Primary Nerve Research Articles

Chapter 14 - Clinical electrophysiology of axonal polyneuropathies

Axonal neuropathies encompass a wide range of acquired and inherited disorders with electrophysiologic characteristics that arise from the unique neurophysiology of the axon. Accurate interpretation of nerve conduction studies and electromyography requires an in-depth understanding of the pathophysiology of the axon. Here we review the unique neurophysiologic properties of the axon and how they relate to clinical electrodiagnostic features. We review the length-dependent Wallerian or "dying-back" processes as well as the emerging body of literature from acquired axonal neuropathies that highlights the importance of axonal disease at the nodes of Ranvier. Neurophysiologic features of individual inherited and acquired axonal diseases, including primary nerve disease as well as systemic immune mediated, metabolic, and toxic diseases involving the peripheral nerve, are reviewed. This comprehensive review of electrodiagnostic findings coupled with the current understanding of pathophysiology will aid the clinician in the evaluation of axonal polyneuropathies.

Long-term efficacy of fractionated conformal radiotherapy for the management of primary optic nerve sheath meningioma

Background/AimFractionated conformal radiotherapy (FCRT) is now used to treat vision-threatening optic nerve sheath meningioma (ONSM), but long-term efficacy and safety data are lacking; the purpose of this study was to...

Irisin regulates the expression of BDNF and glycometabolism in diabetic rats.

Irisin is a proteolytic product of the fibronectin type III domain-containing protein 5. The aim of the present study was to verify whether irisin is involved in the pathogenesis of diabetic mild cognitive impairment and elucidate the associated mechanisms. Diabetic rats were divided into four groups: Control, Model, Irisin (overexpression of irisin) and Irisin-short hairpin (sh)-RNA (irisin interference). The levels of irisin, brain-derived neurotrophic factor (BDNF), glycosylated hemoglobin A1c (GHbA1c) and advanced glycated end products (AGEs) in the serum were determined using ELISA. The expression of BDNF in the hippocampal tissue was evaluated by immunohistochemical analysis. Compared with the Control group, the levels of irisin and BDNF were markedly decreased in the Model and Irisin-shRNA groups, whereas those of GHbA1c and AGEs were markedly increased. However, the levels of irisin and BDNF in the Irisin group were significantly higher than those in the Model group, whereas the levels of GHbA1c and AGEs in the Irisin group were significantly lower. Irisin-shRNA significantly downregulated the expression of irisin and BDNF, and upregulated the levels of GHbA1c and AGEs, compared with those in the Model group. Rat primary hippocampal nerve cells were isolated and identified by microtubule-associated protein-2 labeling. The vitality of primary cells from diabetic rats, evaluated using a methyl thiazolyl tetrazolium assay, was markedly decreased and further reduced following the injection of irisin-shRNA, however, it was markedly improved following irisin treatment. The mRNA and protein levels of BDNF in the primary cells were evaluated by fluorogenic reverse transcription-quantitative polymerase chain reaction and western blot analyses, respectively, following the exposure of cells to different concentrations of glucose: 0 (control), 5.5, 15 and 25 mmol/l for 12, 24 and 48 h. The mRNA and protein expression levels of BDNF in the primary cells following exposure to glucose were significantly lower than those observed in the control. Further exposure to glucose led to a significant decrease in the expression of BDNF. In conclusion, irisin may regulate the expression of BDNF and glycometabolism in diabetic rats.

Clinically Available Low Intensity Ultrasound Devices do not Promote Axonal Regeneration After Peripheral Nerve Surgery-A Preclinical Investigation of an FDA-Approved Device.

The slow axonal regeneration and consecutive delayed muscle reinnervation cause persistent functional deficits following peripheral nerve injury, even following sufficient surgical nerve reconstruction. Preclinically, adjunct ultrasound therapy has shown to significantly accelerate nerve regeneration and thereby improve muscle function compared to nerve reconstruction alone. However, although FDA-approved and clinically well-tested ultrasound devices for other conditions such as delayed-healing fractures are available, they have not been investigated for peripheral nerve injury yet. Aiming to provide a fast clinical translation, we evaluated EXOGEN (Bioventus LLC, Durham, USA), a clinical device for low-intensity ultrasound therapy in various treatment intervals following peripheral nerve surgery. Sixty rats, randomized to five groups of twelve animals each, underwent median nerve transection and primary epineural nerve reconstruction. Post-surgically the ultrasound therapy (duration: 2 min, frequency: 1.5 MHz, pulsed SATA-intensity: 30 mW/cm2, repetition-rate: 1.0 kHz, duty-cycle: 20%) was applied either weekly, 3 times a week or daily. A daily sham-therapy and a control-group served as references. Functional muscle testing, electrodiagnostics and histological analyses were used to evaluate nerve regeneration. The post-surgically absent grip strength recovered in all groups and increased from week four on without any significant differences among groups. The weekly treated animals showed significantly reduced target muscle atrophy compared to sham-treated animals (p = 0.042), however, with no significant differences to three-times-a-week-, daily treated and control animals. The number of myelinated axons distal to the lesion site increased significantly in all groups (p < 0.001) without significant difference among groups (p > 0.05). A full recovery of distal latency was achieved in all groups and muscle function and CMAP recurred with insignificant differences among groups. In conclusion, the clinically available FDA-approved ultrasound device did not promote the axonal regeneration following nerve injury in comparison to control and sham groups. This is in contrast to a conclusive preclinical evidence base and likely due to the insufficient ultrasound-intensity of 30 mW/cm2. We recommend the clinical investigation of 200–300 mW/cm2.

Reactive astrocytosis alters gene expression of ECM components in primary optic nerve head astrocytes

Reactive astrocytosis alters gene expression of ECM components in primary optic nerve head astrocytes

Conduit-based Nerve Repairs Provide Greater Resistance to Tension Compared with Primary Repairs: A Biomechanical Analysis on Large Animal Samples.

Background:When primary repair of transected peripheral nerves is not possible due to large gaps, nerve grafts or repair using conduits are other options to bridge the gap such that the nerve is repaired without tension. When nerve gaps are repaired primarily, there is a worry about tension, failure, and poor healing. In this biomechanical study comparing nerves repaired primarily versus those repaired with conduits, we hypothesized that conduit repair provided greater mechanical breaking strength.Methods:We dissected fresh cadaveric sheep hooves and transacted their peripheral nerves. Subsequently, we divided these transacted nerves into 2 groups: primary repair versus repair using a nerve conduit. After repair using a standardized technique, we tensioned each of these repairs via a load tester and recorded the force required till repair failure occurred.Results:Six nerves using primary nerve repair and 6 nerves repaired with a nerve conduit (10 mm length × 2.5 mm diameter) were studied. The average breaking strength of the nerves repaired with the nerve conduit was 0.92 N and that using the primary nerve repair technique was 0.46 N (P = 0.001). All the nerves repaired using nerve conduit repair had an additional 5 mm added to their total length as compared with the nerves in the other group.Conclusions:Nerve repair using a nerve conduit ensures a higher breaking strength and potentially a greater tension-free repair as compared with primary nerve repairs in a sheep model. This study supports the use of conduits in the bridging of nerve gaps.

An Analytic Study of Nerve Regeneration between End-to-End and End-to-Side Neurorrhaphy: An Experimental Study in Rats

AbstractBackground: In peripheral nerve injury, end-to-side neu-rorrhaphy involves cooptation of the distal stump of a transect-ed nerve to the trunk of an adjacent donor nerve. It has been proposed as an alternative technique when the proximal stump of an injured nerve is unavailable or the nerve gap is too long to be bridged by a nerve graft. End-to-side neurorrhaphy was first documented in the 19th century [1]. However; the tech-nique has not been a clinical routine for almost a century. In early 1990s, Viterbo et al., [2] demonstrated successful nerve regeneration and muscle re-innervation in a rat end-to-side neurorrhaphy model.Aim of Study: A prospective experimental study was done to study, evaluate, and compere the histological results of neurorrhaphy in rats using end-to-end, end-to-side and end-to-side long contact neurorrhaphy. Thereby presenting a different techniques and for the first time a comparative analytic study for the end-to-side long contact neurorrhaphy.Material and Methods: The experiment carried out on 74 male rats, divided into three groups. After two months all rats were evaluated histologically with immunohistochemistry staining.Results: The repaired grafts from the three groups were obtained from the animals for histological examination.Conclusion: End-to-side neurorraphy presently does not replace a sound primary nerve suture. It should be seen as an excellent, viable option when planning to address difficult peripheral nerve injuries.

Améliorer l’issue des lésions nerveuses sensorielles traumatiques de la main par l’utilisation supplémentaire d’un tube nerveux de chitosane dans la réparation du nerf primaire — un essai bicentrique contrôlé randomisé

Peripheral sensory nerve injuries are a major problem of acute hand trauma surgery. Standard treatment is microsurgical end-to-end repair of these nerves whenever possible. If surgery fails, a permanent loss of sensibility and the formation of painful neuroma are consequences. The objective of this study was to evaluate whether the additional use of a chitosan nerve tube in primary nerve repair influences the sensory convalescence. A randomized controlled bicenter trial with parallel group design and double blinded assessment was conducted to show superiority of the additional use of a chitosan nerve tube compared to microsurgical nerve repair alone. 74 participants were enrolled. The ability of static 2-point-discrimanation (2PD) 6 months after surgery was the primary outcome parameter. Considerable secondary outcome parameters were filament recognition (Semmes Weinstein) testing, pain, appearance of neuroma and the Disabilities of the Arm, Shoulder and Hand (DASH)–score. In Intervention group both sensibility (expressed by 2PD) and tactile gnosis (expressed by Semmes Weinstein testing) could be increased significantly. Mean 2PD in control group at 6-month follow-up was 8 (2–20) mm and 6.3 (1–15) mm in intervention group (P = 0.029). 2PD correlated with DASH-score. In control group, 3 neuroma were found whereas none in intervention group. There were no implant-associated complications. Peripheral sensory nerve regeneration can be improved significantly by additional use of a chitosan nerve tube. An augmented ability of static 2-point discrimination has clinical relevancy.

Surgical outcome of prognostic factors for final outcome of hand function following primary median nerve repair

Background: A major problem in surgery of median nerve injuries is the unpredictable final outcome, so identifying the prognostic factors for final outcome is needed in primary median nerve repair following injury. Assessing the functional recovery of hand function following median nerve repair.Methods: Total no. of patients with median nerve injury repaired in our institution was 70. All the patients assessed preoperatively by clinical examination, surgery performed immediately or within 12 hours of injury, performed under axillary block and tourniquet control, Multiple surgeons involved (about 6 surgeons). All are primarily repaired nerves, repair by 70 prolene epineural sutures, postoperative immobilization of 3 weeks.Results: Median nerve injury associated with other flexors involved patients show good functional recovery, the functional recovery deteriorate once involvement of finger flexors, particularly if all the tendons were injured. The arterial injury and repair don’t seem to influence the outcome of the hand function, but both artery involvement usually associated with all tendon injury, it shows poor outcome.Conclusions: The more distal the injury the outcome will be quicker as compared to middle 1/3 and proximal 1/3 injuries. Pure median nerve injuries sensory recovery in S4 grade about 5%, S3+ recovery of sensation is about 36%. Pure median nerve injury patients M4 motor recovery about 54%.Only median nerve injury the final outcome is good but combined median and ulnar nerve injury and associated tendon injury the outcome is poor.

Management of the facial nerve in parotid cancer: preservation or resection and reconstruction.

Management of the facial nerve is instrumental in the surgical treatment of parotid cancer. A literature search was conducted using PubMed and ScienceDirect database. A total of 195 articles were finally included into the analysis, based on relevance, scientific evidence and actuality. In the majority of cases the facial nerve is not involved by tumor. In these cases, identification and preservation of the nerve, in addition to complete tumor removal, are essential for successful surgery. When the nerve is infiltrated by tumor, the affected portion of the nerve must be resected as part of radical parotidectomy. Primary nerve reconstruction or other reanimation techniques give the best long-term functional and cosmetic results. A comprehensive diagnostic evaluation with current imaging and electrophysiological studies will provide the surgeon with the best knowledge of the relationship of the facial nerve to the tumor. Several standardized methods are helpful in finding, dissecting and preserving the nerve during parotid cancer surgery. When radical parotidectomy is indicated, the initial diagnostic work-up can assist in defining the need for adjuvant postoperative therapy and facial reanimation. The aim of rehabilitation is to restore tone, symmetry, and movement to the paralyzed face. The surgical management of facial paralysis has undergone many improvements in recent years. This review gives an overview of recent advances in the diagnostic work-up, surgical techniques and any necessary rehabilitation of the facial nerve in parotid cancer surgery.

Optic nerve sheath meningocele.

Optic nerve sheath meningocele, also called dural ectasia of the optic nerve, is a benign dilation of the optic nerve sheath. We report two interesting cases of primary optic nerve sheath meningocele. Etiology, clinical features, and management options are discussed.

Gastrointestinal Spice Sensors and Their Functions

Capsaicin is a constituent of chili pepper, and induces the burning sensation on the tongue. The site of action for capsaicin has been discovered as transient receptor potential vanilloid receptor subtype 1 (TRPV1) that resides on the membranes of pain- and heat-sensing primary afferent nerves. The immunohistochemical study on the stomach revealed that nerve fibers expressing TRPV1 exist along gastric glands in the mucosa, around blood vessels in the submucosa, in the myenteric plexus, and in the smooth muscle layers. High numbers of TRPV1-immunoreactive axons were observed in the rectum and distal colon. Therefore, capsaicin stimulates TRPV1 not only on the tongue but also in the gut. In this review, the mechanism of gastrointestinal mucosal defense enhanced by capsaicin was summarized. TRPV1 plays a protective role in gastrointestinal mucosal defensive mechanism. Hypersensitivity of afferent fibers occurs during gastrointestinal inflammation. Abnormalities of primary afferent nerve fibers are strongly associated with the visceral hypersensitive state in inflammatory bowel disease (IBD). The alteration of TRPV1 channels in mucosa contributes to the visceral hypersensitivity in colitis model mice. TRPV1-expressing neurons in the gut are thought to be extrinsic sensory afferent neurons that operate to maintain gastrointestinal functions under physiological and inflammatory states.

Enhancing the Outcome of Traumatic Sensory Nerve Lesions of the Hand by Additional Use of a Chitosan Nerve Tube in Primary Nerve Repair: A Randomized Controlled Bicentric Trial.

Peripheral sensory nerve injuries present a significant yet common challenge in acute hand trauma surgery. Standard treatment remains microsurgical end-to-end nerve repair where appropriate. Permanent loss of sensitivity and painful neuroma formation are typical sequelae of unsuccessful surgery. The objective of this study was to evaluate whether the additional use of a chitosan nerve tube in primary nerve repair positively influences sensory recovery. A randomized, controlled, two-center trial with parallel group design and double-blind assessment was conducted to demonstrate the superiority of the additional use of a chitosan nerve tube compared with microsurgical nerve repair alone. Seventy-four participants were enrolled. The primary outcome parameter used was degree of static two-point discrimination at 6 months after surgery. Additional secondary outcome parameters included filament recognition testing (Semmes-Weinstein); pain; neuroma development; and the Disabilities of the Arm, Shoulder and Hand score. Nerve repair with additional use of chitosan nerve tubes (intervention group) significantly increased both tactile gnosis (expressed by two-point discrimination) and sensitivity (expressed by Semmes-Weinstein testing). The mean two-point discrimination at 6-month follow-up was 8 mm (range, 2 to 20 mm) in the control group and 6.3 mm (range, 1 to 15 mm) in the intervention group, respectively (p = 0.029). Two-point discrimination correlated with the Disabilities of the Arm, Shoulder and Hand score. In the control and intervention groups, respectively, three versus zero neuromas were found. Peripheral sensory nerve regeneration can be improved significantly by additional use of a chitosan nerve tube. An improved ability of static two-point discrimination is clinically relevant. Therapeutic, I.

The Role of Deimination in Regenerative Reprogramming of Neurons.

Neurons from the adult central nervous system (CNS) demonstrate limited mRNA transport and localized protein synthesis versus developing neurons, correlating with lower regenerative capacity. We found that deimination (posttranslational conversion of protein-bound arginine into citrulline) undergoes upregulation during early neuronal development while declining to a low basal level in adults. This modification is associated with neuronal arborization from amphibians to mammals. The mRNA-binding proteins (ANP32a, REF), deiminated in neurons, have been implicated in local protein synthesis. Overexpression of the deiminating cytosolic enzyme peptidyl arginine deiminase 2 in nervous systems results in increased neuronal transport and neurite outgrowth. We further demonstrate that enriching deiminated proteins rescues transport deficiencies both in primary neurons and mouse optic nerve even in the presence of pharmacological transport blockers. We conclude that deimination promotes neuronal outgrowth via enhanced transport and local protein synthesis and represents a new avenue for neuronal regeneration in the adult CNS.

Long-term pain relief in canine osteoarthritis by a single intra-articular injection of resiniferatoxin, a potent TRPV1 agonist.

The translational potential of analgesic approaches emerging from basic research can be augmented by client-owned dog trials. We report on a peripheral interventional approach that uses intra-articular injection of the ultrapotent TRPV1 agonist resiniferatoxin (RTX) to produce a selective long-term chemoinactivation of nociceptive primary afferent nerve endings for pain control in naturally occurring canine osteoarthritis. A single injection of 10 µg of RTX, produced suppression of pain, improvement in gait, weight bearing, and improvement in the dog's activities of daily living lasting 4 months or longer. Two to 3 years after the injection, there are no alterations to suggest that removal of inflammatory pain caused accelerated joint degeneration (Charcot joint) in any of the dogs. To amplify the effective use of canine subjects in translational analgesia research, we report a high-quality canine dorsal root ganglion transcriptome. Some targets for analgesia are highly conserved both in protein sequence and level of expression within a target tissue while others diverge substantially from the human. This knowledge is especially important for development of analgesics aimed at peripheral molecular targets and provides a template for informed translational research. The peripheral site of action, long duration of analgesia, apparent safety, and retention of coordination, all resulting from a single dose suggest that intra-articular RTX may be an effective intervention for osteoarthritis pain with few or no side effects and lead to an improved quality of life.

A Short Scenario for Restoration of Reasonable Limb Function in Adults after Upper Brachial Plexus Injuries Using Neurotization and Combined Muscle Transfers

Background: For managing of upper brachial plexus palsyin adult patients, many strategies should be discussed withthe patient. Primary plexus repair, nerve transfer, functionalmuscle transfer and other musculoskeletal approaches maybe followed according the suitability, merits and disadvantagesof each. Time factorsare very crucial for the sound managementfor these patients as time delay can result in a non-achievablechance loss with the neuromuscular end plates loss withintwo years following muscle denervation and progressivemusculoskeletal changes as well.Patients and Methods: Between March 2013 and June2015, six adult patients suffering from upper brachial plexusinjuries were referred to Zagazig University Hospital andoperated upon in two stages. In the first stage, two nervetransfers were performed in the same setting; neurotizationof suprascapular nerve (using a branch of spinal root of theaccessory nerve to the suprascapular nerve) and Oberlin nervetransfer (nerve fascicular transfer from the ulnar nerve tobiceps branch of the musculocutaneous nerve to reinnervatethe biceps muscle). After three to four months of the firststage, the patients were operated upon in the second stage forcombined muscles transfers in the same setting i.e. trapeziustransfer to the humerus and latissimus dorsi with teres majortransfer to rotator calf of the shoulder.Results: By the end of the tenth month of the first stage,half of patients have regained M4 elbow flexion and theremaining patients have been M3. These improvements havebeen primarily noticed by the end of the third month postoperatively.The range of elbow flexion has been graduallyimproved to (100 to 120 degree against resistance) (mean 112degree) with no noticeable deficit in the hand function as adonor site morbidity. The second stage was done 3 to 4 monthsfrom the first stage. Within 6 months of the second stage,shoulder abduction ranged from 80 to 120 degree (mean 98)with the mean of shoulder flexion 77 and externa rotation 47degrees.Conclusion: Multimodal association between distal nervestransfer and combined transfer of trabezius, latissimus dorsiand teres major muscles provides an effective and relativelya short management scenario for upper brachial plexus injuriesin adult patients.

Repair soft tissue defect of middle-and-distal finger with reversed flap based on cutaneous branch of dorsal metacarpal artery

Objective To observe the treatment outcome of using reversed island flap based on cutaneous branch of dorsal metacarpal artery for middle-and-distal finger soft tissue defect. Methods From May, 2015 to March, 2017, 21 cases of middle-and-distal finger soft tissue defect were treated with reversed island flaps based on cutaneous branch of dorsal metacarpal artery which were designed on the dorsal hand pedicled by dorsal metacarpal artery. The flap was then elevated and rotated at the point where digital common artery was anastomosed with the terminal branch of the dorsal metacarpal artery. The cutaneous nerve included in the flap was anastomosed with the terminal branch of digital nerve to restore sensation and the donor site was covered directly. Regular followed-up was performed after operation. Results Except 1 case was suffered with distal 1/3 skin flap necrosis, flaps were well developed. Postoperative follow-up period was 3 to 12 months. All these flaps recovered with satisfying appearance and quality, excellent sensation with grade S3 to S4 and 5 to 8 mm of two-point discrimination. Range of motion(ROM) of the metacarpalphangeal and interphalangeal joint of the injured fingers was good. The excellent and good rate was 95.2%. Conclusion Reversed island flap based on dorsal cutaneous branch of dorsal metacarpal artery transfer is an ideal method for repairing middle-and-distal finger soft tissue defect. The surgery is simple. Reliable blood supply and sensation can be achieved without sacrificing the primary artery and nerve. There is minor donor site damage and very few complications. Key words: Dorsal metacarpal artery; Surgical flap; Finger injury; Microsurgical operation

The Deep Fascia of the Forearm and the Ulnar Nerve: An Anatomical Study.

IntroductionA reoperation for a cubital tunnel syndrome is not uncommon. Patients often complain of sensorimotor symptoms in the ulnar nerve distribution after their primary surgery. The documented etiologies for such a phenomenon include a “new” kinking of the distal ulnar nerve and a “new” compression of the ulnar nerve by the fascial septum in between or tendinous bands over the muscles of the forearm. The deep fascial plane along which the ulnar nerve travels in the forearm has had scant attention. We present an anatomical study to provide a better understanding of such etiologies to aid physicians in performing successful primary ulnar nerve release that does not lead to risky reoperations and ultimately yields improved patient satisfaction.Materials and methodsThe forearms of 12 fresh frozen cadavers (24 arms) underwent dissection, during which the fascial relationships between the ulnar nerve and muscles of the anterior compartment were explored with a blunt technique. The relationship between the fascial planes and the ulnar nerve was quantitatively and qualitatively documented. The ranges of motion of the elbow were also observed for any potential compression points on the nerve during the movement.ResultsIn all specimens (n = 24), the ulnar nerve entered the forearm between the humeral and ulnar heads of the flexor carpi ulnaris, after which it routed deep to a deep fascia between the anterior surface of the flexor carpi ulnaris and the posterior surface of the flexor digitorum superficialis. Ulnar nerve branches to the flexor carpi ulnaris pierced this fascial septum while en route to the posterior surface of the muscle. Medially, the branches to the flexor digitorum profundus also pierced this fascial plane. In most arms, the fascia became thinner near the junction between the proximal two-thirds and distal one-third of the forearm. On no side was the ulnar nerve found to be grossly compressed by this deep fascia. However, with the extension of the elbow, a degree of angulation of the proximal ulnar nerve was observed due to its compact connection with the deep fascia.ConclusionOur study revealed that there is an intimate relationship between the ulnar nerve and the deep fascia of the forearm. Since the ulnar branches to the overlying flexor carpi ulnaris pierce this deep structure, a care should be given to its anatomical course during surgery in this region to prevent denervation of the muscle.

Chitosan Tubes Enriched with Fresh Skeletal Muscle Fibers for Primary Nerve Repair.

Muscle-in-vein conduit is successfully employed for repairing nerve injuries: the vein prevents muscle fiber dispersion, while the muscle prevents the vein collapse and creates a favorable environment for Schwann cell migration and axon regrowth. However, it requires microsurgical skills. In this study we show a simple strategy to improve the performance of a chitosan hollow tube by the introduction of fresh skeletal muscle fibers. The hypothesis is to overcome the technical issue of the muscle-in-vein preparation and to take advantage of fiber muscle properties to create an easy and effective conduit for nerve regeneration. Rat median nerve gaps were repaired with chitosan tubes filled with skeletal muscle fibers (muscle-in-tube graft), hollow chitosan tubes, or autologous nerve grafts. Our results demonstrate that the fresh skeletal muscle inside the conduit is an endogenous source of soluble Neuregulin 1, a key factor for Schwann cell survival and dedifferentiation, absent in the hollow tube during the early phase of regeneration. However, nerve regeneration assessed at late time point was similar to that obtained with the hollow tube. To conclude, the muscle-in-tube graft is surgically easy to perform and we suggest that it might be a promising strategy to repair longer nerve gap or for secondary nerve repair, situations in which Schwann cell atrophy is a limiting factor for recovery.

Nerve Entrapment in Ankle and Foot: Ultrasound Imaging.

Peripheral nerve entrapment of the ankle and foot is relatively uncommon and often underdiagnosed because electrophysiologic studies may not contribute to the diagnosis. Anatomy of the peripheral nerves is variable and complex, and along with a comprehensive physical examination, a thorough understanding of the applied anatomy is essential. Several studies have helped identify specific areas in which nerves are commonly compressed. Identified secondary causes of nerve compression include previous trauma, osteophytes, ganglion cysts, edema, accessory muscles, tenosynovitis, vascular lesions, and a primary nerve tumor. Imaging plays a key role in identifying primary and secondary causes of nerve entrapment, specifically ultrasound (US) and magnetic resonance imaging. US is a dynamic imaging modality that is cost effective and offers excellent resolution. Symptoms of nerve entrapment may mimic other common foot and ankle conditions such as plantar fasciitis.