Clinical effect and prognosis of transoral or endoscope-assisted transoral release for irreducible atlantoaxial dislocation: A retrospective cohort study.

Background: The clinical applications of endoscope-assisted transoral release for irreducible atlantoaxial dislocations are limited. This study aimed to investigate the clinical effect and prognostic factors of traditional and endoscope-assisted transoral release, as well as posterior reduction and fixation, in treating irreducible atlantoaxial dislocations. Materials and methods: We conducted a retrospective study on 59 patients with irreducible atlantoaxial dislocation who underwent either traditional or endoscope-assisted transoral release, posterior fixation, and fusion between January 2018 and January 2023. Various data, including surgical time, blood loss, drainage volume, oral intake, hospital stay, complications, and neurological status (assessed by the Japanese Orthopedic Association [JOA] score and Oswestry Disability Index [ODI]), were recorded. Imaging parameters such as the atlantodontoid interval (ADI), space available for the cord (SAC), and cervicomedullary angle (CMA) were analyzed and compared. In addition, the correlation between ODI, JOA and patient age, course of disease, preoperative ADI, SAC and CMA were analyzed. Results: No significant differences were observed in age, sex, BMI, preoperative ADI, preoperative SAC, or preoperative CMA. All patients achieved excellent reduction with no significant differences between the two groups. Patients in the endoscopic group experienced significantly reduced blood loss, earlier oral intake, and shorter hospital stays compared to those in the open group (P < 0.05). The ODI and JOA scores improved significantly in both groups at 1, 6, 12, 18, and 24 months postoperatively (P < 0.05). Postoperative ADI, SAC, and CMA values in both groups were significantly better than preoperative values (P < 0.001). The patient age, course of disease and the preoperative ADI were negatively correlated with the postoperative ODI and the JOA improvement ratio (P < 0.01), and the preoperative SAC and preoperative CMA had positive correlations with the postoperative ODI and the JOA improvement ratio (P < 0.01) at 6, 12 and 24 months postoperatively. Conclusion: Patient age, course of disease, preoperative ADI, SAC and CMA are correlated with the operative prognosis of irreducible atlantoaxial dislocation. The endoscope-assisted transoral approach, compared to the traditional transoral approach, is minimally invasive, resulting in less operative blood loss, earlier oral intake and a shorter length of hospital stay, which could be offered as an alternative for irreducible atlantoaxial dislocation.

Individualized 3D printed model-assisted posterior screw fixation for the treatment of craniovertebral junction abnormality: a retrospective study.

OBJECTIVE This study was undertaken to evaluate the feasibility and efficacy of individualized 3D printed model-assisted posterior internal fixation in treating craniovertebral junction (CVJ) abnormalities. METHODS Forty-four patients (19 males and 25 females; mean age 36.5 ± 9.2 years, range 11-62 years; symptom duration 1 month-15 years) with a CVJ abnormality who were admitted to the authors' institution between April 2010 and April 2015 were retrospectively studied. The individualized 3D printed model of the CVJ was produced based on the individual CT data by use of 3D printing technology. The posterior internal fixation was simulated on the model to obtain data for individual patients, which were then used for intraoperative assistance. One-stage posterior decompression combined with internal fixation was performed. The results were evaluated using the Japanese Orthopaedic Association (JOA) scale, atlanto-dens interval (ADI), and cervicomedullary angle (CMA). The patients underwent follow-up and outcomes were evaluated using CT, MRI, and the JOA scale score. The comparison between preoperative and postoperative JOA scale scores was done using a paired t-test. RESULTS Thirty-eight individualized 3D printed models were successfully built. The 38 patients underwent successful posterior internal fixation performed with the assistance of 3D printed models. In the 6 patients without an individualized printed model (i.e., the patients who underwent surgery before 3D printed modeling was available at the authors' institution), the pedicle screw was inserted incorrectly into the transverse foramen in 2 patients and inserted incorrectly into the vertebral canal in 1 patient. All patients were observed for a mean of 26 months (range 3-52 months). The postoperative JOA scale scores for all patients significantly improved from the preoperative scores. Among the 41 patients treated with atlantoaxial distraction reduction, postoperative MRI and CT showed complete reduction in 31 patients and incomplete reduction in 10 patients (reduction rate > 50%). The postoperative ADI significantly decreased, and the CMA significantly increased. CONCLUSIONS Individualized 3D printed model-assisted posterior internal fixation seems feasible and effective in optimizing the treatment of CVJ abnormalities. In addition, it offers many advantages, including preoperative simulation, intraoperatve guidance, and intraoperative error minimization.

Pontine encephalocele and abnormalities of the posterior fossa following transclival endoscopic endonasal surgery.

OBJECT: Transclival endoscopic endonasal surgery (EES) has recently been used for the treatment of posterior fossa tumors. The optimal method of reconstruction of large clival defects following EES has not been established. METHODS: A morphometric analysis of the posterior fossa was performed in patients who underwent transclival EES to compare those with observed postoperative anatomical changes (study group) to 50 normal individuals (anatomical control group) and 41 matched transclival cases with preserved posterior fossa anatomy (case-control group) using the same parameters. Given the absence of clival bone following transclival EES, the authors used the line between the anterior commissure and the basion as an equivalent to the clival plane to evaluate the location of the pons. Four parameters were studied and compared in the two populations: the pontine location/displacement, the maximum anteroposterior (AP) diameter of the pons, the maximum AP diameter of the fourth ventricle, and the cervicomedullary angle (CMA). All measurements were performed on midsagittal 3-month postoperative MR images in the study group. RESULTS: Among 103 posterior fossa tumors treated with transclival EES, 14 cases (13.6%) with postoperative posterior fossa anatomy changes were identified. The most significant change was anterior displacement of the pons (transclival pontine encephalocele) compared with the normal location in the anatomical control group (p < 0.0001). Other significant deformities were expansion of the AP diameter of the pons (p = 0.005), enlargement of the fourth ventricle (p = 0.001), and decrease in the CMA (p < 0.0001). All patients who developed these changes had undergone extensive resection of the clival bone (> 50% of the clivus) and dura. Nine (64.3%) of the 14 patients were overweight (body mass index [BMI] > 25 kg/m(2)). An association between BMI and the degree of pontine encephalocele was observed, but did not reach statistical significance. The use of a fat graft as part of the reconstruction technique following transclival EES with dural opening was the single significant factor that prevented pontine displacement (p = 0.02), associated with 91% lower odds of pontine encephalocele (OR = 0.09, 95% CI 0.01-0.77). The effect of fat graft reconstruction was more pronounced in overweight/obese individuals (p = 0.04) than in normal-weight patients (p = 0.52). Besides reconstruction technique, other noticeable findings were the tendency of younger adults to develop pontine encephalocele (p = 0.05) and the association of postoperative meningitis with the development of posterior fossa deformities (p = 0.05). One patient developed a transient, recurrent subjective diplopia; all others remained asymptomatic. CONCLUSIONS: Significant changes in posterior fossa anatomy that have potential clinical implications have been observed following transclival transdural EES. These changes are more common in younger patients or those with meningitis and may be associated with BMI. The use of a fat graft combined with the vascularized nasoseptal flap appears to minimize the risk of pontine herniation following transclival EES with dural opening.