Supercharged End-to-Side Anterior Interosseous to Ulnar Motor Nerve Transfer for Hirayama Disease: A Case Report

Hirayama disease is a rare condition of cervical myelopathy. Its early identification and correction can optimize functional outcomes. However, late presentation and some more severe cases may be associated with loss of hand function. Among the cases described, there are no reports of nerve transfers for this condition. We presented the first case report of a Hirayama disease of isolated ulnar nerve impairment managed with nerve transfer. Electroneuromyography showed isolated preganglionic involvement of C7, C8, and T1, with no sensory changes. The patient underwent nerve transfer with anterior interosseous nerve to ulnar nerve supercharge end-to-side, recovering hand function in 7 months.

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 for multiple nerve transfers to a common target muscle in the upper extremity. This study describes a novel experimental model to investigate the neurophysiological effects of peripheral double nerve transfers. For this purpose, we developed a forelimb model to enable tension-free transfer of one or two donor nerves in the upper extremity. Anatomic dissections were performed to design the double nerve transfer model (n=8). 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 and resected up to its original branch to prevent auto-reinnervation. In all animals, coaptation of both nerves to the motor entry point could be performed tension-free. Mean duration of the procedure was 49 ± 13 min for the single nerve transfer and 78 ± 20 min for the double nerve transfer. 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.

Optimizing nerve transfer surgery in tetraplegia: clinical decision making based on innervation patterns in spinal cord injury

OBJECTIVE Nerve transfers are increasingly being utilized in the treatment of chronic tetraplegia, with increasing literature describing significant improvements in sensorimotor function up to years after injury. However, despite technical advances, clinical outcomes remain heterogenous. Preoperative electrodiagnostic testing is the most direct measure of nerve health and may provide prognostic information that can optimize preoperative patient selection. The objective of this study in patients with spinal cord injury (SCI) was to determine various zones of injury (ZOIs) via electrodiagnostic assessment (EDX) to predict motor outcomes after nerve transfers in tetraplegia. METHODS This retrospective review of prospectively collected data included all patients with tetraplegia from cervical SCI who underwent nerve transfer at the authors’ institution between 2013 and 2020. Preoperative demographic data, results of EDX, operative details, and postoperative motor outcomes were extracted. EDX was standardized into grades that describe donor and recipient nerves. Five zones of SCI were defined. Motor outcomes were then compared based on various zones of innervation. RESULTS Nineteen tetraplegic patients were identified who underwent 52 nerve transfers targeting hand function, and 75% of these nerve transfers were performed more than 1 year postinjury, with a median interval to surgery following SCI of 24 (range 8–142) months. Normal recipient compound muscle action potential and isolated upper motor neuron injury on electromyography (EMG) were associated with greater motor recovery. When nerve transfers were stratified based on donor EMG, greater motor gains were associated with normal than with abnormal donor EMG motor unit recruitment patterns. When nerve transfers were separated based on donor and recipient nerves, normal flexor donors were more crucial than normal extensor donors in powering their respective flexor recipients. CONCLUSIONS This study elucidates the relationship of the preoperative innervation zones in SCI patients to final motor outcomes. EDX studies can be used to tailor surgical therapies for nerve transfers in patients with tetraplegia. The authors propose an algorithm for optimizing nerve transfer strategies in tetraplegia, whereby understanding the ZOI and grade of the donor/recipient nerve is critical to predicting motor outcomes.

Anterior Interosseous Nerve to Ulnar Nerve Transfers: A Systematic Review

Background There has been an increasing utilization of end-to-end (ETE) and reverse “supercharged” end-to-side (SETS) anterior interosseous nerve (AIN) to ulnar nerve transfers (NTs) for treatment of high ulnar nerve injury. This study aimed to review the potential indications for, and outcomes of, ETE and SETS AIN–ulnar NT. Methods A literature review was performed, and 10 articles with 156 patients who had sufficient follow-up to evaluate functional outcomes were included. English studies were included if they reported the outcome of patients with ulnar nerve injuries treated with AIN to ulnar motor NT. Outcomes were analyzed based on the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire scores, grip and key pinch strength, and interosseous Medical Research Council–graded motor strength. Comparisons were made using the independent t-test and the chi-square test. No nerve graft control group was required for eligibility. Ulnar nerve injury types varied. Results NT resulted in 77% of patients achieving M3+ recovery, 53.7 ± 19.8 lb grip strength recovery, 61 ± 21% key pinch recovery, and a mean DASH score of 33.4 ± 16. In this diverse group, NT resulted in significantly greater M3+ recovery and grip strength recovery measured in pounds than in the nerve graft/conventional treatment group, and ETE repairs had significantly better outcomes compared with SETS repairs for grip strength, key pinch strength, and DASH scores, but heterogeneity limits interpretation. Conclusion ETE and SETS AIN–ulnar NTs produce significant restoration of ulnar nerve motor function for high ulnar nerve injuries. For ulnar nerve transection injuries at or above the elbow, ETE NT results in superior motor recovery compared with nerve grafting/conventional repair. However, further research is needed to determine the best treatment for other types of ulnar nerve injury and the role of SETS NT.

Static Suspension of the Paralyzed Face Utilizing the Midfacial Corridor: Anatomic Evaluation and Surgical Technique

Introduction Fascia lata and tendon grafts are frequently utilized to support the paralyzed midface and to extend muscular reach in McLaughin style, orthodromic temporalis transfers. The grafts are frequently placed in a deep subcutaneous positioning that can lead to the development of a, bowstring deformity in the cheek. This paper describes insertion of tendon grafts into the midfacial corridor collectively formed by the buccal, submasseteric and superficial temporal spaces. Methods Over a seven-year period, all patients that underwent insertion of facia lata and tendon grafts in the midfacial corridor were included. Demographic information, perioperative variables and clinical outcomes were collected and analyzed. Results A total of 22 patients were included with a mean age of 64.3 years (33–86). There were multiple etiologies for the facial weakness including acoustic neuroma (9.1%), Bell's palsy (13.6%), facial nerve schwannoma (9.1%), temporal bone fracture (4.6%) and malignancy (22.7%). Midfacial corridor grafts were utilized in combination with nerve transfers (V-VII and XII-VII) in nine patients, McLaughin style temporalis transfers in 12 and as a standalone procedure in one individual. During the study period, no patients exhibited a tethering, or concave deformity in the midface. Additionally, no impingement, difficulties with mastication, parotitis or hematoma were encountered. One patient developed a postoperative infection, that was successfully managed. Conclusion Placement of tendon or fascia grafts for static support or tunneling of an orthodromic temporalis transfer through the midfacial corridor can be performed rapidly while providing midfacial support and avoiding the creation of visible cutaneous deformities.