Spinner, Robert J.

Abstract Introduction: Sacral and presacral schwannomas are rare and account for a minority of spinal schwannomas. We aim to present our institution’s experience surgically treating sacral schwannomas over twenty-one years. Additionally, we assess the literature for surgical cases of sacral schwannomas to compare tumor characteristics and outcomes following resection.Methods: Data on demographics, presenting symptoms, lesion characteristics, surgical management, and outcomes were collected for 27 patients treated surgically for sacral or presacral schwannoma between 1997 and 2018 at all Mayo Clinic locations and compared to those of patients found in the literature. Results: We identified 31 studies in the literature containing 93 patients with sacral schwannoma treated surgically. Our patients and those in the literature experienced similar symptoms, with the most common symptom being pain and the least common being sexual dysfunction, and age at diagnosis. Most of our patients (59.3%) reported full recovery from preoperative symptoms, while a minority reported a partial recovery (33.3%) and no recovery (11.1%). A smaller percentage of patients found in the literature experienced full recovery (31.9%) and partial recovery (29.8%) but also no recovery (1.1%). Our patients experienced fewer complications (14.8% versus 25.5%).Conclusion: Outcomes of patients with sacral or presacral schwannomas vary based on patient demographics, tumor characteristics, symptoms, and surgical treatment. Among the range of symptoms experienced by these patients, the most common is pain. Prognosis improves and overall survival rate is high when the surgical approach towards sacral schwannomas is prepared and executed appropriately.

AbstractAlthough superior gluteal nerve (SGN) injury can have significant morbidity, to date, surgical strategies for its repair are scant in the literature. Specifically, neurotization options have not been explored. To address this deficiency in the literature, the current cadaveric feasibility study was performed. Via a transgluteal approach on 16 cadaveric sides, the proximal sciatic nerve and the entrance of the SGN into the gluteus medius and minimus were identified. Additionally, branches from the sciatic nerve to the hamstring muscles were traced proximally to confirm their position in relation to the sciatic nerve as a whole. These branches were cut at the level of the ischial tuberosity and teased away from the sciatic nerve proximally to the greater sciatic foramen and transferred superolateral to the SGN. The diameter of each nerve branch was measured as well as its available length for reaching the SGN. All branches of the sciatic nerve to the hamstring muscles arose from the anteromedial part of the nerve. The mean diameters of the branches to the semimembranosus, semitendinosus, and biceps femoris muscles were 2.1, 1.9, and 1.5 mm, respectively. The mean diameter of the SGN was 3.1 mm and the mean distance from this entrance point to the ischial spine was 7.2 cm. The mean length of the donor nerve was 8.5 cm. Based on our study, use of a tibial‐innervated hamstring branch as a donor for nerve transfer to the SGN is feasible.

Abstract BACKGROUND Malignant peripheral nerve sheath tumors (MPNST) are rare tumors found throughout the body, with their clinical course in children still to be completely understood. Correspondingly, this study aimed to determine survival outcomes and specific clinical predictors of survival in this demographic from a large national database. METHODS All MPNST patients aged ≤18 year in the U.S. National Cancer Database (NCDB) between 2005-2016 were retrospectively reviewed. Data were summarized and overall survival (OS) was modeled using Kaplan-Meier and Cox regression analyses. RESULTS A total of 251 pediatric MPNST cases were identified. Overall, mean age at diagnosis was 13.1 years (range, 1-18) with there being 132 (53%) females and 119 (47%) males. There were 84 (33%) MPNSTs located in extremities, 127 (51%) less than 1cm in size, and 22 (9%) have metastasis at diagnosis. In terms of treatment, surgery was pursued in 187 (74%) patients, chemotherapy in 116 (46%) patients, and radiation therapy in 129 (61%) patients. Five-year overall survival was estimated to be 52% (95% CI, 45-59%), and with median survival of 64 months (range, 36-136). Multivariate regression revealed older age (HR 1.10, P< 0.01), with metastases at time of diagnosis (HR 2.14, P=0.01), and biopsy only (HR 2.98, P< 0.01) all significantly and independently predicted shorter overall survival. Chemotherapy and radiation therapy were not statistically significant. CONCLUSIONS Pediatric MPNSTs are rare malignant entities, and only approximately half of patients will survive to five years. There remains a clear survival benefit in pursuing maximal safe resection in these patients. As such, judicious workup with meticulous surgical resection by an expert team should then be considered the standard of care for these tumors in children.

OBJECTIVE Neurolymphomatosis (NL) is a rare manifestation of lymphoma confined to the peripheral nervous system that is poorly understood. It can be found in the cauda equina, but extraspinal disease can be underappreciated. The authors describe how extraspinal NL progresses to the cauda equina by perineural spread and the implications of this on timely and safe diagnostic options. METHODS The authors used the Mayo Clinic medical records database to find cases of cauda equina NL with sufficient imaging to characterize the lumbosacral plexus diagnosed from tissue biopsy. Demographics (sex, age), clinical data (initial symptoms, cerebrospinal fluid, evidence of CNS involvement, biopsy location, primary or secondary disease), and imaging findings were reviewed. RESULTS Ten patients met inclusion and exclusion criteria, and only 2 of 10 patients presented with cauda equina symptoms at the time of biopsy, with 1 patient undergoing a cauda equina biopsy. Eight patients were diagnosed with diffuse large B-cell lymphoma, 1 with low-grade B-cell lymphoma, and 1 with mantle cell lymphoma. Isolated spinal nerve involvement was identified in 5 of 10 cases, providing compelling evidence regarding the pathophysiology of NL. The conus medullaris was not radiologically involved in any case. Lumbosacral plexus MRI was able to identify extraspinal disease and offered diagnostically useful biopsy targets. FDG PET/CT was relatively insensitive for detecting disease in the cauda equina but was helpful in identifying extraspinal NL. CONCLUSIONS The authors propose that perineural spread of extraspinal NL to infiltrate the cauda equina occurs in two phases. 1) There is proximal and distal spread along a peripheral nerve, with eventual spread to anatomically connected nerves via junction and branch points. 2) The tumor cells enter the spinal canal through corresponding neural foramina and propagate along the spinal nerves composing the cauda equina. To diffusely infiltrate the cauda equina, a third phase occurs in which tumor cells can spread circumdurally to the opposite side of the spinal canal and enter contralateral nerve roots extending proximally and distally. This spread of disease can lead to diffuse bilateral spinal nerve disease without diffuse leptomeningeal spread. Recognition of this phasic mechanism can lead to identification of safer extraspinal biopsy targets that could allow for greater functional recovery after appropriate treatment.

BACKGROUND: Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive soft tissue sarcomas. Their resection may lead to serious morbidity. Incidence of postoperative motor and sensory deficits is unknown, and reconstruction aimed at restoring such deficits is infrequently carried out. OBJECTIVE: To identify the incidence and risk factors of postoperative morbidity in MPNST as well as the use and outcomes of functional reconstructions in these patients. METHODS: Postoperative function and treatment of MPNSTs diagnosed from 1988 to 2019 in 10 cancer centers was obtained. Two models were constructed evaluating factors independently associated with postoperative motor (<M3) or critical sensory loss. Critical sensation was defined as partial or complete loss of hand, foot, or buttocks sensation. RESULTS: A total of 756 patients (33.4% neurofibromatosis type 1, NF1) were included. MPNSTs originated in 34.4% from a major nerve. Of 658 surgically treated patients, 27.2% had <M3 muscle power and 24.3% critical sensory loss. Amputations were carried out in 61 patients. Independent risk factors for motor and sensory loss included patients with NF1, symptomatic, deep-seated, extremity, or plexus tumors originating from major nerves (all P < .05). A total of 26 patients underwent functional reconstructions. The majority (64%) of these patients regained at least M3 muscle power and 33% M4 despite 86% receiving multimodal therapy. CONCLUSION: Resection of MPNSTs commonly results in motor and sensory deficits. Patients with NF1, symptomatic, deep-seated tumors, arising from major nerves were associated with a higher risk for developing postoperative morbidity. Functional reconstructions are infrequently performed but can improve functional outcomes.