The Feasibility of Condylar Screws for Occipitocervical Fusion in Arabs: Computed Tomography-Based Morphometric Study.

STUDY DESIGN: Retrospective, cross-sectional study. OBJECTIVES: Occipitocervical fusion is indicated for various conditions. Some techniques require placement of screws in the occipital condyle. The objective of this study was to analyze the morphometric features of the occipital condyle among Arabs. METHODS: Computed tomography (CT)-based morphometric analysis of occipital condyles of 200 Arab skeletally mature patients (400 condyles) was done. Axial width of at least 8 mm and coronal height of at least 6.5 mm are the cutoff values for feasibility of condylar screw placement. RESULTS: The mean age of the patients was 48.0 ± 18.3 years. Males were 53.5% (107) of the sample. The mean axial condylar width and length were 8.5 ± 1.5 mm and 20.3 ± 2.6 mm, respectively, while the mean axial screw angle was 35.9° ± 5.5° from midline. The mean sagittal condylar length and height were 16.1 ± 1.9 mm and 8.8 ± 1.5 mm, respectively. The mean condylar coronal height was 8.2 ± 1.4 mm. Based on axial width and coronal height measurements, 150 (37.5%) condyles could safely fit a 3.5 mm condylar screw. One hundred and four (55.9% female condyles) condyles cannot fit a screw in females, while 46 (21.5% male condyles) condyles cannot fit a screw in males. CONCLUSIONS: Condylar screw for occipitocervical fusion is feasible for the majority of Arabs in our sample; however, this applies to slightly less than half of the female condyles. Detailed preoperative radiological planning is critical to avoid complications related to occipital condyle screw placement.

Endoscopic Endonasal Occipitocervical Fixation with a Customized Three-Dimensional Printed Titanium Plate-Screw Construct: A Cadaveric Feasibility Study.

OBJECTIVE: To evaluate the feasibility of a novel method for occipitocervical fixation (OCF) through the endonasal corridor. METHODS: Thin-cut computed tomography scans were obtained for 5 cadaveric specimens. Image segmentation was used to reconstruct 3D models of each O-C1 joint complex. Using computer-aided design software, plates were custom-designed to span each O-C1 joint, sit flush onto the bony surface, and accommodate screws. The final models were 3D-printed in titanium. For implantation, specimens were held in pin-fixation and registered to neuronavigation. A rigid 0º endoscope was used for endonasal visualization. An inverted U-shaped nasopharyngeal flap was raised to expose the occipital condyles and C1. The plates were introduced and fixed with bone screws. Computed tomography scans were obtained to assess screw accuracy and proximity to critical neurovascular structures. Screw entry points and trajectories were recorded. RESULTS: Endonasal OCF was performed on 5 cadaveric specimens. The mean starting point for occipital condyle screws was 6.17 mm lateral and 5.38 mm rostral to the medial O-C1 joint. Mean axial and sagittal trajectories were 7.98° and 6.71°, respectively. The mean starting point for C1 screws was 16.11 mm lateral to the C1 anterior tubercle and 6.39 mm caudal to the medial O-C1 joint. Mean axial and sagittal trajectories were 10.97° and -9.91°, respectively. CONCLUSIONS: Endonasal OCF is technically and anatomically feasible. The application of this technique may allow for same-stage endonasal decompression and fixation, offering a minimally invasive alternative to current methods of fixation and advancing surgeons' ability to treat pathology of the craniovertebral junction. Next steps will focus on biomechanical testing.

Evaluation of the Bone Union Occurring Subsequent to C1-2 Fusion Combined With C1 Laminectomy for the Surgical Treatment of Retro-Odontoid Pseudotumor.

Introduction Surgical treatments for retro-odontoid pseudotumors (ROPs) include C1 laminectomies and C1-2 and occipitocervical (OC) fusions. When a C1 laminectomy is combined with a C1-2 fusion, concerns arise regarding an increased risk of pseudarthrosis due to decreased bone grafting space. Extension of the fusion area to the OC region may be considered to ensure an adequate bone graft bed. However, this procedure is associated with a risk of complications. Thus, in this study, we investigated the bone fusion and clinical outcomes of C1-2 fusion combined with a C1 laminectomy. Methods Between January 2017 and December 2022, seven patients with ROPs who had undergone C1-2 fusion combined with a C1 laminectomy were included in the study. All patients were followed up for >1 year. Bone fusion was evaluated by computed tomography (CT) at one year postoperatively, while implant failure was assessed by radiography at the final follow-up. Clinical evaluations included preoperative and one-year postoperative Japanese Orthopaedic Association (JOA) scores and recovery rates. Results This study included five male and two female patients, with an average age of 71.9 years. The average follow-up duration was 3.3 years. The primary anchor choices included the C1 lateral mass screw and the C2 pedicle screw. In one case, the transarticular screw was utilized unilaterally, and in another case, a lamina screw was utilized unilaterally. One year postoperatively, CT revealed bone fusion in three of the seven patients. Fusion occurred at the lateral and median atlantoaxial joints in two cases and one case, respectively. Screw loosening was observed in one case. None of the patients required reoperations. The average JOA recovery rate was 34.6%. Conclusion This surgical technique is useful for stabilizing and decompressing the C1-2 region while preserving mobility at the OC joint. However, further long-term follow-up studies are required.

Anatomical determinants of occipitocervical fusion in skull base chordoma resection: a systematic review of the literature with illustrative cases.

OBJECTIVE: Skull base chordomas are rare, locally osseo-destructive lesions that present unique surgical challenges due to their involvement of critical neurovascular and bony structures at the craniovertebral junction (CVJ). Radical cytoreductive surgery improves survival but also carries significant morbidity, including the potential for occipitocervical (OC) destabilization requiring instrumented fusion. The published experience on OC fusion after CVJ chordoma resection is limited, and the anatomical predictors of OC instability in this context remain unclear. METHODS: PubMed and Embase were systematically searched according to the PRISMA guidelines for studies describing skull base chordoma resection and OC fusion. The search strategy was predefined in the authors' PROSPERO protocol (CRD42024496158). RESULTS: The systematic review identified 11 surgical case series describing 209 skull base chordoma patients and 116 (55.5%) who underwent OC instrumented fusion. Most patients underwent lateral approaches (n = 82) for chordoma resection, followed by midline (n = 48) and combined (n = 6) approaches. OC fusion was most often performed as a second-stage procedure (n = 53), followed by single-stage resection and fusion (n = 38). The degree of occipital condyle resection associated with OC fusion was described in 9 studies: total unilateral condylectomy reliably predicted OC fusion regardless of surgical approach. After lateral transcranial approaches, 4 studies cited at least 50%-70% unilateral condylectomy as necessitating OC fusion. After midline approaches-most frequently the endoscopic endonasal approach (EEA)-at least 75% unilateral condylectomy (or 50% bilateral condylectomy) led to OC fusion. Additionally, resection of the medial atlantoaxial joint elements (the C1 anterior arch and tip of the dens), usually via EEA, reliably necessitated OC fusion. Two illustrative cases are subsequently presented, further exemplifying how the extent of CVJ bony elements removed via EEA to achieve complete chordoma resection predicts the need for OC fusion. CONCLUSIONS: Unilateral total condylectomy, 50% bilateral condylectomy, and resection of the medial atlantoaxial joint elements were the most frequently described independent predictors of OC fusion in skull base chordoma resection. Additionally, consistent with the occipital condyle harboring a significantly thicker joint capsule at its posterolateral aspect, an anterior midline approach seems to tolerate a greater degree of condylar resection (75%) than a lateral transcranial approach (50%-70%) prior to generating OC instability.

The role of occipital condyle and atlas anomalies on occipital cervical fusion outcomes in Chiari malformation type I with syringomyelia: a study from the Park-Reeves Syringomyelia Research Consortium.

OBJECTIVE: Congenital anomalies of the atlanto-occipital articulation may be present in patients with Chiari malformation type I (CM-I). However, it is unclear how these anomalies affect the biomechanical stability of the craniovertebral junction (CVJ) and whether they are associated with an increased incidence of occipitocervical fusion (OCF) following posterior fossa decompression (PFD). The objective of this study was to determine the prevalence of condylar hypoplasia and atlas anomalies in children with CM-I and syringomyelia. The authors also investigated the predictive contribution of these anomalies to the occurrence of OCF following PFD (PFD+OCF). METHODS: The authors analyzed the prevalence of condylar hypoplasia and atlas arch anomalies for patients in the Park-Reeves Syringomyelia Research Consortium database who underwent PFD+OCF. Condylar hypoplasia was defined by an atlanto-occipital joint axis angle (AOJAA) ≥ 130°. Atlas assimilation and arch anomalies were identified on presurgical radiographic imaging. This PFD+OCF cohort was compared with a control cohort of patients who underwent PFD alone. The control group was matched to the PFD+OCF cohort according to age, sex, and duration of symptoms at a 2:1 ratio. RESULTS: Clinical features and radiographic atlanto-occipital joint parameters were compared between 19 patients in the PFD+OCF cohort and 38 patients in the PFD-only cohort. Demographic data were not significantly different between cohorts (p > 0.05). The mean AOJAA was significantly higher in the PFD+OCF group than in the PFD group (144° ± 12° vs 127° ± 6°, p < 0.0001). In the PFD+OCF group, atlas assimilation and atlas arch anomalies were identified in 10 (53%) and 5 (26%) patients, respectively. These anomalies were absent (n = 0) in the PFD group (p < 0.001). Multivariate regression analysis identified the following 3 CVJ radiographic variables that were predictive of OCF occurrence after PFD: AOJAA ≥ 130° (p = 0.01), clivoaxial angle < 125° (p = 0.02), and occipital condyle-C2 sagittal vertical alignment (C-C2SVA) ≥ 5 mm (p = 0.01). A predictive model based on these 3 factors accurately predicted OCF following PFD (C-statistic 0.95). CONCLUSIONS: The authors' results indicate that the occipital condyle-atlas joint complex might affect the biomechanical integrity of the CVJ in children with CM-I and syringomyelia. They describe the role of the AOJAA metric as an independent predictive factor for occurrence of OCF following PFD. Preoperative identification of these skeletal abnormalities may be used to guide surgical planning and treatment of patients with complex CM-I and coexistent osseous pathology.

Association between structural rib autograft and the rate of arthrodesis in children undergoing occiput-C2 instrumentation and fusion.

OBJECTIVE: The purpose of this study was to identify factors associated with fusion success among pediatric patients undergoing occiput-C2 rigid instrumentation and fusion. METHODS: The Pediatric Spine Study Group registry was queried to identify patients ≤ 21 years of age who underwent occiput-C2 posterior spinal rigid instrumentation and fusion and had a 2-year minimum clinical and radiographic (postoperative lateral cervical radiograph or CT scan) follow-up. Fusion failure was defined clinically if a patient underwent hardware revision surgery > 30 days after the index procedure or radiographically by the presence of hardware failure or screw haloing on the most recent follow-up imaging study. Univariate comparisons and multivariable logistic regression analyses were subsequently performed. RESULTS: Seventy-six patients met inclusion criteria. The median age at surgery was 9 years (range 1.5-17.2 years), and 51% of the cohort was male. Overall, 75% of patients had syndromic (n = 41) or congenital (n = 15) etiologies, with the most frequent diagnoses of Down syndrome (28%), Chiari malformation (13%), and Klippel-Feil syndrome (12%). Data were available to determine if there was a fusion failure in 97% (74/76) of patients. Overall, 38% (28/74) of patients had fusion failure (95% CI 27%-50%). Univariate analysis demonstrated that use of a rigid cervical collar postoperatively (p = 0.04) and structural rib autograft (p = 0.02) were associated with successful fusion. Multivariable logistic regression analysis determined that patients who had rib autograft used in surgery had a 73% decrease in the odds of fusion failure (OR 0.27, 95% CI 0.09-0.82; p = 0.02). Age, etiology including Down syndrome, instrumentation type, unilateral instrumentation, use of recombinant human bone morphogenetic protein, and other variables did not influence the risk for fusion failure. CONCLUSIONS: In this multicenter, multidisciplinary, international registry of children undergoing occiput-C2 instrumentation and fusion, fusion failure was seen in 38% of patients, a higher rate than previously reported in the literature. The authors' data suggest that postoperative immobilization in a rigid cervical collar may be beneficial, and the use of structural rib autograft should be considered, as rib autograft was associated with a 75% higher chance of successful fusion.

Dysphagia, health-related quality of life, and return to work after occipitocervical fixation.

PURPOSE: The purpose of this study was to evaluate patient-reported outcome measures (PROMS) on dysphagia, health-related quality of life (HRQoL) and return to work after occipitocervical fixation (OCF). Postoperative radiographic measurements were evaluated to identify possible predictors of dysphagia. METHODS: All individuals (≥ 18 years) who underwent an OCF at the study center or were registered in the Swedish spine registry (Swespine) between 2005 and 2019, and were still alive when the study was conducted, were eligible for inclusion. There was no overlap between the cohorts. Prospectively collected data on dysphagia (Dysphagia Short Questionnaire DSQ), HRQoL (EQ5D-3L) and return to work were used. Radiological and baseline patient data were retrospectively collected. In addition, HRQoL data of a matched sample of individuals was elicited from the Stockholm Public Health Survey 2006. RESULTS: In total, 54 individuals were included. At long-term follow-up, 26 individuals (51%) had no dysphagia, and 25 (49%) reported some degree of dysphagia: 11 (22%) had mild dysphagia, and 14 (27%) had moderate to severe dysphagia. On a group level, the OCF sample scored significantly lower EQVAS and EQ-5Dindex values compared to the general population (60.0 vs. 80.0, p = 0.016; 0.43 vs. 0.80, p < 0.001). Individuals working preoperatively returned to work after surgery. Of those responding, 88% stated that they would undergo the OCF operation if it was offered today. No predictors of dysphagia based on radiographic measurements were identified. CONCLUSION: Occipitocervical fixation results in a high frequency of long-term dysphagia. The HRQoL of OCF patients is significantly reduced compared to matched controls. However, most patients are satisfied with their surgery. No radiographic predictors of long-term dysphagia could be identified. Future prospective and systematic studies with larger samples and more objective outcome measures are needed to elucidate the causes of dysphagia in OCF.

The impact of social determinants of health on early outcomes after adult Chiari surgery.

We sought to identify social determinants of health (SDoH) for adult patients undergoing Chiari decompression surgery and to analyze their association with postoperative outcomes, including length of stay (LOS), return to the system within 30 days, and the Chicago Chiari Outcomes Score (CCOS). This is a retrospective study of adult patients who underwent Chiari decompression surgery between June 2021 and January 2023. Data was gathered through electronic medical record review and telephone surveys. Descriptive statistics were used to evaluate demographics of all patients meeting inclusion criteria. Fisher's exact tests and logistic regression were used for data analysis. A total of 37 patients underwent Chiari decompression (23 CCOS/SDoH survey respondents): 48% bony decompression only, 30% bony decompression plus intradural exploration, and 22% occipitocervical fusion. Seven patients (30%) had a LOS > 2 days, 1 patient (4%) required inpatient rehabilitation postoperatively, 4 patients (17%) returned to the system within 30 days, 10 patients (43%) had an extremely favorable CCOS (15-16), and 11 patients (48%) reported interaction with a Chiari support group. Mean follow-up was 9.5 months. Patients with occipitocervical fusion were more likely to have a LOS > 2 days (p = 0.03), patients who exercised ≥ 3 days per week were more likely to have a favorable CCOS (p = 0.04), and patients who participated in a Chiari support group were less likely to have a favorable CCOS (p = 0.03). Chiari decompression plus occipitocervical fusion may be associated with increased LOS. While more frequent exercise may be associated with better post-surgical outcomes, participation in a Chiari support group may be correlated with worse outcomes.

Cranial vault suspension for basilar invagination in patients with open cranial sutures: technique and long-term follow-up. Illustrative case.

BACKGROUND: Hajdu-Cheney syndrome (HCS) is an extremely rare genetic disorder characterized by severe osteoporosis, scoliosis, and persistent open cranial sutures (POCSs). Neurological complications include hydrocephalus, Chiari I malformations, and basilar invagination (BI). Surgical intervention in HCS is challenging due to severe osteoporosis, ligamentous laxity, POCSs, and extreme skeletal deformities. Herein, the authors present a case of BI repair in a patient with HCS and POCSs, requiring a novel technique of cranial vault suspension, with long-term follow-up. OBSERVATIONS: A 20-year-old female with HCS and progressive symptomatic BI, initially managed with posterior fossa decompression and occipital to cervical fusion, subsequently required cranial vault expansion due to symptomatic shifting of her cranium secondary to POCS. This custom construct provided long-term stabilization and neurological improvement over a follow-up duration of 9.5 years. A literature review performed revealed three other cases of surgical intervention for BI in patients with HCS and clinicopathological characteristics of each case was compared to the present illustrative case. LESSONS: POCSs in patients with BI complicate traditional surgical approaches, necessitating more invasive techniques to secure all mobile cranial parts for optimal outcomes. Using this cranial vault suspension and fusion technique results in lasting neurological improvement and construct stability.

Partial atlantooccipital assimilation causing atlantoaxial instability and early myelopathy in an adult treated with occipitocervical fusion: A case report.

INTRODUCTION & IMPORTANCE: Atlanto-occipital assimilation is a rare congenital abnormality which can cause atlantoaxial instability. Basilar invagination and instability can lead to cord compression and myelopathy in young individuals. CASE REPORT & DISCUSSION: A 37-year-old male presented with gradually worsening axial neck pain for four years duration His deep tendon reflexes are exaggerated in all four limbs but there is no weakness or imbalance. Following radiological evaluation, he was diagnosed to have partial atlantooccipital assimilation causing atlantoaxial instability, basilar invagination and early myelopathy. He was treated with occipital-cervical fusion after the closed reduction of the atlantoaxial joint. CONCLUSION: Atlanto-axial assimilation can lead to atlantoaxial instability and subsequently myelopathy. Dynamic radiographs and computed tomography are helpful in the diagnosis. Reducible atlantoaxial instability can be managed with closed reduction and occipitocervical fusion.

Comparative Study of Surgical Outcomes of Occipitocervical and Atlantoaxial Fusion for Retro-Odontoid Pseudotumor.

OBJECTIVE: To compare the surgical and radiographic outcomes of occipitocervical fusion (OCF) with those of atlantoaxial fusion (AAF) in patients with cervical myelopathy caused by retroodontoid pseudotumors (ROPs). METHODS: This retrospective, comparative study included 26 patients; 12 underwent occipitocervical fusion (OCF) (group O) and 14 retroodontoid pseudotumor (AAF) (group A) with a minimum 2-year follow-up. Neurologic outcomes were evaluated using the Japanese Orthopedic Association (JOA) score. Radiologic assessment included the maximum anteroposterior (AP) diameter of the anteroposterior-retroodontoid pseudotumor (AP-ROP), C2-7 angle, O-C2 angle, C1-2 angle, atlantodental interval (ADI), range of motion (ROM) of the ADI, C2-C7 sagittal vertical axis (C2-7 SVA), and T1 slope. Global spinal alignments (pelvic incidence [PI] minus lumbar lordosis [LL] [PI-LL], pelvic tilt, sacral slope, and C7 sagittal vertical axis) were also compared between the groups. RESULTS: Both groups had equally good clinical outcomes with equal complication rates. Three patients had a three-level fusion, 5 cases had a four-level fusion, and 4 cases had more than five-level fusion in group O. All cases had a single-level fusion in group A. Surgical time was significantly shorter in group A. AP-ROP was significantly downsized postoperatively in both groups and was more prominent in group O. C2-7 SVA was significantly increased and C2-7A ROM was significantly reduced in group O at the final follow-up. The PI-LL showed a significant increase in group O at the final follow-up. CONCLUSIONS: Although OCF and AAF were similarly effective for cervical myelopathy with ROP, AAF was less invasive, and spinal alignment was better maintained postoperatively in AAF than OCF.

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

PURPOSE: There 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 METHODS: The 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). RESULTS: Clinically 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. CONCLUSION: Occipitocervical 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.

Neurosurgical management of patients with Ehlers-Danlos syndrome: A descriptive case series.

Introduction: Ehlers-Danlos syndrome (EDS) is a connective tissue disorder that has been linked to several neurological problems including Chiari malformations, atlantoaxial instability (AAI), craniocervical instability (CCI), and tethered cord syndrome. However, neurosurgical management strategies for this unique population have not been well-explored to date. The purpose of this study is to explore cases of EDS patients who required neurosurgical intervention to better characterize the neurological conditions they face and to better understand how neurosurgeons should approach the management of these patients. Methods: A retrospective review was done on all patients with a diagnosis of EDS who underwent a neurosurgical operation with the senior author (FAS) between January 2014 and December 2020. Demographic, clinical, operative, and outcome data were collected, with additional radiographic data collected on patients chosen as case illustrations. Results: Sixty-seven patients were identified who met the criteria for this study. The patients experienced a wide array of preoperative diagnoses, with Chiari malformation, AAI, CCI, and tethered cord syndrome representing the majority. The patients underwent a heterogeneous group of operations with the majority including a combination of the following procedures- suboccipital craniectomy, occipitocervical fusion, cervical fusion, odontoidectomy, and tethered cord release. The vast majority of patients experienced subjective symptomatic relief from their series of procedures. Conclusions: EDS patients are prone to instability, especially in the occipital-cervical region, which may predispose these patients to require a higher rate of revision procedures and may require modifications in neurosurgical management that should be further explored.

Radiographic Prediction of the Occipito-C2 Angle Variation with Changes in Distance between the Mandible and Cervical Vertebrae: A Preliminary Study.

The Occipito (O) -C2 angle reflects the correct craniocervical spine alignment; however, the poor image quality of standard intraoperative fluoroscopy at times lead to inaccurate measurements. Herein, we preliminarily investigated the relationship between the O-C2 angle and the Gonion-C2 distance, which is based on the positioning of the mandible and the cervical spine. We enrolled patients who underwent cervical spine radiography in neutral, flexion, and extension positions from January 2020 to October 2020. The difference by posture changes for each parameter was defined as the Δ value, and the Spearman's rank correlation coefficient was determined. Furthermore, we determined the cutoff value of the ΔGonion-C2 distance to predict a decrease of > 10° in the ΔO-C2 angle, which is reported to be related to dysphagia and dyspnea. Seventy-four patients were included. Spearman's rank correlations for the neutral, flexion, and extension positions were 0.630 (P < 0.001), 0.471 (P < 0.001), and 0.625 (P < 0.001), respectively, while the cutoff values of the ΔGonion-C2 distance for predicting > 10° in the ΔO-C2 angle were 9.3 mm for the neutral flexion change (sensitivity: 0.435, specificity: 0.882) and 8.3 mm for the extension-neutral change (sensitivity: 0.712, specificity: 0.909). The O-C2 angle and Gonion-C2 distances correlated; however, this correlation was weaker in the flexed position. Nevertheless, the ΔGonion-C2 distance can be used as a warning sign for postoperative complications after posterior occipital bone fusion surgery, because a decrease of > 10° in the ΔO-C2 angle can be predicted with high specificity.

MR documented craniocervical ligamentous injury at age 18 months: delayed formation of OS odontoideum. Complex management issues. Case-based review.

OBJECTIVE: There are two separate theories regarding the genesis of os odontoideum: congenital and post-traumatic. Trauma documentation in the past has been the presence of a normal odontoid process at the time of initial childhood injury and subsequent development of the os odontoideum. True MR documentation of craniocervical injury in early childhood and subsequent os odontoideum formation has been very rare. METHODS: An 18-month-old sustained craniocervical ligamentous injury documented on MRI with transient neurological deficit. Chiari I abnormality was also recorded. Subsequent serial imaging of craniocervical region showed the formation of os odontoideum and instability. He became symptomatic from the os odontoideum and the Chiari I abnormality. The patient underwent decompression and intradural procedure for Chiari I abnormality and occipitocervical fusion. Postoperative course was complicated by the failure of fusion and redo. He later required transoral ventral medullary decompression. He recovered. RESULTS: This is an MR documented craniocervical ligamentous injury with sequential formation of os odontoideum with accompanying changes in the atlas. Despite a subsequent successful dorsal occipitocervical fusion, he became symptomatic requiring transoral decompression. CONCLUSIONS: Os odontoideum here is recognized as a traumatic origin with the presence of congenital Chiari I abnormality as a separate entity. The changes of the anterior arch of C1 as well as the os formation were serially documented and give credence to blood supply changes in the os and atlas as a result of the trauma. The recognized treatment of dorsal occipitocervical fusion failed in this case requiring also a ventral decompression of the medulla.

Rate and risk factors for pediatric cervical spine fusion pseudarthrosis: opportunity for improvement.

PURPOSE: Although the pediatric population typically has a high union rate, the cervical spine has a reputation for frequent pseduarthrosis, as high as 38% in some prior series. Our purpose was to examine the rate and risk factors for pseudarthrosis in pediatric cervical spine fusions. METHODS: Retrospective review of all patients with ≥ 2 years follow-up undergoing cervical spinal fusion between January 2004 and December 2019 at a tertiary pediatric hospital. Pseudarthrosis was defined as an absence of radiographic union as assessed by the attending surgeon for which revision surgery was performed. RESULTS: 64 patients (mean age: 8.4 ± 4.7 years) met inclusion criteria. Mean follow-up was 63.3 ± 41.4 months (range: 24-187 months). 28 fusions (44%) included the occiput. 41 patients (64%) had instrumentation, while 23 patients (36%) had uninstrumented fusions. 48 (75%) patients had a halo for a mean of 97.6 ± 49.5 days. The incidence of pseudarthrosis was as follows: overall = 8/64 (12.5%); posterior fusion = 14.8% (8/54); anterior fusions = 0% (0/4); and anteroposterior fusions = 0% (0/6). The rate of pseudarthrosis was over 8 times higher in fusions involving the occiput (occipitocervical fusion: 25.0%; 7/28 vs. cervical alone: 2.8%; 1/36; p = 0.02). Although not statistically significant, the rate of pseudarthrosis was 3 times higher in uninstrumented fusions (21.7%; 5/23) than instrumented fusions (7.3%; 3/41) (p = 0.12). In patients with uninstrumented fusion to the occiput, pseudarthrosis rate was 35.7% (5/14), which was higher compared to those who did not (6.0%; 3/50) (p = 0.01). Incidence of pseudarthrosis was similar in patients who received autograft (13.0%; 7/54) compared to allograft alone (10.0%; 1/10) (p > 0.999). CONCLUSIONS: The pseudarthrosis rate in pediatric cervical spine fusions remained high despite frequent use of halo immobilization and autograft. Patients with uninstrumented occipitocervical fusions are at particularly high risk with more than 1 in 3 developing a pseudarthrosis. STUDY DESIGN: Retrospective, Comparative. LEVEL OF EVIDENCE: III.

Radiographic measurements for the prediction of dysphagia after occipitocervical fusion: a systematic review.

BACKGROUND: Occipitocervical fusion (OCF) is a procedure performed for multiple upper cervical pathologies. A common postprocedural complication of OCF is dysphagia, which has been linked to the narrowing of the pharyngeal space due to fixation in a hyper-flexed angle. Postoperative dysphagia is linked to reduced quality of life, prolonged hospital stay, aspiration pneumonia, and increased mortality. This has led to investigations of the association between sagittal radiographic angles and dysphagia following OCF. METHODS: A systematic review of the literature was performed to explore the current evidence regarding cervical sagittal radiographic measurements and dysphagia following OCF. A search strategy was carried out using the PubMed, Embase, and Web of Science databases from their dates of inception until August 2022. Only original English-language studies were considered. Moreover, studies had to include the correlation between dysphagia and at least one radiographic measurement in the sagittal plane. RESULTS: The search and subsequent selection process yielded eight studies that were included in the final review, totaling 329 patients in whom dysphagia had been assessed and graded. The dysphagia score by Bazaz et al. (Spine 27, 22:2453-2458, 2002) was used most often. The pooled incidence of dysphagia, in the early postoperative period, was estimated at 26.4%. At long-term follow-up (range: 17-72 months), about one-third of patients experienced resolution of symptoms, which resulted in a long-term post-OCF dysphagia incidence of 16.5%. Across the studies included, six different radiographic parameters were used to derive several measures which were repeatedly and significantly associated with the occurrence of dysphagia. CONCLUSIONS: The high incidence of postoperative dysphagia following OCF warrants close monitoring of patients, especially in the short-term postoperative period. These patients may be assessed through standardized tools where the one by Bazaz et al. was the most commonly used. Moreover, there are several radiographic measurements that can be used to predict the occurrence of dysphagia. These findings may serve as a basis for strategies to prevent the occurrence of dysphagia after OCF.

Atlanto-occipital dislocation with concomitant severe traumatic brain injury: A retrospective study at a level 1 trauma center.

BACKGROUND: Traumatic atlanto-occipital dislocation (AOD) is a life-threatening injury. Although traumatic brain injury (TBI) is associated with increased mortality in AOD patients, a detailed individual analysis of these patients is lacking in the literature. METHODS: Patients ≥16 years old who were diagnosed of AOD with concomitant severe TBI from 2010 to 2020 were included in this retrospective study. We examined the epidemiology, injury mechanisms, associated injuries, and outcomes of these patients. RESULTS: Eight patients were included. Six patients died before any intervention could be performed, and two patients underwent an occipito-cervical fixation, showing a notorious neurologic improvement on follow-up. Cardiorespiratory arrest (CRA) was a strong predictor of subsequent death. CT signs of diffuse axonal injury (DAI) were present in most patients and were confirmed by magnetic resonance imaging (MRI) in survivors. Although TBI was not the main cause of death, it was responsible for the delayed neurological improvement and deferred stabilization. The average sensitivity of the different used methodologies for AOD diagnosis ranged from 0.50 to 1.00, being the Basion Dens Interval (BDI) and the Condyle-C1 interval (CCI) sum the most reliable criteria. Non-survivors tended to show greater distraction measurements. The high incidence of condylar avulsion fractures suggests that their visualization on the initial CT study should heighten the suspicion for AOD. CONCLUSIONS: Our data suggest that patients with AOD and concomitant severe TBI might be salvageable patients. In those who survive beyond the first hospital days and show neurological improvement, surgical treatment should be performed as they can achieve an important neurologic recovery.

Anterior occipital condyle screw placement through the endonasal corridor: proof of concept study with cadaveric analysis.

PURPOSE: Odontoidectomy for ventral compressive pathology may result in O-C1 and/or C1-2 instability. Same-stage endonasal C1-2 spinal fusion has been advocated to eliminate risks associated with separate-stage posterior approaches. While endonasal methods for C1 instrumentation and C1-2 trans-articular stabilization exist, no hypothetical construct for endonasal occipital instrumentation has been validated. We provide an anatomic description of anterior occipital condyle (AOC) screw endonasal placement as proof-of-concept for endonasal craniocervical stabilization. METHODS: Eight adult, injected cadaveric heads were studied for placing 16 AOC screws endonasally. Thin-cut CT was used for registration. After turning a standard inferior U-shaped nasopharyngeal flap endonasally, 4 mm × 22 mm AOC screws were placed with a 0° driver using neuronavigation. Post-placement CT scans were obtained to determine: site-of-entry, measured from the endonasal projection of the medial O-C1 joint; screw angulation in sagittal and axial planes, proximity to critical structures. RESULTS: Average site-of-entry was 6.88 mm lateral and 9.74 mm rostral to the medial O-C1 joint. Average angulation in the sagittal plane was 0.16° inferior to the palatal line. Average angulation in the axial plane was 23.97° lateral to midline. Average minimum screw distances from the jugular bulb and hypoglossal canal were 4.80 mm and 1.55 mm. CONCLUSION: Endonasal placement of AOC screws is feasible using a 0° driver. Our measurements provide useful parameters to guide optimal placement. Given proximity of hypoglossal canal and jugular bulb, neuronavigation is recommended. Biomechanical studies will ultimately be necessary to evaluate the strength of AOC screws with plate-screw constructs utilizing endonasal C1 lateral mass or C1-2 trans-articular screws as inferior fixation points.

Craniovertebral Junction Instability in the Setting of Chiari Malformation.

Described in the seminal paper by Hans Chiari in 1891, the Chiari I malformation (CMI) is a radiographic diagnosis commonly encountered by neurosurgeons and is often treated surgically with generally positive clinic outcomes. Studies have documented that 1% to 4% of patients undergoing MRI of the brain or cervical spine will be diagnosed with CMI, characterized by greater than 5 mm tonsillar herniation below the foramen magnum. More recently CMI has been described as a spectrum of disease, which includes Chiari 0, Chiari 1.5, and the complex Chiari. Primarily through multicenter clinical outcomes research, our understanding of the pathology continues to evolve.