Lateral Antebrachial Cutaneous Nerve Research Articles

Relationship to the superficial radial nerve and anatomic variations of the first extensor compartment in Thai population: a basis for successful de Quervain tenosynovitis treatment.

Knowledge of the superficial radial nerve (SRN) relationship and anatomic variations of the first extensor compartment (1st EC) will contribute to a better outcome of de Quervain tenosynovitis treatment. We dissected 87 embalmed cadaveric wrists to determine the relationship of the SRN, the 1st EC length, distance from the proximal and distal 1st EC borders to radial styloid process (RSP), abductor pollicis longus (APL) and extensor pollicis brevis (EPB) tendon slip numbers, and the presence of septum. Our results revealed SRN crossing over the 1st EC in 59.5%. The lateral branch of the superficial radial nerve to the 1st EC midline in most cases (61.9%) except for one specimen, where lateral antebrachial cutaneous nerve was the closest. Distances from proximal and distal 1st EC borders to the RSP were 19.7±4.1 mm and 7.6±1.8 mm, respectively. Extensor retinaculum (ER) width over 1st EC (1st EC length) was 14.8±3.2 mm. Complete and incomplete septa were found in 17.2%, and 42.5%, respectively. The most frequent APL tendon slip number in the compartment was two in overall 47 specimens (54.0%). Almost all compartments (85 specimens; 97.7%) contained one EPB tendon slip. We detected bilateral EPB absence in one cadaver. Moreover, we recorded a tendon slip from extensor pollicis longus traveling into 1st EC bilaterally in one cadaver and observed the EPB muscle belly extension into 1st EC in 9 wrists. Awareness of 1st EC anatomic variations would be essential for successful surgical and nonsurgical outcomes.

Superficial branch of the radial nerve passing through the supinator canal, emerging between the extensor digitorum and abductor pollicis longus muscles and consequently supplying the second finger and radial portion of the third finger: a case report and clinical implications.

Awareness of unique path of the superficial branch of the radial nerve and its unusual sensory distribution can help avoid potential diagnostic confusion. We present a unique case encountered during a routine dissection of a Central European male cadaver. An unusual course of the superficial branch of the radial nerve was found in the right forearm, where the superficial branch of the radial nerve originated from the radial nerve distally, within the supinator canal, emerged between the extensor digitorum and abductor pollicis longus muscles and supplied the second and a radial half of the third digit, featuring communications with the lateral antebrachial cutaneous nerve and the dorsal branch of the ulnar nerve. Due to dorsal emerging of the superficial branch of the radial nerve the dorsal aspect of the thumb was innervated by the lateral antebrachial cutaneous nerve. To our best knowledge such variation of the superficial branch of the radial nerve has never been reported before. This variation dramatically changes aetiology and manifestation of possible entrapment syndromes which clinicians should be aware of.

Insights on the Choice and Preparation of the Donor Nerve in Corneal Neurotization for Neurotrophic Keratopathy: A Narrative Review.

The article introduces neurotrophic keratopathy (NK), a condition resulting from corneal denervation due to various causes of trigeminal nerve dysfunctions. Surgical techniques for corneal neurotization (CN) have evolved, aiming to restore corneal sensitivity. Initially proposed in 1972, modern approaches offer less invasive options. CN can be performed through a direct approach (DCN) directly suturing a sensitive nerve to the affected cornea or indirectly (ICN) through a nerve auto/allograft. Surgical success relies on meticulous donor nerve selection and preparation, often involving multidisciplinary teams. A PubMed research and review of the relevant literature was conducted regarding the surgical approach, emphasizing surgical techniques and the choice of the donor nerve. The latter considers factors like sensory integrity and proximity to the cornea. The most used are the contralateral or ipsilateral supratrochlear (STN), and the supraorbital (SON) and great auricular (GAN) nerves. Regarding the choice of grafts, the most used in the literature are the sural (SN), the lateral antebrachial cutaneous nerve (LABCN), and the GAN nerves. Another promising option is represented by allografts (acellularized nerves from cadavers). The significance of sensory recovery and factors influencing surgical outcomes, including nerve caliber matching and axonal regeneration, are discussed. Future directions emphasize less invasive techniques and the potential of acellular nerve allografts. In conclusion, CN represents a promising avenue in the treatment of NK, offering tailored approaches based on patient history and surgical expertise, with new emerging techniques warranting further exploration through basic science refinements and clinical trials.

Superficial branch of the radial nerve regularly contains fibers from the lateral antebrachial cutaneous nerve: A role in neuroma treatment

BackgroundMany surgical strategies aim to treat the symptomatic neuroma of the superficial branch of the radial nerve (SBRN). It is still difficult to treat despite many attempts to reveal a reason for surgical treatment failure. The lateral antebrachial cutaneous nerve (LACN) is known to overlap and communicate with SBRN. Our study aims to determine the frequency of spreading of LACN fibers into SBRN branches through a microscopic dissection to predict where and how often LACN fibers may be involved in SBRN neuroma. MethodsEighty-seven cadaveric forearms were thoroughly dissected. The path of LACN fibers through the SBRN branching was ascertained using microscopic dissection. Distances between the interstyloid line and entry of LACN fibers into the SBRN and emerging and bifurcation points of the SBRN were measured. ResultsThe LACN fibers joined the SBRN at a mean distance of 1.7 ± 2.5 cm proximal to the interstyloid line. The SBRN contained fibers from the LACN in 62% of cases. Most commonly, there were LACN fibers within the SBRN’s third branch (59%), but they were also observed within the first branch, the second branch, and their common trunk (21%, 9.2%, and 22%, respectively). The lowest rate of the LACN fibers was found within the SBRN trunk (6.9%). ConclusionThe SBRN contains LACN fibers in almost 2/3 of the cases, therefore, the denervation of both nerves might be required to treat the neuroma. However, the method must be considered based on the particular clinical situation.

Distal Biceps Tendon Repair Using a Double Intracortical Button Anatomical Footprint Repair Technique

Distal biceps tendon repair is usually performed via a double-incision or single-incision bicortical drilling technique. However, these techniques are associated with specific complications and usually do not allow for anatomical footprint restoration. It was the aim of this study to report the clinical results of a double intracortical button anatomical footprint repair technique for distal biceps tendon tears. We hypothesized that this technique would result in supination strength comparable to the uninjured side with a low re-rupture rate and minimal bony or neurological complications. This was a retrospective, single-surgeon cohort study of a consecutive series of 22 patients with a mean (SD) age of 50.7 (9.4) years and at least 1-year follow-up after distal biceps tendon repair. At final follow-up, complications, range of motion (ROM), the Patient-rated Elbow Evaluation (PREE), Mayo Elbow Performance Score (MEPS), Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire, visual analog scale (VAS) for pain, patient satisfaction and supination strength in neutral as well as 60° of supination were analyzed. Radiographic evaluation was performed on a CT scan. One patient (4.5%) experienced slight paresthesia in the area of the lateral antebrachial cutaneous nerve. Heterotopic ossification was seen in one patient (4.5%). All patients recovered full ROM except for one who had 10° of loss of flexion and extension. Median PREE score was 4.6 (0-39.6), median MEP was 100 (70-100) and median DASH was 1.4 (0-16.7). All but one patient were very satisfied with the outcome. The affected arm had a mean of 98% (± 13) of neutral supination strength (p=0.633) and 94% (± 12) of supination strength in 60° (p=0.054) compared to the contralateral, unaffected side. There were four cases (18.2%) of cortical thinning due to at least one button and one case of button pull-out (4.5%). The double intracortical button anatomical footprint repair technique seems to provide reliable restoration of supination strength, excellent patient satisfaction while minimizing complications, particularly nerve damage and heterotopic ossification.

The 2-by-2 Inch “Key Window” in the Upper Extremity: An Anatomical Appraisal of the Accessibility and Proximity of the Major Nerves and Vessels

The brachial plexus is a network of nerves located between the neck and axilla, which receives input from C5-T1. Distally, the nerves and blood vessels that supply the arm and forearm form a medial neurovascular bundle. The purpose of this study was to illustrate that a peripheral nerve dissection via a 2×2 inch window would allow for identification and isolation of the major nerves and blood vessels that supply the arm and forearm. A right side formalin-fixed latex-injected cadaveric arm was transected at the proximal part of the axillary fold and included the scapular attachments. Step-by-step anatomical dissection was carried out and documented with three-dimensional digital imaging. A 2×2 inch window centered 2 inches distal to the axillary fold on the medial surface of the arm enabled access to the major neurovascular structures of the arm and forearm: the median nerve, ulnar nerve, medial antebrachial cutaneous nerve, radial nerve and triceps motor branches, musculocutaneous nerve and its biceps and brachialis branches and lateral antebrachial cutaneous nerve, basilic vein and brachial artery and vein, and profunda brachii artery. Our study demonstrates that the majority of the neurovascular supply in the arm and forearm can be accessed through a 2×2 inch area in the medial arm. Although this "key window" may not be entirely utilized in the operative setting, our comprehensive didactic description of peripheral nerve dissection in the cadaver laboratory can help in safer identification of complex anatomy encountered during surgical procedures.

All-endoscopic approach for distal biceps tendon pathology: analysis of long-term outcomes in partial and complete ruptures

Distal biceps tendon (DBT) pathology is a spectrum that ranges from tendinopathy to complete retracted ruptures, and surgical treatment is usually performed via open approaches. The purpose of this study was to analyze safety and long-term outcomes of all-endoscopic surgery for entire spectrum of primary DBT pathology. The hypothesis was that at an all-endoscopic technique would result in satisfactory clinical outcomes and a low complication rate. Consecutive patients who underwent all-endoscopic surgery for primary isolated DBT pathology (bursitis, partial and acute/chronic complete tears) between January 2013 and December 2021 were assessed and analyzed retrospectively. Refractory bursitis and low-grade partial tears underwent endoscopic débridement, and high-grade partial tears and complete ruptures underwent all-endoscopic repair or graft reconstruction. Preoperative and follow-up assessment included functional assessment using Mayo Elbow Performance Score (MEPS) and a Patient-Reported Distal Biceps Score (PRDBS), and radiological assessment was performed using plain biplanar radiographs and sonography. Pre- and postoperative scores for the overall group, and for partial and complete tears, were compared using a paired T-test. Overall, 26 male patients underwent an all-endoscopic surgery for distal biceps tendon tears; the pathology was classified by endoscopic findings into 6 types, and follow-up period ranged from 21 to 125 months (mean 79.4 months). Nine chronic partial tears (35%) included predominantly bursitis (type I, n=2) and predominantly partial tears (type IIA and B, n=7). The complete tear group (65%) included isolated short or long head tears (type IIIA and IIIB, n=2) and complete tendon ruptures (types IV, V, and VIA-C, n=15). Endoscopic débridement of the bursitis/ low grade tears and repair of the high-grade and complete ruptures resulted in complete resolution of symptoms and significant improvement in both MEPS and PRDBS (p<0.001). Autografts were necessary in 35% (6/17) of complete tears, and no significant difference was found in functional scores in this group as compared to those where primary repairs were possible. There were 2 minor complications (7.6%) that involved transient lateral antebrachial cutaneous nerve (LACN) neuropraxia. Follow-up sonography and radiographs showed an intact tendon and absence of heterotopic ossification or synostosis. An all-endoscopic approach for treating distal biceps tendon pathology was safe and reliable and was associated with significant improvement in subjective and functional outcomes in the long term. The dual-anchor onlay repair technique showed long-term radiologically demonstrable structural integrity of the tendon and was associated with a low minor complication rate and absence of heterotopic ossification.

Cutaneous nerve distribution around first extensor compartment of the wrist: Clinical implications for ultrasound-guided injections

To evaluate the course of the cutaneous nerve regarding the first extensor compartment to determine whether the dorsal or volar approach is safer for local injection into the first extensor compartment guided by ultrasound. We dissected the radial side of the wrists from 28 cadavers (52 wrists). Four-points along the imaginary line were set: the styloid process and 1 cm, 2 cm, and 3 cm proximal to the styloid process. The numbers of superficial radial nerve (SRN) and lateral antebrachial cutaneous nerve (LACN) branches were counted, and distances from the imaginary line at these points and nerve diameters were recorded. Digital images were superimposed to observe overall distribution of cutaneous nerve. There were means of 3.3 SRN and 0.9 LACN branches observed in each wrist. The mean number of both SRN and LACN branches was 2.3 on the dorsal side and 1.9 on the volar side. The superimposed images indicated that both the dorsal and volar sides comprised abundant cutaneous nerves and that their paths varied markedly between patients. However, we observed that larger nerves with meaningful diameters were more abundant on the dorsal than the volar side. There were similar numbers of cutaneous nerves on both the dorsal and volar sides; however, we observed greater abundance of thicker cutaneous nerves on the dorsal side, and these were closer to the reference line than on the volar side. This anatomical study suggests that the risk imposed to cutaneous nerves would therefore be reduced when injection on the volar side.

Chapter 8 - Axillary and musculocutaneous neuropathies

This chapter covers axillary and musculocutaneous neuropathies, with a focus on clinically relevant anatomy, electrodiagnostic approaches, etiologic considerations, and management principles. Disorders of the lateral antebrachial cutaneous nerve, a derivative of the musculocutaneous nerve, are also reviewed. We emphasize the importance of objective findings, including the physical examination and electrodiagnostic evaluation in confirming the isolated involvement of each nerve which, along with the clinical history, informs etiologic considerations. Axillary and musculocutaneous neuropathies are both rare in isolation and most frequently occur in the setting of trauma. Less commonly encountered etiologies include external compression or entrapment, neoplastic involvement, or immune-mediated disorders including neuralgic amyotrophy, postsurgical inflammatory neuropathy, multifocal motor neuropathy, vasculitic neuropathy, and multifocal chronic inflammatory demyelinating polyradiculoneuropathy.

Clinical anatomy of the lateral antebrachial cutaneous nerve: Is there any safe zone for interventional approach?

IntroductionThe lateral antebrachial cutaneous nerve (LACN) is a somatosensory nerve coursing in the lateral portion of the forearm. The nerve is located in a close proximity to the cephalic vein (CV) all along its course with a danger of being injured during venipuncture. The LACN also overlaps and communicates with the superficial branch of the radial nerve (SBRN) in the distal forearm and hand, making the awareness of their relationship of great importance in the treatment of neuroma. The aim of the study was to observe the relationship of the LACN to surrounding structures as well as its branching pattern and distribution. Materials and methodsNinety-three cadaveric forearms embalmed in formaldehyde were dissected. The relationship of the LACN to surrounding structures was noted and photographed, and distances between the structures were measured with a digital caliper. The cross-sectional relationships of the LACN and SBRN to the CV were described using heatmaps. ResultsThe emerging point of the LACN was found distally, proximally or at the level of the interepicondylar line (IEL). The LACN branched in 76 cases (81.7 %) into an anterior and posterior branch at mean distance of 47.8 ± 34.2 mm distal to the IEL. The sensory distribution was described according to the relationship of the LACN branches to the medial border of the brachioradialis muscle. The LACN supplying the dorsum of the hand was observed in 39.8 % of cases. The LACN and the SBRN intersected in 86 % of upper limbs with communications noticed in 71 % of forearms. The LACN was stated as the most frequent donor of the communicating branch resulting in neuroma located distal to the communication and being fed from the LACN. The relationship of the LACN and the CV showed that the IEL is the most appropriate place for the venipuncture due to maximal calibers of the CV and deep position of the LACN. The LACN was adjacent to the cubital perforating vein and the radial artery in all cases. The medial border of the brachioradialis muscle was observed less than 1.8 mm from the LACN. ConclusionThe study provides morphological data on the LACN distribution, branching pattern and relationship to surrounding structures in a context of clinical use in different spheres of medicine. The branching pattern of the LACN appears to be more constant compared to data provided by previous authors. We emphasized the meaning of cross-sectional relationship of the LACN to the CV to avoid venipuncture outside the cubital fossa if possible. The posterior branch of the LACN was predicted as appropriate donor of the graft for a digital nerve. The LACN appeared to be in a close proximity within the whole length of the brachioradialis muscle what the orthopedic surgeons must be concerned of. The meaning of the donor-nerve of the communicating branch in neuroma treatment was also introduced.

Innervation of thumb carpometacarpal joint: implications for diagnostic block and denervation procedures

IntroductionOsteoarthritis (OA) of the thumb carpometacarpal (CMC) joint is a common disorder that negatively impacts hand function. Denervation of the thumb CMC joint has emerged as a viable treatment option....

Management of Distal Biceps Tendon Ruptures: A Survey of Fellowship-Trained Subspecialist Elbow Surgeons.

There are several approaches to the management of distal biceps tendon ruptures, with no consensus on what constitutes best practice. An online survey queried the perceptions and management of distal biceps tendon ruptures amongst fellowship-trained subspecialist elbow surgeons, which primarily comprised of members of the Shoulder and Elbow Society of Australia, the national subspecialist interest group of the Australian Orthopaedic Association and the Mayo Clinic Elbow Club (Rochester, MN). One hundred surgeons responded. The median (IQR) experience as orthopedic surgeons amongst respondents was 17 (10-23) years. 78% of respondents saw >10 cases of distal biceps tendon ruptures annually. 95% of respondents would recommend surgery for symptomatic radiologically-confirmed partial tears, the most common indications being pain (83%), weakness (60%), and tear size (48%). 43% of respondents would have grafts available for tears older than 6 weeks. The one-incision approach (70%) was preferred over two-incisions (30%). 78% of one-incision users believed that their repair location was anatomic, compared to 100% of two-incision users. One-incision users were more likely to have encountered lateral antebrachial cutaneous nerve (78% vs 46%) and superficial radial nerve palsies (28% vs 11%). Two-incision users were more likely to have encountered posterior interosseus nerve palsy (21% v 15%), heterotopic ossification (54% vs 42%), and synostosis (14% vs 0%). Re-ruptures were the most common cause of reoperation. The more conservative a respondent's postoperative immobilization was, the less likely they were to have ever encountered re-rupture (14% amongst cast users, 29% amongst splint/brace users, 49% amongst sling users, 100% amongst non-immobilizers). 30% of respondents who placed elbow strength restrictions for 6 months postoperatively encountered re-rupture, compared to 40% amongst those who restricted for 6-12 weeks postoperatively. The operation rate for repair of distal biceps tendon ruptures amongst subspecialist elbow surgeons is high, as seen in our cohort. However, there is a large variation in the approach toward its management. One-incision (anterior) was preferred over two-incisions (posterior). Complications from repair of distal biceps tendon ruptures can be expected even amongst subspecialists, and are associated with surgical approach. The responses imply that more conservative postoperative rehabilitation may be associated with a lower risk of re-rupture.

Bridging Gaps in Peripheral Nerves: From Current Strategies to Future Perspectives in Conduit Design.

In peripheral nerve injuries (PNI) with substance loss, where tensionless end-to-end suture is not achievable, the positioning of a graft is required. Available options include autografts (e.g., sural nerve, medial and lateral antebrachial cutaneous nerves, superficial branch of the radial nerve), allografts (Avance®; human origin), and hollow nerve conduits. There are eleven commercial hollow conduits approved for clinical, and they consist of devices made of a non-biodegradable synthetic polymer (polyvinyl alcohol), biodegradable synthetic polymers (poly(DL-lactide-ε-caprolactone); polyglycolic acid), and biodegradable natural polymers (collagen type I with/without glycosaminoglycan; chitosan; porcine small intestinal submucosa); different resorption times are available for resorbable guides, ranging from three months to four years. Unfortunately, anatomical/functional nerve regeneration requirements are not satisfied by any of the possible alternatives; to date, focusing on wall and/or inner lumen organization/functionalization seems to be the most promising strategy for next-generation device fabrication. Porous or grooved walls as well as multichannel lumens and luminal fillers are the most intriguing options, eventually also including the addition of cells (Schwann cells, bone marrow-derived, and adipose tissue derived stem cells) to support nerve regeneration. This review aims to describe common alternatives for severe PNI recovery with a highlight of future conduits.

The communication patterns between the lateral antebrachial cutaneous nerve and the superficial branch of the radial nerve

IntroductionThe superficial branch of the radial nerve (SBRN) and the lateral antebrachial cutaneous nerve (LACN) are sensory nerves coursing within the forearm in a close relationship. This high degree of overlap and eventual communication between the nerves is of great surgical importance. The aim of our study is to identify the communication pattern and overlap of the nerves, to localize the position of this communication in relation to a bony landmark, and to specify the most common communication patterns. Materials and methodsOne hundred and two adult formalin-fixed cadaveric forearms from 51 cadavers of Central European origin were meticulously dissected. The SBRN, as well as the LACN, were identified. The morphometric parameters concerning these nerves, as well as their branches and connections, were measured with a digital caliper. ResultsWe have described the primary (PCB) and secondary communications (SCB) between the SBRN and the LACN and their overlap patterns. One hundred and nine PCBs were found in 75 (73.53%) forearms of 44 (86.27%) cadavers and fourteen SCBs in eleven hands (10.78%) of eight cadavers (15.69%). Anatomical and surgical classifications were created. Anatomically, the PCBs were classified in three different ways concerning: (1) the role of the branch of the SBRN within the connection; (2) the position of the communicating branch to the SBRN; and (3) the position of the LACN branch involved in the communication to the cephalic vein (CV). The mean length and width of the PCBs were 17.12 mm (ranged from 2.33 to 82.96 mm) and 0.73 mm (ranged from 0.14 to 2.01 mm), respectively. The PCB was located proximally to the styloid process of the radius at an average distance of 29.91 mm (ranged from 4.15 to 97.61 mm). Surgical classification is based on the localization of the PCBs to a triangular zone of the SBRN branching. The most frequent branch of the SBRN involved in the communication was the third (66.97%). Due to the frequency and position of the PCB with the third branch of the SBRN, the danger zone was predicted. According to the overlap between the SBRN and the LACN, we have divided 102 forearms into four types: (1) no overlap; (2) present overlap; (3) pseudo-overlap; and (4) both present and pseudo-overlap. Type 4 was the most common. ConclusionThe patterns of communicating branch arrangements appeared to be not just a rare phenomenon or variation, but rather a common situation highlighting clinical importance. Due to the close relationship and connection of these nerves, there is a high probability of simultaneous lesion.

Distal Biceps Tendon Reconstruction with Achilles Tendon Allograft: A Case-Series

Background: Chronic, complete ruptures of the distal biceps tendon are often difficult to surgically repair due to significant fibrosis and retraction. The use of a graft is recommended, with recent literature suggesting that an Achilles tendon allograft leads to superior clinical outcomes. The purpose of this study is to present the surgical technique and retrospectively review the clinical outcomes of a distal biceps reconstruction technique that utilizes an Achilles tendon allograft with an Endobutton bicortical fixation system through a single S-shaped incision. Methods: Seven male patients and eight cases of distal biceps reconstruction with Achilles tendon allograft were identified between January 2017 and March 2022. The mean age was 48.3 ± 8.9 years with a mean time from initial injury to surgery of 6.1 ± 3.8 months. Charts were retrospectively reviewed for patient demographics, procedural technique, preoperative and postoperative evaluation, and complications. Results: The cohort had a mean follow-up of 4.6 ± 2.0 months (range, 1.4-8.2). At the final office visit, full range of motion had returned for all patients except one, who had a persistent 10° extension deficit. Flexion strength had returned to equal preoperative and preinjury gross strength out of 5 (4.7 ± 0.5 preoperatively vs. 4.4 ± 0.5 postoperatively) and supination improved from preoperative strength (2.2 ± 1.1 preoperatively vs. 3.6 ± 1.2 postoperatively). Four out of eight cases resulted in a new neuropraxia identified in postoperative care: two lateral antebrachial cutaneous nerves, one superficial branch of radial nerve, and one ulnar nerve, with insufficient follow-up duration to determine resolution. One patient reported excessive scar formation; otherwise, there were no major complications. Conclusion: Reconstruction of the distal biceps tendon using an Achilles tendon allograft is a technically challenging, yet effective approach for the treatment of complete distal biceps tendon ruptures that are chronic in nature, resulting in an improvement in preoperative disability with few postoperative complications.

Selective Denervation for the Thumb Carpometacarpal Joint: Clinical Outcome and Comparison Based on Eaton Stage.

Various operative treatment options for advanced thumb carpometacarpal (CMC) joint arthritis have been presented without a definite surgical guideline. Selective denervation is a less invasive method for thumb CMC arthritis. However, it is unclear whether the clinical outcome varies with the stage of thumb CMC arthritis. This study aimed to evaluate the effectiveness of selective denervation on CMC arthritis for pain relief and functional outcome and to determine whether selective denervation depends on the stage of thumb CMC arthritis. We evaluated 29 thumbs of 28 patients with thumb CMC arthritis treated with selective denervation. The disease stage was determined with the classification system described by Eaton. The denervation was performed in the articular branches of the palmar cutaneous branch of the median nerve, lateral antebrachial cutaneous nerve, and superficial branch of radial nerve. The clinical outcomes were evaluated using the visual analog scale (VAS) and Disabilities of the Arm, Shoulder, and Hand (DASH) scores, along with evaluation of the improvement in both postoperative range of motion and strength recovery. The mean duration of follow-up was 24 months (range, 18-48 months). The average VAS and DASH scores decreased from 6.1 to 1.3 and from 54.3 to 24.1, respectively. The range of motion during palmar abduction and opposition of the metacarpophalangeal joint improved with an increase in mean value from 44.1 to 53.7 degrees, and the Kapandji score increased from 7.2 to 9.2, respectively. The grip and key pinch strengths increased from mean preoperative values of 14.3 and 3.1 kg to 27.1 and 6.2 kg, respectively, as measured at the 12-month follow-up. The rate of change in the VAS and DASH scores was significantly higher in stages I to III than in stage IV ( P = 0.01, P < 0.01, respectively). The selective denervation for thumb CMC arthritis was effective in pain relief and functional recovery with several advantages, including less invasive procedure, quick recovery time, and regaining of strength. The clinical outcomes were more effective in the early-stage group (Eaton stages I and II) compared with the advance-stage group (Eaton stages III and IV).

Bilateral Sequential Brachial Plexus Neuritis Following Immune Checkpoint Inhibitor Combination Treatment (P13-8.003)

<h3>Objective:</h3> To report a rare, debilitating neurotoxicity to combination immunotherapy. <h3>Background:</h3> Neurologic immune related adverse events associated with ICI are rare; rapid diagnosis and treatment can limit morbidity. Combined ICI treatment is associated with more severe and rapid neurotoxicity. Only 4 BPN cases have been reported. Three were unilateral, predominantly involving the lower trunk (C8-T1) and highly steroid responsive. One affected the anterior interosseous and lateral antebrachial cutaneous nerves. <h3>Design/Methods:</h3> A 76-year-old woman with lung adenocarcinoma received 3 doses of Nivolumab and one dose of Ipilimumab. She developed numbness and pain, followed by worsening bilateral asymmetric arm weakness 3 weeks after receiving her last Nivolumab dose. Her weakness was diffuse, worse on the right, associated with loss of reflexes. It started on the right arm and involved left arm a week after. <h3>Results:</h3> EMG confirmed bilateral brachial plexopathy, predominantly affecting roots derived from C6–C7 on right and C5–C6 on left. CSF showed WBC 7, elevated protein 58 g/dL, no malignant cells, normal IgG index and infectious studies. MRI cervical spine and brachial plexus were unremarkable. She received IV methylprednisolone 1 mg/kg for 5 days, IV immunoglobulin total of 2 grams/kg with rapid improvement in her strength and pain. <h3>Conclusions:</h3> This may be the first report of bilateral sequential BPN with predominantly upper-mid trunk involvement after dual treatment with Nivolumab and Ipilimumab. Rapid workup, exclusion of confounding factors, and treatment with steroids and immunomodulating agents can lead to significant recovery of function from a debilitating process. <b>Disclosure:</b> Dr. Ozel has nothing to disclose. Dr. Chen has nothing to disclose. Dr. Woodman has nothing to disclose.

MRI negative Varicella zoster virus (VZV) plexopathy in a young man with history of malignancy (P2-4.001)

<h3>Objective:</h3> To emphasize the importance of including VZV plexopathy in differential diagnosis in young individuals and to prevent the delay in diagnosis and treatment <h3>Background:</h3> VZV-associated plexopathy in mainly patients over 60 years old. Post herpetic neuralgia is a well-known complication of Herpes Zoster (HZ), however segmental zoster paresis secondary to HZ was reported in 1–20% of the cases in literature. MRI findings may be positive in up to 70% of the patients. <h3>Design/Methods:</h3> N/A <h3>Results:</h3> 43 years-old man with history of grade 2 left frontal oligodendroglioma which was treated with 2 partial resections, radiation and adjuvant procarbazine/lomustine presented with left upper extremity pain and developed a blistering rash in dermatomal pattern in left proximal upper extremity 2 weeks after the initial symptoms. He was diagnosed with shingles and treated with steroids and acyclovir with minimal improvement. 6 weeks after presentation, physical exam revealed left deltoid, supraspinatus and infraspinatus weakness with normal muscle stretch reflexes and decreased sensation on C5 dermatome. EMG revealed absent left lateral antebrachial cutaneous sensory nerve action potentials (SNAP) amplitude, and a small left radial SNAP amplitude compared to the right side. Evidence of ongoing denervation with reinnervation was seen in the left upper trunk supplied muscles. MRI of the brachial plexus was negative for any abnormalities. Patient was diagnosed with VZV-associated plexopathy, improved with pregabalin and physical therapy. <h3>Conclusions:</h3> Our patient was significantly younger than expected in HZ group. MRI usually shows T2 hyperintensities and thickening of the nerve roots in patients with VZV-associated plexopathy. However, the presentation, onset of symptoms, characteristics of the rash and clinical course was diagnostic of HZ, and the weakness pattern, supported by the EMG findings were diagnostic for VZV-associated plexopathy. <b>Disclosure:</b> Dr. Gul has nothing to disclose. Ms. Ahmed has nothing to disclose. Dr. McGraw has nothing to disclose. Dr. Alshiekh Nasany has nothing to disclose.

Computer-Assisted Surgical Anatomical Mapping of the Antebrachial Cutaneous Nerves: An Anatomical Study with a Proposition for Alternative, Cutaneous Nerve-Sparing Anterior Elbow Incisions.

The lateral antebrachial cutaneous nerve (LABCN) and medial antebrachial cutaneous nerve (MABCN) were identified in the coronal plane around the elbow joint in 10 fresh-frozen human arm specimens. Marked photographs of the specimens were analyzed using computer-assisted surgical anatomical mapping (CASAM). Common anterior surgical approaches to the elbow joint and the distal humerus were then compared with merged images, and nerve-sparing alternatives are proposed. The arm was divided longitudinally, from medial to lateral in the coronal plane, into 4 quarters. The LABCN crossed the central-lateral quarter of the interepicondylar line (i.e., was somewhat lateral to the midline at the level of the elbow crease) in 9 of 10 specimens. The MABCN ran medial to the basilic vein and crossed the most medial quarter of the interepicondylar line. Thus, 2 of the quarters were either free of cutaneous nerves (the most lateral quarter) or contained a distal cutaneous branch in only 1 of 10 specimens (the central-medial quarter). The Boyd-Anderson approach, which is often used to access anteromedial structures of the elbow, should be placed slightly further medially than traditionally advised. The distal part of the Henry approach should deviate laterally, so that it runs over the mobile wad. In distal biceps tendon surgery, the risk of cutaneous nerve injury may be reduced if a single distal incision is placed slightly more laterally (in the most lateral quarter), as in the modified Henry approach. If proximal extension is required, LABCN injury may be prevented by using the modified Boyd-Anderson incision, which runs in the central-medial quarter. Cutaneous nerve injury may be prevented by slightly altering the commonly used skin incisions around the elbow on the basis of the safe zones that were identified by depicting the cumulative course of the MABCN and LABCN using CASAM.

Clinical, Electrophysiological, and Sonographic Findings in Patients With Nerve Injury After Vessel Puncture.

This study aimed to describe the clinical, electrophysiological, and ultrasonographic findings of patients with nerve injury after vessel puncture. Data on ten patients (three males and seven females) with nerve injury after vessel puncture were reviewed. Demographic and clinical data were analyzed retrospectively. Bilateral electrophysiological studies were performed based on clinical findings. Ultrasonographic examinations were performed on both the affected and unaffected sides of the injured nerve. The nerves of nine patients were injured following vein puncture, and injury occurred following arterial sampling in one patient. Seven patients had superficial radial sensory nerve injury: five medial, one lateral, and one at both branches. One patient had injury to the dorsal ulnar cutaneous nerve, one to the lateral antebrachial cutaneous nerve, and one to the median nerve. Nerve conduction studies produced abnormal findings in 80% of patients, whereas ultrasonographic examinations produced abnormal findings in all of the patients. Spearman's coefficient for the correlation between the amplitude ratio and nerve cross-sectional area ratio was not significant, at -0.127 (95% confidence interval=-0.701 to 0.546, p=0.721). Ultrasonography supported by electrodiagnosis was found to be a useful method for identifying the lesion location and structural abnormalities of vessel-puncture-related neuropathy.