Remnant Tumor Margin as Predictive Factor for Its Growth After Incomplete Resection of Cervical Dumbbell-Shaped Schwannomas

Clinical Implications of Surgical Resection without Spinal Fixation in Lumbar Dumbbell Tumors: Evaluating Postoperative Lumbar Alignment and Patient Outcomes

OBJECTIVE

This study examined radiographic changes in local and global spinal alignments and clinical outcomes following tumor resection without spinal fixation in patients with lumbar dumbbell tumors (LDTs).

METHODS

We included 28 patients with LDTs who were followed for at least 2 years after surgery. We analyzed variations in the outcome variables by measuring individual coronal and sagittal parameters from radiographs. Clinical outcomes were assessed using the modified McCormick scale, the Japanese Orthopedic Association score, and the visual analog scale. To evaluate the impact of tumor location on these outcomes, we categorized the patients into 3 groups based on tumor location: upper (T12-L1), middle (L2-3), or lower (L4-S1) group.

RESULTS

The local and global spinal parameters (including Cobb angle, cervical lordosis, T1 slope, thoracic kyphosis, thoracolumbar kyphosis, lumbar lordosis [global, upper, middle, lower], sacral slope, pelvic incidence, and pelvic tilt) did not show significant changes after surgery. Preoperatively, all patients experienced gait disturbances, but at the final follow-up, nearly all of them (27 cases, 96.4%) could walk without support. The Japanese Orthopedic Association score and visual analog scale demonstrated significant postoperative improvements. There were no statistically significant group differences in postoperative coronal and sagittal profiles or clinical outcomes among the upper, middle, and lower groups.

CONCLUSIONS

Tumor resection without spinal fixation had no substantial impact on local and global spinal alignments and led to satisfactory clinical outcomes, suggesting that spinal fixation may not always be necessary when resecting LDTs.

Resection of Cervical Dumbbell-Shaped Schwannoma Using Posterior Unilateral Approach: Impact on Postoperative Cervical Function and Clinical Outcomes

STUDY DESIGN

A retrospective comparative study.

OBJECTIVES

This study aimed to evaluate the radiographical changes in cervical sagittal alignment (CSA) and clinical outcomes after tumor resection using a posterior unilateral approach without spinal fixation for patients with cervical dumbbell-shaped schwannoma (DS).

METHODS

Seventy-three patients with DS who were followed up for at least 2 years were included. The Eden classification was used to designate the types of DS. The CSA and range of motion (ROM) were analyzed using radiographs. The clinical outcomes were assessed using the Japanese Orthopaedic Association (JOA) score and JOA cervical myelopathy questionnaire.

RESULTS

The CSA in the neutral, flexion, and extension position and cervical ROM were not significantly reduced in the follow-up period. The JOA scores showed significant improvement after surgery. The postoperative radiographic parameters and clinical outcomes of Eden type II or III DS, which needed facetectomy for the resection, did not show any statistically significant difference compared with those of Eden type I tumor, which was resected without facetectomy. Fifty-two cases (71.2%) achieved gross total resection, whereas 21 cases (28.8%) remained in partial resection (PR). One case underwent reoperation due to the regrowth of the remnant tumor whose margin was at the entrance of the intervertebral foramen.

CONCLUSIONS

Tumor resection using the posterior unilateral approach preserved CSA and resulted in favorable clinical outcomes in patients with DS. When the resection ends in PR, the proximal margin of the remnant tumor should be located distally away from the entrance of the foramen to prevent regrowth.

A Complete Facet Resection and Cervical Pedicle Screw Placement Enhances Both Gross Total Resection and Motion Preservation for the Cervical Spinal Dumbbell Tumor

OBJECTIVE

To describe single-index-level fusion surgery using a cervical pedicle screw (CPS) after the complete facet resection of spinal dumbbell tumors and to compare it with partial facet resection without fusion.

METHODS

We retrospectively reviewed patients who underwent surgery for dumbbell-shaped cervical spine tumors. They were categorized into the fused group (complete facet resection with fusion using CPS) and the unfused group (partial facet resection without fusion). We compared demographics, tumor characteristics, resection rates (gross total, subtotal, or partial), and regrowth rates between the groups. Complete facet resection was performed for maximal tumor removal. In the fused group, single-index-level fusion was achieved using CPS. Despite tumor-associated erosion of the index vertebra's pedicle and/or lateral mass, the CPS was directly inserted into the vertebral body through an imaginary virtual pedicle without a lateral mass or pedicle purchase.

RESULTS

A total of 34 patients underwent surgery for dumbbell-shaped cervical tumors; half were classified into each group. There were no significant differences in demographic or tumor characteristics, including Asazuma classification, or histological diagnosis (P > 0.05). However, the gross total resection rate was significantly higher in the fused group (16/17, 94.1% vs. 9/17, 52.9%; P value = 0.011). Tumor recurrence was observed in 3 (17.6%) patients in the unfused group; no recurrence (0%) occurred in the fused group.

CONCLUSIONS

Complete facet resection with fusion using CPS significantly increased the gross total tumor removal rate, compared with partial resection without fusion. Therefore, CPS improved fusion surgery for maximal motion preservation, resulting in single-level fusion surgery.

A Novel and Reproducible Classification of Cervical Dumbbell Tumors to Inform Surgical Approach and Reconstruction Techniques

STUDY DESIGN

A retrospective case series.

OBJECTIVE

This study developed a novel classification system based on imaging and anatomy to select optimal surgical approaches and reconstruction strategies to achieve total resection of cervical dumbbell tumors and restore spinal stability.

SUMMARY OF BACKGROUND DATA

Total resection is necessary to decrease the recurrence rate of cervical dumbbell tumors. Previous cervical dumbbell tumor classifications are insufficient for determining surgical strategies; therefore, a practical classification is needed.

MATERIALS AND METHODS

This study included 295 consecutive patients with cervical dumbbell tumors who underwent total surgical resection. A novel classification of cervical dumbbell tumors was developed based on magnetic resonance imaging and computed tomography. Continuous variables were expressed as mean±SD and were compared using an unpaired two-tailed Student t test. The χ 2 test or the Fisher exact test was used for categorical variables. Kendall's W test assessed three independent raters' inter-rater and intrarater reliabilities on 140 cervical dumbbell tumors.

RESULTS

The inter-rater and intrarater consistency coefficient was 0.969 (χ 2 =404.3, P <0.001) and 0.984 (χ 2 =273.7, P <0.001). All patients with type I and II tumors underwent single-posterior surgeries to achieve total resection. Of the patients in this study, 86.1%, 25.9%, 75.9%, and 76.9% underwent posterior surgeries for types IIIa, IIIb, IVa, and V tumors, respectively. All patients with type IVb tumors underwent a combined anterior and posterior approach. Posterior internal fixation was used for all patients in posterior surgery. Anterior reconstruction was applied for patients with type IVb tumors (20/20, 100%) and some with type V tumors (3/13, 23.1%). The mean follow-up duration was 93.6±2.6 months. A recurrence was observed in 19 (6.4%) patients.

CONCLUSION

The authors describe a novel classification system that is of practical use for planning the complete resection of cervical dumbbell tumors.

Quantitative Analysis of the Effect of Stereotactic Radiosurgery for Postoperative Residual Cervical Dumbbell Tumors: A Multicenter Retrospective Cohort Study

OBJECTIVE

Stereotactic radiosurgery (SRS) has been performed for spinal tumors. However, the quantitative effect of SRS on postoperative residual cervical dumbbell tumors remains unknown. This study aimed to quantitatively evaluate the efficacy of SRS for treating postoperative residual cervical dumbbell tumors.

METHODS

We retrospectively reviewed cases of postoperative residual cervical dumbbell tumors from 1995 to 2020 in 2 tertiary institutions. Residual tumors underwent SRS (SRS group) or were observed with clinical and magnetic resonance imaging (MRI) follow-up (observation group). Tumor regrowth rates were compared between the SRS and observation groups. Additionally, risk factors for tumor regrowth were analyzed.

RESULTS

A total of 28 cervical dumbbell tumors were incompletely resected. Eight patients were in the SRS group, and 20 in the observation group. The mean regrowth rate was not significantly lower (p = 0.784) in the SRS group (0.18 ± 0.29 mm/mo) than in the observation group (0.33 ± 0.40 mm/mo). In the multivariable Cox regression analysis, SRS was not a significant variable (hazard ratio [HR], 0.57; 95% confidence interval [CI], 0.18-1.79; p = 0.336).

CONCLUSION

SRS did not significantly decrease the tumor regrowth rate in our study. We believe that achieving maximal resection during the initial operation is more important than postoperative adjuvant SRS.

Review of Cervical Schwannomas: Presentation, Pathogenesis, Management, Complications and Future Directions

Cervical schwannomas are benign peripheral nerve sheath tumors, relatively uncommon pathologies. The purpose of this review is to summarize and expand on the existing literature on cervical schwannomas, focusing on clinical presentation, pathogenesis, surgical and radiologic management and innovative therapies including ultrasound-guided techniques. Pubmed and SCOPUS databases were searched using combinations of terms including "cervical schwannoma", "surgery", "fusion", "complications", "radiosurgery", and others. The findings regarding these unique clinical entities are presented below.