Basilar Invagination Patients Research Articles

Evaluation of Craniometric Parameters and Efficacy of Posterior Surgical Intervention Types in Basilar Invagination Patients

OBJECTIVEBasilar invagination is one of the most frequently observed abnormalities at the craniovertebral junction, in which the odontoid process of C2 prolapses into the foramen magnum. METHODSThe current study included 27 patients who underwent surgery for basilar invagination between October 2013 and January 2023. The study group was divided into 2 groups according to basilar invagination types; type I (the presence of type A atlantoaxial instability and instability is the main pathology) and type II (the presence of type B and C atlantoaxial instability and skull base dysgenesis is the main pathology). Craniometric parameters included in the study were; atlantodental interval, posterior atlantodental interval, Chamberlain’s line violation, clivus-canal angle, Welcher’s basal angle, and Boogaard angle. RESULTSThe mean age of the patients was 24.30 ± 14.36 years (5-57 years). Fourteen patients (51.9%) were female, and 13 patients (48.1%) were male. Ten patients (37%) had type I basilar invagination, 17 patients (63%) had type II basilar invagination. Preoperative and postoperative atlantodental interval and Boogaard angle were significantly higher in type I basilar invagination, as preoperative and postoperative posterior atlantodental interval and clivus-canal angle were significantly higher in type II basilar invagination. There was a positive strong correlation between Chamberlain‘s line violation and Boogaard angle. Postoperative Chamberlain‘s line violation was significantly higher in occipitocervical fixation (p=0.035). C1 lateral mass screw fixation was found more successful in Chamberlain‘s line violation correction than occipital plates. Occipitocervical fixation was found to be associated with higher postoperative Nurick scores (p=0.015) and complication rates (p=0.020). Cages applied to the C1-C2 joint space were found to be associated with higher fusion rates (p = 0.023) and lower complication rates (p = 0.024). CONCLUSIONSIn the present study, it was found that C1-C2 fixation was more successful in correcting craniometric parameters and had lower complication rates than occipitocervical fixation. In appropriate patients, it was determined that cage application increased the success rates of the operations.

Facet-occiput slope angle: A novel predictor of cage placement feasibility during surgery in basilar invagination patients

Background and aimDirect posterior reduction and manipulation of the C1-2 joints, accompanied by placement of spacers, is the state-of-the-art technique for treating basilar invagination (BI) and atlantoaxial dislocation (AAD). The hindrance of occiput to reaching up to the true atlantoaxial facets (AAF) during the surgery remains challenging for cage placement. The aim of this study was to explore an objective and precise method of measuring the effect of the hindrance of occiput to reaching up to the true AAF and cage placement during surgery. MethodWe collected the clinico-imaging data of 58 patients with BI and AAD (Group A) who underwent surgery in our hospital, and 78 control cohorts (Group B) were retrieved retrospectively. We measured facet-occiput slope angle (FOSA) in midsagittal CT. Patients were positioned prone for surgery based on preoperative flexion O–C2a, and access to the true AAF was observed intraoperatively. The cut-off value of FOSA for the feasibility of cage placement in BI and AAD patients was appointed when access to the true AAF was impossible due to the hindrance of occiput during surgery. ResultsThe cut-off value of FOSA for the feasibility of cage placement was 34o with an area under the curve AUC of 0.800 (95 % CI: 0.672–0.928, P < 0.001) and the Youden index of 0.607. In patients with FOSA >34o, reaching up to the true AAF and 3D-printed cage placement was impossible. FOSA was negative in Group A and positive in Group B, significantly larger in females compared to males in both groups and significantly larger postoperatively in Group A. ConclusionFOSA can objectively measure the feasibility of cage placement when the patient is positioned prone per preoperative flexion O–C2a. A FOSA >34o is contraindication for cage placement.

Chamberlain's Line Violation in Basilar Invagination Patients Compared with Normal Subjects: A Systematic Literature Review and Meta-Analysis

To compare the measured odontoid tip violation above Chamberlain's line described in the literature to diagnose basilar invagination (BI) and to establish the normal placement of the dens tip defining individuals without BI (normal subjects). A systematic literature review was performed to identify clinical or radiological studies that expressed the amount of odontoid violation above Chamberlain's line in patients with a BI diagnosis. In addition, a meta-analysis was performed to evaluate normal subjects' values of Chamberlain's line violation (CLV). There were 23 studies included (13 radiological and 10 clinical). Most studies used computed tomography and/or magnetic resonance imaging. Eight different cutoff values were used to measure dislocated odontoid apexes above Chamberlain's line regardless of the radiological modality. The mean measured amount of CLV was 3.95 mm (median 5 mm; range, 0-9 mm). The meta-analysis included 8 studies (1233 patients) with a normal sample population with a mean normal CLV of-0.63 mm (below the line) (95% confidence interval [-0.8, 1.18 mm], random effects model). Different values were found in the assessed studies used for CLV in BI diagnosis. This variability is especially important for type B BI, as type A BI has other craniocervical diagnostic parameters. Considering the results obtained in this meta-analysis, BI should be diagnosed in the case of any dens violation >1.18 mm.

Ideal entry point and trajectory for C2 pedicle screw placement in basilar invagination patients with high-riding vertebral artery based on 3D computed tomography

BACKGROUNDC2 pedicle screw placement in patients with basilar invagination (BI) is fraught with risks because of a high incidence of anatomical variations and high-riding vertebral artery (HRVA). However, no study can be found in the literature that attempted to identify the ideal entry point and trajectory through the C2 pedicle in BI patients with HRVA. PURPOSETo investigate the parameters of ideal entry point and trajectory for C2 pedicle screw placement in BI patients with HRVA and compare them with those in BI patients without HRVA and patients without BI as control. These parameters would serve as a guide to pedicle screw placement. STUDY DESIGNA retrospective comparative study. PATIENT SAMPLEA total of 396 patients (198 consecutive BI patients and 198 matched patients without BI as control) and 792 unilateral pedicles from April 2017 to October 2021 at two medical centers were included. OUTCOME MEASURESThe insertion parameters of mediolateral angle, surface distance, cephalad angle, and vertical distance from the superior border of the lamina were the primary outcome measures for the reference of C2 pedicle screw placement. Furthermore, factors that affect the primary insertion parameters were assessed via multiple linear regression analyses. METHODAccording to the diagnosis of BI and HRVA, the unilateral pedicles were assigned into HRVA of BI, non-HRVA of BI, HRVA of control, and non-HRVA of control groups. Subgroup analyses based on Goel types A and B were also performed. Moreover, vertebral artery (VA) anomalies that might result in potentially serious complications were identified and systematically compared. RESULTSThe measurements of insertion parameters in BI patients with HRVA indicated a mean mediolateral angle of 27.42°, a mean cephalad angle of 43.02°, a mean surface distance of 9.74 mm, and a mean vertical distance from the superior border of the lamina of 3.85 mm. Compared with that in BI patients without HRVA, the measurements suggested that the entry point in BI patients with HRVA should be shifted upward by 0.38 mm and the trajectory should be angled cephalad by 6.05° and medially by 4.78°. In the control group, changes in the insertion parameters between HRVA and non-HRVA showed a similar trend to the BI group. Multiple linear regression showed that mediolateral angle was significantly associated with the male gender (B=−0.930, p=.017) and the diagnoses of HRVA (B=6.964, p<.001), Goel type A (B=−1.656, p=.003), and Goel type B (B=0.981, p=.030). Moreover, cephalad angle was significantly associated with the length of lateral mass (B=−0.319, p=.001) and the diagnoses of HRVA (B=3.254, p<.001) and Goel type A (B=6.924, p<.001). The VA anomalies were significantly higher in the BI group than in the control group. CONCLUSIONSThe insertion parameters of the ideal entry point and trajectory for C2 screw placement in BI patients with HRVA were remarkably different from those of non-HRVA of BI, HRVA of control, and non-HRVA of control cohorts. Preoperative 3D computed tomography (CT) and CT angiography are highly recommended in such patients to improve intraoperative safety and reduce postoperative complications.

Occipital Condyle-C1 Complex Screw for Fixation of Basilar Invagination Patients with Atlas Assimilation.

Occipital Condyle-C1 Complex Screw for Fixation of Basilar Invagination Patients with Atlas Assimilation.

Occipital condyle-c1 complex screw for fixation of basilar invagination patients with atlas assimilation

Occipital condyle-c1 complex screw for fixation of basilar invagination patients with atlas assimilation

Occipital Condyle-C1 Complex Screw for Fixation of Basilar Invagination Patients with Atlas Assimilation.

To investigate whether C1-occipital condyle complex (CC complex) screws can be safely and rapidly placed without guidance in basilar invagination patients with atlas assimilation. The occipital-cervical (OC) junction was fixed posteriorly in 8 basilar invagination patients with atlas assimilation using polyaxial titanium screws inserted unicortically into the CC complex and C2 pedicles and subsequent fixation to a 3-mm rod. Anatomic landmarks were used during the drilling. The screw angles and lengths of the CC complex were analyzed. The width, length, and height values of the left-side CC complex were 7.96±2.23, 16.06±2.73, and 13.76±2.06 mm; those of the right-side CC complex were 7.84±1.38, 16.66±2.58, and 12.81±2.62 mm. The CC complex entry point was at the central point of posterior surface of the CC complex. The angle used for medialization was 10-15°, which was also the maximal superior screw angulation in the sagittal plane. The screw length required for unicortical purchase was 16-22 mm. The screw was not misplaced or poorly positioned, and no neurovascular complications associated with screw insertion were detected. In patients with atlas assimilation, CC complex screws can be placed safely. The CC complex screws can be safely inserted assisted by microscope without image guidance.

The odontoid process invagination in normal subjects, Chiari malformation and Basilar invagination patients: Pathophysiologic correlations with angular craniometry.

Background:Craniometric studies have shown that both Chiari malformation (CM) and basilar invagination (BI) belong to a spectrum of malformations. A more precise method to differentiate between these types of CVJM is desirable. The Chamberlain's line violation (CLV) is the most common method to identify BI. The authors sought to clarify the real importance of CLV in the spectrum of craniovertebral junction malformations (CVJM) and to identify possible pathophysiological relationships.Methods:We evaluated the CLV in a sample of CVJM, BI, CM patients and a control group of normal subjects and correlated their data with craniocervical angular craniometry.Results:A total of 97 subjects were studied: 32 normal subjects, 41 CM patients, 9 basilar invagination type 1 (BI1) patients, and 15 basilar invagination type 2 (BI2) patients. The mean CLV violation in the groups were: The control group, 0.16 ± 0.45 cm; the CM group, 0.32 ± 0.48 cm; the BI1 group, 1.35 ± 0.5 cm; and the BI2 group, 1.98 ± 0.18 cm. There was strong correlation between CLV and Boogard's angle (R = 0.82, P = 0.000) and the clivus canal angle (R = 0.7, P = 0.000).Conclusions:CM's CLV is discrete and similar to the normal subjects. BI1 and BI2 presented with at least of 0.95 cm CLV and these violations were strongly correlated with a primary cranial angulation (clivus horizontalization) and an acute clivus canal angle (a secondary craniocervical angle).

Safety and efficacy of microscope-assisted insertion of screws into fused C1-occipital condyle complex for occipital cervical fixation in atlantal cervical nonsegmentation patients.

To explore the safety and efficacy of the insertion of screws into fused C1-occipital condyle(CC)complex without image guidance in atlantal-cervical nonsegmentation patients. The occipital condyle junction was fixed posteriorly in 10 basilar invagination patients with atlantal-cervical nonsegmentation using polyaxial titanium screws(3.5 mm)inserted unicortically into the CC complex and C2 pedicles,followed by fixation to a 3 mm rod. Drilling was guided by anatomic landmarks. The entry point was at the center of posterior surface of the CC complex. The angle of medicalization was 10-15 degrees. In the sagittal plane,the angle for maximal superior screw angulation was also 10-15 degrees. The screw length to obtain unicortical purchase was 16 to 22 mm. CT scans were obtained before and after the surgery. The length,width,and height of CC complex were measured on computed tomography(CT)preoperatively. The position of screws and the condition of fixation were analyzed on postoperative CT scan. Postoperative complications were recorded. The mean follow-up was(30.2±4.38)months(range: 24-36 months). The width,length,height of left side CC complex were(7.96±2.23)mm,(16.06±2.73)mm,and(13.76±2.06)mm,and the width,length,height of right side CC complex were(7.84±1.38)mm,(16.66±2.58)mm,and(12.81±2.62)mm. No fracture was identified. There was no screw malposition or neurovascular complication related to screw insertion. No screw loosening or construct failure was observed during the follow-up. In patients with atlantal cervical nonsegmentation,the CC complex screws can be safely inserted assisted by microscope without image guidance. Occipital condyle junction fixation using polyaxial CC complex screws is feasible and can be a good alternative where other fixation techniques are not satisfactory.

Evaluation of osteal posterior cranial fossa in adults by multi-slice CT measurements before and after operation in basilar invagination patients

Objective To evaluate the clinical effect of MSCT measurements in the pre- and postoperational osteal posterior cranial fossa for the adult patients of basilar invagination.Methods We reviewed the images of a cohort of 31 adult patients with basilar invagination,which were treated by surgical operation.According to the presence of atlantoaxial dislocation,the patients were divided into groups A and B.The basion-dens interval (BDI),atlanto-dental interval (ADI),space available of the spinal cord ( SAC),clivus-canal angle( CCA),Highly index( HI),and Chamberlian line(CBL) of the posterior cranial fossa were obtained in all the patients.Independent-sample Student's t test was used to compare the differences between groups A and groups B.Spearman correlations were analyzed between CT measurement data and effects of operations.Results In Group A,the BDI,ADI,SAC,CCA,HI,CBL before and after surgery were 12.6 mm,8.3 mm,4.5 mm,3.3 mm;18.2 mm,20.8 mm,138.3°,150.4°,28.7 mm,43.4 mm,6.3 mm,3.3 mm respectively.There were significant differences ( t = 5.603,2.323,3.124,5.531,4.278 and 2.375,respectively,P ＜0.05 ).Preoperative JOA score in groups A was 10 points,and was 14 points after surgery.There was significant difference between the JOA scores before and after surgery ( t = 3.526,P ＜ 0.05 ).There were 7 effective cases and 4 stable cases after surgery in group A.Before and after surgery,JOA score and BDI,ADI,SAC,CCA,HI,CBL were significantly correlated( r = -0.667,- 0.673 ; - 0.571,- 0.619 ; 0.642,0.513 ; 0.525,0.558 ; 0.587,0.511 ; - 0.532,- 0.596,respectively,P＜0.05).The SAC,CCA,and CBL before and after surgery in group B were 18.3 mm,19.6 mm,146.8°,150.2°,2.7 mm,1.8 mm.The difference was statistically significant after operation ( t = 5.359,4.126,0.769,P ＜0.05).The BDI,ADI,and HI before and after surgery in group B were 7.2 mm,6.6 mm,2.4 mm,2.1 mm,39.3 mm,41.5 mm.And there were no significant differences (t = 1.482,2.374,0.153,P＞0.05).The preoperative JOA score in groups B was 11 points,and the postoperative score was 16 points.JOA scores before and after surgery were significantly different (t =2.874,P ＜0.05).There were 14 effective cases and 6 stable cases after operation in group B.The JOA score before and after surgery and BDI,ADI,and HI had no correlation (r =0.341,0.387;0.154,0.182; 0.192,0.167,P ＞0.05),and CBL,SAC and CCA were correlated (r = -0.756,-0.728;0.651,0.672; 0.726,0.695,P ＜0.05).Conclusion MSCT measurements for basilar invagination before and after surgery are helpful for understanding changes of osteal posterior fossa anatomy and comprehensive evaluation of surgical treatment. Key words: Basilar invagination; Tomography, X-ray computed; Cephalometry; Surgical procedures,operation; Evaluation studies