Anterior Interosseus Nerve Research Articles

Median nerve lesions in pediatric displaced supracondylar humerus fracture: A prospective neurological, electrodiagnostic and ultrasound characterization.

Supracondylar humerus fractures (SCHFs) are the most common elbow fractures in children. Traumatic median nerve injury and isolated lesions of its pure forearm motor branch, anterior interosseus nerve (AIN), have both been independently reported as complications of displaced SCHFs. Our main objectives were to characterize the neurological syndrome to distinguish median nerve from AIN lesions and to determine the prognosis of median nerve lesions after displaced SCHFs. Ten children were prospectively followed for an average of 11.6 months. Patients received a standardized clinical examination and high-resolution ultrasound of the median nerve every 1-3 months starting 1-2 months after trauma. Electrodiagnostic studies were performed within the first 4 months and after complete clinical recovery. All children shared a clinical syndrome with predominant but not exclusive affection of AIN innervated muscles. High-resolution ultrasound uniformly excluded persistent nerve entrapment and neurotmesis requiring revision surgery but visualized post-traumatic median nerve neuroma at the fracture site in all patients. Electrodiagnostic studies showed axonal motor and sensory median nerve neuropathy. All children achieved complete functional recovery under conservative management. Motor recovery required up to 11 months and differed between involved muscles. It was shown that neurological deficits of the median nerve in displaced SCHFs exceeded an isolated AIN lesion. Notably, detailed neurological follow-up examinations and sonographic exclusion of persistent nerve compression were able to guide conservative therapy in affected children. Under these conditions the prognosis of median nerve lesions was excellent despite severe initial deficits, development of neuroma and axonal injury.

Hourglass-like fascicular constriction of the median nerve: case series

Background. The anterior interosseus nerve (AIN) syndrome is a rare pathology, with cause is discussed. The findings in isolated AIN patients are in the main trunk of median nerve. It is confirmed by neuroimaging data and intraoperative picture in the form of the construction of fascicles in the nerve.Aim. To describe the clinical and instrumental characteristics of patients with isolated non-traumatic lesion of AIN.Materials and methods. The clinical, electrophysiological and neuroimaging data of 7 patients with isolated nontraumatic lesion of AIN were retrospectively analyzed, three of whom underwent surgical treatment.Results. All patients complained of neuropathic pain in the affected upper limb, with an average intensity of 8 points according to visual analog scale and a duration of 1.5 to 4 weeks. Weakness of the flexor pollicis longus from 1 to 3 points on the MRC (Medical Research Council Weakness) scale was observed in all cases, weakness of flexion of the distal phalanx of the index finger in 6 patients from 1 to 3 points, which indicated an isolated lesion of the anterior interosseous nerve.Needle electromyogram revealed denervation in c in all cases, 5 patients – in the pronator teres.The fascicular constriction from 1 or 2 sections of the median nerve were detected at the shoulder level on the affected side by ultrasound in 6 patients. An increase in the cross-sectional area of the median nerve at the shoulder level in 2 cases we observed, in one case the changes were o bilateral and asymmetric. In 2 cases, an increase in cross-sectional area of С5 root was noted on the affected side by no more than 23 % of the normal value. A change in echogenicity and size decrease of the pronator quadratus, when compared with the opposite side, was noted in all cases.Conclusion. Patients with isolated AIN syndrome needs intensive evaluation to identify the localization of the level of damage to the median nerve.

The 3D muscle morphology and intramuscular innervation of the digital bellies of flexor digitorum profundus: Clinical implications for botulinum toxin injection sites.

Spasticity of flexor digitorum profundus is frequently managed with botulinum toxin injections. Knowledge of the 3D morphology and intramuscular innervation of the digital bellies of flexor digitorum profundus is necessary to optimize the injections. The purpose of this study was to digitize and model in 3D the contractile and connective tissue elements of flexor digitorum profundus to determine muscle morphology, model and map the intramuscular innervation and propose sites for botulinum toxin injection. Fiber bundles (FBs)/aponeuroses and intramuscular nerve branches were dissected and digitized in 12 formalin embalmed cadaveric specimens. Cartesian coordinate data were reconstructed into 3D models as insitu to visualize and compare the muscle morphology and intramuscular innervation patterns of the bellies of flexor digitorum profundus. The 3rd, 4th and 5th digital bellies were superficial to the 2nd digital belly and located adjacent to each other in all specimens. Each digital belly had distinct intramuscular innervation patterns. The 2nd digital belly received intramuscular branches from the anterior interosseus nerve (AIN). The superior half of the 3rd digital belly was innervated intramuscularly by the ulnar nerve (n = 4) or by both the anterior interosseus and ulnar nerves (n = 1). The inferior half of the belly received dual innervation from the anterior interosseus and ulnar nerves in 2 specimens, or exclusively from the AIN (n = 2) or the ulnar nerve (n = 1). The 4th digital belly was innervated by intramuscular branches of the ulnar nerve. One main branch, after coursing through the 4th digital belly, entered the lateral aspect of the 5th digital belly and arborized intramuscularly. The morphology of the FBs, aponeuroses and intramuscular innervation of the digital bellies of FDP were mapped and modelled volumetrically in 3D as insitu. Previous studies were not volumetric nor identified the course of the intramuscular nerve branches within each digital belly. Based on the intramuscular innervation of each of the digital bellies, one possible optimized botulinum toxin injection location was proposed. This injection location, at the junction of the superior and middle thirds of the forearm, would be located in dense nerve terminal zones of the anterior interosseus and ulnar nerves. Future anatomical and clinical investigations are necessary to evaluate the efficacy of these anatomical findings in the management of spasticity.

Anterior Interosseus to Ulnar Motor Nerve Transfers: A Canadian Perspective.

The anterior interosseus nerve (AIN) to ulnar motor nerve transfer has been popularized as an adjunct to surgical decompression in patients with severe cubital tunnel syndrome (CuTS) and high ulnar nerve injuries. The factors influencing its implementation in Canada have yet to be described. An electronic survey was distributed to all members of the Canadian Society of Plastic Surgery (CSPS) using REDCap software. The survey examined 4 themes: previous training/experience, practice volume of nerve pathologies, experience with nerve transfers, and approach to the treatment of CuTS and high ulnar nerve injuries. A total of 49 responses were collected (12% response rate). Of all, 62% of surgeons would use an AIN to ulnar motor supercharge end-to-side (SETS) transfer for a high ulnar nerve injury. For patients with CuTS and signs of intrinsic atrophy, 75% of surgeons would add an AIN-SETS transfer to a cubital tunnel decompression. Sixty-five percent would also release Guyon's canal, and the majority (56%) use a perineurial window for their end-to-side repair. Eighteen percent of surgeons did not believe the transfer would improve outcomes, 3% cited lack of training, and 3% would preferentially use tendon transfers. Surgeons with hand fellowship training and those less than 30 years in practice were more likely to use nerve transfers in the treatment of CuTS (P < .05). Most CSPS members would use an AIN-SETS transfer in the treatment of both a high ulnar nerve injury and severe CuTS with intrinsic atrophy.

Anatomy of the Superficial Radial Nerve and Its Target Nerves for Targeted Muscle Reinnervation: An Anatomical Cadaver Study.

Targeted muscle reinnervation (TMR) is a surgical procedure for treating symptomatic neuroma, in which the neuroma is removed and the proximal nerve stump is coapted to a donor motor branch innervating a nearby muscle. This study aimed to identify optimal motor targets for TMR of the superficial radial nerve (SRN). Seven cadaveric upper limbs were dissected to describe the course of the SRN in the forearm and motor nerve supply-number, length, diameter, and entry points in muscle of motor branches-for potential recipient muscles. The radial nerve provided three (three of six) motor branches, two (two of six) motor branches, or one (one of six) motor branch to the brachioradialis muscle, entering the muscle 21.7 ± 17.9 to 10.8 ± 15 mm proximal to the lateral epicondyle. One (one of seven), two (three of seven), three (two of seven), or four (one of seven) motor branches innervated the extensor carpi radialis longus muscle, with entry points 13.9 ± 16.2 to 26.3 ± 14.9 mm distal from the lateral epicondyle. In all specimens, the posterior interosseous nerve gave off one motor branch to the extensor carpi radialis brevis, which divided into two or three secondary branches. The distal anterior interosseus nerve was assessed as a potential recipient for TMR coaptation and had a freely transferable length of 56.4 ± 12.7 mm. When considering TMR for neuromas of the SRN in the distal third of the forearm and hand, the distal anterior interosseus nerve is a suitable donor target. For neuromas of the SRN in the proximal two-thirds of the forearm, the motor branches to the extensor carpi radialis longus, extensor carpi radialis brevis, and brachioradialis are potential donor targets.

Kommentar zu "Combined Reconstruction of the Ulnar Nerve after its wide Resection by Nerve Grafting at the Site of the Resection and distal Transfer of the Anterior Interosseus Nerve to the deep Branch of the Ulnar Nerve".

The authors present the case of a 46 year old patient who was treated for recurrent neurofibroma of the proximal ulnar nerve by complete resection and primary grafting in combination with transfer of the anterior interosseous nerve (AIN) to the deep motor branch of the ulnar nerve (DMBUN) [1]]. Although motor recovery did not occur, the authors conclude that this approach should always be considered in proximal injuries of the ulnar nerve.

Response to the Comment on the Article Titled: "Combined Reconstruction of the Ulnar Nerve After its Wide Resection by Nerve Grafting at the Site of the Resection and Distal Transfer of the Anterior Interosseus Nerve to the Deep Branch of the Ulnar Nerve".

The authors thank very much for the critical comment on our article. We agree with all critical arguments concerning not really correct selection of the patient to this type of operation. We agree with an argument that long time of complete ulnar nerve palsy might cause degeneration of the motor end plates at the time of reconstruction. In this situation neither reconstruction done in our patient had chance to work. Nevertheless, the final outcome was surprisingly good, in spite of no improvement of the ulnar nerve function. As we stated in the article, it may be partly explained by successful treatment of the pain that the patient experienced for a long time. The uncontrolled pain in the course of CRPS constituted the primary problem in our patient at presentation and it was successfully eliminated by continuous brachial plexus analgesia. Likewise, the resection of a large fragment of the nerve with recurrent tumours probably resulted in additional alleviating the pain. There was also no recurrence of the pain after main operation. Accepting all critical comments the authors believe that this case can incline surgeons to more careful consideration the treatment options which are the most beneficial for the patient with long-lasting nerve palsy. The lesson we learned from this case and from the comment is that sophisticated surgery is not necessary the best solution in difficult clinical case and that ground for decision making should not be surgeons’ ambitions, but scientific evidence and rational thinking.

Distal nerve transfer (PT-AIN, SUP-PIN) for regaining hand function in C8, T1 root injury following extirpation of the right C8, T1 schwannoma.

A 48-year-old female was admitted to the authors' department due to hand weakness as a consequence of C8, T1 root injury. Eight months earlier, the patient had been treated by a pulmonary surgeon due to an expansive lesion near the apex of the right lung, which resulted in right lower brachial plexus palsy. Postoperative pathohistological findings indicated that the lesion was nerve schwannoma. The diagnostic process included physical examination, electromyoneurography, and MRI. A distal nerve transfer (pronator teres-anterior interosseus nerve [PT-AIN], supinator-posterior interosseus nerve [SUP-PIN]) was performed in order to restore hand function. The video can be found here: https://stream.cadmore.media/r10.3171/2022.10.FOCVID22110.

Anatomical Study of the Innervation of Triangular Fibrocartilage Complex and Distal Radioulnar and Radiocarpal Joints: Implications for Denervation

Open and percutaneous denervation is an emerging technique for joint pain. This study investigated the course and distribution of the articular branches innervating the triangular fibrocartilage complex (TFCC), distal radioulnar joint (DRUJ), and radiocarpal joint (RCJ) relative to bony and soft tissue landmarks to guide wrist denervation procedures. Fourteen formalin-embalmed specimens were serially dissected to expose the origin, course, and distribution of articular branches innervating the TFCC, DRUJ, and RCJ. Bony and soft tissue landmarks to localize each articular branch were documented and visualized on a 3-dimensional reconstruction of the bones of the distal forearm and hand. The TFCC was innervated by articular branches from the posterior interosseus nerve (10 of 14 specimens), dorsal cutaneous branch of the ulnar nerve (14 of 14 specimens), palmar cutaneous branch of the ulnar nerve (12 of 14 specimens), and medial antebrachial cutaneous nerve (9 of 14 specimens). The DRUJ was innervated by the posterior interosseus nerve (9 of 14 specimens) and anterior interosseus nerve (14 of 14 specimens). The RCJ was innervated by the posterior interosseus nerve (14 of 14 specimens), superficial branch of the radial nerve (5 of 14 specimens), lateral antebrachial cutaneous nerve (14 of 14 specimens), and palmar cutaneous branch of the median nerve (10 of 14 specimens). Multiple nerves were found to innervate the TFCC, DRUJ, and RCJ. The relationship of anatomical landmarks to specific articular branches supplying the TFCC, DRUJ, and RCJ can inform selective denervation procedures based on the structural origin of pain. The detailed documentation of the spatial relationship of the nerve supply to the wrist provides clinicians with the anatomical basis to optimize current, and develop new denervation protocols to manage chronic wrist pain.

An Especially Unique Case of Accessory Flexor Muscles to All Five Digits with Clinical Implications for Occupational Therapy

INTRODUCTIONAnatomical variations in antebrachial musculature are relatively common. Most are asymptomatic, but some develop serious sequelae. Extra tendon structures in the carpal tunnel can cause carpal tunnel syndrome (CTS), accessory muscle attachments can cause symptomatic supernumerary muscle belly (SSMB) syndrome, and compression of the anterior interosseus nerve from overlaying supernumerary muscles can cause anterior interosseus nerve syndrome (AINS). Many studies have reported accessory muscles to the flexor pollicis longus (aFPL) or flexor digitorum profundus (aFDP), but few have examined co‐occurrences of these muscles, and none have documented a case where they collectively send isolated flexion forces to all five digits. The objective of this study is to analyze an especially unique case of accessory flexor muscles to all five digits with respect to CTS, SSMB syndrome, and AINS clinical implications for Occupational Therapy (OT).METHODSOne aFPL and four aFDPs were found co‐occurring during routine cadaver dissection at the University of Nebraska Medical Center. All neurovascular and muscular components within the flexor compartment of the antebrachium were carefully cleaned of extraneous fascia. Contiguous muscles were reflected to view the muscle bellies, tendons, proximal attachments (origins), and distal attachments (insertions) of the aFPL and aFDPs. The aFPL and aFDPs were measured and photographed in situ, and maximal isometric force (Fmax) was calculated for each muscle. The normal FPL and FDP were also analyzed to gauge accessory muscle impact. A review of relevant literature was conducted to discuss clinical implications of these muscles for OT practice.RESULTSA bicipital accessory muscle to FDP, with radial (aFDPr) and ulnar (aFDPu) heads, was discovered adjacent to an accessory muscle to FPL (aFPL). The aFDPr/u and aFPL originated from the coronoid process of the ulna and were innervated by the posterior‐lying anterior interosseus nerve. The aFDPr flexed digits 3 and 4, and aFDPu flexed digits 4 and 5. The aFPL was especially unique: part of its tendon merged with the proximal third of FPL (to flex digit 1) while the remainder continued distal, drawing two additional distinct muscle bellies from FPL (aFDPFPL) and FDP (aFDPFDP) and distributing these adjoining forces to digits 2, 3, and 4 via an aponeurosis in the carpal tunnel. The calculated Fmax for aFPL, aFDPr, aFDPu, aFDPFPL, and aFDPFDP were 3.80 N, 1.22 N, 0.98 N, 2.47 N, and 0.62 N respectively and are used to discuss potentials for eliciting a quadriga effect associated with SSMB syndrome. CTS is discussed as a result of carpal tunnel crowding, and AINS is discussed in regard to neuropathy of FDP (radial half), FPL, and pronator quadratus. Each of these conditions is conferred with their predominant implications for OT intervention and treatment.CONCLUSIONS &amp; SIGNIFICANCEThe present study reports a previously undocumented and especially unique case of accessory flexor muscles to all five digits. Its use as a reference may help OT providers better determine when supernumerary muscles are present in clients being treated for prehension, distal pinch, and digit independence limitations caused by CTS, SSMB syndrome, or AINS and adapt treatment modalities accordingly.

Combined Reconstruction of the Ulnar Nerve after its wide Resection by Nerve Grafting at the Site of the Resection and Distal Transfer of the Anterior Interosseus Nerve to the deep Branch of the Ulnar Nerve.

Combined Reconstruction of the Ulnar Nerve after its wide Resection by Nerve Grafting at the Site of the Resection and Distal Transfer of the Anterior Interosseus Nerve to the deep Branch of the Ulnar Nerve.

Proof of concept for multiple nerve transfers to a single target muscle.

Surgical nerve transfers are used to efficiently treat peripheral nerve injuries, neuromas, phantom limb pain, or improve bionic prosthetic control. Commonly, one donor nerve is transferred to one target muscle. However, the transfer of multiple nerves onto a single target muscle may increase the number of muscle signals for myoelectric prosthetic control and facilitate the treatment of multiple neuromas. Currently, no experimental models are available. This study describes a novel experimental model to investigate the neurophysiological effects of peripheral double nerve transfers to a common target muscle. In 62 male Sprague-Dawley rats, the ulnar nerve of the antebrachium alone (n=30) or together with the anterior interosseus nerve (n=32) was transferred to reinnervate the long head of the biceps brachii. Before neurotization, the motor branch to the biceps' long head was transected at the motor entry point. Twelve weeks after surgery, muscle response to neurotomy, behavioral testing, retrograde labeling, and structural analyses were performed to assess reinnervation. These analyses indicated that all nerves successfully reinnervated the target muscle. No aberrant reinnervation was observed by the originally innervating nerve. Our observations suggest a minimal burden for the animal with no signs of functional deficit in daily activities or auto-mutilation in both procedures. Furthermore, standard neurophysiological analyses for nerve and muscle regeneration were applicable. This newly developed nerve transfer model allows for the reliable and standardized investigation of neural and functional changes following the transfer of multiple donor nerves to one target muscle.

Nerve Transfer of Brachialis Branch to Anterior Interosseus Nerve Using In Situ Lateral Antebrachial Cutaneous Nerve Graft in Tetraplegia

Reconstruction of finger motion is a therapeutic goal in tetraplegic patients. Although nerve transfer of the brachialis branch of the musculocutaneous nerve to the anterior interosseus nerve has been previously described, this results in unreliable reinnervation because the donor nerve is proximal to the target muscle. We describe an alternative technique in which nerve transfer is performed using the lateral antebrachial cutaneous nerve as a vascular in situ nerve graft. The clinical results are reported. Nine upper limbs of 6 patients (mean age 25 years) with tetraplegia were subjected to brachialis-to-anterior interosseus nerve transfer using the lateral antebrachial cutaneous nerve as a vascular in situ nerve graft, at a mean of 6 months after injury. Additional supinator branch transfer to the posterior interosseous nerve was performed for 6 upper limbs and to the flexor digitorum superficialis motor branch for 1 upper limb. At a mean of 2 years of follow-up, thumb and finger flexion strength scored M3-M4 in 5 of the 9 limbs according to the Medical Research Council scale. Key pinch and grip pinch averaged 0.6 kg (range, 0-1.0 kg) and 2.2 kg (range, 0-8 kg), respectively. No donor-site deficit was observed. Brachialis-to-anterior interosseus nerve transfer with an in situ lateral antebrachial cutaneous nerve graft can be used to reconstruct thumb and finger flexion in tetraplegic patients. Combined with supinator-to- posterior interosseous nerve transfer, simultaneous active extension of the fingers can be achieved. Therapeutic V.

Tumeur d’Abrikossof (tumeur à cellules granuleuses) du nerf ulnaire au bras. À propos d’un cas et revue de la littérature des tumeurs à cellules granuleuses du nerf ulnaire

Granular cell tumours are extremely rare on peripheral nerves, with an incidence of 0.029% of pathologic samples. In a literature review, we found only 5 cases involving the ulnar nerve, although considered the most frequently involvement nerve. A 32 year-old female from the French West Indies presented a severe arm pain with deficit of interosseous hand muscles. Imaging studies were in favour of a Schwanoma, but during surgery, we found an unremovable intra-neural tumour. Nerve biopsy revealed a granular cell tumour. Initial decision was observation only. However, within two years, tumour increased in size, along with pain aggravation and functional deficit. We performed a nerve resection (with adequate margins) with reconstruction using sural nerve graft associated with a neurotisation of the motor branch with the anterior interosseus nerve. At two years follow-up, no recurrence was observed. The scar is hypersensitive with moderate neuropathic pain. There is a sensory reinnervation of the fourth finger, with no motor recovery of the hand. We observed a slight recovery of flexor profundus tendons, which, in turn increased the claw hand. The five cases described in the literature were managed differently (biopsy only, excision, excision with reconstruction), with modest results. There is no recommended treatment. Our case is the first at arm level. We were able to perform complete resection, but functional result is poor. Granular cell tumours require treatment if symptomatic (pain, function loss), but, at the moment, there is no recommended treatment.

Accessory Head of the Flexor Pollicis Longus: A Cadaveric Study on the Gantzer’s Muscle

Introduction: The anterior interosseus nerve syndrome is a compression neuropathy affecting the anterior interosseus nerve, resulting in motor weakness of the long tendons to the index finger and thumb. Of the many conditions leading to this syndrome, one of the more common yet most overlooked aetiologies is the presence of accessory head of the flexor pollicis longus muscle, also called the Gantzer’s muscle. Even though numerous studies have been done in both Indian and international populations regarding the frequency of the Gantzer’s muscle, there are hardly any studies involving the South Indian population. Aim: To analyse the frequency and morphology of the Gantzer’s muscle in the sub-population of Malabar region, Kerala. Materials and Methods: This descriptive observational study was performed in Department of Anatomy at Malabar Medical College, Atholi, Kerala, India, from July 2021 to August 2021. Study included 60 upper limbs from the cadavers provided for undergraduate medical education. In the limbs where the muscle was identified, parameters such as proximal and distal attachments, shape and length of muscle and tendon, relation to adjacent median and anterior interosseus nerves were studied. Frequencies of each of these parameters were analysed using Statistical Package for the Social Sciences (SPSS) software version 21.0. Percentages obtained were compared with existing studies. Results: The Gantzer’s muscle was found in 28 of the 60 limbs dissected. It was more common on the right side (17 limbs), and the most common origin was the medial epicondyle (53.6%). All the cases identified were inserted onto the ulnar aspect of the Flexor Pollicis Longus tendon, mostly in the upper third. In all cases, the Median Nerve was superficial and the Anterior Interosseus Nerve was deep to the accessory head. In majority of the cases, the Anterior Interosseus Nerve was related to the posterior aspect of the belly of the Gantzer’s muscle (82.1%). Conclusion: Clinicians and surgeons should be conscious of the possibility of the Gantzer’s muscle being the aetiology, in cases of isolated Anterior Interosseus nerve palsies.

Anatomical Study of Accessory Head of Flexor Pollicis Longus and Its Clinical Significance

Background: Cases of nerve entrapment are commonly seen in medical practice. The flexor pollicis longus muscle of the front of the forearm sometimes may have an accessory head. The accessory head of flexor pollicis longus muscle (AHFPL) may compress the anterior interosseus nerve (AIN) to cause weakness of the deep muscles of the front of the forearm. The aim of the present study is to find the incidence of AHFPL and to identify its structural relationships to the median nerve and AIN. Methods: A total of sixty upper limbs of thirty embalmed cadavers were dissected and studied for the presence of AHFPL. Parameters studied were incidence of AHFPL, whether it is bilateral or unilateral, its origin and insertion, and its relationship with AIN. Results: AHFPL was found in 16 cadavers (53%). In 7 out of the 16 cadavers (43.75%), AHFPL was bilateral and in 9 out of 16 cadavers (56.25%), AHFPL was unilateral. AIN was located below the AHFPL in 14 cadavers and in 2 cadavers, it was passing above the AHFPL. The nerve supply of AHFPL was through AIN in the 16 cadavers. Conclusion: Knowledge of AHFPL and its relations with AIN may help medical professionals in diagnosis and treatment as this anatomical variation can lead to compression neuropathy.

Ulnar Nerve Monitoring During Percutaneous Pinning of Supracondylar Fractures in Children

Supracondylar fractures of the humerus in children are frequently managed by closed reduction and percutaneous pinning. Insertion of medial and lateral pins is more stable than lateral pinning alone, but carries an increased risk for ulnar nerve damage. This study describes the use of electrical stimulation concurrent with medial pin insertion as a monitoring technique for avoiding iatrogenic ulnar nerve injury. A retrospective review was conducted on 138 children, mean age 5.6 years (SD±2.5), who were admitted to the hospital between 2007 and 2010 with uncomplicated supracondylar fractures, Gartland type II and above, and intact neurovascular presentation. The location of the ulnar nerve was identified and marked preoperatively by observing twitch contractions in response to electrical stimulation. The medial pin served as an active electrode during pin insertion, and repeated stimulation throughout the insertion process ensured no contact with the response of the ulnar nerve. After pin insertion, ulnar nerve stimulation was used again to ensure nerve continuity viability. All fractures were stabilized with 2 to 4 cross K-wires (size 1.6 mm), with number depending on stability of the fracture. The children were discharged home 2 days after fracture fixation, with no iatrogenic ulnar nerve injury observed in any of the children. The only postoperative complication involved 2 cases of anterior interosseus nerve neuropraxia, which resolved spontaneously after 4 to 6 months. Primary fracture healing was achieved without nonunions or delayed unions in all cases. Ulnar nerve stimulation before and during the percutaneous pinning of supracondylar fractures in children is a simple, economical, and easy-to-implement technique that can prevent iatrogenic ulnar nerve injury. Level IV.

Flexor pollicis longus reconstruction using the palmaris longus in anterior interosseus nerve syndrome.

In anterior interosseus nerve syndrome, reconstruction of the paralyzed flexor pollicis longus is occasionally required. Traditionally, the brachioradialis has been used as a motor, but we utilised the palmaris longus, which is expendable. The palmaris longus tendon was transferred in an end-to-side manner, leaving the flexor pollicis longus in situ. The procedure was performed in three patients. All patients regained a full range of thumb interphalangeal joint motion and an average 90% of the pinch strength. The only complication noted was thenar pain due to the adhesion of the palmar branch of the median nerve with the transferred tendon in one patient. This can be avoided if the interlacing suture was placed more proximally. Palmaris longus transfer is a simple technique that gives a satisfactory result.

Endoscopically assisted nerve decompression of rare nerve compression syndromes at the upper extremity

Besides carpal tunnel and cubital tunnel syndrome, other nerve compression or constriction syndromes exist at the upper extremity. This study was performed to evaluate and summarize our initial experience with endoscopically assisted decompression. Between January 2011 and March 2012, six patients were endoscopically operated for rare compression or hour-glass-like constriction syndrome. This included eight decompressions: four proximal radial nerve decompressions, and two combined proximal median nerve and anterior interosseus nerve decompressions. Surgical technique and functional outcomes are presented. There were no intraoperative complications in the series. Endoscopy allowed both identifying and removing all the compressive structures. In one case, the proximal radial neuropathy developed for 10years without therapy and a massive hour-glass nerve constriction was observed intraoperatively which led us to perform a concurrent complementary tendon transfer to improve fingers and thumb extension. Excellent results were achieved according to the modified Roles and Maudsley classification in five out of six cases. All but one patient considered the results excellent. The poorest responder developed a CRPS II and refused post-operative physiotherapy. Endoscopically assisted decompression in rare compression syndrome of the upper extremity is highly appreciated by patients and provides excellent functional results. This minimally invasive surgical technique will likely be further described in future clinical studies.

A Study on the Accessory Head of the Flexor Pollicis Longus Muscle (Gantzer’s Muscle)A Study on the Accessory Head of the Flexor Pollicis Longus Muscle (Gantzer’s Muscle)

The present study was planned to analyze the Accessory Head of the Flexor Pollicis Longus muscle' (AHFPL) or Gantzer's muscle and its incidence. It is an additional muscle in the forearm which might cause pressure symptoms to the underlying structures, especially to the anterior interosseus nerve. This study was performed on 180 upper limbs (90 right and 90 left). The morphology and the morphometry of AHFPL was done. In this investigation, we observed the various shapes, origins, insertions, nerve supplies and relations of the muscle. The incidence of the accessory head of the flexor pollicis longus muscle was seen in 92 cases (51.11%). It was found bilaterally in 66 (71.73%) cases and unilaterally in 26 cases (28.26%), among which, in 16, it was seen on the right side and in 10 on the left side. With the increasing incidence of the Gantzer's muscle, one can call it as an evolutionary muscle. The present study supplements the knowledge on the morphology of AHFPL muscle and its relationship with the anterior interosseus nerve. An increased incidence of this muscle may be the causative factor for the complete anterior interosseous nerve syndrome.