Comparative structural analysis of neuromuscular junctions in mice at different ages

The authors studied the histochemical and ultrastructural modifications that occur in the neuromuscular junctions (NMJ) of fibularis longus muscles of mice with an age range of 3 to 21 months. Twenty-four male and female animals were killed at 3, 5, 14 and 21 months of age: 7 of them at 3 months, 4 of them at 5 month, 9 at 14 months and 4 at 21 months. The fibularis longus muscles were processed and their NMJ examined with the transmission electron microscope. The most relevant changes were associated with the degeneration and retraction of terminal axons, i.e., axons poor in synaptic vesicles with degenerated mitochondria, and exhibiting multivesicular bodies and vacuoles; exposed and widened junctional folds and cytoplasmic processes of Schwann cells located in the synaptic gutter. The presence of lysosomes or lipofuchsin in the juxtajunctional sarcoplasm was also noted. These observations suggest that the phenomena of retraction and budding occur in the NMJ with advancing age, with a predominance of events associated with degeneration, leading to profound changes in NMJ shape.

Inside-out vs. standard vein graft to repair a sensory nerve in rats

Nerve regeneration in a sensory nerve was obtained by the application of different techniques: inside-out vein graft (IOVG group) and standard vein graft (SVG group). These techniques provide a good microenvironment for axon regeneration in motor nerves, but their efficiency for regeneration of sensory nerves is controversial. The saphenous nerve was sectioned and repaired by the inside-out and standard vein graft techniques in rats. After 4, 12, and 20 weeks the graft and the distal stump were observed under electron microscopy. In each studied period, the pattern, diameters, and thickness of the myelin sheaths of the regenerated axons were measured in the graft and distal stump. A comparative study about the regenerated nerve fibers by these two different techniques was performed. Regenerated nerve fibers were prominent in both vein grafts 4 weeks after the surgical procedures. On the other hand, in the distal stump, regenerated nerve fibers were observed only from 12 weeks. In both inside-out vein graft and standard vein graft statistical difference was not observed about the diameters and thickness of the myelinated fibers after 20 weeks. On the other hand, the inside-out group had greater regenerated axon number when compared to the standard group. There is a capillary invasion in both graft and distal stump, especially in the IOVG group. The regenerated axons follow these capillaries all the time like satellite microfascicles. After 20 weeks, the diameters of regenerated fibers repaired by the standard vein graft technique were closer to the normal fibers compared to the inside-out vein graft. On the other hand, the pattern of these regenerated axons was better in the IOVG group.

Ulnar-to-median nerve anastomosis in the forearm. Review and report of 2 new cases

The ulnar-to-median nerve anastomosis in the forearm is a very rare occurrence, not mentioned in many anatomical text books. We found only 4 cases cited in medical literature. Here we describe 2 new cases, for which diagnosis was suspected when the compound muscle action potential of the abductor pollicis brevis muscle (APB), obtained by maximal stimulation of the median nerve at the elbow, was lower than that obtained at the wrist. The diagnosis was confirmed by stimulation of the ulnar nerve at the elbow, which evoked a compound muscle action potential of the APB with a clear negative initial deflection without volume-conducted potential.

Mononeuropathy of the suprascapular nerve: Study of 3 South American cases

In this work 3 new cases of suprascapular nerve mononeuropathy are described. ENMG diagnosis criteria were: a) normal sensory conduction studies of the ipsolateral ulnar, median and radial nerves; b) bilateral suprascapular nerve latencies with bilateral compound muscle action potential, obtained from the infraspinatus muscle with symmetrical techniques; and c) abnormal neurogenic infraspinatus muscle electromyographic findings, coexisting with normal electromyographical data of the ipsolateral deltoideus and supraspinatus muscles. These 3 cases of suprascapular mononeurpathy were found in 6,080 ENMG exams from our University Hospital. For us this mononeuropathy is rare with a 0.05% occurrence.

The mandibular lingula's position in children as a reference to inferior alveolar nerve block

Purpose: The objective of this study was to evaluate the position of the mandibular lingula (ML) to provide data for inferior alveolar nerve block techniques in children. Methods: One hundred fifty-four panoramic radiographs of 7- to 10-year-old boys and girls were analyzed. Measurements were taken from the ML to the occlusal plane, and the percentile distances of the ML to ramal borders were determined. Results: The distance between the ML and the occlusal plane showed a gradual increase, but only in the male group was it statistically significant. MLs ratio position on the ramus remained constant in all analyzed groups. In the 7-year-old group, the ML was observed above the occlusal plane in 70% of girls and 55% of boys. That percentage reached 85% of all children by age 10. Conclusions: The mandibular lingula's ratio position remained constant. Inferior alveolar anesthesia should be administered at least 6 mm above the occlusal plane in 7- to 8-year-old children, while 10 mm could be indicated for 9- to 10-year-old children. The mandibular lingula should be considered a reliable reference for further studies of inferior alveolar nerve block techniques.

Evaluation of microcurrent electrical nerve stimulation (mens) effectiveness on muscle pain in temporomandibular disorders patients

The effect of Microcurrent Electrical Nerve Stimulation (MENS) was evaluated and compared with occlusal splint therapy in temporomandibular disorders (TMD) patients with muscle pain. Twenty TMD patients were divided into four groups. One received occlusal splint therapy and MENS (I); other received splints and placebo MENS (II); the third, only MENS (III) and the last group, placebo MENS (IV). Sensitivity derived from muscle palpation was evaluated using a visual analogue scale. Results were submitted to analysis of variance (p<0.05). There was reduction of pain level in all groups: group I (occlusal splint and MENS) had a 47.7% reduction rate; group II (occlusal splint and placebo MENS), 66.7%; group III (MENS), 49.7% and group IV (placebo MENS), 16.5%. In spite of that, there was no statistical difference (analysis of variance / p<0.05) between MENS and occlusal splint therapy regarding muscle pain reduction in TMD patients after four weeks.

The role of membranous urethral afferent autonomic innervation in the continence mechanism after nerve sparing radical prostatectomy: a clinical and prospective study

Purpose: We evaluated the somatic and autonomic innervation of the pelvic floor and rhabdosphincter before and after nerve sparing radical retropubic prostatectomy using neurophysiological tests and correlated findings with clinical parameters and urinary continence. Materials and Methods: From February 2003 to October 2005, 46 patients with prostate cancer were enrolled in a controlled, prospective study. Patients were evaluated before and 6 months after nerve sparing radical retropubic prostatectomy using the UCLA-PCI urinary function domain and neurophysiological tests, including somatosensory evoked potential, and the pudendo-urethral, pudendo-anal and urethro-anal reflexes. Clinical parameters and urinary continence were correlated with afferent and efferent innervation of the membranous urethra and pelvic floor. We used strict criteria to define urinary continence as complete dryness with no leakage at all, not requiring any pads or diapers and with a UCLA-PCI score of 500. Patients with a sporadic drop of leakage, requiring up to 1 pad daily, were defined as having occasional urinary leakage. Results: Two patients were excluded from study due to urethral stricture postoperatively. We evaluated 44 patients within 6 months after surgery. The pudendo-anal and pudendo-urethral reflexes were unchanged postoperatively (p = 0.93 and 0.09, respectively), demonstrating that afferent and efferent pudendal innervation to this pelvic region was not affected by the surgery. Autonomic afferent denervation of the membranous urethral mucosa was found in 34 patients (77.3%), as demonstrated by a postoperative increase in the urethro-anal reflex sensory threshold and urethro-anal reflex latency (p <0.001 and 0.0007, respectively). Six of the 44 patients used pads. One patient with more severe leakage required 3 pads daily and 23 showed urinary leakage, including 5 who needed 1 pad per day and 18 who did not wear pads. Afferent autonomic denervation at the membranous urethral mucosa was found in 91.7% of patients with urinary leakage. Of 10 patients with preserved urethro-anal reflex latency 80% were continent. Conclusions: Sensory and motor pudendal innervation to this specific pelvic region did not change after nerve sparing radical retropubic prostatectomy. Significant autonomic afferent denervation of the membranous urethral mucosa was present in most patients postoperatively. Impaired membranous urethral sensitivity seemed to be associated with urinary incontinence, particularly in patients with occasional urinary leakage. Damage to the afferent autonomic innervation may have a role in the continence mechanism after nerve sparing radical retropubic prostatectomy.

Neurorrafia do ramo bucal dorsal do nervo facial em coelhos com proteção de segmento intestinal alógeno

18 rabbits, New Zealand, males, adults were used for clinical and histological evaluation of repair dorsal buccal branch of facial nerve after 15, 30 and 60 days postoperatively (PO). The animals were divided into two groups for transection and 10-0 nylon monofilament epineural suture of buccal branch. In animals in Group I, the nerve was coated with protection of jejunum allograft preserved in glycerin 98% and in group II was applied epineural suture. Both groups occurred the return of movement of the upper lip from the eighth week. There was infiltrated cellular and giant cells with fibrosis unsystematic and collagen fibers of the allograft jejunum joing to the connective tissue. At 15 and 30 days of PO, the distal nerve stumps of both groups were found with degeneration wallerian and in 60 days, regenerated fibers. The repair of the dorsal buccal branch of facial nerve with the allograft wasn't significantly different between the control rabbits as to the assessment of histological and functional recovery.

Orbitoethmoidal impacted injury by kitchen knife causing abducens nerve palsy

Introduction: Impacted knife injuries in the maxillofacial region are rare and infrequently reported. In cases of injury involving orbit or eye, these reports are even rarer. Discussion: Damage to the orbital contents may result in a rupture of the globe, extraocular muscle injury, lacrimal gland damage, and others. Orbital foreign bodies are not only difficult to detect, and clinical features vary according to its size, characteristics, shape, penetrating method, and site. In this report, a case of abducens nerve palsy after orbitoethmoidal knife injury is presented. © 2010 Springer-Verlag.

Partial external mitral annuloplasty in dogs with myxomatous mitral valve degeneration and congestive heart failure: Outcome in 9 cases

Objective: To report the outcome of partial external mitral annuloplasty in dogs with congestive heart failure (CHF) due to mitral regurgitation caused by myxomatous mitral valve degeneration (MMVD). Animals, materials and methods: Nine client-owned dogs with CHF due to mitral regurgitation caused by MMVD. Surgery consisted of a double row of pledget-butressed continuous suture lines placed into the left ventricle parallel and just ventral to the atrioventricular groove between the subsinuosal branch of the left circumflex coronary artery and the paraconal branch of the left coronary artery. Results: Two dogs died during surgery because of severe hemorrhage. Two dogs died 12 and 36 h after surgery because of acute myocardial infarction. Three dogs were euthanized 2 and 4 weeks after surgery because of progression of CHF, 1 was euthanized 30 days after surgery for non-cardiac disease, and 1 survived for 48 months. In the 5 dogs that survived to discharge there was no significant change in the left atrium to aortic ratio with surgery (3.6 ± 0.56 before surgery; 3.1 ± 0.4 after surgery; p = 0.182), and no significant change in mitral regurgitant fraction in 4 dogs in which this measurement was made (78.7 ± 2.0% before surgery; 68.7 ± 7.5% after surgery; p = 0.09). Conclusions: Partial external mitral annuloplasty in dogs with CHF due to MMVD was associated with high perioperative mortality and most dogs that survived to discharge failed to show clinically relevant palliation from this procedure. Consequently, partial external mitral annuloplasty is not a viable option for dogs with mitral regurgitation due to MMVD that has progressed to the stage of CHF. © 2011 Elsevier B.V. All rights reserved.

Role of nitric oxide in the remodelling of extracellular matrix in myxomatous mitral valve degeneration of dogs and pigs

Myxomatous mitral valve degeneration (MMVD) or endocardiosis is a heart valve disease that occurs in many mammalian species, especially in humans, dogs and pigs. Nitric oxide (NO) plays an important role in the MMVD development. NO can be indirectly evaluated by the nitric-oxide synthase (NOS) expression and by the histochemical reaction of nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d). The aim of this study was to evaluate NOS activity, by NADPH-d reaction, in the anterior leaflet of dogs with regular mitral valves and in those with MMVD, as well as in young swine and old females, comparing the reaction level with the degree of endocardiosis disease and also the histological alterations. Twelve mitral valves of dogs and 22 of swine were used for the research. All the valves were macroscopically analyzed for the occurrence or not of endocardiosis. They were fixed in a 4% paraformaldehyde, exposed to NADPH-d reaction, routinely processed and microscopically evaluated for the detection of mucopolysaccharides (MPS) deposition, collagen degeneration, fibrosis and level of endocardiosis. In dogs, relation was observed between higher intensity of the NADPH-d reaction, higher endocardiosis degree, MPS deposition as well as the collagen degeneration. No alteration in color was observed in pigs ́ valves during NADPH-d reaction. In conclusion, NO works in canine mitral valve remodeling extracellular matrix and plays an important role in endocardiosis disease. In swine, the lack of reaction reinforces the absence of macroscopical endocardiosis lesions, suggesting restrict NO action or major differences in the structures of swine valves.

Trochlear nerve palsy associated with claude bernard-horner syndrome after brainstem stroke

The association of unilateral trochlear nerve palsy with Claude Bernard-Horner syndrome represents a rare clinical condition. We present the case of a patient with this unusual presentation. The investigation performed implicated cerebrovascular disease as the underlying cause of the condition in this patient. © 2011 S. Karger AG, Basel.

Diet-induced obesity impairs AKT signalling in the retina and causes retinal degeneration

Retinopathy, a common complication of diabetes, is characterized by an unbalanced production of nitric oxide (NO), a process regulated by nitric oxide synthase (NOS). We hypothesized that retinopathy might stem from changes in the insulin receptor substrate (IRS)/PI3K/AKT pathway and/or expression of NOS isoforms. Thus, we analysed the morphology and apoptosis index in retinas of obese rats in whom insulin resistance had been induced by a high-fat diet (HFD). Immunoblotting analysis revealed that the retinal tissue of HFD rats had lower levels of AKT1, eNOS and nNOS protein than those of samples taken from control animals. Furthermore, immunohistochemical analyses indicated higher levels of iNOS and 4-hydroxynonenal and a larger number of apoptotic nuclei in HFD rats. Finally, both the inner and outer retinal layers of HFD rats were thinner than those in their control counterparts. When considered alongside previous results, these patterns suggest two major ways in which HFD might impact animals: direct activity of ingested fatty acids and/or via insulin-resistance-induced changes in intracellular pathways. We discuss these possibilities in further detail and advocate the use of this animal model for further understanding relationships between retinopathy, metabolic syndrome and type 2 diabetes. © 2012 John Wiley & Sons, Ltd.

Bothropstoxin-I reduces evoked acetylcholine release from rat motor nerve terminals: Radiochemical and real-time video-microscopy studies

Understanding the biological activity profile of the snake venom components is fundamental for improving the treatment of snakebite envenomings and may also contribute for the development of new potential therapeutic agents. In this work, we tested the effects of BthTX-I, a Lys49 PLA2 homologue from the Bothrops jararacussu snake venom. While this toxin induces conspicuous myonecrosis by a catalytically independent mechanism, a series of in vitro studies support the hypothesis that BthTX-I might also exert a neuromuscular blocking activity due to its ability to alter the integrity of muscle cell membranes. To gain insight into the mechanisms of this inhibitory neuromuscular effect, for the first time, the influence of BthTX-I on nerve-evoked ACh release was directly quantified by radiochemical and real-time video-microscopy methods. Our results show that the neuromuscular blockade produced by in vitro exposure to BthTX-I (1 μM) results from the summation of both pre- and postsynaptic effects. Modifications affecting the presynaptic apparatus were revealed by the significant reduction of nerve-evoked [3H]-ACh release; real-time measurements of transmitter exocytosis using the FM4-64 fluorescent dye fully supported radiochemical data. The postsynaptic effect of BthTX-I was characterized by typical histological alterations in the architecture of skeletal muscle fibers, increase in the outflow of the intracellular lactate dehydrogenase enzyme and progressive depolarization of the muscle resting membrane potential. In conclusion, these findings suggest that the neuromuscular blockade produced by BthTX-I results from transient depolarization of skeletal muscle fibers, consequent to its general membrane-destabilizing effect, and subsequent decrease of evoked ACh release from motor nerve terminals. © 2012 Elsevier Ltd.

Incomplete mandibular fracture after lateralization of the inferior alveolar nerve for implant placement

PURPOSE: The present case describes an inferior alveolar nerve lateralization for implant placement that caused mandible fracture a few days after surgery. CLINICAL REPORT: In this case, a 56-year-old female patient who had a severely atrophied jaw and showing bone height less than 7 mm from the bone crest and the mandibular canal was submitted to surgery lateralization of the inferior alveolar conducted with piezzo. Even with all postoperative care, the patient suffered an incomplete fracture of the mandible a few days after lateralization of the inferior alveolar nerve for implant placement. The patient was treated with soft diet and medications for pain and antibiotics, besides removing the implant associated with the fracture. CONCLUSION: It is suggested that this procedure may be conducted in 2 operative periods: firstly, the lateralization of the inferior alveolar; and secondly, after a period of 3 months, the implant placement in a situation of more bone stability. Copyright © 2013 by Mutaz B. Habal, MD.