Maldonado, Andres A.

Despite advances in imaging, instrumentation, surgical techniques, and postoperative care, outcomes for certain peripheral nerve procedures remain consistently disappointing. In this article, we describe five surgical scenarios--adult pan-brachial plexus injuries, peroneal nerve injury after knee dislocation, sciatic nerve injury after total hip arthroplasty, radiation-induced brachial plexopathy, and lower trunk injury after cardiac surgery--that, in our experience and review of the literature, frequently lead to limited and consistently poor functional recovery after nerve surgery. These challenging cases reflect not only technical and anatomical complexity but the profound biological limitations of nerve regeneration in specific contexts. By critically analyzing these five procedures, we aim to promote more realistic patient counseling, support timely and individualized decision-making, and foster a more nuanced understanding of when and what type of surgical intervention may or may not be beneficial.

OBJECTIVE Neuromuscular choristoma (NMC) is a rare developmental lesion that may give rise to desmoid-type fibromatosis (DTF) within the same nerve territory (NMC-DTF). While MRI features of NMC are well established, the natural history of progression to NMC-DTF has not been systematically described. This study aimed to define radiological groups from NMC to NMC-DTF using serial MRI and a literature review. METHODS Following IRB approval, the authors retrospectively analyzed 28 patients with NMC from their institutional database. Diagnosis was based on pathology or classic clinicoradiological features. Sequential MR images were reviewed to evaluate nerve enlargement, enhancement patterns, low T1/T2 foci, and NMC-DTF formation. Cases were classified into 3 radiological groups: 1) classic NMC with typical MRI features (group I), 2) NMC plus, with atypical features (foci of low T1/T2 signal intensity and/or at least moderate postcontrast enhancement; group II), and 3) NMC-DTF with a mass outside of the epineurium (group III). Data were correlated with pathology results and prior reports from the literature. RESULTS Of the 28 patients, 24 underwent serial MRI. Eleven patients presented with group I features, 4 with group II, and 9 with group III. Among group I patients with follow-up imaging, 4 (36.4%) progressed to group III over a mean of 6.2 years and 1 (9.1%) to group II. All 4 group II patients (100%) developed NMC-DTF within a mean of 3.0 years. All group III patients demonstrated NMC-DTF extending beyond the epineurium. No prior cases in the literature documented radiological progression from NMC to NMC-DTF on serial MR images. CONCLUSIONS The authors propose a framework for NMC progression based on radiological features, identifying group II as being high risk and a potential transitional phase for the formation of DTF. Structured surveillance with serial MRI is essential to prevent iatrogenic triggers and improve management strategies in patients with NMC.

BACKGROUND The articular origin of intraneural ganglion cysts has been previously described and well supported, except for the median nerve at the level of the elbow. OBSERVATIONS The authors present a patient with a median intraneural ganglion cyst at the elbow region and magnetic resonance imaging (MRI) evidence of a joint connection to the proximal radioulnar joint. A 63-year-old man presented with thumb flexion weakness and dysesthesias in the thumb, index, and middle fingers. Electromyography confirmed a median nerve lesion at the elbow. MRI demonstrated a median intraneural cyst as well as an extraneural cyst, both arising from the proximal radioulnar joint. The articular branch between the cyst and the proximal radioulnar joint was identified preoperatively on MRI and intraoperatively using indocyanine green. Following disconnection of the articular branch and pedicle and decompression of the intra- and extraneural cysts, the patient recovered grade M4 motor function after 6 months, with resolution of neuropathic pain immediately after surgery. LESSONS The authors present the first case of a median intraneural cyst with a joint connection to the proximal radioulnar joint. The authors believe that this report along with other historical data strengthens the articular theory for intraneural ganglion cysts not only at this site but at all sites. https://thejns.org/doi/10.3171/CASE24564

BACKGROUND AND IMPORTANCE: Snapping of the triceps muscle occurs when a portion of the medial head dislocates over the medial epicondyle with elbow flexion. Resection or redirection of a portion of the triceps muscle is the main surgical treatment. The extent of triceps resection/redirection is difficult to evaluate. A novel intraoperative technique, stimulating the musculocutaneous nerve, to simulate active elbow flexion is proposed to help ensure that the snapping triceps has been adequately treated. CLINICAL PRESENTATION: A patient presented with a several year history of bilateral elbow pain, snapping, and ulnar nerve (UN) paresthesias. Previous staged bilateral subcutaneous UN transpositions were performed at another institution for documented UN dislocation and neuritis. Postoperatively symptoms of painful snapping persisted. Bilateral snapping triceps was diagnosed. The left elbow was reoperated. Intraoperative electrical stimulation of the musculocutaneous nerve was performed to reproduce the snapping triceps. Activation of the biceps/brachialis muscles produced powerful elbow flexion, allowed direct visualization of the forceful snapping triceps, and helped assess the adequacy of muscle resection/redirection. CONCLUSION: Intraoperative biceps/brachialis stimulation can potentially help determine how much triceps muscle should be resected/redirected to treat patients with snapping triceps.

Learning Objectives: After reading this article and viewing the videos, the participant should be able to: 1. Recognize the following five wrist operations as consistent options for different wrist injuries: carpal tunnel release, medial femoral condyle bone flap for scaphoid nonunion associated with carpal collapse and avascular necrosis, scaphocapitate arthrodesis for Kienböck disease, percutaneous screw fixation of nondisplaced scaphoid fracture, and four-corner arthrodesis. 2. Know the state-of-the-art of these five procedures. 3. State the indications of each operation. 4. List the surgical steps of these five procedures. Summary: The wrist is a complex joint that concentrates different types of tissues (e.g., bone, cartilage, ligaments, nerves, vessels) and a broad different spectrum of diseases. Treatment of wrist injuries has improved during recent years, mainly because of improvement in strategy, techniques, microsurgical equipment, understanding anatomy and improvements in technology. In this article, we present the five operations (i.e., carpal tunnel release, medial femoral condyle bone flap for scaphoid nonunion associated with carpal collapse and avascular necrosis, scaphocapitate arthrodesis for Kienböck disease, percutaneous screw fixation of nondisplaced scaphoid fracture, and four-corner arthrodesis) that have consistently given good outcomes in patients suffering from different wrist injuries/maladies.

Abstract BACKGROUND Neuromuscular choristoma (NMC) is a peripheral nerve malformation frequently associated with a fibromatosis (NMC-DTF) that mimics sporadic desmoid-type fibromatosis (DTF). Sporadic DTF is often managed conservatively but its clinical behavior varies. CTNNB1 mutational subtypes in sporadic DTF have prognostic value. We have previously identified CTNNB1 mutations in NMC, and 3 paired NMC-DTF but the clinical behavior of NMC-DTF is poorly understood. OBJECTIVE To evaluate patients with NMC-DTF to determine (1) CTNNB1 mutational subtypes in NMC-DTF, and (2) associated clinical behavior and response to treatment. METHODS Retrospective review of clinical, imaging, and pathologic features of patients with NMC and NMC-DTF, and molecular testing for CTNNB1 mutations. RESULTS Among 7 patients with NMC of the sciatic nerve (median age: 18 yr), NMC-DTF (mean size 10.7 cm) developed shortly following NMC biopsy (N = 5) or spontaneously (N = 2): 6 NMC-DTF had CTNNB1 p.S45X mutations and 1 NMC-DTF had a p.T41A mutation. All patients with CTNNB1 -p.S45-mutated NMC-DTF developed local progression after wide local excision or active surveillance, including one distal metachronous NMC-DTF. No patient had spontaneous disease stabilization. Following adjuvant radiation or systemic therapy, disease stabilization was achieved in 4 (of 6) patients. One patient progressed on sorafenib treatment. CONCLUSION NMC-DTF frequently contain CTNNB1 p.S45 mutations, behave aggressively, and require adjuvant therapies for disease stabilization. We now use imaging alone to diagnose NMC, and routinely surveille the NMC-affected nerve segment to identify early NMC-DTF. In contrast to sporadic DTF, earlier adoption of systemic therapeutic strategies may be required for optimal disease management of NMC-DTF.

The authors present the cases of 3 patients with severe injuries affecting the peroneal nerve combined with loss of tibialis posterior function (inversion) despite preservation of other tibial nerve function. Loss of tibialis posterior function is problematic, since transfer of the tibialis posterior tendon is arguably the best reconstructive option for foot drop, when available. Analysis of preoperative imaging studies correlated with operative findings and showed that the injuries, while predominantly to the common peroneal nerve, also affected the lateral portion of the tibial nerve/division near the sciatic nerve bifurcation. Sunderland’s fascicular topographic maps demonstrate the localization of the fascicular bundle subserving the tibialis posterior to the area that corresponds to the injury. This has clinical significance in predicting injury patterns and potentially for treatment of these injuries. The lateral fibers of the tibial division/nerve may be vulnerable with long stretch injuries. Due to the importance of tibialis posterior function, it may be important to perform internal neurolysis of the tibial division/nerve in order to facilitate nerve action potential testing of these fascicles, ultimately performing split nerve graft repair when nerve action potentials are absent in this important portion of the tibial nerve.