FET PET provides adjunctive value to FDG PET in distinction of spinal cord tumors.

Objective: This study aimed to compare the diagnostic efficacy of O-(2-18F-fluoroethyl)-l-tyrosine (18F-FET) PET and 2-deoxy-2-[18F]fluoro-d-deoxyglucose (18F-FDG) PET for spinal cord lesions. Materials and methods: Paired preoperative 18F-FDG PET/MRI and 18F-FET PET/MRI scans were conducted on patients with suspected spinal cord tumors. Clinical manifestations and PET performance, including SUVmean, SUVmax, TBRmean, TBRmax, metabolic tumor volume (MTV), and total lesion metabolism (TLM), and tumor volume, were compared using group analysis and receiver operating characteristic (ROC) curves. Results: Thirty-five patients were categorized into three groups based on their pathological diagnosis: high-grade tumors (HGTs, n = 6), low-grade tumors (LGTs, n = 19), and non-tumor diseases (NTDs, n = 10). The background SUVmean of 18F-FET PET was significantly lower than that of 18F-FDG PET (p < 0.0001), while the delineated tumor volumes showed no significant difference (p > 0.05). The mass SUVmean, SUVmax, MTV, and TLM values of both 18F-FDG PET and 18F-FET PET were statistically different between HGTs and LGTs (p < 0.05). Similarly, the mass SUVmax, TBRmax, MTV, and TLM values of both 18F-FDG PET and 18F-FET PET, as well as the mass SUVmean of 18F-FET PET, exhibited statistical differences between HGTs and NTDs (p < 0.05). But none were able to distinguish LGTs and NTDs (p > 0.05). Notably, 18F-FET PET provided valuable supporting diagnostic evidence in 1 case of mixed neuronal-glial tumor (MNGT) and 2 cases of intramedullary inflammatory lesions. Optimal cut-off values of all measured parameters for distinguishing tumors and NTDs were determined through ROC analysis. Conclusion: 18F-FET PET presented comparable diagnostic performance to 18F-FDG PET in differentiating HGTs, LGTs, and NTDs, but exhibited particular utility in MNGT and inflammatory lesions.

Spinal neurenteric cysts: experience with 9 cases via an anterior cervical approach.

OBJECTIVE: Intraspinal cysts are uncommon, and the success rate of complete resection is still low for spinal neurenteric cysts (NCs). The aim of this study was to evaluate the efficacies of an anterior microscopic surgical approach in the treatment of ventral and ventrolateral subaxial cervical NCs (SCNCs). METHODS: Between 2019 and 2022, 9 patients with NCs of the subaxial spine underwent an anterior microsurgical approach. Their clinical presentations, radiological features, operative findings, and follow-up data were retrospectively reviewed and analyzed. RESULTS: All spinal cysts were intradural and extramedullary in origin. Five patients were first-time cases while 4 patients with recurrence underwent revision surgery. The most common clinical manifestation was pain (77.78%). One patient was found to have a concomitant disorder of Klippel-Feil syndrome. Microscopically confirmed gross-total resection was achieved in 8 patients (88.89%) based on clinical comparisons between pre- and postoperative MRI and intraoperative video. One patient had symptom recurrence 1 year after subtotal resection, while there was no evidence of recurrence during follow-up for the other patients. Dense adhesions within the spinal cord were observed in 8 patients (88.89%) intraoperatively. Most importantly, the surgical outcome was significantly improved in all patients, and the mean (± SE) Japanese Orthopaedic Association score increased from 11.33 ± 0.91 preoperatively to 16.22 ± 0.32 postoperatively (p = 0.008). CONCLUSIONS: An anterior surgical approach was proven to be both safe and effective in treating the ventral or ventrolateral SCNCs. The authors believe that an anterior microsurgical approach should be considered as a useful approach especially in patients with ventral recurrent SCNCs. Its clinical efficacy compared with a posterior approach in ventral spinal cyst may be better as most of the neurenteric cysts are ventrally or ventrolaterally located.

A novel computed tomography scoring system for evaluating the risk of dural defects in anterior surgery for cervical ossification of the posterior longitudinal ligament.

OBJECTIVE: To develop and validate a computed tomography (CT)-based scoring system for evaluating the risk of dural defects (DDs) in anterior surgery for cervical ossification of the posterior longitudinal ligament (OPLL). METHODS: We retrospectively analyzed CT imaging features of 114 OPLL patients in our institute who received anterior decompression surgery. Intraoperative DDs were found in 16 patients. A multivariable logistic regression was used to evaluate the predictors. According to the odd ratio of the included risk factors, we developed a CT scoring system for evaluating the risk of DDs in anterior OPLL surgery. The system was further validated in an independent group of 39 OPLL patients. RESULTS: We developed a CT scoring system as follows: hook sign (2 points), K-line (-) (1 point) and broad base (1 point). Thus, the system comprised 4 total points, and patients were at high risks of dural defects when the score ≥3 points. The operating characteristics of a score ≥3 for predicting DDs in the validation group were: sensitivity of 0.83, specificity of 0.94, LR positive of 13.75, LR negative of 0.18 and AUC of 0.886. The discriminatory ability of the proposed score could be demonstrated in the validation cohort. CONCLUSIONS: The relatively simple and easy-to-use scoring system we propose integrates the 3 most reliable spinal CT findings observed in patients with OPLL and a DD. The likelihood to identify the underlying risks of spinal CSF leaks may be useful to triage patients who may benefit from indirect decompression techniques.

Single-cell sequencing reveals VEGFR as a potential target for CAR-T cell therapy in chordoma.

BACKGROUND: Chordomas are rare osseous neoplasms with a dismal prognosis when they recur. Here we identified cell surface proteins that could potentially serve as novel immunotherapeutic targets in patients with chordoma. METHODS: Fourteen chordoma samples from patients attending Xuanwu Hospital Capital Medical University were subjected to single-cell RNA sequencing. Target molecules were identified on chordoma cells and cancer metastasis-related signalling pathways characterised. VEGFR-targeting CAR-T cells and VEGFR CAR-T cells with an additional TGF-ß scFv were synthesised and their in vitro antitumor activities were evaluated, including in a primary chordoma organoid model. RESULTS: Single-cell transcriptome sequencing identified the chordoma-specific antigen VEGFR and TGF-ß as therapeutic targets. VRGFR CAR-T cells and VEGFR/TGF-ß scFv CAR-T cells recognised antigen-positive cells and exhibited significant antitumor effects through CAR-T cell activation and cytokine secretion. Furthermore, VEGFR/TGF-ß scFv CAR-T cells showed enhanced and sustained cytotoxicity of chordoma cell lines in vitro compared with VRGFR CAR-T cells. CONCLUSIONS: This study provides a comprehensive single-cell landscape of human chordoma and highlights its heterogeneity and the role played by TGF-ß in chordoma progression. Our findings substantiate the potential of VEGFR as a target for CAR-T cell therapies in chordoma which, together with modulated TGF-ß signalling, may augment the efficacy of CAR-T cells.

Posterior intra-articular distraction technique to treat pediatric atlantoaxial instability.

PURPOSE: Surgical treatment for atlantoaxial instability in pediatric patients is challenging. We report our experience with posterior intra-articular distraction technique in treating this disorder. METHODS: This is a retrospective descriptive study which included 15 patients of atlantoaxial instability whose age was less than 16 years at the time of clinical presentation. All patients underwent anterior soft tissue released through a posterior-only approach, followed by intra-facet cage implantation, cantilever correction, and instrumentation. Clinical results were measured using the Japanese Orthopedic Association (JOA) scale and radiographic measurements including the atlantodental interval (ADI), posterior atlantodental interval (pADI), the distance of odontoid tip above Chamberlain's line, clivuscanal angle (CCA), and triangular area (TA) of craniovertebral junction. RESULTS: The follow-up period ranged from 18 to 72 months, with an average of 41.2 ± 15.2 months. The JOA score increased from 13.6 ± 2.3 to 16.6 ± 0.8. ADI decreased from 4.31 ± 2.37 to 1.85 ± 1.09 mm, and TA decreased from 261.96 ± 107.99 to 197.12 ± 72.37 mm2. pADI increased from 12.89 ± 3.52 to 18.25 ± 3.89 mm, and CCA improved from 132.19 ± 16.34 to 144.35 ± 13.91°. All changes in measurements showed statistically significant. There were no evidence of surgery-related complications or iatrogenic secondary cervical deformity during follow-up. Radiological evaluation showed satisfactory corrections and bony fusions of C1-2 facet joint in all cases. CONCLUSION: Posterior intra-articular distraction followed by cage implantation and cantilever correction can be one of the safe and effective ways to solve atlantoaxial instability in pediatric patients.

Role of Preoperative Albumin Quotient in Surgical Planning for Posttraumatic Syringomyelia: A Comparative Cohort Study.

OBJECTIVE: Surgical procedures for patients with posttraumatic syringomyelia (PTS) remain controversial. Until now, there have been no effective quantitative evaluation methods to assist in selecting appropriate surgical plans before surgery. METHODS: We consecutively enrolled PTS patients (arachnoid lysis group, n = 42; shunting group, n = 14) from 2003 to 2023. Additionally, 19 intrathecal anesthesia patients were included in the control group. All patients with PTS underwent physical and neurological examinations and spinal magnetic resonance imaging preoperatively, 3-12 months postoperatively and during the last follow-up. Preoperative lumbar puncture was performed and blood-spinal cord barrier disruption was detected by quotient of albumin (Qalb, cerebrospinal fluid/serum). RESULTS: The ages (p = 0.324) and sex (p = 0.065) of the PTS and control groups did not differ significantly. There were also no significant differences in age (p = 0.216), routine blood data and prognosis (p = 0.399) between the arachnoid lysis and shunting groups. But the QAlb level of PTS patients was significantly higher than that of the control group (p < 0.001), and the shunting group had a significantly higher QAlb (p < 0.001) than the arachnoid lysis group. A high preoperative QAlb (odds ratio, 1.091; 95% confidence interval, 1.004-1.187; p = 0.041) was identified as the predictive factor for the shunting procedure, with the receiver operating characteristic curve showing 100% specificity and 80.95% sensitivity for patients with a QAlb > 12.67. CONCLUSION: Preoperative QAlb is a significant predictive factor for the types of surgery. For PTS patients with a QAlb > 12.67, shunting represents the final recourse, necessitating the exploration and development of novel treatments for these patients.

Long-Term Impairment of the Blood-Spinal Cord Barrier in Patients With Post-Traumatic Syringomyelia and its Effect on Prognosis.

STUDY DESIGN: Cohort study. OBJECTIVE: The aim of this study was to explore the association between blood-spinal cord barrier (BSCB) markers and other factors associated with an unfavorable outcome among patients with post-traumatic syringomyelia (PTS) who achieved successful intradural adhesion lysis (IAL). SUMMARY OF BACKGROUND DATA: Only approximately half of PTS patients receiving IAL have a favorable outcome. PATIENTS AND METHODS: Forty-six consecutive patients with PTS and 19 controls (CTRL) were enrolled. All PTS patients underwent physical and neurological examinations and spinal magnetic resonance imaging before and 3 to 12 months after IAL. All patients underwent myelography before surgery. BSCB disruption was detected by increased intrathecal and serum concentrations of albumin, immunoglobulin (Ig)G, IgA, and IgM. A multivariable analysis was performed with a logistic regression model to identify factors associated with unfavorable outcomes. Receiver operating characteristic curves were calculated to investigate the diagnostic value of biomarkers. RESULTS: The ages and general health of the PTS and CTRL groups did not differ significantly. QAlb, IGAQ, IGGQ, and IGMQ was significantly higher in PTS patients than in controls ( P =<0.001). The degree of intradural adhesion was significantly higher in the unfavorable outcome group than in the favorable outcome group ( P <0.0001). QAlb, immunoglobulin (Ig)AQ, IGGQ, and IGMQ was significantly correlated with clinical status ( R =-0.38, P <0.01; R =-0.47, P =0.03; R =-0.56, P =0.01; R =-0.43, P =0.05, respectively). Higher QAlb before surgery (odds ratio=2.66; 95% CI: 1.134-6.248) was significantly associated with an unfavorable outcome. The receiver operating characteristic curve analysis demonstrated a cutoff for QAlb higher than 10.62 with a specificity of 100% and sensitivity of 96.3%. CONCLUSION: This study is the first to detect increased permeability and BSCB disruption in PTS patients. QAlb>10.62 was significantly associated with unfavorable clinical outcomes following intradural decompression. LEVEL OF EVIDENCE: Level III-prognostic.

A novel scoring system for assessing adult syringomyelia associated with CM I treatment outcomes.

BACKGROUND: A specific scoring system for syringomyelia is lacking. Our objective was to investigate the value of a novel scoring system (Syringomyelia Outcome Scale of Xuanwu hospital, SOS-XW) in assessing surgical outcomes in the treatment of syringomyelia (SM) associated with Chiari malformation type I (CM I). METHODS: A quantitative evaluation system (SOS-XW) of SM includes 4 parameters: pain (P), sensation (S), movement (M), and syringomyelia tension index (STI). The clinical data of 88 patients with CM I-related syringomyelia treated by foramen magnum and Magendie dredging (FMMD) from January 2018 to January 2019 were retrospectively analysed with a mean follow-up of 14.3 months, and the SOS-XW score was used to assess the efficacy. RESULTS: The higher the SOS-XW score, the more severe was the SM and related symptoms. The mean preoperative score was 5.97, and the postoperative score was 2.66. The symptom improvement rates were 77.78% for P, 69.01% for S, 31.82% for M, and 95.06% for the syringomyelia tension index (STI). The symptom improvement rate of the PSM score was weakly correlated with the improvement rate of STI, R2 = 0.0016. The percentage of PSM (P + S + M) improvement was lower in patients with an STI of 0. The postoperative SOS-XW score was positively correlated with the postoperative JOA score, R2 = 0.8314. The positive detection rate of SOS-XW was higher than that of the JOA score. CONCLUSIONS: To evaluate the surgical procedure efficacy in the treatment of syringomyelia, the SOS-XW score can provide a more objective, detailed, and comprehensive analysis, especially STI. A reduction in STI is the practical standard for assessing the effectiveness of surgery.

Correlation Among Syrinx Resolution, Cervical Sagittal Realignment, and Surgical Outcome After Posterior Reduction for Basilar Invagination, Atlantoaxial Dislocation, and Syringomyelia.

BACKGROUND: The correlation among syrinx resolution, occipitoaxial sagittal alignment, and surgical outcome in long-term follow-up seems to have not been clarified. OBJECTIVE: To further explore the relationship between the syrinx resolution and occipitoaxial realignment after posterior reduction and fixation in basilar invagination (BI)-atlantoaxial dislocation (AAD) patients with syringomyelia. METHODS: A continuous series of 32 patients with BI-AAD and syringomyelia who received direct posterior reduction met the inclusion criteria of this study. Their clinical and imaging data were analyzed retrospectively. Before surgery and at the last follow-up, we used the Japanese Orthopedic Association (JOA) score and the Neck Disability Index (NDI) to assess the neurological status, respectively. The Pearson correlation coefficient and multiple stepwise regression analysis were used to explore the relevant factors that may affect surgical outcomes. RESULTS: There were significant differences in atlantodental interval, clivus-axial angle, occiput-C2 angle (Oc-C2A), cervicomedullary angle (CMA), subarachnoid space (SAS) at the foramen magnum (FM), syrinx size, NDI, and JOA score after surgery compared with those before surgery. ΔCMA and the resolution rate of syrinx/cord as relevant factors were correlated with the recovery rate of JOA (R 2 = 0.578, P < .001) and NDI (R 2 = 0.369, P < .01). What's more, ΔSAS/FMD (SAS/FM diameter) and ΔOc-C2A were positively correlated with the resolution rate of syrinx/cord (R 2 = 0.643, P < .001). CONCLUSION: With medulla decompression and occipital-cervical sagittal realignment after posterior reduction and fusion for BI-AAD patients with syringomyelia, the structural remodeling of the craniovertebral junction and occipitoaxial realignment could contribute to syringomyelia resolution.

Comparison of 3D-printed Navigation Template-assisted Pedicle Screws versus Freehand Screws for Scoliosis in Children and Adolescents: A Systematic Review and Meta-analysis.

BACKGROUND: There is a lack of attention to screw placement techniques for surgical treatment of scoliosis in children and adolescents. This meta-analysis aims to compare the accuracy and safety of pedicle screw placement between the 3D-printed navigation template technique and the freehand technique during corrective surgery for scoliosis in children and adolescents. METHODS: A comprehensive search was conducted for relevant articles up to December 2021 in databases including PubMed, Embase, MEDLINE, Cochrane, and Web of Science. The systematic meta-analysis compared the efficacy of pedicle screw placement between the two techniques, including accuracy of pedicle screw placement, complication rate, operation time, blood loss, mean placement time per screw, and mean times for fluoroscopy. RESULTS: The seven articles analyzed in this study involved 229 patients altogether. A total of 2,805 pedicle screws were placed by the two methods. Our results revealed that the 3D-printed guide template technique was more accurate than the freehand technique in pedicle screw placement (odds ratio [OR] =2.96; 95% confidence interval [CI]: 2.24-3.91; p < 0.000) with a lower complication rate (OR = 0.21; 95% CI: 0.06-0.78; p = 0.02). The operation time (mean difference [MD] = -34.37; 95% CI: -67.47 to -1.28; p = 0.04) and mean placement time per screw (MD = -3.11; 95% CI: -6.13 to -0.09; p = 0.04) and mean times for fluoroscopy (MD = -6.60; 95% CI: -8.66 to -4.55; p < 0.000) significantly decreased among patients in the 3D-printed navigation template group compared with those in the freehand technique group. In addition, the two techniques had no significant statistical difference in blood loss. CONCLUSIONS: Compared with the traditional freehand technique, the 3D-printed guide template is a promising technique with higher accuracy and safety in screw placement for surgical treatment of scoliosis in children and adolescents, and is worth popularizing and validating through more prospective clinical studies.

Neurological deterioration after posterior fossa decompression for adult syringomyelia: Proposal for a summarized treatment algorithm.

Background: Patients with syringomyelia who present with new neurological symptoms after posterior fossa decompression (PFD) are not uncommon. However, systematic reports on different pathologies are few in the literature. Objective: The purpose of this study was to summarize our experience for failed PFD. Methods: Between January 2015 and December 2019, 85 consecutive failed PFD patients were identified. The neurological courses were summarized with Klekamp J (KJ) or mJOA score system for all patients. Long-term results were summarized with Kaplan-Meier method. Results: Twenty-eight consecutive patients underwent FMDD (Foramen magnum and foramen of Magendie dredging) (Group I), extradural PFD and manipulation of tonsil was significantly associated with lower failure rates. Twenty patients underwent craniocervical fixation (Group II), nine underwent local spinal segment decompression (Group III), six underwent CSF diversion procedures, and one were treated for persistent pain by radiofrequency. Neuropathic pain was most significantly improved in Group I while swallowing improved in Group II within 1 year after the surgery. In the long term, late postoperative deterioration-free possibility in Group II was better than in Group I. All patients in Group III improved (P = 0.0088). Six cases of CSF diversion procedures were relieved in a short time. Pain in one patient persisted after PFD, and trial of radiofrequency failed. Conclusion: Not only does the recurrent cerebrospinal fluid flow obstruct the foramen magnum, but also spinal pathologies and craniocervical instabilities may occur. This study provides the largest summarized clinical experience that may assist surgeons with different therapeutic decisions for failed PFD.

Dural ossification associated with ossification of posterior longitudinal ligament in the cervical spine: a retrospective analysis.

OBJECTIVE: Dural ossification (DO) is common in patients with ossification of the posterior longitudinal ligament (OPLL). The existence of DO makes surgery challenging and increases the risk of complications. The aim of this study was to investigate the incidence, distribution and radiological characteristics of DO associated with OPLL. METHODS: From January 2017 to January 2019, 55 patients with cervical OPLL were treated in our single center using an anterior cervical approach microsurgery. Preoperative CT images of decompressed segments were evaluated to identify imaging signs of DO. The 'double-layer sign' (DLS), 'parenthese sign' (PS) and 'hook sign' (HS) were considered to be characteristic imaging findings of DO in OPLL. Two kinds of confusing signs (false double-layer) were identified. RESULTS: Nineteen segments from 15 patients with OPLL had DO related to OPLL. The incidence of DO in OPLL segments was 30.16% (19/63), and the incidence of DO in patients with OPLL was 27.27% (15/55). DO occurred at the intervertebral space level in 14 cases and at the posterior level of the vertebral body in 5 cases. The sensitivity and specificity of imaging diagnosis were 89.47% (17/19) and 81.82% (36/44), respectively. The positive predictive value was relatively low, 68.00% (17/25), due to the false-positive double-layer sign. The negative predictive value was 94.74% (36/38). CONCLUSION: DO was relatively common in cervical OPLL. DLS might be misdiagnosed. PS and HS can vividly and intuitively describe the imaging features of DO and have high diagnostic accuracy.

A novel surgical protocol for safe and accurate placement of C1 lateral mass screws in patients with atlas assimilation, basilar invagination and atlantoaxial instability: technical details, accuracy assessment and perioperative complications.

PURPOSE: To introduce a novel surgical protocol for safe and accurate placement of C1 lateral mass screws in patients with atlas assimilation, basilar invagination and atlantoaxial instability, and to categorize the screw accuracy and perioperative complications regarding this technique in a large case series. METHODS: Between January 2015 and January 2020, patients who had atlas assimilation, basilar invagination and atlantoaxial instability, and underwent atlantoaxial fixation using C1 lateral mass screws were reviewed. C1 lateral mass screws were placed with a novel surgical protocol following a series key steps, including posterior para-odontoid ligament release, panoramic exposure of the invaginated lateral mass, and diligent protection of the abnormal VA. Screw accuracy and related complications were specifically evaluated. RESULTS: A total of 434 C1 lateral mass screws were placed. Fifteen screws (3.5%) were classified as unacceptable, 54 screws (12.4%) were classified as acceptable, and 365 screws (84.1%) were classified as ideal. Overall, 96.5% of screws were deemed safe. There were no cases of vascular injury or permanent neurological defects. One patient with an unacceptable screw presented with hypoglossal nerve paralysis and recovered after an immediate revision surgery. Thirty-seven patients complained about occipital neuralgia and were successfully managed with medication. CONCLUSION: Placement of C1 lateral mass screws in patients with atlas assimilation, basilar invagination and atlantoaxial instability following this surgical protocol is safe and accurate. Thorough para-odontoid ligamental release, wide exposure of the invaginated lateral mass, and diligent protection of the vertebral artery are critical to maximize the chances of successful screw placement.

Posterior atlantoaxial facet joint reduction, fixation and fusion as revision surgery for failed suboccipital decompression in patients with basilar invagination and atlantoaxial dislocation: Operative nuances, challenges and outcomes.

OBJECTIVE: To report the technical nuances and clinical outcomes of posterior atlantoaxial facet joint reduction, fixation and fusion (AFRF) technique as a revision procedure for BI and AAD patients with failed suboccipital decompression and large occipital bone defect. PATIENTS AND METHODS: We reviewed 32 patients with BI and AAD who were misdiagnosed as a simple Chiari malformation and received a suboccipital decompression surgery before admission. All patients underwent AFRF as a revision surgery. The separating, fusing, opacifying and false-coloring-volume rendering (SFOF-VR) technique was used to identify the course of the VA. Clinical and radiological outcomes were assessed after revision surgeries. RESULTS: Clinical symptoms improved in all patients. The postoperative atlantodens interval, Wackenheim line and clivus-canal angle significantly improved (all P < 0.01). Intraoperative dural tear and cerebrospinal fluid leakage occurred in 3 patients and were managed by suture repair and lumbar drain. Abnormal VA was identified in 7 patients and no VA injury occurred with the aid of SFOF-VR technique. The average follow-up was 19.1 months and atlantoaxial bone fusion was confirmed in 31 patients. CONCLUSION: For BI and AAD patients with failed suboccipital decompression, revision surgery is challenging. Occipitocervical fixation and posterior midline bone grafting are rather difficult due to the large occipital bone defect. The current study demonstrated that the posterior AFRF is a simple, safe and highly effective technique in revision surgery for such cases. For VA variations, the SFOF-VR technique is an effective tool to delineate the course VA.

Repeat Craniocervical Decompression in Patients with a Persistent or Worsening Syrinx: A Preliminary Report and Early Results.

OBJECTIVE: Foramen magnum decompression (FMD) remains the first-line treatment for Chiari malformation type I associated with syringomyelia, although consistent approaches are not used. However, there are few reports on a persistent or recurrent syrinx or worsening neurologic symptoms after FMD. METHODS: We retrospectively reviewed medical records of patients who attended Xuanwu Hospital between January 2018 and July 2019 with persistent or recurrent syringomyelia after FMD. RESULTS: All 8 patients had syringomyelia preoperatively with a mean disease course of 43 (range, 3-120) months and underwent FMD. The presenting symptoms improved in 1 patient. There was radiologic evidence of decreased syrinx size in 1 patient. Worsening syringomyelia presented at a median of 65 (range, 7-168) months after the primary FMD. Secondary decompression was performed in all patients. A structural, pathological cause for the first FMD failure was identified in all cases at the time of the second decompression. Symptoms were resolved in all patients after repeat decompression surgery. Radiologically, 6 patients had a decrease in syringomyelia size. The level of the upper segment of the syringomyelia was higher in 7 of our revision patients, among which 6 patients had a decrease in syringomyelia size. The median follow-up duration after the secondary decompression was 11.5 (range, 6-22) months. CONCLUSIONS: Adults with persistent syringomyelia after FMD and the higher level of the upper segment of the syringomyelia often have a surgically remediable structural cause. The beneficial effect of a secondary decompression should be considered and guide the decision-making of patients with Chiari malformation type I-related syringomyelia.

Usefulness of 3D Printed Models in the Management of Complex Craniovertebral Junction Anomalies: Choice of Treatment Strategy, Design of Screw Trajectory, and Protection of Vertebral Artery.

OBJECTIVE: To evaluate the usefulness of 3-dimensional (3D) printed models as an aid for the treatment of complex CVJ anomalies. METHODS: 3D printed models were fabricated for 21 patients with complex CVJ anomalies, including vertebral artery anomaly, thin C2 pedicle, vertical atlantoaxial facet joint, or rotational dislocation combined with atlantoaxial dislocation and basilar invagination. Preoperative planning, surgical simulation, and intraoperative reference were achieved using the 3D model during the surgical treatment. The usefulness of 3D printed models, and postoperative clinical and radiological outcomes were assessed. RESULTS: Direct posterior reduction and atlantoaxial fixation were achieved in 19 patients. Transoral odontoidectomy followed by posterior fixation was implemented for 2 patients with vertical facet joint and rotational dislocation. All screws were safely inserted with no complication, and 90% patients achieved a >60% reduction of both horizontal and vertical dislocation. Clinical symptoms improved in all patients, with the averaged Japanese Orthopedic Association scores increasing from 11.14 to 14.43 (P < 0.01). CONCLUSIONS: The patient-specific 3D printed model would be an effective tool for evaluation of the reducibility of the atlantoaxial dislocation and basilar invagination, decision making in choosing the optimal surgical approach and way of fixation, and precise placement of the screw while protecting the vertebral artery and spinal cord. The risk of neurovascular injury was minimized, and encouraging outcomes were achieved with the aid of this technique.

The Value and Limitation of Cervical Traction in the Evaluation of the Reducibility of Atlantoaxial Dislocation and Basilar Invagination Using the Intraoperative O-Arm.

OBJECTIVE: To assess the value and limitation of cervical traction in the evaluation of the reducibility of atlantoaxial dislocation (AAD) and basilar invagination (BI) using the intraoperative O-arm. METHODS: A total of 22 patients with hyperextensive, irreducible AAD were included. The cervical traction test under general anesthesia was performed, and the degree of reduction was evaluated using the O-arm before the operation started. The traction effects both vertically and horizontally were evaluated. All cases then underwent modified direct posterior reduction and fixation. Clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) scale. Radiologic measurements included the anterior atlantodental interval, the distance of odontoid tip above Chamberlain line, and the clivus-canal angle. Magnetic resonance imaging signal changes, size of syringomyelia, and the space ventral to medulla also were used to evaluate the postoperative reduction result. RESULTS: After the cervical traction test, 7 patients achieved incomplete reduction, 5 achieved only vertical reduction, 6 achieved only horizontal reduction, and 4 achieved complete reduction in both horizontal and vertical orientations as assessed by the O-arm. All patients underwent a direct reduction technique. The mean JOA score increased from 11.1 to 14.5. Complete reduction of AAD and BI were achieved in 19 patients (86.4%), with partial reduction achieved in 3 (13.6%). Sufficient cerebrospinal fluid space anterior to the medulla with improved JOA score was achieved in the 3 partially reduced patients. CONCLUSIONS: With the innovations of direct posterior reduction techniques, cervical traction under anesthesia may not sufficiently predict the reducibility of BI and AAD. Cervical traction still plays an important role during the direct posterior reduction procedure.

Predictors for Development of Symptomatic Myelopathy in Patients with Radiculopathy Caused by Cervical Ossification of Posterior Longitudinal Ligament.

OBJECTIVE: To identify clinical factors predicting the development of myelopathy in cervical ossification of the posterior longitudinal ligament (OPLL) patients with radiculopathy. METHODS: We retrospectively reviewed 83 cervical OPLL patients who presented with radiculopathy. On the basis of the symptoms and physical findings, we divided patients into 2 groups: myelopathy group and nonmyelopathy group. Demographic, clinical, and radiologic characteristics were reviewed and analyzed among the 2 groups. Predictors for the development of myelopathy were assessed via univariate and multivariate analysis. RESULTS: Univariate analysis demonstrated that a high occupying ratio and the presence of an intramedullary high signal were risk factors for development of myelopathy from radiculopathy in OPLL patients. Multivariate analysis further identified that a high occupying ratio was the only independent predictor (odds ratio 1.05, 95% confidence interval 1.003-1.091, P = 0.035). The cervical range of motion and minor trauma were not related to the development of myelopathy in our study. CONCLUSIONS: Nonmyelopathic OPLL patients with radiculopathy and a high occupying ratio were at higher risk of developing myelopathy, and surgical intervention should be recommended in these cases. However, for elderly patients with significant comorbid conditions, the risks and benefits of surgery should be carefully considered.

Carotid Artery-Related Perioperative Stroke Following Anterior Cervical Spine Surgery: A Series of 3 Cases and Literature Review.

BACKGROUND: Vascular complications following anterior cervical spine surgery are rare but potentially devastating. Complications associated with the carotid artery are even more disastrous but largely anecdotal, with no more than 4 reported cases. MATERIALS AND METHODS: We report 3 new cases of carotid artery-related perioperative stroke following anterior cervical spine surgery. All 3 patients had carotid artery atherosclerosis and the time of intraoperative carotid artery retraction was longer than 1 hour. One patient underwent hypotension during surgery. Risk factors as well as prevention and management protocols of carotid artery-related perioperative stroke based on the literature review and our clinical experience are discussed. CONCLUSIONS: Carotid artery-related perioperative stroke following anterior cervical spine surgery is extremely rare. Prolonged traction, carotid artery atherosclerosis, and intraoperative hypotension can produce cerebral hypoperfusion and cause ischemic stroke. Preoperative risk assessment, adequate perioperative manipulation, and postoperative management can minimize overall morbidity and mortality.

Risk Factors and Management of Dural Defects in Anterior Surgery for Cervical Ossification of the Posterior Longitudinal Ligament.

OBJECTIVE: To investigate risk factors and outcomes and to develop a cogent perioperative management algorithm for dural defects (DDs) in anterior surgery for cervical ossification of the posterior longitudinal ligament (OPLL). METHODS: Ninety OPLL patients who had undergone anterior cervical decompression between January 2014 and December 2016 were reviewed. DDs occurred in 12 patients. Demographic, clinical, and radiologic data; intraoperative and postoperative management; and complications were analyzed. Risk factors for DDs were assessed with multivariate analysis. A treatment algorithm was identified based on these findings and our experience. RESULTS: The prevalence of DDs was 13.3% (12/90). Univariate and multivariate analyses showed that the ratio of OPLL base to spinal canal (odds ratio [OR] 1.09, P = 0.012), kyphotic cervical alignment with thick OPLL masses (OR 9.44, P = 0.026), and lateral, curved, and irregular OPLL masses (OR 8.28, P = 0.037) could be risk factors for DDs. DDs were repaired intraoperatively with onlay grafts, and lumbar drains were placed in all DD patients. The treatment was successful in all DD patients, and outcome measures did not differ between the DD and no DD groups. No patient had experienced complications associated with DDs and CSF leaks at the final follow-up visit. CONCLUSIONS: Patients with broad-based OPLL, kyphotic cervical alignment with thick OPLL masses, and lateral, curved, and irregular OPLL masses have a higher risk of DD in anterior surgery for OPLL. Intraoperative primary repair with onlay grafts combined with early lumbar drains is a simple, safe, and effective strategy for DDs. The outlook for the long-term sequelae of DDs is optimistic if they are managed adequately.