Clivus-canal Angle Research Articles

Analysis of Failed Posterior Fossa Decompression and an Effective Revision Surgery in Patients with Basilar Invagination and Atlantoaxial Dislocation.

The objective of this study was to analyze failed posterior fossa decompression (PFD) in patients with basilar invagination and atlantoaxial dislocation (BI-AAD). Revision surgery in these patients is challenging and has been rarely reported. In addition, the anatomical variations of the vertebral artery increase the risk of revision surgery. Here, we introduce the implementation of a new type of one-stage posterior revision surgery, whose difficulties and effects are summarized. A total of 21 patients with BI-AAD who underwent PFD were retrospectively analyzed in our center from November 2017 to April 2021. The revision surgery in all patients was performed through the posterior approach. The Japanese Orthopaedic Association (JOA) score and the Short Term 12 (SF-12) score were employed to evaluate the clinical symptoms and health status. The distance from the tip of the odontoid to Chamberlain's line (DCL), the atlantodental interval (ADI), the clivus-canal angle (CCA), the diameter of the subarachnoid space (DSS), and the craniovertebral junction triangular area (CTA) were assessed radiographically. The pre- and postoperative results were compared by paired t test. The data of 21 consecutive patients were reviewed, with an average follow-up period of 28 ± 14 months. Postoperative imaging showed effectively reduced compression of BI-AAD. No implant failure or neurovascular injury occurred. Eleven patients had vertebral artery abnormalities, but none had vertebral artery injury. All patients had evidence of bone fusion on the CT scan images within a 12-month follow-up period. The JOA and SF-12 scores were significantly improved 1 year postoperatively (p < 0.001). Posterior surgery using the technique of interarticular distraction, fusion with cage grafting, and fixation is a safe and effective revision surgery to treat patients with basilar invagination and atlantoaxial dislocation who failed PFD, which will result in good outcome.

Analysis of Failed Atlantoaxial Reduction: Causes of Failure and Strategies for Revision.

The craniovertebral junction (CVJ) presents intricate anatomical challenges. In severe or irreducible malformations, complications such as reduction loss and fixation failure may occur, necessitating revision surgery. The posterior facet joint distraction and fusion (PFDF) technique, offers a solely posterior approach for revisions. Hence, we delineate varied revision scenarios, proposing surgical strategies and technical details to enhance outcomes and mitigate risks, thereby enriching the neurosurgical community's repertoire. This was a retrospective cohort study, analyzed patient data from Xuanwu Hospital, between 2017 to 2023. All patients had a history of surgical treatment for CVJ malformations, and experienced failure or loss of reduction. The distance from the odontoid process tip to the Chamberlain's line (DCL), the atlantodental interval (ADI), clivus-canal angle, cervicomedullary angle, width of subarachnoid space, CVJ area, and width of syrinx were used for radiographic assessment. Japanese Orthopaedic Association (JOA) scores and SF-12 scores were used for clinical assessment. Independent sample t-tests were employed. A significance level of p < 0.05 indicates statistically significant differences. We analyzed data from 35 patients. For patients who underwent PFDF, the postoperative DCL, ADI, and clivus-canal angle significantly improved. For all patients, the postoperative cervicomedullary angle, width of subarachnoid space, CVJ area, and width of syrinx all demonstrated significant improvement, indicating the relief of neural compression. All patients showed significant improvement in both symptoms and clinical assessments. Severe atlantoaxial joint locking or ligament contracting are the fundamental cause of reduction and fixation failure. Anterior odontoidectomy is indicated for patients with robust bony fusion of the atlantoaxial joint in an unreduced position. The PFDF technique is safe and effective for patients with incomplete atlantoaxial bony fusion. Preoperative assessment of surgical feasibility and vertebral artery status ensures surgical safety and efficacy.

Effect of the Basilar Invagination (Type B) on Cervical Spine: A Case-control Study with MRI

To evaluate the effect of the basilar invagination (BI) type B on cervical spine. The research protocol used head magnetic resonance imaging (MRI) exams from 41 participants with BI type B and 158 controls. The criterion for BI was the distance of the odontoid apex to Chamberlain's line (DOCL) equal to or greater than 7 mm. The clivus length (CLI), clivus canal angle (CCA), Welcker's basal angle (WBA), Boogaard's angle (BOA), upper cervical lordosis angle (UCL), and total cervical lordosis angle (CL) were evaluated. The descriptive analysis, group comparisons, and correlations between skull base and cervical spine parameters were performed at the 95% confidence interval. Participants with BI type B showed shorter clivus length (CLI: 25.7mm±7.3); greater angulation of the skull base (WBA: 126.5±10.4); greater inclination foramen magnum (BOA: 151.5±14.5); decrease in the value of the (CCA: 131.6±15); and greater angulations of UCL (17.9 ±13.8) and CL (29.7 ±19.9) in comparison to the control group (P < 0.05). Clivus length and CCA correlated inversely with UCL and CL, while BOA correlated directly with UCL and CL. The WBA did not correlate with CL (P < 0.05). The deformation of skull base in the BI of type B caused, on average, a hyperlordosis of almost 30 degrees in the C2-C6 segment. This change was approximately 17º in the C2-C4, with the clivus hypoplasia being a risk factor for cervical hyperlordosis.

C2 pedicle screw insertion assisted by mobilization of the vertebral artery in cases with high-riding vertebral artery

ObjectiveTo describe the feasibility, safety and efficacy of mobilization of the vertebral artery for C2 pedicle screws in cases with the high-riding vertebral artery (HRVA). MethodsDuring the period January 2020 to September 2022, fifteen patients underwent posterior occipitocervical fixation in our department. All patients had unilateral HRVA on at least one side that prohibited the insertion of C2 pedicle screws. There were 2 males and 13 females aged 47 ± 11.9 years (range: 17–64 years). After the correction of the vertical dislocation during the operation, the C2 pedicle screw insertion and occipitocervical fixation and fusion were performed using the vertebral artery mobilization technique. A routine three-dimensional reconstructed CT examination was executed to confirm the trajectory of C2 pedicle screws post-operation, and a CT angiography examination was performed when necessary. Neurological function was assessed using the Japanese Orthopedic Association (JOA) scale. The preoperative and postoperative JOA score and the main radiological measurements, including anterior atlantodental interval (ADI), the distance of odontoid tip above Chamberlain line, and clivus-canal angle (CCA), were collected and compared by paired t-test. ResultsAll 15 patients had atlas assimilation, among which 12 patients had C2–C3 fusion (Klippel-Feil syndrome). Mobilization of the HRVA was successfully completed, and C2 pedicle screws were then fulfilled after the vertebral artery was protected. There was no injury to the vertebral artery during the operation. Meanwhile, no severe surgical complications such as cerebral infarction or aggravated neurological dysfunction occurred during the perioperative period. Satisfactory C2 pedicle screw placement and reduction were reached in all 15 patients. All the patients achieved bone fusion 6 months after surgery. No looseness and shift of internal fixation or reduction loss was observed during the follow-up period. Compared to the preoperative, the postoperative JOA score and the main radiological measurements were remarkably improved and statistically significant. ConclusionsC2 pedicle screw insertion assisted by mobilization of the vertebral artery is safe and considerably effective, providing a choice for internal fixation in cases with high-riding vertebral arteries.

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.

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

Surgical treatment for atlantoaxial instability in pediatric patients is challenging. We report our experience with posterior intra-articular distraction technique in treating this disorder. This is a retrospective descriptive study which included 15 patients of atlantoaxial instability whose age was less than 16years 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. The follow-up period ranged from 18 to 72months, with an average of 41.2 ± 15.2months. The JOA score increased from 13.6 ± 2.3 to 16.6 ± 0.8. ADI decreased from 4.31 ± 2.37 to 1.85 ± 1.09mm, and TA decreased from 261.96 ± 107.99 to 197.12 ± 72.37 mm2. pADI increased from 12.89 ± 3.52 to 18.25 ± 3.89mm, 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. 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.

Morphometric analysis of posterior cranial fossa and foramen magnum and it’s clinical implications in craniovertebral junction malformations: a computed tomography based institutional study in a tertiary care hospital of northern part of India

BackgroundThe posterior cranial fossa (PCF) and the foramen magnum (FM) are the critical anatomical components of the craniovertebral junction region, which comprise and transmit numerous vital neurovascular structures. So, a fundamental knowledge of the basic radiological anatomy of PCF and FM is of paramount importance in the evaluation of associated pathologies and approaching these areas surgically. The aim of this study is to describe different linear and angular craniometric parameters of PCF, FM and surrounding territory based on reconstructed computed tomography (CT) images.Material and methodsThis study was conducted in our tertiary care hospital in northern India from the period of January 2023 to June 2023 on 120 patients, and CT screening was done for the head and spine region following a history of head injury.ResultsIn this study, 120 patients were included, of whom 50.83% (n = 61) were females and 49.17% (n = 59) were males. Age ranged from 18 to 70 years with mean age of 43.5 ± 14.08 years. The mean values for linear craniometric parameters of PCF were statistically nonsignificant for different age groups. Statistically significant differences were found for twinning line (TL) (p < 0.0001), McRae’s line (< 0.0001), clivus length (< p < 0.0001), internal occipital protuberence -opisthion line (p = 0.01), Klaus’ index (p < 0.0001), height of posterior fossa (h) (p < 0.0001), h/TL (p = 0.028), when these values were compared for the genders. The measurements of FM transverse diameter, anteroposterior diameter and area were 27.12 ± 1.42 mm (range 23.6–30.1 mm), 30.99 ± 2.23 mm (range 27.6–35.8 mm) and 691.32 ± 30.35 mm2 (range 632.7–777.7 mm2). The values of clivus canal angle (p = 0.038) and clivoodontoid angle (p = 0.012) were statistically significant when compared for different age groups. The values of Boogard’s angle (p = 0.021) and tentorial slope (p = 0.031) were statistically significant when these were compared for the genders.ConclusionsThis study described almost all the linear and angular craniometric parameters used in the morphometric analysis of PCF and FM. The findings of this study provide valuable data regarding linear and angular craniometric parameters of PCF and FM which can redefine reference values.

Functional and radiological outcomes following craniovertebral junction surgery.

Craniovertebral junction (CVJ) pathologies include atlantoaxial instability/deformities resulting in myelopathy, respiratory failure, and even death. Here, we describe the indications, preoperative planning, and intra-operative/postoperative complications following surgical management of CVJ anomalies. A prospective analysis of 34 patients with CVJ pathology was evaluated between 2015 and 2022. Their various etiologies included atlantoaxial instability, trauma, tuberculosis, Down's syndrome, Morquio syndrome, os odontoideum, and atlantoaxial abnormalities. Clinical outcomes were assessed using the American spinal injury association (ASIA) impairment scale score and Benzel's modified Japanese Orthopedic Association (mJOA) score. Surgical assessments included length of hospital stay, operative time, blood loss, and intraoperative postoperative complications. Radiological parameters included fusion (i.e., implant loosening/implant failure), preoperative/ postoperative atlanto-dens interval (ADI), clivus canal angle (CCA), and space available for cord (SAC). Five patients were managed conservatively, while 29 patients had surgery. Operations included occipitocervical fusion (14 patients), C1-2 fusion (10 patients), C1-2 transarticular screw fixation (four patients), and one patient underwent anterior corpectomy decompression/fusion. Seven patients had vertebral artery anomalies, and 13 patients had atlantoaxial abnormalities. At the final follow-up, atlantoaxial instability (i.e., mean preoperative ADI of 6.6 ± 2.3 mm) was restored to 4.2 ± 0.6 mm, significant cord compression (i.e., with mean SAC of 8.3 ± 2.9 mm) was relieved to 17.2 ± 1.6 mm, and the mean preoperative CCA (i.e., 130.2 ± 15.3) was improved to 143.3 ± 8.3°. There was also a statistically significant improvement in the ASIA scale and mJOA score. Surgical management of CVJ abnormalities requires expertise and meticulous planning to avoid devastating complications such as wound dehiscence and catastrophic vertebral artery injury.

Tomographic Evaluation of the Upper Cervical Spine in Patients with Cleft lip and Palate and Class III Malocclusion.

To perform a morphometric analysis of the upper cervical spine (UCS) by means of cone-beam computed tomography (CBCT) for the diagnosis of malformations or craniocervical instabilities in patients with cleft lip and palate (CLP) and class III malocclusion. A total of 72 CBCTs from adult patients (48 male and 24 female) with Angle Class III malocclusion were divided into three groups: 1) Unilateral cleft lip and palate (UCLP) (n = 29; male = 65.5%; age = 24, 2 ± 4.2 years); 2) Bilateral cleft lip and palate (BCLP) (n = 18; male = 83.3%; age = 26.4 ± 6.0 years); 3) Control group (CON) (n = 25; male = 56.0%; age = 27.8 ± 9.3 years). The version 11.7 of the Dolphin® software (Chatsworth, California, USA) was used to evaluate the morphometric measurements and anomalies of the UCS. Data were analyzed by descriptive and inferential statistics (p ≤ 0.05). For the UCLP, BCLP and CON groups, respectively, the measures were: atlantodental interval (2.1 ± 0.5; 2.1 ± 0.4; 2.0 ± 0.3 mm), basion-opisthion (35.9 ± 3.2; 36.4 ± 3.0; 34.7 ± 1.9 mm), hyoid-C3 (34.5 ± 3.7; 34.5 ± 5.2; 35.3 ± 4.5 mm), and hyoid-sella (108.1 ± 9.8; 111.3 ± 9.2; 109.7 ± 10 mm); clivus-canal angle (152.3 ± 13; 150.3 ± 10; 150.7 ± 10°) and Torg-Pavlov index (1.0 ± 0.2; 1.0 ± 0.1; 1.1 ± 0.2). Potentially unstable anomalies and malformations were more prevalent in the UCLP group (34,4%). Subjects with UCLP presented compressive or unstable anomalies on upper cervical spine, more frequently than controls and BCLP, despite the lack of statistically significant differences among groups. Future studies could increase the safety of patients and healthcare professionals specialized in craniofacial anomalies.

C2 pedicle screw insertion assisted by mobilization of the vertebral artery in cases with high-riding vertebral artery

Objective: To examine the feasibility, safety, and efficacy of mobilization of the vertebral artery for C2 pedicle screws in cases with high-riding vertebral artery (HRVA). Methods: The clinical data of 12 patients with basilar invagination and atlantoaxial dislocation underwent atlantoaxial reduction and fixation in the Department of Neurosurgery, the First Affiliated Hospital of University of Science and Technology of China between January 2020 and November 2021 were retrospectively analyzed. All patients had high-riding vertebral artery on at least one side that prohibited the insertion of C2 pedicle screws. There were 2 males and 10 females aged (48.0±12.8) years (range: 17 to 67 years). After correction of vertical dislocation during the operation, the C2 pedicle screw insertion and occipitocervical fixation and fusion were performed using the vertebral artery mobilization technique. Neurological function was assessed using the Japanese Orthopedic Association (JOA) scale. The preoperative and postoperative JOA score and the main radiological measurements, including the anterior atlantodental interval (ADI), the distance of the odontoid tip above the Chamberlain line, the clivus-canal angle, were collected and compared by paired t-test. Results: Mobilization of the high-riding vertebral artery was successfully completed, and C2 pedicle screws were then fulfilled after the vertebral artery was protected. There was no injury to the vertebral artery during the operation. Meanwhile, no severe surgical complications such as cerebral infarction or aggravated neurological dysfunction occurred during the perioperative period. Satisfactory C2 pedicle screw placement and reduction were achieved in all 12 patients. All patients achieved bone fusion 6 months after surgery. No looseness and shift in internal fixation or reduction loss was observed during the follow-up period. Compared to the preoperative, the postoperative ADI decreased from (6.1±1.9) mm to (2.0±1.2) mm (t=6.73, P<0.01), the distance of the odontoid tip above Chamberlain line decreased from (10.4±2.5) mm to (5.5±2.3) mm (t=7.12, P<0.01), the clivus-canal angle increased from (123.4±11.1) ° to (134.7±9.6) ° (t=2.50, P=0.032), the JOA score increased from 13.3±2.1 to 15.6±1.2 (t=6.99, P<0.01). Conclusion: The C2 pedicle screw insertion assisted by mobilization of the vertebral artery is safe and considerably effective, providing a choice for internal fixation in cases with high-riding vertebral arteries.

Intra-articular Distraction Versus Decompression to Treat Basilar Invagination Without Atlantoaxial Dislocation: A Retrospective Cohort Study of 54 Patients.

The surgical management of basilar invagination without atlantoaxial dislocation (type B basilar invagination) remains controversial. Hence, we have reported the use of posterior intra-articular C1-2 facet distraction, fixation, and cantilever technique versus foramen magnum decompression in treating type B basilar invagination as well as the results and surgical indications for this procedure. This was a single-center retrospective cohort study. Fifty-four patients who underwent intra-articular distraction, fixation, and cantilever reduction (experimental group) and foramen magnum decompression (control group) were enrolled in this study. Distance from odontoid tip to Chamberlain's line, clivus-canal angle, cervicomedullary angle, craniovertebral junction (CVJ) triangle area, width of subarachnoid space and syrinx were used for radiographic assessment. Japanese Orthopedic Association (JOA) scores and 12-item Short Form health survey (SF-12) scores were used for clinical assessment. All patients in the experimental group had a better reduction of basilar invagination and better relief of pressure on nerves. JOA scores and SF-12 scores also had better improvements in the experimental group postoperation. SF-12 score improvement was associated with preoperative CVJ triangle area (Pearson index, 0.515; p = 0.004), cutoff value of 2.00 cm2 indicating the surgical indication of our technique. No severe complications or infections occurred. Posterior intra-articular C1-2 facet distraction, fixation, and cantilever reduction technique is an effective treatment for type B basilar invagination. As various factors involved, other treatment strategies should also be investigated.

Surgical treatment of craniocervical instability: comparison of two constructs regarding clinical and radiological outcomes of 100 patients

PurposeThere is an increased demand for surgical solutions to treat craniocervical instability. This retrospective study demonstrates the clinical and radiological outcomes of unstable craniocervical junction treated with occipitocervical fusion.Material and methodsThe mean age of 52 females and 48 males was 56.89 years. The clinical and radiological outcomes were assessed, including NDI, VAS, ASIA score, imaging, complications and bony fusion in two used constructs: a modern occipital plate–rod–screw system (n = 59) and previous bilateral contoured titanium reconstruction plates–screws (n = 41).ResultsClinically and on imaging, patients presented with neck pain, myelopathy, radiculopathy, vascular symptoms and craniocervical instability. The mean follow-up was 6.47 years. A solid bony fusion was achieved in 93.81% of the patients. The NDI and the VAS improved significantly from 28.3 and 7.67 at the presentation to 16.2 and 3.47 at the final follow-up. The anterior and posterior atlantodental interval (AADI and PADI), the clivus canal angle (CCA), the occipitoaxial angle (OC2A) and the posterior occipitocervical angle (POCA) improved significantly. Six patients required early revision.ConclusionOccipitocervical fusion can yield excellent results regarding clinical improvement and long-term stability with a high fusion rate. Simple reconstruction plates, though more demanding surgically, achieve similar results. Preserving a neutral patient’s position for fixation avoids postoperative dysphagia and may help prevent adjacent segment disease development.

Retrospective Investigation of Brainstem Volume and Craniovertebral Junction Morphometry in Migraine Patients

Aim: Migraine, a complex, multifactorial neurovascular brain disorder, might cause several functional and morphometric changes in the brain. Despite many studies, a consensus has not emerged on its pathophysiology, and it is not fully elucidated so far. Recently, changing brain structures in migraine with aura has been attracting the attention of the scientific periphery. The brainstem is a critical region in the pathogenesis of migraine. Another transition point is the craniovertebral junction. Regional pathologies might trigger off the pathogenesis of neurodegenerative and neurological diseases by affecting hydrodynamics. Moreover, there is insufficient data on the relationship between migraine and the craniovertebral junction. The present study aimed to make the volumetric analysis of brainstem volume in migraine with and without aura, perform some angular and linear measurements of the craniovertebral junction, and evaluate the effects of these parameters in migraine patients. Material and Methods: The study retrospectively analyzed the brain Magnetic Resonance Images of 108 migraine patients (aged 18 to 65). Their brainstem volumes were measured using volBrain (online brain MRI volumetry system). Also, the angular and linear parameters of craniovertebral junctions were derived from the images. The obtained data were transferred to the SPSS 22 package program and analyzed. Results: The mean brainstem volume was 17.21±2.79 cm3 in the migraine with aura group, 17.33±2.48 cm3 in the migraine without aura, and 19.27±2.76 cm3 in the control group. There was no statistically significant difference between migraine with and without aura groups (p&amp;gt;0.05). There was a statistically significant difference between the control and both migraine groups (p&amp;lt;0.05). Furthermore, the clivus-canal angle was significantly different between the control and patient groups. Conclusion: The study found that the brainstem volume was lower in the migraine groups (with and without aura) than in the control group. Also, the different clivus-canal angles between the control and patient groups show that this issue should be more comprehensively studied.

Transoropharyngeal closed reduction for traumatic atlantoaxial dislocation: a novel technique for fast and precise reduction

PurposeThe aim of this study is to introduce a new technique for the rapid and accurate reduction of traumatic atlantoaxial dislocation (TAAD) and to investigate its radiological and clinical outcomes.MethodsThe clinical outcomes of 18 patients who were diagnosed with acute TAAD and underwent rapid transoropharyngeal closed reduction in our hospital were retrospectively analyzed from January 2015 to December 2020. Following general anaesthesia, all patients were immediately treated with oropharyngeal reduction under somatosensory evoked potential monitoring. The Japanese Orthopedic Association score, neck disability index and visual analog scale score for neck pain were used to evaluate clinical efficacy. Atlantodental distance, posterior atlantodental interval, and the clivus-canal angle were used to assess reduction and spinal cord compression.ResultsThe mean follow-up time was 23.3 months, with a range of 13–38 months. No neurovascular injury occurred during the operations. For all patients, the closed reduction method through the oropharynx under general anaesthesia was successful, and the success rate of reduction was 100%. All patients recovered uneventfully with marked improvement in clinical outcomes and imaging parameters (P < 0.01). Two patients developed mild postoperative dysphagia. One patient developed postoperative fever and pulmonary infection.ConclusionRapid trans-oropharyngeal closed reduction can safely, effectively, and rapidly reduce acute TAAD. This method provides a new strategy for treatment of the condition.

Evaluation of the Normal Craniocervical Junction Craniometry in 137 Asymptomatic Patients

To our best knowledge, most of the craniometric studies on the normal craniocervical junction (CCJ), are still poorly studied and based on measurements taken from plain radiographs. In this study, the authors conducted a craniometric evaluation of the CCJ in a population without known CCJ abnormalities. The purpose of the study was to assess the normal CCJ craniometry based on measures obtained from CT scans. The authors examined 137 consecutive CCJ CT scans obtained in patients evaluated at their hospital for treatment of non-CCJ conditions between 2018 and 2019. Twelve craniometrical dimensions were conducted, including the relation of the odontoid with the cranial base, the atlantodental interval (ADI), the clivus length, and the clivus-canal angle (CCA).

Measuring the shape and dimensions of normal the bony structures in the craniovertebral junction from computed tomography images of the pediatric age group.

The aim of this study is to contribute to the literature by determining the morphometric reference values of the bony structures in the craniovertebral junction (CVJ) from computer tomography (CT) images of the pediatric age group. In this study, CT's of 151 simple trauma patients aged between 3 and 15 years between 2016 and 2020 were evaluated. All CT examinations were performed using a 32-slice CT and included images of the skull base and C1-C2 junction. A total of 10 measurements were obtained from these images, including Wachenheim clivus canal angle (WCA), Welcher basal angle (WBA), Cran-iocervical tilt angle (CCT), power ratio (PR), Atlantodens interval, McRae Line (MRL), McRae - Dens distance, basion-dens interval (BDI), basion-axis interval (BAI), and atlantooccipital measurement (AOM). In comparison between gender groups, MRL (p=0.011) and AOM (p<0.001) measurements were found to be significantly higher in males. McRae-Dens distance, BDI, and AOM were significantly higher in patients aged 3-9 years (respectively, p=0005, p=0.003, p<0.001), and BAI (p=0.001) was significantly higher in patients aged 10-15 years. The McRae - Dens distance (p=0.119) was similar between patients with and without terminal ossicle in odontoid apex. But BDI of patients without terminal ossicle was significantly higher (p=0.048). All parameters, except the WCA, WBA, CCT, and PR, were statistically significantly correlated with the patient age (respectively, p=0.21, p=0.13, p=0.70, p=0.99). In this study, the morphometric reference values of the bone structures at the CVJ were determined from the CT images of the pediatric age group.

Basilar invagination without atlantoaxial dislocation: treatment by correction of clivus canal angle with interfacet distraction and fixation

BackgroundThis study reports on the surgical technique used and clinical outcomes obtained during the treatment of basilar invagination (BI) without atlantoaxial dislocation (AAD) through the correction of the clivus canal angle (CCA) using interfacet distraction and fixation.MethodsNineteen cases with BI without AAD treated by the correction of the clivus canal angle were retrospectively analyzed. Pre- and postoperative computed tomography scans and three-dimensional reconstruction views were obtained to measure the size of the CCA, pB-C2 distance, and degree of BI. Chiari malformation and syringomyelia were evaluated by magnetic resonance imaging (MRI). The clinical outcomes for all patients were measured using the Japanese Orthopedic Association (JOA) scale. The CCA was corrected by using interfacet distraction and fixation techniques. The Wilcoxon test was used to compare pre- and postoperative measurements.ResultsAll the patients were followed up for 24.95 ± 5.22 months (range 12-36 months); no patient suffered intraoperative nerve or vascular injury. Clinical symptoms improved in 17 patients (89.5%). The mean JOA score increased from 12.32 ± 1.89 to 14.37 ± 1.30 (Z = -3.655, P < 0.001). The mean CCA improved from 129.34 ± 8.52° preoperatively to 139.75 ± 8.86° postoperatively (Z = -3.824, P < 0.001). The mean pB-C2 decreased from 7.47 ± 2.21 to 5.68 ± 3.13 (Z = -3.060, P = 0.002). Syringomyelia was significantly reduced in 10 out of 13 patients by the first follow-up year. All patients achieved bony fusion.ConclusionPosterior interfacet distraction and fixation to correct the CCA is a feasible and effective method for treating BI without AAD.

Surgical, Clinical, and Radiological Outcomes Analysis of Craniovertebral Junction Anomalies Cases: An Institutional Experience.

Objective The aim of this study was to evaluate the clinical and radiological outcomes analysis of craniovertebral junction (CVJ) anomalies cases. Materials and Methods Retrospective analysis of 43 CVJ anomalies cases, which were surgically managed at Uttar Pradesh University of Medical Sciences, Saifai, Etawah, Uttar Pradesh, India, from period between June 2015 and June 2019. They were analyzed for age, sex, clinical characteristics, radiological diagnosis, and treatment given. Patient's clinical and radiological status was assessed pre- and postoperatively during time of discharge and at 6 months of follow-up. For clinical assessment we used visual analogue scale (VAS) and Nurick grading system. Radiological assessment was done by atlantodental interval (ADI), craniobasal angle, and craniometric lines. Overall outcomes were depicted as favorable, stabilized, and mortality at 6 to 18 months (mean 12.69 ± 3.77) of follow-up. Results The age range of our cases was 7 to 71 years (mean 29.93 ± 17.39). Male-to-female ratio was 2.91:1. Majority of the cases were presented with neck pain ( n = 38; 88.37%), motor weakness ( n = 35; 81.40%), and sensory deficits ( n = 25; 58.14%). Congenital atlantoaxial dislocation ( n = 31; 72.09) was the most common CVJ anomaly. Clinically, there were significant improvements in VAS ( p = 0.001) and Nurick grade ( p = 0.007) postoperatively. Radiologically, ADI ( p = 0.003) had decreased, clivus canal angle ( p = 0.005) become less acute, and odontoid process ( p = 0.003 for McRae's line) goes downwards in postoperative period. Bony fusion was achieved in 41 (95.35%) cases. Out of 43, 73% cases had favorable outcomes, 21% were stabilized, and mortality was seen in 2.33% cases at 6 months (mean ± standard deviation = 12.69 ± 3.77) of follow-up. Conclusion Proper preoperative evaluation and selection of individualized surgical technique was the key for excellent clinical and radiological outcomes with minimal complications.

Analyzing variability of craniometric parameters using computed tomography scan in Indian population

Background: The craniovertebral junction (CVJ) is a crucial region of the spine designed for optimal movements of head and is also a frequent site for various pathological processes. The importance of knowing the CVJ parameters in normal population cannot be overstated when instrumentation and correction of deformities in this region is so frequently being performed. There is paucity of data defining the craniometrics of CVJ osteology in Indian population on the literature search. Accordingly, we present a study in an attempt to quantitate the normal craniometric indices for anatomically normal CVJ in Indian population and compare them with the existing literature from other regions. Aims and Objectives: The aims of this study were to quantitate the normal craniometric indices for anatomically normal CVJ in Indian population and compare them with the existing literature from other regions. Materials and Methods: Two hundred and forty computed tomography (CTs) belonging to Indians were looked at over a 6-month period retrospectively. These patients had normal CVJs and were ordered imaging for other health reasons. A total of eight parameters were analyzed for each CT. Results: There were 166 (69.2%) males and 74 (30.8%) females in our study. The values (in mm) were as follows: anterior atlantodental interval (AADI), 1.78±0.42; PADI (posterior atlantodental interval), 18.12±1.97; distance of tip of odontoid process to chamberlain’s line, –2.73±2.63; distance of tip of odontoid process to McGregor’s line, –2.29±2.79; distance of tip of odontoid process to McRae’s line, –5.91±1.4; Clivus-canal angle, 160.82°±7.14°; basion dens interval, 5.6±1.45; and powers ratio, 0.71±0.07. No patient had an odontoid process extending beyond the McRae’s line. Males were more likely to have higher AADI and PADI values than females. Our study shared significant differences between the other studies (even the studies where an Indian population was used) except one. The AADI, from our study, did not vary significantly when compared to the AADI from a Chinese study. Conclusion: Due to the significant differences from our study and the available literature, a greater compilation of studies belonging to different races will be required to understand the flexibility of the CVJ metrics.

Posterior atlanto-axial intraarticular distraction technique as revision surgery to treat atlanto-axial dislocation associated with basilar invagination

Objective: To examine the effect of posterior atlanto-axial intraarticular distraction technique as revision surgery for failed posterior fossa decompression in patients with basilar invagination(BI) and atlanto-axial dislocation(AAD). Methods: The clinical data of 13 cases of AAD accompanied with BI treated at Department of Neurosurgery, Xuanwu Hospital, Capital Medical University were retrospectively analyzed. There were 3 males and 10 females,aged (42.6±9.5) years (range:30 to 63 years). All cases had assimilation of atlas and once underwent posterior fossa decompression. Anterior tissue was released through posterior approach followed by cage implantation into facet joint and occipital-cervical fixation with cantilever technique. The clinical results were evaluated using Japanese Orthopedic Association scale(JOA) and the main radiological measurements including atlantodental interval (ADI), the distance of odontoid tip above Chamberlain line(DCL),clivus-canal angle(CCA) and the length of syrinx were collected. Paired sample t test was used to compared the data before and after operation. Results: All patients underwent surgery successfully, the mean surgical time was (187.7±47.4) minutes (range from 116 to 261 minutes). Twenty occipital condyle screws, 26 C2 pedicle screws and 3 occipital plates were implanted. Clinical symptoms improved in all patients. Twelve patients had complete reduction of basilar invagination and atlanto-axial dislocation, 1 achieved near completely reduction of basilar invagination. The postoperative ADI, DCL and CCA significantly improved((4.3±1.1) mm vs. (1.8±0.8) mm, (11.7±5.0) mm vs. (6.4±2.8) mm, (142.4±7.9)° vs. (133.3±7.9)°, all P<0.01).There were 5 cases with syringomyelia before surgery, and shrinkage of syrinx was observed 1 week after surgery in all cases. Eight patients achieved bone fusion 3 months after surgery, all patients achieved bone fusion 6 months after surgery. The JOA score increased from 12.8±2.3 before surgery to 14.8±1.3 one year after surgery, with statistically significant difference (t=4.416, P<0.01).No implant failure, spacer subsidence and infection were observed. Conclusion: In cases of failure posterior fossa decompression of basilar invagination and atlanto-axial dislocation, using posterior atlanto-axial intraarticular distraction and cantilever technique with cage implantation could achieve complete reduction and symptomatic relief.