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Biomechanics

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Biomechanical Evaluation of Anterior Plate Fixation With Cage for Basilar Invagination With Atlantoaxial Dislocation: A Cadaveric Study
Neurospine. 2025;22(4):974-986.   Published online December 31, 2025
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Biomechanical Evaluation of Anterior Plate Fixation With Cage for Basilar Invagination With Atlantoaxial Dislocation: A Cadaveric Study
Neurospine. 2025;22(4):974-986.   Published online December 31, 2025
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Objective
To evaluate the biomechanical characteristics of 2 anterior fixation techniques (clival plate fixation [CPF], transoral atlantoaxial reduction plate [TARP]) versus posterior occipitocervical fixation (POCF) for basilar invagination with atlantoaxial dislocation (BI-AAD), under varying atlantoaxial lateral mass cage heights (4–10 mm).
Methods
Seven fresh cadaveric specimens (occiput to C3, Oc–C3) were tested in the following conditions: (1) intact state; (2) BI-AAD state; (3) BI-AAD+CPF; (4) BI-AAD+TARP fixation; (5) BI-AAD+POCF. A pure 1.5 N·m moment loads to specimens in flexion/extension, lateral bending and axial rotation. Range of motion (ROM) and neutral zone (NZ) values at Oc–C2 were calculated and compared.
Results
ROM of the C1–2 segment under the intact and BI-AAD states were as follows: 9.3°±4.6° versus 21.3°±8.3° in flexion, 4.6°±1.9° versus 9.3°±3.8° in extension, 3.6°±2.2° versus 12.0°±6.5° in lateral bending, and 68.9°±14.4° versus 76.6°±6.6° in axial rotation, respectively. Compared with BI-AAD states, all internal fixation techniques significantly reduced the ROM of the Oc–C2 segment. TARP fixation exhibited larger ROM in flexion-extension. While in lateral bending and axial rotation, the ROM values for the anterior plate constructs were smaller than that of POCF, with a statistically significant difference observed between CPF and POCF. Cage height variations showed no significant impact on overall biomechanical stability.
Conclusion
Anterior plate fixation techniques demonstrated superior resistance to lateral bending and rotational forces compared to posterior approaches, with clival plate fixation exhibiting optimal biomechanical stability for BI-AAD. Variations in cage height exhibited negligible impact on stability when internal fixation achieved adequate rigidity.

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  • Reducibility-Based Posterior Reduction and Fusion Strategies for Atlantoaxial Dislocation: A Clinical and Radiological Study
    Guipeng Zhao, Haotian Long, Dingyu Du, Dean Chou, Longyi Chen, Junting Hu, Hailong Feng, Qidong Liu, Jinping Liu
    Neurospine.2026; 23(2): 411.     CrossRef
  • 1,284 View
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Endoscopic Transnasal Approach to Atlantoaxial Decompression and C1–2 Fixation in Basilar Invagination of Adults: A Feasibility Study
Neurospine. 2025;22(2):543-555.   Published online June 30, 2025
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Endoscopic Transnasal Approach to Atlantoaxial Decompression and C1–2 Fixation in Basilar Invagination of Adults: A Feasibility Study
Neurospine. 2025;22(2):543-555.   Published online June 30, 2025
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Objective
To explore a surgical technique for completing ventral bone decompression and C1–2 plate-screw fixation in the craniocervical junction (CVJ) through nasal approach by stage I at the imaging and physical anatomy levels, and to evaluate its feasibility.
Methods
Radiographic parameters of 80 patients with basilar invagination (BI) and 56 with normal CVJ anatomy were retrospectively analyzed. Three-dimensional (3D) reconstructions were performed in 31 patients with BI. Key anatomical landmarks, screw entry points, and fixation trajectories were evaluated. Customized plate-screw constructs were designed. Finally, surgical feasibility was tested on a 3D-printed anatomical model and a cadaveric.
Results
In 80 BI patients, the average distances between 4 screw insertion points were 16.04 mm, 21.10 mm, 6.83 mm, and 7.10 mm. C2 lateral mass oblique lengths were 16.81 mm (right) and 17.12 mm (left); C1 lengths were 18.71 mm (right) and 19.07 mm (left), with significant differences between C1 and C2 (p<0.001). A 28.5×14.1-mm titanium plate with 16 mm screws was successfully implanted via the nasal route in the polyether ether ketone 3D-printed BI model and the cadaveric. Radiology indicated that the screws were all in the lateral mass and the plates fit tightly.
Conclusion
In BI, transnasal odontoidectomy and plate-screw fixation of C1–2 are feasible theoretically. This may enable a new alternative approach for nasal minimally invasive decompression and immobilization, following the completion of biomechanics and clinical trials.
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Biomechanical Study of Atlanto-occipital Instability in Type II Basilar Invagination: A Finite Element Analysis
Neurospine. 2024;21(3):1014-1028.   Published online September 30, 2024
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Biomechanical Study of Atlanto-occipital Instability in Type II Basilar Invagination: A Finite Element Analysis
Neurospine. 2024;21(3):1014-1028.   Published online September 30, 2024
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Objective
Recent studies indicate that 3 morphological types of atlanto-occipital joint (AOJ) exist in the craniovertebral junction and are associated with type II basilar invagination (BI) and atlanto-occipital instability. However, the actual biomechanical effects remain unclear. This study aims to investigate biomechanical differences among AOJ types I, II, and III, and provide further evidence of atlanto-occipital instability in type II BI.
Methods
Models of bilateral AOJ containing various AOJ types were created, including I-I, I-II, II-II, II-III, and III-III models, with increasing AOJ dysplasia across models. Then, 1.5 Nm torque simulated cervical motions. The range of motion (ROM), ligament and joint stress, and basion-dental interval (BDI) were analyzed.
Results
The C0–1 ROM and accompanying rotational ROM increased progressively from model I-I to model III-III, with the ROM of model III-III showing increases between 27.3% and 123.8% indicating ultra-mobility and instability. In contrast, the C1–2 ROM changes were minimal. Meanwhile, the stress distribution pattern was disrupted; in particular, the C1 superior facet stress was concentrated centrally and decreased substantially across the models. The stress on the C0–1 capsule ligament decreased during cervical flexion and increased during bending and rotating loading. In addition, BDI gradually decreased across the models. Further analysis revealed that the dens showed an increase of 110.1% superiorly and 11.4% posteriorly, indicating an increased risk of spinal cord impingement.
Conclusion
Progressive AOJ incongruity critically disrupts supportive tissue loading, enabling incremental atlanto-occipital instability. AOJ dysplasia plays a key biomechanical role in the pathogenesis of type II BI.
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The Morphological Evaluation of the Cervical Muscle in Patients With Basilar Invagination: A Magnetic Resonance Imaging-Based Study
Neurospine. 2023;20(3):908-920.   Published online August 7, 2023
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The Morphological Evaluation of the Cervical Muscle in Patients With Basilar Invagination: A Magnetic Resonance Imaging-Based Study
Neurospine. 2023;20(3):908-920.   Published online August 7, 2023
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Objective
To investigate the characteristics of functional muscle and muscle size in patients with basilar invagination (BI) and explore the effects of atlantoaxial dislocation.
Methods
Eighty BI patients (BI group) and 80 age- and sex-matched asymptomatic people (control group) were included. Axial T2 magnetic resonance imaging image was used to measure the cross-sectional area (CSA) and functional CSA (FCSA). The sternocleidomastoid (SCM), longus capitis and longus colli (LCap & LC), trapezius (Trap), splenius capitis (SpCap), splenius cervicis (SpC), semispinalis capitis (SSCap), semispinalis cervicis (SSC), multifidus (MS), levator scapulae (LS) and posterior deep layer muscles (PDLM) were evaluated. Correlations between age, atlantodental interval (ADI), Chamberlain distance and muscles were observed.
Results
BI group (39.4 ± 18.4 years; 33 males/47 females) exhibited significantly lower FCSA/CSA ratios than the control group in all extensor and flexor muscles, and presented smaller CSAs on the right and left Trap, SSC, LS, SCM, and left LCap & LC. FCSA/CSA ratios were significantly lower in BI patients with dislocation on the right Trap, SpCap, SpC, SSCap, MS, LS, LCap & LC, and PDLM, and the left SSCap, MS, and LCap & LC than in patients without deformity. Additionally, functional muscles of all parameters decreased with age in BI patients. Excluding children, the Trap, SpC, MS, and LS muscle sizes of BI patients tended to increase with age. ADI and Chamberlain distance tended to correlate negatively with FCSA/CSA ratio.
Conclusion
The BI patients, especially those with atlantoaxial dislocation, had less functional muscles compared with the control group. Moreover, their functional muscles decreased with age more obviously.

Citations

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  • Posterior reduction and temporary fixation for odontoid fractures: an intermuscular dissection approach versus a midline standard muscle stripping approach
    Zhenji Xu, Wenqing Wang, Ji Wu, Wenwen Wang, Dongqing Zhu, Qunfeng Guo
    The Spine Journal.2026; 26(2): 221.     CrossRef
  • Factors Associated With the Absence of Cervical Spine Instability in Rheumatoid Arthritis: A >10-Year Prospective Multicenter Cohort Study
    Takashi Yurube, Yutaro Kanda, Hiroaki Hirata, Masatoshi Sumi
    Neurospine.2024; 21(4): 1230.     CrossRef
  • 5,761 View
  • 173 Download
  • 2 Web of Science
  • 2 Crossref

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Intra-articular Distraction Versus Decompression to Treat Basilar Invagination Without Atlantoaxial Dislocation: A Retrospective Cohort Study of 54 Patients
Neurospine. 2023;20(2):498-506.   Published online June 30, 2023
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Intra-articular Distraction Versus Decompression to Treat Basilar Invagination Without Atlantoaxial Dislocation: A Retrospective Cohort Study of 54 Patients
Neurospine. 2023;20(2):498-506.   Published online June 30, 2023
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Objective
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.
Methods
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.
Results
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.
Conclusion
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.

Citations

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  • Posterior Only Reduction and Fixation of The Basilar Invagination and Atlantoaxial Dislocation Secondary to Severe Rheumatoid Arthritis: A Technical Note
    Sadegh Bagherzadeh, Faramarz Roohollahi, Morteza Faghih jouibari, Mohammad Jafari, Toufigh Mohaddes Javadi
    European Spine Journal.2026; 35(4): 1891.     CrossRef
  • Hot topics and trends in adult Chiari malformation and basilar invagination: a bibliometric analysis [2005–2025]
    Youhai Xin, Zeyu Xie, Yanchun Guo, Zhesheng Chen, Weiwu Zheng, Wen Zhou, Zibi Xu, Weida Hong, Qinguo Huang
    Egyptian Journal of Neurosurgery.2026;[Epub]     CrossRef
  • A Surgical Technique Guide for C1–2 Fixation By the Cervical Spine Research Society
    Marc Prablek, Ashel C. Dsouza, Brian W. Su, Lee A. Tan
    Clinical Spine Surgery.2026;[Epub]     CrossRef
  • Impact of Additional Tonsillar Manipulation or Intra-articular Distraction on Syrinx Remission for Type B Basilar Invagination
    Qiang Jian, Zhe Hou, Xingang Zhao, Cong Liang, Yinqian Wang, Dongao Zhang, Kun Wu, Jichao Wang, Tao Fan
    Neurosurgery.2026;[Epub]     CrossRef
  • C2 Vertebra: An Enigma for Young Spine/Neurosurgeons
    Mayank Garg, Raghavendra K. Sharma, Vikas Janu, Mohit Agrawal, Ashutosh Jha, Pushpinder Khera, Deepak K. Jha
    Journal of Neurological Surgery Part B: Skull Base.2025; 86(01): 092.     CrossRef
  • Surgical Treatment of Basilar Invagination
    Ricardo V. Botelho, Oscar L. Alves, Geraldo Sá Carneiro, Zan Chen, Onur Yaman, Jutty Parthiban, Massimiliano Visocchi, Jörg Klekamp, Atul Goel, Mehmet Zileli
    Spine.2025; 50(11): 751.     CrossRef
  • Surgical Treatment of Basilar Invagination without Evident Atlantoaxial Instability (Type B) - A Systematic Review
    Andrei Fernandes Joaquim, Eloy Rusafa Neto, Leon Cleres Penido Pinheiro, Osmar Jose Santos de sMoraes, Eberval Gadelha Figueiredo, Carlos Gilberto Carloti, Roger Schimdt Brock
    Neurology India.2025; 73(3): 423.     CrossRef
  • Analysis of Failed Atlantoaxial Reduction: Causes of Failure and Strategies for Revision
    Boyan Zhang, Yueqi Du, Can Zhang, Maoyang Qi, Hongfeng Meng, Tianyu Jin, Guoqing Cui, Jian Guan, Wanru Duan, Zan Chen
    Orthopaedic Surgery.2024; 16(11): 2741.     CrossRef
  • Biomechanical Study of Atlanto-occipital Instability in Type II Basilar Invagination: A Finite Element Analysis
    Junhua Ye, Qinguo Huang, Qiang Zhou, Hong Li, Lin Peng, Songtao Qi, Yuntao Lu
    Neurospine.2024; 21(3): 1014.     CrossRef
  • From the Editor-in-Chief: Featured Articles in the June 2023 Issue
    Inbo Han
    Neurospine.2023; 20(2): 413.     CrossRef
  • 6,948 View
  • 230 Download
  • 8 Web of Science
  • 10 Crossref

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Measurement of Deformity at the Craniovertebral Junction: Correlation of Triangular Area and Myelopathy
Neurospine. 2022;19(4):889-895.   Published online December 31, 2022
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Measurement of Deformity at the Craniovertebral Junction: Correlation of Triangular Area and Myelopathy
Neurospine. 2022;19(4):889-895.   Published online December 31, 2022
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Objective
Diseases of the craniovertebral junction (CVJ) are commonly associated with deformity, malalignment, and subsequent myelopathy. The misaligned CVJ might cause compression of neuronal tissues and subsequently clinical symptoms. The triangular area (TA), measured by magnetic resonance imaging/images (MRI/s), is a novel measurement for quantification of the severity of compression to the brain stem. This study aimed to assess the normal and pathological values of TA by a comparison of patients with CVJ disease to age- and sex-matched controls. Moreover, postoperative TAs were correlated with outcomes.
Methods
Consecutive patients who underwent surgery for CVJ disease were included for comparison to an age- and sex-matched cohort of normal CVJ persons as controls. The demographics, perioperative information, and pre- and postoperative 2-year cervical MRIs were collected for analysis. Cervical TAs were measured and compared.
Results
A total of 201 patients, all of whom had pre- or postoperative MRI, were analyzed. The TA of the CVJ deformity group was larger than the healthy control group (1.62 ± 0.57 cm2 vs. 1.01 ± 0.18 cm2, p < 0.001). Moreover, patients who had combined anterior odontoidectomy and posterior laminectomy with fixation had the greatest reduction in the TA (1.18 ± 0.58 cm2).
Conclusion
In CVJ deformity, the measurement of the cervical TA could indicate the severity of brain stem compression. After surgery, the TA had a varying degree of improvement, which could represent the efficacy of surgery.

Citations

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  • 3D printing enabled biomechanical evaluation of a novel expandable wedge spacer for atlantoaxial reduction
    Chih-Chang Chang, Shao-Fu Huang, Rong-Chen Lin, Chun-Li Lin
    3D Printing in Medicine.2026;[Epub]     CrossRef
  • Prognostic Factors in Craniocervical Realignment for Crainovertebral Junction Kyphosis With Negative Cervical Imbalance: A Comprehensive Study
    Dong Hun Kim, Jae Taek Hong, Jin Young Kim, Kang Bin Koo, Dae Hee Lee, Jung Woo Hur, Ho Jin Lee, Il Sup Kim
    Neurospine.2025; 22(3): 725.     CrossRef
  • Evaluation of Cervicomedullary Compression Around the Craniovertebral Junction: Commentary on “Measurement of Deformity at the Craniovertebral Junction: Correlation of Triangular Area and Myelopathy”
    Jae Taek Hong
    Neurospine.2022; 19(4): 896.     CrossRef
  • 6,231 View
  • 228 Download
  • 3 Web of Science
  • 3 Crossref

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Characteristics and Comparisons of Morphometric Measurements and Computed Tomography Hounsfield Unit Values of C2 Laminae for Translaminar Screw Placement Between Patients With and Without Basilar Invagination
Neurospine. 2022;19(4):899-911.   Published online December 31, 2022
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Characteristics and Comparisons of Morphometric Measurements and Computed Tomography Hounsfield Unit Values of C2 Laminae for Translaminar Screw Placement Between Patients With and Without Basilar Invagination
Neurospine. 2022;19(4):899-911.   Published online December 31, 2022
Close
Objective
Patients with basilar invagination (BI) had high incidences of vertebral variations and high-riding vertebral artery (HRVA) that might restrict the use of pedicle or pars screw and increase the use of translaminar screw on axis. Here, we conducted a radiographic study to investigate the feasibility of translaminar screws and the bone quality of C2 laminae in patients with BI, which were compared with those without BI as control to provide guidelines for safe placement.
Methods
In this study, a total of 410 patients (205 consecutive patients with BI and 205 matched patients without BI) and 820 unilateral laminae of the axis were included at a 1:1 ratio. Comparisons with regard to insertion parameters (laminar length, thickness, angle, and height) for C2 translaminar screw placement and Hounsfield unit (HU) values for the assessment of the appropriate bone mineral density of C2 laminae between BI and control groups were performed. Besides, the subgroup analyses based on the Goel A and B classification of BI, HRVA, atlas occipitalization, and C2/3 assimilation were also carried out. Furthermore, the factors that might affect the insertion parameters and HU values were explored through multiple linear regression analyses.
Results
The BI group showed a significantly smaller laminar length, thickness, height, and HU value than the control group, whereas no significant difference was observed regarding the laminar angle. By contrast, the control group showed significantly higher rates of acceptability for unilateral and bilateral translaminar screw fixations than the BI group. Subgroup analyses showed that the classification of Goel A and B, HRVA, atlas occipitalization, and C2/3 assimilation affected the insertion parameters except the HU values. Multiple linear regression indicated that the laminar length was significantly associated with the male gender (B = 0.190, p < 0.001), diagnoses of HRVA (B = -0.109, p < 0.001), Goel A (B = -0.167, p < 0.001), and C2/3 assimilation (B = -0.079, p = 0.029); the laminar thickness was significantly associated with the male gender (B = 0.353, p < 0.001), diagnoses of HRVA (B = -0.430, p < 0.001), Goel B (B = -0.249, p = 0.026), and distance from the top of odontoid to the Chamberlain line (B = -0.025, p = 0.003); laminar HU values were significantly associated with age (B = -2.517, p < 0.001), Goel A (B = -44.205, p < 0.001), Goel B (B = -25.704, p = 0.014), and laminar thickness (B = -11.706, p = 0.001).
Conclusion
Patients with BI had narrower and smaller laminae with lower HU values and lower unilateral and bilateral acceptability for translaminar screws than patients without BI. Preoperative 3-dimensional computed tomography (CT) and CT angiography were needed for BI patients.

Citations

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  • High-Riding Vertebral Artery in Cervical Spine Surgery: A Review of Preoperative Identification and Surgical Implications
    Alexander Kucherina, Paul G Mastrokostas, Themistocles S Protopsaltis, Charla R Fischer
    Cureus.2026;[Epub]     CrossRef
  • Letter to the Editor regarding “Types of high-riding vertebral artery: a classification system for preoperative planning of C2 instrumentation based on 908 potential screw insertion sites” by Klepinowski et al.
    Yuwang Du, Hua Jiang
    The Spine Journal.2025; 25(5): 1069.     CrossRef
  • MORPHOMETRIC PARAMETERS OF THE AXIS RELATED TO INTRALAMINAR FIXATION
    VITOR ARAúJO GONçALVES, MATHEUS PIPPA DEFINO, GABRIEL MATTOS GOES, THIAGO DE OLIVEIRA DORIGãO, HELTON LUIZ APARECIDO DEFINO
    Coluna/Columna.2025;[Epub]     CrossRef
  • Development and Evaluation of an Automated Computational Approach for the Precise Placement of Pedicle Screws in Spinal Surgery Leveraging Three-Dimensional Point Cloud Registration Methods
    Guoli Song, Andi Li, Yuhan Ying, Yiwen Zhao, Xingang Zhao, Lei Zhang
    IEEE Transactions on Automation Science and Engineering.2025; 22: 19606.     CrossRef
  • 6,279 View
  • 183 Download
  • 3 Web of Science
  • 4 Crossref

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A Universal Craniometric Index for Establishing the Diagnosis of Basilar Invagination
Neurospine. 2021;18(1):206-216.   Published online January 25, 2021
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A Universal Craniometric Index for Establishing the Diagnosis of Basilar Invagination
Neurospine. 2021;18(1):206-216.   Published online January 25, 2021
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Objective
The conventional criteria for defining the basilar invagination (BI) focus on the relationship of odontoid tip to basion and opisthion, landmarks that are intrinsically variable especially in presence of occipitalised atlas. A universal single reference line is proposed that helps in unequivocally establishing the diagnosis of BI, may be relevant in establishing both Goel types A and B BI, as well as in differentiating a ‘very high’ from ‘regular’ BI.
Methods
Study design – case-control study. In 268 patients (group I with BI [n = 89] including Goel type A BI [n = 66], Goel type B BI [n = 23], and group II controls [n = 179]), the perpendicular distance between odontoid tip and line subtended between posterior tip of hard palate-internal occipital protuberance (P-IOP line) was measured. Logistic regression analysis determined factors influencing the proposed parameter (p < 0.05).
Results
In patients with a ‘very high’ BI (n = 5), the odontoid tip intersected/or was above the P-IOP line. In patients with a ‘regular’ BI (n = 84), the odontoid tip was 6.56 ± 3.9mm below the P-IOP line; while in controls, this distance was 12.53 ± 4.28 mm (p < 0.01). In Goel type A BI, the distance was 7.01 ± 3.78 mm and in type B BI, it was 5.07 ± 4.19 mm (p = 0.004). Receiver-operating characteristic curve analysis identified 9.0 mm (8.92–9.15 mm) as the cut-point for diagnosing BI using the odontoid tip-P-IOP line distance as reference.
Conclusion
The odontoid tip either intersecting the P-IOP line (very high BI) or being < 9 mm below the P-IOP line (Goel types A and B BI) is recommended as highly applicable criteria to establish the diagnosis of BI. This parameter may be useful in establishing the diagnosis in all varieties of BI.

Citations

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  • A review and commentary on congenital anomalies of the craniocervical junction
    Aaron S McAllister, Eric A Sribnick
    Pediatric Radiology.2026;[Epub]     CrossRef
  • Basilar Invagination Diagnosis, Classification, and Radiology
    Onur Yaman, Mehmet Zileli, İdris Avci, Zan Chen, June Ho Lee, Geraldo Sá-Carneiro, Francesco Costa, Said Ait Ben Ali, Fernando Dantas, Joachim Oertel, Massimiliano Visocchi, Jutty Parthiban, Atul Goel, Ricardo Botelho, Oscar L. Alves
    Spine.2025; 50(11): E200.     CrossRef
  • Evaluation of Angular Parameters of Craniocervical Junction and Establishing their Relevance in the Diagnosis of Basilar Invagination
    Kulwant Singh, Vikrant Yadav, Ravi Shankar Prasad, Anurag Sahu, Nityanand Pandey
    Indian Journal of Neurosurgery.2025; 14(02): 148.     CrossRef
  • Current update and trend of 3D printing in spinal surgery: A bibliometric analysis and review of literature
    Rieva Ermawan, Hubertus Corrigan, Nanang Wiyono
    Journal of Orthopaedics.2024; 50: 22.     CrossRef
  • Forensic evaluation of craniometric characteristics of the Kazakhstan population
    Saule A. Mussabekova, Anastasiya O. Stoyan, Xeniya E. Mkhitaryan, Saule B. Zhautikova
    Journal of Oral Biology and Craniofacial Research.2024; 14(4): 370.     CrossRef
  • Chamberlain's Line Violation in Basilar Invagination Patients Compared with Normal Subjects: A Systematic Literature Review and Meta-Analysis
    Andrei F. Joaquim, Alécio Cristino Evangelista Santos Barcelos, Jefferson Walter Daniel, Ricardo Vieira Botelho
    World Neurosurgery.2023; 173: e364.     CrossRef
  • Risk Factors of Postoperative Cerebrospinal Fluid Leak After Craniovertebral Junction Anomalies Surgery: A Case-Control Study
    Yu Xiao, Bing Wang, Yulian Chen, Lingqiang Chen, Zhenkai Lou, Zhiqiang Gong
    Neurospine.2023; 20(1): 255.     CrossRef
  • Intra-articular Distraction Versus Decompression to Treat Basilar Invagination Without Atlantoaxial Dislocation: A Retrospective Cohort Study of 54 Patients
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Weak Ligaments and Sloping Joints: A New Hypothesis for Development of Congenital Atlantoaxial Dislocation and Basilar Invagination
Neurospine. 2020;17(4):843-856.   Published online December 31, 2020
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Weak Ligaments and Sloping Joints: A New Hypothesis for Development of Congenital Atlantoaxial Dislocation and Basilar Invagination
Neurospine. 2020;17(4):843-856.   Published online December 31, 2020
Close
Objective
Developmental bony craniovertebral junction (CVJ) anomalies seem to have a genetic basis and also abnormal joint morphology causing atlantoaxial dislocation (AAD) and basilar invagination (BI).
Methods
DNA extracted polymerase chain reaction single-stranded conformation polymorphism (SSCP) performed for mutation screening of FBN1 gene (n = 50 cases+ 50 age/sex-matched normal; total: 100). Samples with a deviated pattern of bands in SSCP were sequenced to detect the type of variation. Computed tomography (CT) scans of 100 patients (15–45 years old) compared with an equal number of age/sex-matched controls (21.9 ± 8.2 years). Joint parameters studied: sagittal joint inclination (SI), craniocervical tilt (CCT), coronal joint inclination (CI).
Results
Thirty-nine samples (78%) showed sequence variants. Exon 25, 26, 27, and 28 showed variable patterns of DNA bands in SSCP, which on sequencing gives various types of DNA sequence variations in intronic region of the FBN1 gene in 14%, 14%, 6%, and 44% respectively. CT radiology:SI and CCT correlated with both BI and AAD (p < 0.01). The mean SI value in controls: 83.35° ± 8.65°, and in patients with BI and AAD:129° ± 24.05°. Mean CCT in controls: 60.2° ± 9.2°, and in patients with BI and AAD: 86.0° ± 18.1°. Mean CI in controls:110.3° ± 4.23°, and in cases: 125.15° ± 16.4°.
Conclusion
The study showed mutations in FBN1 gene (reported in Marfan syndrome). There is also an alteration of joint morphology, correlating with AAD and BI severity. Hence, we propose a double-hit hypothesis: the presence of weak ligaments (due to FB1 gene alterations) and abnormal joint morphology may contribute to AAD and BI.

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Evaluation and Surgical Planning for Craniovertebral Junction Deformity
Neurospine. 2020;17(3):554-567.   Published online September 30, 2020
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Evaluation and Surgical Planning for Craniovertebral Junction Deformity
Neurospine. 2020;17(3):554-567.   Published online September 30, 2020
Close
Craniovertebral junction (CVJ) deformity is a challenging pathology that can result in progressive deformity, myelopathy, severe neck pain, and functional disability, such as difficulty swallowing. Surgical management of CVJ deformity is complex for anatomical reasons; given the discreet relationships involved in the surrounding neurovascular structures and intricate biochemical issues, access to this region is relatively difficult. Evaluation of the reducibility, CVJ alignment, and direction of the mechanical compression may determine surgical strategy. If CVJ deformity is reducible, posterior in situ fixation may be a viable solution. If the deformity is rigid and the C1–2 facet is fixed, osteotomy may be necessary to make the C1–2 facet joint reducible. C1–2 facet release with vertical reduction technique could be useful, especially when the C1–2 facet joint is the primary pathology of CVJ kyphotic deformity or basilar invagination. The indications for transoral surgery are becoming as narrow as a treatment for CVJ deformity. In this article, we will discuss CVJ alignment and various strategies for the management of CVJ deformity and possible ways to prevent complications and improve surgical outcomes.

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Original Article

APCSS special Topic-Craniovertebral Junction Surgery

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Basilar Invagination and Atlantoaxial Dislocation: Reduction, Deformity Correction and Realignment Using the DCER (Distraction, Compression, Extension, and Reduction) Technique With Customized Instrumentation and Implants
Neurospine. 2019;16(2):231-250.   Published online June 30, 2019
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Basilar Invagination and Atlantoaxial Dislocation: Reduction, Deformity Correction and Realignment Using the DCER (Distraction, Compression, Extension, and Reduction) Technique With Customized Instrumentation and Implants
Neurospine. 2019;16(2):231-250.   Published online June 30, 2019
Close
Objective
The technique of distraction, compression, extension, and reduction (DCER) is effective to reduce, realign, and relieve cranio-spinal compression through posterior only approach.
Methods
Study included all patients with atlantoaxial dislocation and basilar invagination (BI) with occipitalized C1 arch. Study techniques included Nurick grading, computed tomography scan to study atlanto-dental interval, BI, hyper-lordosis, and neck tilt. Sagittal inclination (SI), coronal inclination (CI), cranio-cervical tilt, presence of pseudo-joints, and anomalous vertebral artery were also noted. Patients underwent DCER with/without joint remodeling or extra-articular distraction (EAD) based on the SI being <100°, 100°–160°, or >160° respectively. In cases with pseudo-joints, joint remodeling was performed in type I and EAD in type II. Customized ‘bullet shaped’ PSC spacers (n=124) and prototype of the universal craniovertebral junction reducer (UCVJR, n=36) were useful.
Results
A total of 148 patients with average age 27.25±17.43 years, ranging from 3 to 71 years (87 males) were operated. Nurick’s grading improved from 3.14±1.872 to 1.22±1.17 (p<0.0001). Fifty-two percent of total joints (n=154/296 joints) were either type I (19%)/type II (33%) pseudo-j oints. All traditional indices such as Chamberlein line, McRae line, atlanto-dental interval, and Ranawat line improved (pConclusion
Occipito-C2 pseudo-joints are important in determining the severity of BI. Asymmetrical pseudo-joint causes coronal/neck tilt. Type of pseudo-joint can strategize by DCER. Customized instruments and implants make technique safe, effective and easier.

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  • Weak Ligaments and Sloping Joints: A New Hypothesis for Development of Congenital Atlantoaxial Dislocation and Basilar Invagination
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    Neurospine.2020; 17(4): 843.     CrossRef
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  • 14,958 View
  • 353 Download
  • 26 Web of Science
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Review Article

APCSS special Topic-Craniovertebral Junction Surgery

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Is Cervical Stabilization for All Cases of Chiari-I Malformation an Overkill? Evidence Speaks Louder Than Words!
Neurospine. 2019;16(2):195-206.   Published online June 30, 2019
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Is Cervical Stabilization for All Cases of Chiari-I Malformation an Overkill? Evidence Speaks Louder Than Words!
Neurospine. 2019;16(2):195-206.   Published online June 30, 2019
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Chiari I malformation is characterized by the downward displacement of cerebellar tonsils through the foramen magnum. While discussing the treatment options for Chiari I malformation, the points of focus include: (1) Has the well-established procedure of posterior fossa decompression become outdated and has been replaced by posterior C1–2 stabilization in every case? (2) In case posterior stabilization is required, should a C1–2 stabilization, rather than an occipitocervical fusion, be the only procedure recommended? The review of literature revealed that when there is bony instability like atlantoaxial dislocation (AAD), occipito-atlanto-axial facet joint asymmetry or basilar invagination (BI) associated with Chiari I malformation, one should address the anterior bony compression as well as perform stabilization. This takes care of the compromised canal at the foramen magnum and re-establishes the cerebrospinal fluid flow along the craniospinal axis; and also provides treatment for CVJ instability. In the cases with a pure Chiari I malformation without AAD or BI and with completely symmetrical C1–2 joints, however, posterior fossa decompression with or without duroplasty is sufficient to bring about neurological improvement. The latter subset of cases with pure Chiari I malformation have, thus, shown significant (>70%) rates of neurological improvement with posterior fossa decompression alone. A C1–2 posterior stabilization is a more stable construct due to the strong bony purchase provided by the C1–2 lateral masses and the short lever arm of the construct. However, in the cases with significant bleeding from paravertebral venous plexus; a very high BI, condylar hypoplasia and occipitalized atlas; gross C1–2 rotation or vertical C1–2 joints with unilateral C1 or C2 facet hypoplasia, as well as the presence of subaxial scoliosis; maldevelopment of the lateral masses and facet joints (as in very young patients); or, the artery lying just posterior to the C1–2 facet joint capsule (being endangered by the C1–2 stabilization procedure), it may be safer to perform an occipitocervical rather than a C1–2 fusion.

Citations

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  • Incidence and Management of Basilar Invagination With Associated Chiari I Malformation
    Jörg Klekamp, Oscar L. Alves, Mehmet Zileli, Joachim Oertel, Onur Yaman, Salman Sharif, Massimiliano Visocchi, Atul Goel, Ricardo Botelho
    Spine.2025; 50(11): 786.     CrossRef
  • Surgical Management of Chiari 1.5 in Children: A Truly Different Disease?
    Ignazio G. Vetrano, Arianna Barbotti, Tommaso Francesco Galbiati, Sabrina Mariani, Alessandra Erbetta, Luisa Chiapparini, Veronica Saletti, Laura G. Valentini
    Journal of Clinical Medicine.2024; 13(6): 1708.     CrossRef
  • Technical Considerations in Surgical Fixation of Jefferson Fracture
    Hitesh Kumar Gurjar, Hitesh Inder Singh Rai, Shashwat Mishra, Kanwaljeet Garg
    Indian Journal of Neurotrauma.2023; 20(02): 140.     CrossRef
  • Full‐endoscopic technique for posterior fossa decompression in Chiari malformation type I: An anatomical feasibility study in human cadavers
    I. Dolas, A. G. Yorukoglu, A. Sencer, Tugrul Cem Unal, C. I. Gulsever, A. Aydoseli, Y. Aras, P. A. Sabanci, S. Ruetten
    Clinical Anatomy.2023; 36(4): 660.     CrossRef
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    Neurospine.2019; 16(2): 212.     CrossRef
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  • 12,256 View
  • 242 Download
  • 24 Web of Science
  • 17 Crossref

Original Article

APCSS special Topic-Craniovertebral Junction Surgery

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Suture Repair in Endoscopic Surgery for Craniovertebral Junction
Neurospine. 2019;16(2):257-266.   Published online June 30, 2019
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Suture Repair in Endoscopic Surgery for Craniovertebral Junction
Neurospine. 2019;16(2):257-266.   Published online June 30, 2019
Close
Objective
Endoscopic approaches to the craniovertebral junction (CVJ) have been established as viable and effective surgical treatments in the past decade. One of the major complications is leakage of the cerebrospinal fluid (CSF). This study aimed to investigate the efficacy and feasibility of suture closure at the nasopharyngeal mucosa upon durotomy.
Methods
A series of consecutive patients who underwent different endoscopic approaches to the CVJ were retrospectively reviewed. The pathologies, surgical corridors, neurological and functional outcomes, radiological evaluations, and complications were analyzed. Different strategies of repair for the intraoperative CSF leakage were described and compared.
Results
A total of 22 patients covering 13 years were analyzed. There were 12, 2, and 8 patients who underwent transnasal, transoral, and combined approaches, respectively. There were 8 patients (36.4%) who experienced intraoperative CSF leakage, and were grouped into 2: 4 in the nonsuture (NS) group and 4 in the suture-repaired (SR) group. The NS group had 3 (75%) persistent CSF leakages postoperation that caused 1 mortality, whereas patients of the SR group had only 1 minor CSF rhinorrhea that healed spontaneously within days.
Conclusion
In this series of 22 patients who required anterior endoscopic resection of pathologies at the CVJ, there was 1 (4.5%) serious complication related to CSF leakage. For patients who had no durotomy, the mucosal incision at the nasopharynx usually healed rapidly and there were few procedure-related complications. For patients with intraoperative CSF leakage, suture closure was technically challenging but could significantly lower the risks of postoperative complications.

Citations

Citations to this article as recorded by  Crossref logo
  • Surgical treatment and clinical outcome in non-inflammatory atlantoaxial degeneration and retro-odontoid pseudotumor
    Raimunde Liang, Bernhard Meyer, Vicki M. Butenschoen
    Brain and Spine.2025; 5: 105621.     CrossRef
  • Navigated Anterior Full-Endoscopic Transcervical Approach Odontoidectomy for Traumatic Posterior Atlantoaxial Dislocation Without Odontoid Fracture
    Juan Felipe Abaunza-Camacho, Sara Gomez-Niebles, Humberto Madrinan-Navia, Alberto Daza-Ovalle, Natalia Guevara-Moriones, Mario Fernando Rodríguez, Jorge Torres Mancera, Camilo Peña, William Mauricio Riveros-Castillo, Javier M. Saavedra
    Operative Neurosurgery.2024; 27(5): 641.     CrossRef
  • Minimally invasive surgery for invaginated CII odontoid process
    A.N. Shkarubo, I.V. Chernov, D.N. Andreev, N.A. Konovalov, M.E. Sinelnikov
    Burdenko's Journal of Neurosurgery.2023; 87(3): 5.     CrossRef
  • Comparative analysis of endoscopic transnasal and microsurgical transoral odontoidectomy: Literature review and own experience
    Alexey N. Shkarubo, Anton G. Nazarenko, Ilya V. Chernov, Dmitry N. Andreev, Alexandr A. Kuleshov, Nikolai A. Konovalov, Igor N. Lisyanskiy, Mikhail E. Sinelnikov
    N.N. Priorov Journal of Traumatology and Orthopedics.2023; 30(1): 41.     CrossRef
  • Endoscopic Transnasal Odontoidectomy for Ventral Decompression of the Craniovertebral Junction: Surgical Technique and Clinical Outcome in a Case Series of 19 Patients
    Vicki M Butenschoen, Maria Wostrack, Bernhard Meyer, Jens Gempt
    Operative Neurosurgery.2021; 20(1): 24.     CrossRef
  • Nonrheumatoid Retro-Odontoid Pseudotumors: Characteristics, Surgical Outcomes, and Time-Dependent Regression After Posterior Fixation
    Ryoko Niwa, Keisuke Takai, Makoto Taniguchi
    Neurospine.2021; 18(1): 177.     CrossRef
  • 10,133 View
  • 148 Download
  • 4 Web of Science
  • 6 Crossref

Technical Note

APCSS special Topic-Craniovertebral Junction Surgery

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Anterior Retropharyngeal Cage Distraction and Fixation for Basilar Invagination: “The Wedge Technique”
Neurospine. 2019;16(2):286-292.   Published online June 30, 2019
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Anterior Retropharyngeal Cage Distraction and Fixation for Basilar Invagination: “The Wedge Technique”
Neurospine. 2019;16(2):286-292.   Published online June 30, 2019
Close
Objective
Surgery is indicated for basilar invagination (BI) in symptomatic patients. In many patients, symptoms and signs occur due to an upward-migrated and malaligned odontoid with fixed or mobile atlantoaxial instability. Posterior distraction and fixation of the atlantoaxial joints has evolved to become the standard of care, but has some inherent morbidity. In this study, we propose that the unilateral anterior submandibular retropharyngeal approach with customized wedge-shaped titanium cages inserted into both atlantoaxial joints and anterior atlantoaxial fixation with a plate screw construct is a safer and easier option in many cases of BI.
Methods
From February 2014 to February 2019, 52 patients (age range, 15–78 years; 40 males and 12 females) with symptomatic BI with atlantoaxial dislocation and minimal sagittal facetal inclination and only mild Chiari malformation without syringomyelia were offered anterior submandibular retropharyngeal atlantoaxial distraction and fixation surgery.
Results
Neurological improvement occurred in 80% of patients, while the neurological status of 20% remained unchanged. No patients worsened, and no major complications or mortality was observed.
Conclusion
In properly selected cases of symptomatic BI, anterior wedge cage distraction with anterior atlantoaxial fixation is a safe and simple option.

Citations

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  • C2 Vertebra: An Enigma for Young Spine/Neurosurgeons
    Mayank Garg, Raghavendra K. Sharma, Vikas Janu, Mohit Agrawal, Ashutosh Jha, Pushpinder Khera, Deepak K. Jha
    Journal of Neurological Surgery Part B: Skull Base.2025; 86(01): 092.     CrossRef
  • Surgical Treatment of Basilar Invagination
    Ricardo V. Botelho, Oscar L. Alves, Geraldo Sá Carneiro, Zan Chen, Onur Yaman, Jutty Parthiban, Massimiliano Visocchi, Jörg Klekamp, Atul Goel, Mehmet Zileli
    Spine.2025; 50(11): 751.     CrossRef
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    Hongfeng Meng, Zong Xin, Boyan Zhang, Maoyang Qi, Yueqi Du, Wanru Duan, Zan Chen
    World Neurosurgery.2024; 185: e1361.     CrossRef
  • Modified interfacet technique using shaped autologous occipital bone mass for basilar invagination
    Qiang Jian, Xingang Zhao, Zhe Hou, Yinqian Wang, Tao Fan
    Clinical Neurology and Neurosurgery.2023; 232: 107848.     CrossRef
  • Unstable odontoid fractures: technical appraisal of anterior extrapharyangeal open reduction internal fixation for irreducible unstable odontoid fractures. Patient series
    Sushil Patkar
    Journal of Neurosurgery: Case Lessons.2021;[Epub]     CrossRef
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    Sushil Patkar
    Neurosurgical Focus: Video.2020; 3(1): V11.     CrossRef
  • Editorial: Are there any indications of transoral odontoidectomy today?
    P. Sarat Chandra
    Neurosurgical Focus: Video.2020; 3(1): V7.     CrossRef
  • 9,967 View
  • 212 Download
  • 6 Web of Science
  • 7 Crossref

Review Article

APCSS special Topic-Craniovertebral Junction Surgery

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A Review of a New Clinical Entity of ‘Central Atlantoaxial Instability’: Expanding Horizons of Craniovertebral Junction Surgery
Neurospine. 2019;16(2):186-194.   Published online June 30, 2019
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A Review of a New Clinical Entity of ‘Central Atlantoaxial Instability’: Expanding Horizons of Craniovertebral Junction Surgery
Neurospine. 2019;16(2):186-194.   Published online June 30, 2019
Close
The author discusses the novel form of central or axial atlantoaxial instability and analyses its clinical significance. High degree of clinical and radiological understanding of the region is mandatory to diagnose and then treat such atlantoaxial instability. Evaluation of alignment of facets of atlas and axis and observations on direct manipulation of facets of atlas and axis forms the basis of diagnosis. The treatment of clinical entities like basilar invagination, Chiari formation, syringomyelia and myelopathy related to cervical spinal degeneration, spinal deformities, ossified posterior longitudinal ligament, and Hirayama disease can be influenced by the understanding of central or axial atlantoaxial instability.

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  • Characterizing Initial Cervical Spine and Neurovascular Findings in 84 Consecutive Patients with Hypermobile Ehlers–Danlos Syndrome: A Retrospective Study
    Ross A. Hauser, Morgan Griffiths, Ashley Watterson, Danielle Matias, Benjamin R. Rawlings
    Journal of Clinical Medicine.2026; 15(6): 2212.     CrossRef
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    Atul Goel
    Journal of Craniovertebral Junction and Spine.2026; 17(2): 95.     CrossRef
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    Guipeng Zhao, Haotian Long, Dingyu Du, Dean Chou, Longyi Chen, Junting Hu, Hailong Feng, Qidong Liu, Jinping Liu
    Neurospine.2026; 23(2): 411.     CrossRef
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    Mayank Garg, Raghavendra K. Sharma, Vikas Janu, Mohit Agrawal, Ashutosh Jha, Pushpinder Khera, Deepak K. Jha
    Journal of Neurological Surgery Part B: Skull Base.2025; 86(01): 092.     CrossRef
  • Chiari Formation, Basilar Invagination and Atlantoaxial Instability - Presentation as 6th Nerve Paresis
    Atul Goel, Dikpal Jadhav, Abhidha Shah, Neha Jadhav, Tejas Vaja
    Neurology India.2025; 73(2): 377.     CrossRef
  • Craniovertebral junction degenerative arthritis- evolving understanding
    Atul Goel, Nasser M.F. El–Ghandour, Abhidha Shah, Apurva Prasad, Ravikiran Vutha, Siddharth Gautam, Tejas Vaja, Arjun Dhar
    Journal of Clinical Neuroscience.2025; 142: 111638.     CrossRef
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    Cukurova Medical Journal.2025; 50(3): 732.     CrossRef
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  • Defining role of atlantoaxial and subaxial spinal instability in the pathogenesis of cervical spinal degeneration: Experience with “only-fixation” without any decompression as treatment in 374 cases over 10 years
    Atul Goel, Ravikiran Vutha, Abhidha Shah, Apurva Prasad, Ashutosh Kumar Shukla, Shradha Maheshwari
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    Atul Goel
    Journal of Neurosurgery: Spine.2022; : 1.     CrossRef
  • Is evidence of bone “formation” and “fusion” in the spinal segment an evidence of segmental spinal instability?
    Atul Goel
    Journal of Craniovertebral Junction and Spine.2022; 13(4): 365.     CrossRef
  • Type I Chiari Malformation Without Concomitant Bony Instability: Assessment of Different Surgical Procedures and Outcomes in 73 Patients
    Kamlesh Rangari, Kuntal Kanti Das, Suyash Singh, Krishna G. Kumar, Kamlesh Singh Bhaisora, Jayesh Sardhara, Anant Mehrotra, Arun Kumar Srivastava, Awadhesh Kumar Jaiswal, Sanjay Behari
    Neurospine.2021; 18(1): 126.     CrossRef
  • The management of Chiari malformation type 1 and syringomyelia in children: a review of the literature
    Veronica Saletti, Mariangela Farinotti, Paola Peretta, Luca Massimi, Palma Ciaramitaro, Saba Motta, Alessandra Solari, Laura Grazia Valentini
    Neurological Sciences.2021; 42(12): 4965.     CrossRef
  • Degenerative arthritis of the craniovertebral junction
    Atul Goel
    Journal of Craniovertebral Junction and Spine.2021; 12(4): 323.     CrossRef
  • Indicators of atlantoaxial instability
    Atul Goel
    Journal of Craniovertebral Junction and Spine.2021; 12(2): 103.     CrossRef
  • Chiari Malformation and Syringomyelia Associated with Hirayama Disease
    Atul Goel, Neha Jadhav, Abhidha Shah, Survendra Rai, Ravikiran Vutha
    World Neurosurgery.2020; 135: 241.     CrossRef
  • Adjacent-segment “central” atlantoaxial instability and C2–C3 instability following lower cervical C3–C6 interbody fusion: Report of three cases
    Atul Goel, Shashi Ranjan, Abhidha Shah, Survendra Rai, Saswat Dandpat, Abhinandan Patil, Ravikiran Vutha
    Journal of Craniovertebral Junction and Spine.2020; 11(1): 51.     CrossRef
  • Is C2-3 fusion an evidence of atlantoaxial instability? An analysis based on surgical treatment of seven patients
    Atul Goel, Dikpal Jadhav, Abhidha Shah, Survendra Rai, Saswat Dandpat, Neha Jadhav, Tejas Vaja
    Journal of Craniovertebral Junction and Spine.2020; 11(1): 46.     CrossRef
  • Letter to the editor: Cervical spondylotic myelopathy treated with laminectomy versus open-door laminoplasty
    Ahmed Ansari
    Surgical Neurology International.2020; 11: 126.     CrossRef
  • Chiari malformation type I and basilar invagination originating from atlantoaxial instability: a literature review and critical analysis
    Arthur Wagner, Lukas Grassner, Nikolaus Kögl, Sebastian Hartmann, Claudius Thomé, Maria Wostrack, Bernhard Meyer
    Acta Neurochirurgica.2020; 162(7): 1553.     CrossRef
  • Chiari 1 Formation Redefined–Clinical and Radiographic Observations in 388 Surgically Treated Patients
    Atul Goel, Dikpal Jadhav, Abhidha Shah, Survendra Rai, Saswat Dandpat, Ravikiran Vutha, Arjun Dhar, Apurva Prasad
    World Neurosurgery.2020; 141: e921.     CrossRef
  • Letter to the Editor. Cervical spondylotic myelopathy
    Atul Goel
    Journal of Neurosurgery: Spine.2020; 32(4): 631.     CrossRef
  • Central Atlantoaxial Instability: A New Clinical Entity?
    Justin S. Smith
    Neurospine.2019; 16(2): 212.     CrossRef
  • The Role of Atlantoaxial Instability on Chiari, Ossification of the Posterior Longitudinal Ligament, Spondylosis and Stenosis
    K. Daniel Riew
    Neurospine.2019; 16(2): 214.     CrossRef
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