Brain functional connectivity alterations in patients with anterior cruciate ligament injury.

Recent advancements in neuroimaging have illustrated that anterior cruciate ligament (ACL) injuries could impact the central nervous system (CNS), causing neuroplastic changes in the brain beyond the traditionally understood biomechanical consequences. While most of previous functional magnetic resonance imaging (fMRI) studies have focused on localized cortical activity changes post-injury, emerging research has suggested disruptions in functional connectivity across the brain. However, these prior investigations, albeit pioneering, have been constrained by two limitations: a reliance on small-sample participant cohorts, often limited to two to three patients, potentially limiting the generalizability of findings, and an adherence to region of interest based analysis, which may overlook broader network interactions. To address these limitations, our study employed resting-state fMRI to assess whole-brain functional connectivity in 15 ACL-injured patients, comparing them to matched controls using two distinct network analysis methods. Using Network-Based Statistics, we identified widespread reductions in connectivity that spanned across multiple brain regions. Further modular connectivity analysis showed significant decreases in inter-modular connectivity between the sensorimotor and cerebellar modules, and intra-modular connectivity within the default-mode network in ACL-injured patients. Our results thus highlight a shift from localized disruptions to network-wide dysfunctions, suggesting that ACL injuries induce widespread CNS changes. This enhanced understanding has the potential to stimulate the development of strategies aiming to restore functional connectivity and improve recovery outcomes.

Clinical Characteristics, Treatment, and Survival Outcome of Ependymoma in Infants.

BACKGROUND: Treatment modalities of ependymoma in infants remain controversial. Postoperative adjuvant radiotherapy could prolong overall survival but has the potential to affect nervous system development in infants. The role of adjuvant chemotherapy in prolonging overall survival for infants with ependymoma is still unclear. Therefore we designed this study to explore the effect of treatment modalities on survival time of infants with ependymoma. METHODS: We studied 72 infants with ependymoma from the Surveillance, Epidemiology, and End Results database in this retrospective analysis. Univariate and multivariate Cox proportional hazard models were adopted to determine hazard ratios and compare overall survival. RESULTS: Among 72 infants with ependymoma, 35 were male (48.6%) and 37 were female (51.4%). The 5-year overall survival of all patients was 67%. Forty-six infants (63.9%) received gross total resection, 20 (27.8%) received subtotal resection, and 6 (8.3%) did not receive surgical resection or only autopsy. Twenty-one infants (29.2%) received radiotherapy, and 45 (62.5%) received chemotherapy. Multivariate analysis revealed that patients accepted surgical resection (No vs. gross total resection, P < 0.001; No vs. subtotal resection, P = 0.026) and chemotherapy (No vs. Yes, P = 0.024) are the independent prognostic factors for overall survival. CONCLUSIONS: Treatment modality is associated with survival time in infants with ependymoma. The extent of resection and chemotherapy were independent prognostic factors for infants with ependymoma.

Rapid detection of isocitrate dehydrogenase 1 mutation status in glioma based on Crispr-Cas12a.

The aim is to use Crispr-Cas12a for the rapid detection of the single nucleotide polymorphism (SNP) of isocitrate dehydrogenase 1 (IDH1)-R132H locus and explore the effectiveness and consistency of this method with direct sequencing method for detecting IDH1-R132H of glioma tissue samples. 58 previous frozen tissue and 46 recent fresh tissue samples of adult diffuse glioma were selected to detect IDH1-R132H using Crispr-Cas12a. The results of immunohistochemistry (IHC) and direct sequencing methods were analyzed. We calculated the efficiency index of Crispr-Cas12a and IHC, and analyzed the consistency among Crispr-Cas12a, IHC and direct sequencing method using paired Chi-sequare test and Kappa identity test. We accomplished the rapid detection of IDH1-R132H in 60 min using Crispr-Cas12a. Regarding direct sequencing method as the gold standard, the sensitivity, specificity and consistency rate of Crispr-Cas12a was 91.4%, 95.7% and 93.1% in the frozen sample group, while 96.1%, 89.7% and 92.0% in the fresh sample group, respectively. Kappa test showed good consistency between the two methods (k = 0.858). Crispr-Cas12a can quickly and accurately detect IDH1-R132H and has good stability. It is a promising method to detect IDH1 mutation status intraoperatively.

Wavelet Analysis of Cerebral Oxygenation Signal Measured by Near-Infrared Spectroscopy in Moyamoya Disease.

BACKGROUND: Spontaneous low-frequency oscillations (LFOs) have been widely studied in cerebrovascular disease, but little is known about their role in moyamoya disease (MMD). The objective of this study was to assess the value of spontaneous LFOs in MMD based on wavelet analysis of near-infrared spectroscopy signals. METHODS: Sixty-four consecutive idiopathic adult patients were prospectively enrolled. The regional tissue oxygenation index (TOI) obtained from continuous near-infrared spectroscopy signals. Five frequency intervals of spontaneous LFOs (I, 0.0095-0.02 Hz; II, 0.02-0.06 Hz; III, 0.06-0.15 Hz; IV, 0.15-0.40 Hz; and V, 0.40-2.00 Hz) were extracted based on wavelet analysis. The data were compared between the patients and healthy control groups. Clinical features, cognitive function, and disease progression of MMD were analyzed using TOI and frequency interval data. RESULTS: Compared with the healthy control group, patients with MMD had a higher cerebral TOI in both hemispheres. Based on wavelet analysis, the spontaneous LFO of TOI was found to be significantly lower for patients with MMD in frequency intervals II to IV than that for the controls. The spontaneous LFO of TOI is also related to the Suzuki stages in intervals II to IV, stroke in interval III, and cognitive impairment in intervals III to Ⅳ. CONCLUSIONS: There were significant differences in spontaneous LFO between patients with MMD and healthy controls. The change in spontaneous LFO in MMD is related to Suzuki stage, cerebral infarction, and cognitive impairment. This might be an effective method for evaluating the severity and monitoring the progression of MMD.

Regional brain atrophy in patients with chronic ankle instability: A voxel-based morphometry study.

The objective of this study was to investigate whether brain volume changes occur in patients with chronic ankle instability (CAI) using voxel-based morphometry and assessing correlations with clinical tests. Structural magnetic resonance imaging data were prospectively acquired in 24 patients with CAI and 34 healthy controls. CAI symptoms and pain intensity were assessed using the Foot and Ankle Ability Measure (FAAM), Cumberland Ankle Instability Tool (CAIT), American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, and visual analog scale (VAS). The gray matter volume (GMV) of each voxel was compared between the two groups while controlling for age, sex, weight, and education level. Correlation analysis was performed to identify associations between abnormal GMV regions and the FAAM score, AOFAS score, VAS score, disease duration, and body mass index. Patients with CAI exhibited reduced GMV in the right precentral and postcentral areas, right parahippocampal area, left thalamus, left parahippocampal area, and left postcentral area compared to that of healthy controls. Furthermore, the right parahippocampal (r = 0.642, p = 0.001), left parahippocampal (r = 0.486, p = 0.016), and left postcentral areas (r = 0.521, p = 0.009) were positively correlated with disease duration. The left thalamus was positively correlated with the CAIT score and FAAM activities of daily living score (r = 0.463, p = 0.023 and r = 0.561, p = 0.004, respectively). A significant positive correlation was found between the local GMV of the right and left parahippocampal areas (r = 0.487, p = 0.016 and r = 0.763, p < 0.001, respectively) and the AOFAS score. Neural plasticity may occur in the precentral and postcentral areas, parahippocampal area, and thalamus in patients with CAI. The patterns of structural reorganization in patients with CAI may provide useful information on the neuropathological mechanisms of CAI.

The Potential Mechanism Behind Native and Therapeutic Collaterals in Moyamoya.

Background and Purpose: To explore the genetic basis and molecular mechanism of native arteriogenesis and therapeutic synangiosis in moyamoya disease (MMD). Methods: An angiography-based study using patients from a prospective trial of encephaloduroarteriosynangiosis (EDAS) surgery was performed. The spontaneous collaterals grades were evaluated according to the system described by a new grading system. Blood samples were collected from all the recruited patients before EDAS and during the second hospitalization 3 months post-EDAS. We performed Boolean analysis using a combination of specific cell surface markers of CD34briCD133+CD45dimKDR+. Genotyping of p.R4810K was also performed. The correlation of age, sex, initial symptoms at diagnosis, collateral grade, Suzuki stages, the RNF213 genotype, time to peak (TTP), and endothelial progenitor cell (EPC) count with good collateral circulation was evaluated. Results: Eighty-five patients with MMD were included in this study. The mutation rate of RNF213 p.R4810K in our study was 25.9% (22/85). The heterozygous mutations were occurred significantly more frequently in the cases that were presented with infarction, worse neurological status, severe posterior cerebral artery (PCA) stenosis, and longer TTP delay. Further, the heterozygous mutations occurred significantly more frequently in the poor collateral stage group. Lower grades were significantly correlated with severe ischemia symptoms, worse neurological status, and a longer TTP delay. The post-operative angiographic findings showed that a good Matsushima grade was correlated with heterozygous mutations, a lower collateral stage, and a longer TTP delay. The CD34briCD133+CD45dimKDR+ cell count in patients 3 months post-EDAS was significantly higher as compared to the count before EDAS in the good Matsushima grade group. However, this change was not observed in the poor Matsushima grade group. Conclusions: These data imply that mutations of RNF213 p.R4810K affect the establishment of spontaneous collateral circulation, and EPCs are involved in the process of formation of new EDAS collaterals.

Long-term efficacy, prognostic factors, and safety of deep brain stimulation in patients with refractory Tourette syndrome: A single center, single target, retrospective study.

BACKGROUND: To evaluate the long-term efficacy, prognostic factors, and safety of posteroventral globus pallidus internus deep brain stimulation (DBS) in patients with refractory Tourette syndrome (RTS). METHODS: This retrospective study recruited 61 patients with RTS who underwent posteroventral globus pallidus internus (GPi) DBS from January 2010 to December 2020 at the Chinese People's Liberation Army General Hospital. The Yale Global Tic Severity Scale (YGTSS), Yale-Brown Obsessive-Compulsive Scale (YBOCS), Beck Depression Inventory (BDI), Gilles de la Tourette Syndrome Quality-of-Life Scale (GTS-QOL) were used to evaluate the preoperative and postoperative clinical condition in all patients. Prognostic factors and adverse events following surgery were analyzed. RESULTS: Patient follow up was conducted for an average of 73.33 ± 28.44 months. The final postoperative YGTSS (32.39 ± 22.34 vs 76.61 ± 17.07), YBOCS (11.26 ± 5.57 vs 18.31 ± 8.55), BDI (14.36 ± 8.16 vs 24.79 ± 11.03) and GTS-QOL (39.69 ± 18.29 vs 78.08 ± 14.52) scores at the end of the follow-up period were significantly lower than those before the surgery (p < 0.05). While age and the duration of follow-up were closely related to prognosis, the disease duration and gender were not. No serious adverse events were observed and only one patient exhibited symptomatic deterioration. CONCLUSIONS: Posteroventral-GPI DBS provides long-term effectiveness, acceptable safety and can improve the quality of life in RTS patients. Moreover, DBS is more successful among younger patients and with longer treatment duration.

Indirect Ventral Brainstem Decompression by Posterior C1-C2 Distraction and Fixation for Basilar Invagination.

OBJECTIVE: Basilar invagination usually shows a decrease of clivus axis angle (CAA), which could give rise to progressive neural compression. Exploring a safe and effective fixation technique to achieve atlantoaxial stability and neural decompression remains necessary. In this study, we introduce a modified posterior C1-C2 distraction and fixation technique by which we obtained indirect ventral neural decompression and atlantoaxial stability in a series of patients with decreased CAA. METHODS: Thirty patients of basilar invagination were enrolled in our series. All patients underwent thin-slice computed tomography (CT) scan, magnetic resonance imaging, and dynamic plain radiography examinations before surgery, at discharge and during the follow-ups. Posterior C1-C2 facet joint release and intraoperative reduction by fastening rods were performed in all patients. The CAA was measured on midsagittal CT scans. Patients' neurologic status was evaluated by the Japanese Orthopaedic Association score. RESULTS: No neurovascular injury and serious postoperative complication occurred in all patients. Complete ventral brainstem decompression was achieved in 20 patients and partial in 10 patients. The mean postoperative CAA significantly improved to 132.6 degrees compared with the preoperative 123.6 degrees (P < 0.01). The bone fusion was confirmed in all patients on the basis of the last follow-up spine CT scans. CONCLUSIONS: Indirect ventral brainstem decompression by posterior C1-C2 distraction and fixation is a safe and effective technique for treatment of basilar invagination.

Can C1 lateral mass and C3 pedicle screw fixation be used as an option for atlantoaxial reduction and stabilization in Klippel-Feil patients? A study of its morphological feasibility, technical nuances, and clinical efficiency.

In Klippel-Feil patients with atlantoaxial dislocation, narrow C2 pedicles are often encountered preventing pedicle screw placement. Alternative techniques, including translaminar screws, pars screws, and inferior process screws could not achieve 3-column rigid fixation, and have shown inferior biomechanical stability. The present study aimed to evaluate the feasibility, safety, and efficacy of C3 pedicle screws (C3PSs) as an option for atlantoaxial stabilization in Klippel-Feil patients, and to introduce a freehand technique, the "medial sliding technique," for safe and accurate C3PS insertion. Thirty-seven Klippel-Feil patients with congenital C2-3 fusion who have received atlantoaxial fixation were reviewed. Preoperative CT and CT angiography were acquired to evaluate the feasibility of C3PS placement. C1 lateral mass and C3PS constructs were used for atlantoaxial stabilization. The "medial sliding technique" was introduced to facilitate C3PS insertion. Clinical outcomes and complications were evaluated, and screw accuracy was graded on postoperative CT scans. Morphological measurements showed that more than 80% C3 pedicles could accommodate a 3.5-mm screw. Fifty-eight C3PSs were placed in 33/37 patients using the medial sliding technique. Overall, 96.7% screws were considered safe and there was no related neurovascular complications; 27/33 patients exhibited neurological improvement and 30/33 patients had a solid bone fusion at an average 19.3-month follow-up. Therefore, the C3PS was a feasible option for atlantoaxial fixation in Klippel-Feil patients. The clinically efficiency of C3PS was satisfied with high fusion rates and low complications. The medial sliding technique we used could facilitate safe and accurate placement of C3PSs in Klippel-Feil patients with fused C2-3 vertebra.

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

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

Feasibility of occipital condyle screw placement in patients with Chiari malformation type I: a computed tomography-based morphometric study.

BACKGROUND: The occipital condyle (OC) screw is an alternative technique for occipitocervical fixation that is especially suitable for revision surgery in patients with Chiari malformation type I (CMI). This study aimed to investigate the feasibility and safety of this technique in patients with CMI. METHODS: The CT data of 73 CMI patients and 73 healthy controls were retrospectively analyzed. The dimensions of OCs, including length, width, height, sagittal angle, and screw length, were measured in the axial, sagittal, and coronal planes using CT images. The OC available height was measured in the reconstructed oblique parasagittal plane of the trajectory. RESULTS: The mean length, width, and height of OCs in CMI patients were 17.79 ± 2.31 mm, 11.20 ± 1.28 mm, and 5.87 ± 1.29 mm, respectively. All OC dimensions were significantly smaller in CMI patients compared with healthy controls. The mean screw length and sagittal angle were 19.13 ± 1.97 mm and 33.94° ± 5.43°, respectively. The mean OC available height was 6.36 ± 1.59 mm. According to criteria based on OC available height and width, 52.1% (76/146) of OCs in CMI patients could safely accommodate a 3.5-mm-diameter screw. CONCLUSIONS: The OC screw is feasible in approximately half of OCs in CMI patients. Careful morphometric analyses and personalized surgical plans are necessary for the success of this operation in CMI patients.

Identification of risk factors for poor language outcome in surgical resection of glioma involving the arcuate fasciculus: an observational study.

The arcuate fasciculus is a critical component of the neural substrate of human language function. Surgical resection of glioma adjacent to the arcuate fasciculus likely damages this region. In this study, we evaluated the outcome of surgical resection of glioma adjacent to the arcuate fasciculus under the guidance of magnetic resonance imaging and diffusion tensor imaging, and we aimed to identify the risk factors for postoperative linguistic deficit. In total, 54 patients with primary glioma adjacent to the arcuate fasciculus were included in this observational study. These patients comprised 38 men and 16 women (aged 43 ± 11 years). All patients underwent surgical resenction of glioma under the guidance of magnetic resonance imaging and diffusion tensor imaging. Intraoperative images were updated when necessary for further resection. The gross total resection rate of the 54 patients increased from 38.9% to 70.4% by intraoperative magnetic resonance imaging. Preoperative language function and glioma-to-arcuate fasciculus distance were associated with poor language outcome. Multivariable logistic regression analyses showed that glioma-to-arcuate fasciculus distance was the major independent risk factor for poor outcome. The cutoff point of glioma-to-arcuate fasciculus distance for poor outcome was 3.2 mm. These findings suggest that intraoperative magnetic resonance imaging combined with diffusion tensor imaging of the arcuate fasciculus can help optimize tumor resection and result in the least damage to the arcuate fasciculus. Notably, glioma-to-arcuate fasciculus distance is a key independent risk factor for poor postoperative language outcome. This study was approved by the Ethics Committee of the Chinese PLA General Hospital, China (approval No. S2014-096-01) on October 11, 2014.

A morphometric study of the atlanto-occipital joint in adult patients with Chiari malformation type I.

BACKGROUND: There are many morphometric studies on Chiari malformation type I (CMI) patients, most of which focus on the posterior cranial fossa (PCF). Less attention has been paid to the atlanto-occipital joint. In this study, we aim to evaluate the morphological characteristics of the atlanto-occipital joint in CMI patients. MATERIALS AND METHODS: The cervical CT imaging data of adult patients diagnosed with CMI but without any bony malformation in craniovertebral junction (CVJ) who were treated by the authors between January 2014 and December 2019 were retrospectively analyzed. The equal number of sex and age-matched healthy individuals were included as the control group. The morphometric analysis was performed by measuring the length and depth of the atlanto-occipital joint, and the depth/length ratio was calculated to evaluate the curvature of the joint. RESULTS: A total of 47 patients (15 males and 32 females) were included. The mean age of patients was 47.49 ± 9.01 years (range 19-62 years). The mean depth/length ratio of the atlanto-occipital joint in CMI patients was 0.141 ± 0.065 (range 0.027 - 0.274), which was smaller than that of control individuals (0.228 ± 0.057, range 0.069 - 0.379). And the difference was statistically significant (p < .01). CONCLUSIONS: The atlanto-occipital joints in CMI patients are significantly flatter compared with those in healthy controls. This morphological variation could lead to differences of the atlanto-occipital stability between CMI patients and normal population, which may be related to the pathogenesis of CMI.

TRIM24 promotes stemness and invasiveness of glioblastoma cells via activating Sox2 expression.

BACKGROUND: Glioblastoma stem cells (GSCs) are a subpopulation of glioblastoma (GBM) cells that are critical for tumor invasion and treatment resistance. However, little is known about the function and mechanism of tripartite motif-containing 24 (TRIM24) in GSCs. METHODS: Immunofluorescence, flow cytometry, and western blot analyses were used to evaluate TRIM24 and cluster of differentiation (CD)133 expression profiles in GBM surgical specimens and GSC tumorspheres. Different TRIM24 expression levels in patients' tumors, as measured by both immunohistochemistry and western blot, were related to their corresponding MRI data. Wound healing, Matrigel invasion, and xenograft immunohistochemistry were conducted to determine GBM cell invasion. RESULTS: We identified that TRIM24 was coexpressed with CD133 and Nestin in GBM tissues and tumorsphere cells. Limiting dilution assays and xenotransplantation experiments illustrated that knockdown of TRIM24 expression reduced GSC self-renewal capacity and invasive growth. TRIM24 expression levels were positively associated with the volumes of peritumoral T2 weighted image abnormality. Rescue experiments indicated TRIM24 participation in GBM infiltrative dissemination. Chromatin immunoprecipitation, reporter gene assay, PCR, western blot, and immunohistochemistry demonstrated that TRIM24 activated the expression of the pluripotency transcription factor sex determining region Y-box 2 (Sox2) to regulate GBM stemness and invasion in vitro and in vivo. Finally, the close relationship between TRIM24 and Sox2 was validated by testing samples enrolled in our study and exploring external databases. CONCLUSIONS: Our findings uncover essential roles of the TRIM24-Sox2 axis in GBM stemness and invasiveness, suggesting TRIM24 as a potential target for effective GBM management.

The Role of Transverse Connectors in C1-C2 fixation for Atlantoaxial Instability: Is It Necessary? A Biomechanical Study.

OBJECTIVE: To investigate the biomechanical effect of C1 lateral mass-C2 pedicle screw-rod (C1LM-C2PS) fixation with and without transverse connectors (TC) in an atlantoaxial instability (AAI) model. METHODS: Ten freshly frozen cadaveric specimens were tested using an industrial robot under the following conditions: intact model, AAI model, C1-C2 model, C1-C2 with one TC model, and C1-C2 with two TCs model. Three types of motion, flexion-extension (FE), lateral bending (LB), and axial rotation (AR), were applied (1.5 Nm) to the specimens. The range of motion (ROM) and neutral zone (NZ) between C1 and C2 in all directions were measured. RESULTS: Compared with those of the intact and AAI models, the C1-C2 ROM and NZ of all instrumented groups were decreased significantly in each direction of loading motion (P < 0.05). The mean FE ROM in the no TC, 1 TC, and 2 TC groups was 2.12° ± 0.41°, 2.29° ± 0.42°, and 2.04° ± 0.69°, respectively (P = 0.840, 0.981, 0.628, respectively); the mean LB ROM in the 3 intervention groups was 1.26° ± 0.67°, 1.02° ± 0.51° and 1.03° ± 0.57°, respectively (P = 0.489, 0.501, 1.000, respectively). During AR, the ROM and NZ of the no TC group (3.19° ± 0.89° and 1.51° ± 0.42°) were significantly reduced by more than 60% compared with those in the 1 (0.98° ± 0.28° and 0.40° ± 0.11°) and 2 TC groups (1.17° ± 1.69° and 0.42° ± 0.61°) (P < 0.001). Two TCs were equivalent for all loading motions to 1 TC (P > 0.05). CONCLUSIONS: Adding TCs to C1LM-C2PS can effectively decrease the axial rotation ROM and enhance the stability of C1-C2 segment. Therefore, it is necessary to use TC-strengthened C1 lateral mass -C2 pedicle screw-rod fixation in patients with instability of C1-C2.

C2 medial pedicle screw: a novel "in-out-in" technique as an alternative option for posterior C2 fixation in cases with a narrow C2 isthmus.

OBJECTIVE: The authors describe a novel "in-out-in" technique as an alternative option for posterior C2 screw fixation in cases that involve narrow C2 isthmus. Here, they report the preliminary radiological and clinical outcomes in 12 patients who had a minimum 12-month follow-up period. METHODS: Twelve patients with basilar invagination and atlantoaxial dislocation underwent atlantoaxial reduction and fixation. All patients had unilateral hypoplasia of the C2 isthmus that prohibited insertion of pedicle screws. A new method, the C2 medial pedicle screw (C2MPS) fixation, was used as an alternative. In this technique, the inner cortex of the narrow C2 isthmus was drilled to obtain space for screw insertion, such that the lateral cortex could be well preserved and the risk of vertebral artery injury could be largely reduced. The C2MPS traveled along the drilled inner cortex into the anterior vertebral body, achieving a 3-column fixation of the axis with multicortical purchase. RESULTS: Satisfactory C2MPS placement and reduction were achieved in all 12 patients. No instance of C2MPS related vertebral artery injury or dural laceration was observed. There were no cases of implant failure, and solid fusion was demonstrated in all patients. CONCLUSIONS: This novel in-out-in technique can provide 3-column rigid fixation of the axis with multicortical purchase. Excellent clinical outcomes with low complication rates were achieved with this technique. When placement of a C2 pedicle screw is not possible due to anatomical constraints, the C2MPS can be considered as an efficient alternative.

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

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

Biomechanical evaluation of two alternative techniques to the Goel-Harms technique for atlantoaxial fixation: C1 lateral mass-C2 bicortical translaminar screw fixation and C1 lateral mass-C2/3 transarticular screw fixation.

OBJECTIVE: The authors conducted a study to investigate the biomechanical feasibility and stability of C1 lateral mass-C2 bicortical translaminar screw (C1LM-C2TL) fixation, C1 lateral mass-C2/3 transarticular screw (C1LM-C2/3TA) fixation, and C1LM-C2/3TA fixation with transverse cross-links (C1LM-C2/3TACL) as alternative techniques to the Goel-Harms technique (C1 lateral mass-C2 pedicle screw [C1LM-C2PS] fixation) for atlantoaxial fixation. METHODS: Eight human cadaveric cervical spines (occiput-C7) were tested using an industrial robot. Pure moments that were a maximum of 1.5 Nm were applied in flexion-extension (FE), lateral bending (LB), and axial rotation (AR). The specimens were first tested in the intact state and followed by destabilization (a type II odontoid fracture) and fixation as follows: C1LM-C2PS, C1LM-C2TL, C1LM-C2/3TA, and C1LM-C2/3TACL. For each condition, the authors evaluated the range of motion and neutral zone across C1 and C2 in all directions. RESULTS: Compared with the intact spine, each instrumented spine significantly increased in stability at the C1-2 segment. C1LM-C2TL fixation demonstrated similar stability in FE and LB and greater stability in AR than C1LM-C2PS fixation. C1LM-C2/3TA fixation was equivalent in LB and superior in FE to those of C1LM-C2PS and C1LM-C2TL fixation. During AR, the C1LM-C2/3TA-instrumented spine failed to maintain segmental stability. After adding a cross-link, the rotational stability was significantly increased in the C1LM-C2/3TACL-instrumented spine compared with the C1LM-C2/3TA-instrumented spine. Although inferior to C1LM-C2TL fixation, the C1LM-C2/3TACL-instrumented spine showed equivalent rotational stability to the C1LM-C2PS-instrumented spine. CONCLUSIONS: On the basis of our biomechanical study, C1LM-C2TL and C1LM-C2/3TACL fixation resulted in satisfactory atlantoaxial stabilization compared with C1LM-C2PS. Therefore, the authors believe that the C1LM-C2TL and C1LM-C2/3TACL fixation may serve as alternative procedures when the Goel-Harms technique (C1LM-C2PS) is not feasible due to anatomical constraints.

Can Posterior Reduction Replace Odontoidectomy as Treatment for Patients With Congenital Posterior Atlantoaxial Dislocation and Basilar Invagination?

BACKGROUND: For patients with odontoid process protrusion and basilar invagination, posterior screw-rod fixation can usually achieve satisfactory horizontal reduction, but in some cases satisfactory reduction in the vertical direction cannot be achieved at the same time. OBJECTIVE: To propose a method for calculation of the theoretical maximum vertical reduction possible in individual patients. METHODS: The computed tomography imaging data of patients with occipitalization and basilar invagination who were treated at our institute between January 2013 and June 2016 were retrospectively analyzed. The direction of odontoid reduction was decided by the inclination of the lateral joint. The atlanto-dental distance was assumed to be the maximum possible reduction in the horizontal direction. The maximum vertical reduction possible was calculated based on these values. RESULTS: A total of 82 patients (34 males and 48 females) were included. The theoretical vertical reduction value was 4.2 ± 3.0 mm, which was significantly smaller than that of the dental protrusion (14.5 ± 3.8 mm, P = .000). Analysis of follow-up data (29 cases) showed that, the difference between the theoretical vertical reduction value H (4.7 ± 3.5 mm) and the actual vertical reduction value Ha (5.6 ± 3.5 mm) was not significant (P = .139). CONCLUSION: The theoretical calculation method we proposed can well predict the actual degree of vertical reduction. The theoretical vertical reduction value is significantly lower than the odontoid protrusion value, indicating that satisfactory reduction in the vertical direction is difficult with a posterior approach alone.