Minimally Invasive Surgical Technique for the Management of Giant Dumbbell Spinal Schwannoma

Background Completely extradural spinal schwannomas have a unique morphology (dumbbell tumors) with an intra- and extraspinal component. When they compromise two contiguous vertebral bodies or have an extraspinal extension >2.5 cm, they are classified as giant spinal schwannomas. The aim of this study is to present our experience in the surgical management of completely extradural giant spinal schwannomas with a minimally invasive approach. Methods This study is a case series of patients treated at the Neurosurgery Department of the University Clinical and Provincial Hospital of Barcelona, Spain, between January 2016 and December 2019. Results Fifteen patients met the inclusion criteria, with thoracic and lumbar spines being the most frequent locations. All patients underwent surgical treatment, with a mini-open interlaminar and far-lateral technique. Total gross resection was accomplished in all patients and spine instrumentation was not necessary. Conclusions Microsurgery is the treatment of choice for spinal schwannomas, and gross total resection with low morbidity must be the surgical goal. Mini-open interlaminar and far-lateral access is a valid surgical option, with low morbidity in experienced hands, and there is no need for spinal instrumentation.

Concurrent and overlapping surgery: perspectives from surgeons on spinal posterior instrumented fusion for adolescent idiopathic scoliosis

Purpose The purpose of this study was to determine perspectives of surgeons regarding simultaneous surgery in patients undergoing posterior spine instrumentation and fusion (PSIF) for adolescent idiopathic scoliosis (AIS). Methods A survey was administered to orthopaedic trainees and faculty regarding simultaneous surgery for primary PSIF for AIS. A five-point Likert scale (1: ‘Strongly Disagree’ to 5: ‘Strongly Agree’) was used to assess agreement with statements about simultaneous surgery. We divided simultaneous surgery into concurrent, when critical portions of operations occur at the same time, and overlapping, when noncritical portions occur at the same time. Results The 72 respondents (78.3% of 92 surveyed) disagreed with concurrent surgery for ‘one of my patients’ (response mean 1.76 (sd 1.03)) but were more accepting of overlapping surgery (mean 3.94 (sd 0.99); p < 0.0001). The rating difference between concurrent and overlapping surgery was smaller for paediatric and spine surgeons (-1.25) than for residents or those who did not identify a subspecialty (-2.17; p = 0.0246) or other subspecialty surgeons (-2.57; p = 0.0026). Respondents were more likely to agree with explicit informed consent for concurrent surgery compared with overlapping (mean 4.32 (sd 0.91) versus 3.44 (sd 1.14); p < 0.001). Conclusion Orthopaedic surgeons disagreed with concurrent but were more accepting of overlapping surgery and anaesthesia for PSIF for AIS. Respondents were in greater agreement that patients should be explicitly informed of concurrence than of overlap. The surgical community’s evidence and position regarding simultaneous surgery, in particular overlapping, must be more effectively presented to the public in order to bridge the gap in perspectives. Level of Evidence IV

Assessment of conformity of actual thoraco-lumbar pedicle screw dimensions to manufacturers’ specifications

Although correct selection of pedicle screw dimensions is indispensable to achieving optimum results, manufacturer-specified or intended dimensions may differ from actual dimensions. Here we analyzed the reliability of specifications made by various manufacturers by comparing them to the actual lengths and diameters of pedicle screws in a standardized experimental setup. We analyzed the actual length and diameter of pedicle screws of five different manufacturers. Four different screw lengths and for each length two different diameters were measured. Measurements were performed with the pedicle screws attached to a rod, with the length determined from the bottom of the tulip to the tip of the screw and the diameters determined at the proximal and distal threads. Differences in length of > 1 mm were found between the manufacturers’ specifications and our actual measurements in 24 different pedicle screws. The highest deviation of the measured length from the manufacturers’ specification was 3.2 mm. The difference in length between the shortest and longest screw with identical specifications was 3.4 mm. The highest deviation of the measured proximal thread diameters and the manufacturer’s specifications was 0.5 mm. The diameter of the distal thread depends on the shape of the pedicle screw and hence varies between manufacturers in conical screws. We found clear differences in the length of pedicle screws with identical manufacturer specifications. Since differences between the actual dimensions and the dimensions indicated by the manufacturer may vary, this needs to be taken into account during the planning of spine instrumentation.

Long-segment posterior cervical decompression and fusion: does caudal level affect revision rate?

OBJECTIVE Posterior cervical decompression and fusion (PCDF) is a commonly performed procedure to address cervical myelopathy. A significant number of these patients require revision surgery for adjacent-segment disease (ASD) or pseudarthrosis. Currently, there is no consensus among spine surgeons on the inclusion of proximal thoracic spine instrumentation. This study investigates the benefits of thoracic extension in long-segment cervical fusions and the potential drawbacks. The authors compare outcomes in long-segment subaxial cervical fusion for degenerative cervical myelopathy with caudal vertebral levels of C6, C7, and T1. METHODS A retrospective analysis identified 369 patients who underwent PCDF. Patients were grouped by caudal fusion level. Reoperation rates for ASD and pseudarthrosis, infection, and blood loss were examined. Data were analyzed with chi-square, 1-way ANOVA, and logistic regression. RESULTS The total reoperation rate for symptomatic pseudarthrosis or ASD was 4.8%. Reoperation rates, although not significant, were lower in the C3–6 group (2.6%, vs 8.3% for C3–7 and 3.8% for C3–T1; p = 0.129). Similarly, rates of infection were lower in the shorter-segment fusion without achieving statistical significance (2.6% for C3–6, vs 5.6% for C3–7 and 5.5% for C3–T1; p = 0.573). The mean blood loss was documented as 104, 125, and 224 mL for groups 1, 2, and 3, respectively (p < 0.001). CONCLUSIONS Given the lack of statistical difference in reoperation rates for long-segment cervical fusions ending at C6, C7, or T1, shorter fusions in high-risk surgical candidates or elderly patients may be performed without higher rates of reoperation.

A 3D-Printed Model-Assisted Cervical Spine Instrumentation after Tumor Resection in a 4-Year-Old Child: A Case Report

<b><i>Introduction:</i></b> In the case of tumor resection in the upper cervical spine, a multilevel laminectomy with instrumented fixation is required to prevent kyphotic deformity and myelopathy. Nevertheless, instrumentation of the cervical spine in children under the age of 8 years is challenging due to anatomical considerations and unavailability of specific instrumentation. <b><i>Case Presentation:</i></b> We present a case of 3D-printed model-assisted cervical spine instrumentation in a 4-year-old child with post-laminectomy kyphotic decompensation of the cervical spine and spinal cord injury 1 year after medulloblastoma metastasis resection in the upper cervical spine. Due to unavailability of specific instrumentation, 3D virtual planning was used to assess and plan posterior cervical fixation. Fixation with 3.5 mm lateral mass and isthmic screws was suggested and the feasibility of fixation was confirmed “in vitro” in a 3D-printed model preoperatively to reduce the possibility of intraoperative implant-spine mismatch. Intraoperative conditions completely resembled the preoperative plan and 3.5 mm polyaxial screws were successfully used as planned. Postoperatively the child made a complete neurological recovery and 2 years after the instrumented fusion is still disease free with no signs of spinal decompensation. <b><i>Discussion/Conclusion:</i></b> Our case shows that posterior cervical fixation with the conventional screw-rod technique in a 4-year-old child is feasible, but we suggest that suitability and positioning of the chosen implants are preoperatively assessed in a printed 3D model. In addition, a printed 3D model offers the possibility to better visualize and sense spinal anatomy “in vivo,” thereby helping screw placement and reducing the chance for intraoperative complications, especially in the absence of intraoperative spinal navigation.