellular Ca(2+) concentration. We also studied the role of the endothelium on the Ca(2+)-induced relaxation, and we verified the participation of endothelial/nonendothelial nitric oxide and cyclooxygenise-arachidonic acid metabolites. Additionally, the role of the sarcoplasmic reticulum, K(+) channels and L-type Ca(2+) channels on the Ca(2+)-induced relaxation were evaluated. We have observed that the Ca(2+)-induced relaxation is completely nerve independent, and it is potentiated by endothelial nitric oxide (NO). In endothelium-denuded aortic rings, indomethacin and AH6809 (PGF(2 alpha) receptor antagonist) enhance the relaxing response to Ca(2+). This relaxation is inhibited by thapsigargin and verapamil, while was not altered by tetraethylammonium. In conclusion, we have shown that perivascular nervous fibers do not participate in the Ca(2+)-induced relaxation, which is potentiated by endothelial NO. In endothelium-denuded preparations, indomethacin and AH6809 enhance the relaxation induced by Ca(2+). The relaxing response to Call was impaired by verapamil and thapsigargin, revealing the importance of L-type Ca(2+) channels and sarcoplasmic reticulum in this response. (c) 2008 Elsevier Inc. All rights reserved.

Effects of Commonly Used Solubilizing Agents on a Model Nerve-Muscle Synapse

Solubility represents a limiting factor when testing new compounds in animal experiments, since solubilizing agents generally have pharmacological effects that can interfere with the studied substance. Vehicles are commonly used for solubilizing certain substances including apolar and polar extracts obtained from medicinal plants. In this study, fifteen vehicles were investigated on mice neuromuscular preparations. A known in vitro neuroblocker myotoxin from Bothrops jararacussu venom, bothropstoxin-I, was used as a pharmacological tool for testing the medicinal potential of apolar and polar extracts (hexane, dichloromethane, ethyl acetate and methanol) obtained from Casearia sylvestris Sw. leaves, which in turn were used for testing their solubility and concomitantly to produce no change on basal response of indirectly stimulated mouse phrenic nerve-diaphragm preparations. Taken together in vitro biological system and extracts solubility, our results showed that dimethyl sulphoxide and polyethylene glycol 400 were the better vehicles, and methanol extract solubilized on PEG 400 was the only one able to act against the paralysis induced by the myotoxin. Thus, this study points out to the relevant role that vehicles exhibit for extracting the potential pharmacological activity of plants in a given test system.

Longitudinal excursion and strain in the median nerve during novel nerve gliding exercises for carpal tunnel syndrome

Nerve and tendon gliding exercises are advocated in the conservative and postoperative management of carpal tunnel syndrome (CTS). However, traditionally advocated exercises elongate the nerve bedding substantially, which may induce a potentially deleterious strain in the median nerve with the risk of symptom exacerbation in some patients and reduced benefits from nerve gliding. This study aimed to evaluate various nerve gliding exercises, including novel techniques that aim to slide the nerve through the carpal tunnel while minimizing strain (sliding techniques). With these sliding techniques, it is assumed that an increase in nerve strain due to nerve bed elongation at one joint (e.g., wrist extension) is simultaneously counterbalanced by a decrease in nerve bed length at an adjacent joint (e.g., elbow flexion). Excursion and strain in the median nerve at the wrist were measured with a digital calliper and miniature strain gauge in six human cadavers during six mobilization techniques. The sliding technique resulted in an excursion of 12.4 mm, which was 30% larger than any other technique (p 0.0002). Strain also differed between techniques (p 0.00001), with minimal peak values for the sliding technique. Nerve gliding associated with wrist movements can be considerably increased and nerve strain substantially reduced by simultaneously moving neighboring joints. These novel nerve sliding techniques are biologically plausible exercises for CTS that deserve further clinical evaluation. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:972-980, 2007

Enhanced downregulation of the p75 nerve growth factor receptor by cholesteryl and bis-cholesteryl antisense oligonucleotides

The effects of conjugating cholesterol to either or both ends of a phosphorothioate (PS) oligonucleotide were analyzed in terms of cellular uptake and antisense efficacy. The oligo sequence was directed against the p75 nerve growth factor receptor (p75), and was tested in differentiated PC12 cells, which express high levels of this protein. The addition of a single cholesteryl group to the 5'-end significantly increased cellular uptake and improved p75 mRNA downregulation compared with the unmodified PS oligo, However, only a minor degree of downregulation of p75 protein was obtained with 5' cholesteryl oligos, Three different linkers was used to attach the 5' cholesteryl group but were found not to have any impact on efficacy. Addition of a single cholesteryl group to the 3'-end led to greater p75 mRNA downregulation (31%) and p75 protein downregulation (28%) than occurred with the 5' cholesteryl oligos. The biggest improvement in antisense efficacy, both at the mRNA and protein levels, was obtained from the conjugation of cholesterol to both ends of the oligo. One of the bis-cholesteryl oligos was nearly as effective as cycloheximide at decreasing synthesis of p75, The bis-cholesteryl oligos also displayed significant efficacy at 1 mu M, whereas the other oligos required 5 mu M to be effective. The enhanced efficacy of bis-cholesteryl oligos is likely to be due to a combination of enhanced cellular uptake and resistance to both 5' and 3' exonucleases.