Spinner, Robert J.

OBJECTIVE The role of amputation and myoelectric prosthetic fitting for hand function in traumatic pan–brachial plexus injury (pBPI) continues to evolve. This study evaluated the function and activity performance of patients with traumatic pBPI who underwent amputation and prosthetic fitting with a myoelectric prosthesis (MEP) for hand function. METHODS A retrospective analysis of adult patients who underwent elective amputation after sustaining a pBPI followed by MEP for hand function was performed. Demographics, mechanisms of injury, amputation details, and outcomes were collected from medical records. The Disabilities of the Arm, Shoulder and Hand (DASH) outcome measure was used to evaluate the impact of impairment, the visual analog scale (VAS) to assess pain, and the Activities Measure for Upper Limb Amputees (AM-ULA) to determine functional activity performance pre- and post-MEP usage. Follow-up time, prosthesis usage, satisfaction, and site of electrical signal used were recorded. Paired t-tests were used to compare outcomes. RESULTS Twenty-one adult patients with pBPI (90% male, mean age 32 years at the time of BPI) underwent amputations and were fitted with MEPs for hand function controlled by nonintuitive signals. Fifteen patients underwent a trans-radial amputation and 6 underwent a trans-humeral amputation. While all patients sought improved terminal grasp function, 3 patients subsequently declined prosthetic fitting after amputation. Of the 18 patients who underwent myoelectric prosthetic hand fittings, linear transducers activated by the contralateral shoulder protraction were used in 66% of patients, and traditional electrode signals from ipsilateral nonintuitive muscle were used in 33% to control MEP grasp function. Disability (DASH) and pain (VAS) scores significantly improved after amputation (p = 0.04 and p < 0.01, respectively). AM-ULA scores showed a significant improvement in activity performance after application of the MEP, with an average increase of 23 points from 0 points on a 40-point scale before amputation and prosthetic fitting (p < 0.0001). Daily users of the MEP averaged 6 hours per day and reported the prosthesis was useful during daily activities with great satisfaction at an average of 22 months of follow-up. CONCLUSIONS Amputation followed by MEP fitting in adult traumatic pBPI significantly improved function, reduced pain, and had a high prosthetic usage. The AM-ULA, a tool for quantitatively evaluating activity performance, was applied to measure the bimanual functional activity performance of patients before and after using MEPs, which revealed a significant improvement. Patients reported using their prosthetics daily with a high satisfaction rate with functional terminal grasp and release.

BACKGROUND MRI-guided targeted fascicular biopsy has been a valuable technique for diagnosing idiopathic neuropathies. It has an 80% yield and a minor permanent morbidity rate of 5%. OBSERVATIONS A 48-year-old woman with a history of localized amyloidosis to the orbital muscle 2 years earlier presented with new neurological symptoms. Extensive evaluations including skin, muscle, and distal cutaneous nerve biopsies were negative, and empirical treatment trials did not improve her condition. An MRI-guided targeted biopsy of the right ulnar nerve in the distal arm was planned. During surgery, a medial triceps branch arising from the ulnar nerve was identified and was biopsied along with a neighboring fascicle of the ulnar nerve to the flexor carpi ulnaris. The pathology of the ulnar nerve fascicle but not the contiguous triceps branch showed amyloid (AL [kappa] subtype on mass spectroscopy). The patient was started on treatment. LESSONS The positive biopsy of the ulnar nerve fascicle allowed targeted treatment of the neural amyloidosis. While the negative biopsy of the triceps branch could be attributed to sampling error, it could also be due to the fact that this branch found within the ulnar nerve is thought to originate from the radial nerve. https://thejns.org/doi/10.3171/CASE25484

ABSTRACT The microvasculature of peripheral nerve not only is important for the understanding of the development of compression syndromes, but it plays a critical role in the evolution of other nerve pathologies, including, for example, the distribution of intraneural ganglion cysts and lymphoma. We investigated the anatomical course of vessels around the human sciatic nerve and its bifurcation in eight human cadavers. Specifically, the presence of fenestrations on the epineurium and paraneurium's thickness in relation to the intraneural vessels was investigated. The sciatic, tibial, peroneal and sural nerves at the level of the bifurcation are surrounded by different layers, including the epineurium and paraneurial layers. Multiple fenestrations were observed in all membranes surrounding these nerves, which formed openings for the transfer of adipocytes and vessels from one compartment to the neighboring one. The openings were relatively large compared to the size of the vessels. In conclusion, vessels always travel through a natural opening in the paraneurial and epineurium. These vessels are important connections between the extrinsic and intrinsic nerve vasculature. In addition, the fenestration provides an important anatomical explanation for the possibility of transfer of anesthetic agents or different nerve pathologies, including intraneural ganglion cyst and tumors.

Abstract Background Malignant peripheral nerve sheath tumors (MPNSTs) are rare, aggressive sarcomas, with 40% associated with neurofibromatosis type 1 (NF1). Surgical excision is the main treatment for localized disease; however, local recurrence (LR) remains high. Radiotherapy (RTx) is increasingly used to enhance local control in STS, but its use remains controversial due to the potential for increased major wound complications and an increased risk of secondary malignancies in NF1 patients. This study investigated the use and impact of RTx on local control in MPNSTs, particularly in the NF1 setting. Methods Surgically treated primary MPNSTs from 1988 to 2019 in the MONACO multicenter cohort were included. Differences in demographics, treatment, and RTx use between NF1 and non-NF1 cases were examined. Factors influencing RTx administration and LR were assessed via multivariable analyses. Results Among 499 patients (33.1% NF1), 143 (28.7%) experienced LRs. Radiotherapy was administered to 56.3% of patients (57.0% in the NF1 group), with 27.3% receiving neoadjuvant and 72.7% adjuvant RTx. RTx was administered significantly more often to high-grade and extremity tumors. While RTx did not affect overall survival, it reduced LR risk in sporadic cases (hazard ratio [HR] 0.530; 95% confidence interval [CI], 0.354–0.793) but not in the NF1 subgroup (HR 1.00; 95% CI, 0.545–1.85). In NF1 patients, a microscopically positive margin (R1) was the only risk factor for LR development (HR 2.1; 95% CI, 1.19–3.79). Conclusions RTx is frequently used in the treatment of MPNSTs, regardless of NF1 status. While it may affect the LR rate in sporadic cases, its impact on NF1 patients is less clear.

ABSTRACT Iatrogenic spinal accessory nerve (SAN) injuries can occur as complications of posterior triangle of the neck surgery, resulting in lateral scapular winging and a shoulder droop. Rarely has this complication been described after a cosmetic rhytidectomy (face‐lift procedure). Here, we present two cases of iatrogenic SAN injuries that occurred after cosmetic rhytidectomies. The use of electrodiagnostic and ultrasound examinations provides invaluable information to assess peripheral nerve injuries. Electrodiagnostic testing can confirm the presence and severity of the injury, while ultrasound can provide additional anatomical information and direct visualization to confirm the continuity of the nerve and assess muscle denervation changes.

Case: An upper trunk brachial plexus injury patient underwent ulnar motor fascicular to biceps motor nerve transfer. At 6 months postoperative, the patient had trace biceps firing but was diagnosed with an unrecognized rupture of the distal biceps tendon, requiring reconstruction. Another patient with C5-T1 injury was noted to have distal biceps tendon rupture at the time of gracilis muscle transfer. Both patients had gravity-assisted elbow flexion at 1-year follow-up. Conclusion: Biceps rupture is an uncommon concomitant injury with brachial plexus trauma and challenging to diagnose in the context of a paretic limb. Thorough history and intraoperative biceps tendon palpation will ensure these injuries are identified.

BACKGROUND Lipomatosis of the nerve (LN) is a rare peripheral nerve pathology characterized by abundant proliferation of fat within the epineurium giving it pathognomonic features on MRI. Any nerve may be affected, but major nerves such as the median and sciatic nerves are most reported. One of the clinical hallmarks of LN is associated bony and soft tissue overgrowth occurring distal to the nerve lesion. While macrodactyly and limb length overgrowth are well known in LN, this study aims to look at nerve territory bony overgrowth affecting the knee. OBSERVATIONS An initial search revealed 59 cases of LN in the Mayo Clinic system. Of 19 patients with LN of the lower limbs, 12 cases involved nerves in the pelvis, buttock, or thigh. Three cases fulfilled the criteria (LN of lower extremity with available MR images and knee radiographs) that affected the femoral, sciatic, and combined femoral/sciatic nerves. Knee radiographs revealed bony overgrowth in the respective nerve territories in each case: anterior, posterior, and both anterior and posterior portions of the knee. LESSONS These illustrative cases of LN with overgrowth of the knee demonstrate that bone overgrowth follows the territory of the associated nerve in LN, which supports the previously published evidence on LN-associated nerve territory overgrowth. https://thejns.org/doi/10.3171/CASE25132

OBJECTIVE The formation and propagation of intraneural ganglion cysts (INGCs) is being elucidated by the unified articular theory. Its principles include a connection for joint fluid to egress from a synovial joint via an articular branch to a parent nerve and cyst following the path of least resistance, dependent on pressures and pressure fluxes. The occurrence of so-called extreme peroneal or tibial INGCs in the popliteal fossa extending to the sciatic nerve has been reported. One rarely described variant with a circumferential cyst within the subparaneurial compartment outside the epineurium of nerve(s) has been previously illustrated, but its mechanism and morphology have not been clarified. In this study, the authors aimed to investigate this type of cyst to challenge the principles of the unified articular theory. METHODS Four novel cases of patients with peroneal INGCs and "extreme subparaneurial cyst(s)" of the sciatic nerve and its distal branches were investigated: 3 arose from the superior tibiofibular joint (STFJ) and 1 from the knee joint. Three other cases of recognized extreme subparaneurial cyst (2 peroneal and 1 tibial from the STFJ) and 1 case of a peroneal subparaneurial cyst in the literature were reinterpreted. Data on clinical presentation, MR images, and surgical results were analyzed. RESULTS In all 8 cases, subparaneurial extension was observed to different degrees along the sciatic, tibial, common peroneal, sural, and deep and superficial peroneal nerves, as was subparaneurial-to-subparaneurial communication at the sciatic nerve bifurcation (i.e., crossover). Sequential MRI performed in 7 patients showed variable dynamic changes, including extreme ascent and descent. Extraneural rupture of the subparaneurial cyst, with spread into the surrounding tissue, was present at the sciatic nerve bifurcation in 6 cases. CONCLUSIONS The authors provide pathoanatomical and pathophysiological evidence supporting that extreme subparaneurial cysts follow the principles of the articular theory. They propose a distribution pattern that explains the occurrence and evolution of extreme subparaneurial cysts along the sciatic nerve and its distal branches in patients with peroneal or tibial INGCs and subepineurial cysts. Crossover in the subparaneurial compartment allows potentially extensive circumferential distribution within connected nerves. Also, dynamic factors can lead to dramatic changes in cyst size and appearance from reabsorption or extraneural rupture. In Part 2 of this study, the authors provide evidence showing that a fenestration in the epineurium allows cysts to pass from the subepineurial-to-subparaneurial, subparaneurial-to-subparaneurial, and subparaneurial-to-subepimyseal compartments.

OBJECTIVE Extreme subparaneurial ganglion cysts are poorly understood. In Part 1, the authors demonstrated that patterns of distribution in the subparaneurial space are consistent with the principles of the articular theory for intraneural ganglion cysts (INGCs). How a cyst transfers from the subepineurial to the subparaneurial compartment remains to be determined. In this part, the authors provide evidence supporting that cyst transfer occurs at the sciatic nerve bifurcation based on MRI and histological analysis, and introduce the geyser theory as an explanation for the redistribution of cysts. METHODS The authors analyze MR images obtained in patients with extreme subparaneurial cysts as well as newly identified cases of nearly extreme subparaneurial cysts (i.e., cysts visible in the subparaneurial compartment but not to the extreme degree as defined in Part 1) for potential crossover sites. They also analyze histological sections from 10 cadavers around the sciatic nerve bifurcation for the presence of openings in the epineurium and paraneurium. RESULTS MRI studies performed in 8 patients in Part 1 and 8 newly identified examples with nearly extreme subparaneurial INGCs showed evidence to support communication between different compartments at the sciatic nerve bifurcation (subepineurial-to-subparaneurial and subparaneurial-to-neighboring soft tissues). Openings in the epineurium of the common peroneal and tibial nerves at the sciatic nerve bifurcation were consistently found in all 10 cadaver specimens, as were openings in the paraneurium. CONCLUSIONS The authors expand on the evidence to support cyst redistribution at the sciatic nerve bifurcation for INGCs in the knee region. They put forth a logical explanation for the development of a spectrum of extreme INGCs (ranging from a faint amount of cyst around the epineurium [wedding ring sign] to extreme subparaneurial INGCs [owl eyes]) based on principles seen in a geyser. The authors believe that radiological occurrence of crossover can be explained by the presence of fenestrations in both the epineurium and paraneurium at the sciatic nerve bifurcation, allowing cyst crossover in two steps: from the subepineurial to the subparaneurial space ("cross") and between a shared subparaneurial space of different nerves ("over"). Finally, the frequent occurrence of extraneural rupture ("cross-out") is due to cyst transfer into the soft tissue compartment via an opening in the outermost circumneurial layer.

ABSTRACTPrimary lymphedema (i.e., a chronic condition characterized by the accumulation of protein‐rich fluid in the interstitial spaces due to impaired lymphatic drainage) and lipomatosis of nerve (LN) (i.e., a congenital lesion characterized by the presence of fat interspersed within nerve) can involve a significant overgrowth of the affected limb, but their pathophysiology and treatment are totally different. This report addresses the misdiagnosis of both entities. The purpose is to highlight how both entities can be differentiated through two case reports. The first patient, a 69‐year‐old man, presented in our lymphedema clinic with multiple debulking operations; he was diagnosed with right upper extremity lymphedema during childhood. The thumb, index, and middle fingers had previously been amputated due to sequelae from the bony overgrowth. MRI of the right upper extremity showed pathognomonic features of LN affecting the median nerve associated with soft tissue fatty overgrowth. He had a 3 months follow‐up for this condition in our institution during which his symptoms remained stable. The second patient, an 81‐year‐old man, presented in our lymphedema clinic. He carried a long time diagnosis of primary left lower extremity lymphedema and had been followed at our institution for more than 25 years. Physical examination revealed overgrowth (increased volume) affecting the entire leg and foot. MRI showed pathognomonic features of LN of the left sciatic nerve. No surgical interventions were performed. At the last follow‐up, his extremity showed slightly worsened diameter measurements. Based on our 2 cases presented and 2 additional cases identified in the literature, we believe that primary lymphedema and LN are two different entities that could be confused. Plastic surgeons treating patients with lymphedema should be aware of LN and rule out this condition clinically and with imaging (US or MRI).