Surgical outcomes of intraoperative O-arm versus C-arm fluoroscopy in occipitocervical fixation: a retrospective analysis

PURPOSE

This study aims to compare the effect of using O-arm and C-arm fluoroscopy on the surgical outcomes of occipitocervical fixation.

METHODS

The study included patients who underwent occipitocervical fixation using O-arm or C-arm between 2005 and 2021. Of 56 patients, 34 underwent O-arm-assisted surgery (O-group) and 22 underwent C-arm-assisted surgery (C-group). We assessed surgical outcomes, including operative time, intraoperative blood loss, perioperative complications, and bone union.

RESULTS

Almost half of the patients had rheumatoid arthritis-related disorders in both groups. Sixteen cases (47.1%) in the O-group and 12 cases (54.5%) in the C-group were fixed from occipito (Oc) to C3, 12 cases (38.2%) in the O-group and 7 cases (31.8%) in the C-group from Oc to C4-7, 5 cases (14.7%) in the O-group, and 3 cases (13.6%) in the C-group from Oc to T2 (p = 0.929). There was no significant difference in operative time (p = 0.239) and intraoperative blood loss (p = 0.595) between the two groups. Dysphagia was the most common complication in both groups (O-group vs. C-group, 11.7% vs. 9.1%). Regarding implant-related complications, occipital plate dislodgement was observed in four cases (18.2%) in the C-group (p = 0.02). The bone union rate was 96.3% in the O-group and 93.3% in the C-group (P = 1).

CONCLUSIONS

O-arm use is associated with a reduced rate of occipital plate dislodgment and has a similar complication incidence compared with C-arm-assisted surgery and does not prolong operative time despite the time needed for setting and scanning. Accordingly, an O-arm is safe and useful for occipitocervical fixation surgery.

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.

Anterior atlanto-occipital transarticular screw fixation: a biomechanical comparison with posterior fixation techniques

OBJECTIVE

Atlanto-occipital instability is commonly treated with posterior fixation. However, in patients with congenital or acquired factors, posterior fixation may not be possible. For these situations, a novel anterior atlanto-occipital transarticular screw (AATS) fixation technique has been introduced recently. However, biomechanical study of this technique is lacking. This study was designed to evaluate the biomechanical stability of AATS fixation for the atlanto-occipital joint and compare it with conventional posterior occipitocervical fixation (POCF).

METHODS

Six cadaveric specimens (occiput-C4) were tested in four conditions, including intact, injury, injury + AATS, and injury + POCF states. A pure moment of 1.5 Nm was applied to specimens in flexion, extension, lateral bending, and axial rotation. The range of motion (ROM) and neutral zone (NZ) were calculated and compared from the occiput to C1.

RESULTS

The AATS fixation constrained ROMs to 0.4° in flexion (p < 0.001), 0.4° in extension (p < 0.001), 1.0° in lateral bending (p < 0.001), and 0.7° in axial rotation (p < 0.001) when compared with the injury state. In all directions, there was no statistically significant difference observed in ROMs and NZs between AATS fixation and POCF (p > 0.05).

CONCLUSIONS

This study identified that the novel AATS fixation, as stand-alone anterior fixation, was equivalent to POCF in all directions. The results suggest that anterior transarticular screw fixation is a biomechanically effective salvage technique for posterior atlanto-occipital fixation, and may also serve as supplemental fixation.

Craniocervical instability in patients with Ehlers-Danlos syndrome: controversies in diagnosis and management

Ehlers-Danlos syndrome (EDS) is a rare hereditary condition that can result in ligamentous laxity and hypermobility of the cervical spine. A subset of patients can develop clinical instability of the craniocervical junction associated with pain and neurological dysfunction, potentially warranting treatment with occipitocervical fixation (OCF). Surgical decision-making in patients with EDS can be complicated by difficulty distinguishing from hypermobility inherent in the disease and true pathological instability necessitating intervention. Here we comprehensively review the available medical literature to critically appraise the evidence behind various proposed definitions of instability in the EDS population, and summarize the available outcomes data after OCF. Several radiographic parameters have been used, including the clivo-axial angle, basion-axial interval, and pB-C2 measurement. Despite increasing recognition of EDS by spine surgeons, there remains a paucity of data supporting proposed radiographic parameters for spinal instability among EDS patients. Furthermore, there is a lack of high-quality evidence concerning the efficacy of surgical treatments for chronic debilitating pain prevalent in this population. More standardized clinical measures and rigorous study methodologies are needed to elucidate the role of surgical intervention in this complex patient population.

Anatomical Parameters for Occipital Condyle Screws: An Analysis of 500 Condyles Using CT Scans

STUDY DESIGN

Retrospective observational study.

OBJECTIVE

To establish occipital condyle dimensions (length, width, height), as well as the medialization angle necessary for safe occipital condyle screw placement in occipitocervical fixation.

METHODS

Between 1/2014-6/2014, patients who presented to a single level 1 academic trauma center emergency room and received computed tomography (CT) imaging of the cervical spine as part of routine clinical care were identified. After excluding patients with cervical fractures, neoplastic disease, or infection, 500 condyles representing 250 patients were analyzed. Condyle length, height, and width (all reported in millimeters [mm]) were evaluated on the sagittal, coronal, and axial series, respectively. Medialization angle (reported in degrees) was evaluated on the axial series of CT imaging. Measurements were compared by sex and age.

RESULTS

The average condyle length, width, and height were 18.6 millimeters (mm) (range, 14.5-23.0 mm), 10.5 mm (range, 7.4-13.8 mm), and 11.3 mm (7.1-15.3 mm), respectively. Additionally, the average occipital condyle medialization angle was 23° (range, 14-32°). Occipital condyles of men were significantly longer, wider, and taller (all comparisons, p < 0.05). The medialization angle was significantly steeper for women than men (p < 0.05). No measurement differences were appreciated by age.

CONCLUSION

Our findings are similar to previous studies in the field; however, length appears slightly shorter. Further, measurement differences were appreciated by sex but not age. Thus, our measurement findings emphasize the importance of preoperative planning utilizing individual patient anatomy to ensure safe placement of occipital condyle screws for optimal outcomes.

Occipitocervical Revision Surgery Using the Bicortical Screw and Plate System for Failed Craniovertebral Junction Stabilization

Background

To evaluate the clinical efficacy and safety of the modified technique utilizing the occipital bicortical screws and plate system in occipitocervical revision surgery.

Methods

Between October 2010 and May 2018, 12 consecutive patients were retrospectively evaluated. All patients had posterior occipitocervical resurgery utilizing modified technique of bicortical screws and occipital plate. The measurements of extracranial occiput on midline were conducted on computed tomography (CT) scans. The thickness of the occipital bone at the location of external occipital protuberance and below 15 mm were evaluated, respectively. For the procedure, the trajectory was drilled perpendicular to the external occipital protuberance for the specified depth with a depth‐limited drilling, 2 mm away from the internal bone plate, then the trajectory was deepened at intervals of 1 mm each time until reaching the internal bone plate. Meanwhile, a probe was used to explore all the walls of the trajectory. Bicortical screws were inserted to the occipital plate and the depth of penetration was less than 2 mm from the internal bone plate. Clinical efficacy and radiographic evaluation were followed up.

Results

The thickest point was the external occipital protuberance, which was 15.49 ± 1.47 mm and decreased gradually on the midline to 13.41 ± 1.60 mm at below 15 mm. Twelve cases (mean age 41.17 years; range, 24–62 years), including five males and seven females, were followed up for 24.08 months (14–32 months). The interval time was 40.42 months (3–156 months) after the initial operation. At the final follow‐up, JOA score increased from 8.58 ± 2.53 before surgery to 12.67 ± 1.84 (P < 0.05) and VAS score improved from 6.17 ± 1.21 to 2.08 ± 1.32 (P < 0.05). Besides, clinical symptoms were relieved in all patients after revision surgery. All patients had rigid internal fixations with bone fusion and no major complications occurred.

Conclusions

Posterior occipitocervical plate‐screw system with bicortical screws had the advantages of safety, simple and promising efficacy without excessive tissue release or intraspinal manipulation, proving that it's valuable as a modified technique for occipitocervical revision surgery.

Occipitocervical fixation: A case report of our techniques and results

INTRODUCTION

Occipitocervical fixation (OCF) can provide good fusion rate to treat various craniovertebral junction (CVJ) pathologies. Biomechanically it gives rigid fixation, good fusion rate, and allows for effective decompression. However, rigid fixation on the mobile occipitocervical junction has shortcomings that affect the post-operative clinical functional outcomes and range of motion. This study aimed to evaluate and elaborate the functional outcomes, range of motions, and radiographic findings in our patients underwent OCF.

CASE REPORT

We presented a report of 3 patients underwent posterior decompression procedure followed by occipitocervical fixation. All three patients' clinical outcome was assessed clinically by, Japanese Orthopaedic Association (JOA) score and grading, Karnofsky, range of motion and radiographic cervical alignment evaluation parameters.

RESULT

All patients have seen improvement (minimal 1 grade in JOA and >30 points of Karnofsky score) in 3 months after the procedure, had a tolerable range of motion limitation, normal range of cervical lordotic and cervical brow vertebral angle (CBVA). Unfortunately, one patient with loss of cranial fixation may be related to history of infection and lack of post-operative wound care.

CONCLUSSION

Our cases conclude that Occipitocervical fixation is a safe technique that provides excellent fusion rate with good functional outcome and tolerable range of motion limitation. Due to its unique anatomy and technically demanding, serial post-operative monitoring evaluation of this procedure is paramount.

Complications of occipitocervical fixation: retrospective review of 128 patients with 5-year mean follow-up

PURPOSE

Occipitocervical fusion is necessary for many pathologies of the craniocervical junction. The anatomy of the region is unique, and fusion can cause significant morbidity. This retrospective review aims to investigate the complication rates and outcomes of occipitocervical fixation.

MATERIAL AND METHODS

This is a retrospective review of 128 patients with occipitocervical fixation operated between 1994 and 2020. The average follow-up is 63 months.

RESULTS

The indications of occipitocervical fixation were basilar invagination (53 patients; 41.4%), trauma (25 patients; 19.5%), tumor (23 patients; 18%), instability due to rheumatoid arthritis (13 patients; 10.2%), cervical deformity (7 patients; 5.5%) and os odontoideum (7 patients; 5.5%). There were six early postoperative (1st month) deaths. We observed complications in 67 patients (52%). Most common complication was implant-related (32%), followed by wound problems (23.4%), systemic and other complications (11.7%), neurologic complications (6.2%). Implants are removed in 31 patients (24%) for different reasons: deep wound infection (7), local pain and restriction of head movements (21), respiratory distress and swallowing problems (2), screw fracture and local pain (1).

CONCLUSIONS

Occipitocervical fixation has quite large number of complications and significantly restricts head movements. With the advent of our biomechanical concepts, indications should be limited, and shorter cervical fixations should be preferred.

LEVEL OF EVIDENCE

Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

Morphological Evaluation of the Subaxial Cervical Spine in Patients with Basilar Invagination: A CT-based Study

STUDY DESIGN

Retrospective study.

OBJECTIVE

To evaluate the morphologic features of the subaixal cervical spine in patients with basilar invagination (BI) and provide information for the accurate screw placement in this region.

SUMMARY OF BACKGROUND DATA

BI is a congenital anomaly, comprising a wide range of abnormal structures. The screw fixation can be required in situation that BI is combined with subaxial cervical spine pathologies. However, there are no literatures specifically addressed the subaxial cervical morphology of BI.

METHOD

A total of 42 BI patients were included in this retrospective study. Forty-two patients without head or cervical disease were matched for sexes and ages. Information on radiographic features of the subaxial cervical spine was collected and compared systematically.

RESULTS

There were no differences in the age and sex between the BI and control group. The BI group manifested a wider pedicle and laminar than the control group at all cervical levels, except for the pedicle of C6 and C7, and the laminar of C3 and C6. In addition, the BI group had a wider lateral mass from C3 to C5 than the control group. There were no differences in most measurements of the length of pedicle, laminar, and lateral mass.

CONCLUSION

BI patients have a wider pedicle and laminar than the general population in the subaxial cervical spine, but the same size in length of pedicle, laminar, and lateral mass.Level of Evidence: 4.

Safety, efficacy, surgical, and radiological outcomes of short segment occipital plate and C2 transarticular screw construct for occipito-cervical instability

Objective:

Our study aims to assess the safety, efficacy, clinicoradiological, functional, neurological outcomes, and complications of posterior occipitocervical fixation using an occipital plate and C1-2 transarticular screw (TAS) construct.

Study Design:

This was a retrospective analysis of prospectively collected data.

Methods:

Data of 27 patients who underwent occipital plate and C1-2 TAS construct at a single institute from 2010 to 2015 were collected and analyzed. Demographics, clinical parameters (Visual Analog Score, Oswestry Disability Index, and modified JOA score), radiological parameters – mean atlantodens interval, posterior occipitocervical angle, occipitocervical-2 angle, surgical parameters (operative time, blood loss, hospital stay, and fusion), and complications were evaluated.

Results:

The mean age of the patients was 54.074 ± 16.52 years (18–81 years), the mean operative time was 116.29 ± 12.23 min, and the mean blood loss was 196.29 ± 38.94 ml. The mean hospital stay was 5.22 ± 1.28 days. The mean ± standard deviation follow-up duration was 62.52 ± 2.27 months. There was a significant improvement in clinical parameters and radiological parameters postoperatively. One patient with implant failure, one patient with pseudoarthrosis, one with neurological deterioration, two wound complications, and two dural tears were noted.

Conclusion:

Posterior occipitocervical reconstruction with O-C1-2 TAS construct provided excellent clinical outcomes, radiological outcomes, optimal correction of malalignment in the occipitocervical region, and with biomechanically sound fixation. Extending the instrumentation into the subaxial spine will lead to a decrease in the range of motion, increased surgical time, blood loss, more extensive muscle damage, and also increase the costs.

4-Point C2 Fixation for Occipitocervical Fusion: Technical Case Report

BACKGROUND

Occipitocervical fusion is an important surgical procedure to treat instability of the upper cervical and craniocervical junction. Fixation to the dense cortical bone of the occiput, contemporaneously typically accomplished with a plate and screws, is known to be strong and durable, but there are many competing methods used to secure an adequate number of fixation points of sufficient strength at the cervical end. Extension of hardware to the midcervical region to acquire additional fixation points, however, results in loss of subaxial motion segments and additional potential morbidity. The C2 vertebra is unique in that its morphology and dimensions permit fixation with longer screws than are typically possible to place in the midcervical lateral masses. Translaminar and pars screw techniques, both commonly used to achieve C2 fixation, are not mutually exclusive, as their respective trajectories are considerably different and engage different portions of the bony anatomy.

METHODS

We describe a novel, 4-point C2 fixation technique for OC fusion that may avoid the need to extend fusion to the subaxial spine.

RESULTS

This technical note illustrates how 4-point C2 fixation can be employed in occiptocervical fusion.

CONCLUSIONS

4-point fixation of C2 combining translaminar and pars screw placement is technically feasible and may be a suitable strategy to spare subaxial motion segments in OC fusion procedures. Futher investigation may establish its applicability to additional surgical procedures.

Acute Spinal Cord Contusion in a Patient with Multiple Upper Cervical Fractures, Parkinson's Disease, and Torticollis: Surgical Management

Case Report. Spine surgery in patients with Parkinson's disease (PD) involves increased risk. We describe a case of cervical myelopathy in a patient with PD, multiple fractures involving the atlas and axis vertebrae, and spasmodic torticollis. The patient was successfully treated with an upper cervical decompression and occipital-cervical (OC) fusion surgery. Strategies for torticollis reduction and successful surgical outcome are discussed. Risks and benefits must be carefully weighed when considering occipital cervical fusion in PD patients. Conclusion. Intraoperative manual reduction of laterocollis is possible after general endotracheal anesthesia, and continuous neuromonitoring is established. Use of optimizing strategies such as perioperative botulinum injections and intraoperative O-arm navigation should be considered.

Occipitocervical Fusion via Cervical Pedicle Fixation Assisted with O-arm Navigation

Objective

To describe the clinical outcomes of occipitocervical fusion (OCF) using cervical pedicle fixation with assistance of O‐arm navigation and present its clinical feasibility.

Methods

From January 2015 to December 2016, eight patients with a variety of diagnoses were surgically treated with occipitocervical fusion using cervical pedicle screws under O‐arm navigation. All patients received full workup consisting of clinical and radiological assessments. Perioperative parameters including operating time, intraoperative blood loss, postoperative complications, surgical outcomes were recorded. Postoperative data were acquired resorting to the scheduled follow‐up 3, 6 and 12 months after their discharge and annually afterwards. The Japanese Orthopaedic Association (JOA) Scores and American Spinal Injury Association (ASIA) Scale were used to evaluate neurological function. The accuracy of screw placement was classified according to a modified classification of Gertzbein and Robbins. The fusion status was evaluated in reference to the Bridwell's posterior fusion grades.

Results

The patient cohort comprised of five males and three females, with the average age of 51.9 years (range from 18 to 74 years). The patients all showed indications for OCF and were performed with polyaxial screws through cervical pedicles. The average operation time was 274 min (range from 226 to 380 min), with the intraoperative blood loss of 437.5 mL and the blood transfusion volume of 481.3 mL. The average follow‐up time was 23.5 months (range from 17 to 32 months). All patients exhibited radiographic evidence of osseous fusion by X‐ray and computed tomography (CT) at the final follow‐up. No neurovascular complications were found during the follow‐up time, and the clinical symptoms were observed to be significantly improved in all the patients. Thirty‐four cervical pedicle screws were implanted within the eight patients, with the accuracy of cervical pedicle screw placements as 94.1% (32/34), among which, two pedicle screws were found to broken through the cervical pedicles that were evaluated as Grade II.

Conclusions

Occipitocervical fusion via cervical pedicle fixation assisted with O‐arm navigation is a feasible and safe procedure with a vast range of indications.

Anatomical analysis of the occipital bone in patients with basilar invagination: a computed tomography-based study

BACKGROUND CONTEXT

The occipital bone is often involved in the surgical treatment of basilar invagination (BI). However, the anatomy of the occipital bone associated with BI patients has yet to be investigated.

PURPOSE

To present a morphological map of the occipital bone in BI patients and help guide screw placement for occipitocervical fusion.

STUDY DESIGN

A retrospective case-control study.

METHODS

Radiological measurements of the occipital bone were performed on computed tomography images based on a matrix of 99 points centered around the external occipital protuberance (EOP) in a cohort of 50 BI patients and 50 cases with no head and cervical disease. The comparison between the BI group and the control group was assessed using Student t analysis and p<.05 was considered statistically significant.

RESULTS

All thicknesses measured from points of the matrix in the BI group were thinner than those in the control group (p<.05). The maximum thicknesses in both groups were located at the center of the EOP, which were 15.11±2.84 mm in the BI group and 17.56±3.03 mm in the control group, respectively. Additionally, thickness decreased with the distance away from the center of EOP.

CONCLUSIONS

The occipital bone in BI patients is thinner than that in the general population. A limited safe zone in BI patients is available for surgeons to place screws, which may need to be fully evaluated before operation.

Occipitocervical fusion complicated with cerebellar abscess: a case report

BACKGROUND

Occipitocervical (OC) fusion is indicated for OC instability and other conditions. Surgical complications include infection, malunion, and instrument failure.

CASE PRESENTATION

We described a patient who underwent OC fusion and subsequently developed complication of cerebellar abscess and obstructive hydrocephalus. A 63-year-old male patient had been suffering from long-term neck pain and limb numbness and weakness. Cervical spine examination revealed tight stenosis at C1 level and instability in the C1-C2 joints. A C1 laminectomy with OC fusion was performed, and the patient was discharged. Unfortunately, a few days later, he went to the emergency department and complained of persistent dizziness, vomiting, and unsteady gait. Computed tomography (CT) and magnetic resonance imaging (MRI) images revealed a suspicious cerebellar abscess formation and hydrocephalus. Furthermore, CT images indicated that the left screw was loose, and the diameter of the right screw hole was much larger than the size of the screw. Besides, inappropriate length of the screw penetrated the occipital bone and may cause the disruption of dura mater. The patient underwent external ventricular drainage first, followed by abscess drainage and C1-C2 fixation a few days later. He was discharged without any further neurological deficits or infectious problems. The patient recovered with intact consciousness, full muscle strength, and improved numbness throughout the extremities, with a Nurick grade of 1. A follow-up magnetic resonance imaging at 3 months after surgery revealed near total resolution of the abscess. Inform consent was obtained from this patient.

CONCLUSIONS

Carefully conducting the procedure using the most tailored approach is essential to successful surgery, but this rare complication should always be kept in mind.

Occiput-to-Pelvis Spinal Arthrodesis: A Case Series

STUDY DESIGN

Retrospective case series.

OBJECTIVES

To describe the indications, operative course, and outcomes in eight pediatric patients who underwent occiput-to-pelvis (O-P) spinal arthrodesis.

SUMMARY

Spinal arthrodesis from the occiput to pelvis is needed for some children with extensive spine deformity. There are few reports of patients with O-P arthrodesis.

METHODS

We reviewed records of pediatric patients who underwent spinal arthrodesis to treat spine deformity between 1987 and 2017 at one institution. Eight patients (six girls) who underwent staged O-P arthrodesis were identified. Underlying conditions, indications for surgery, medical comorbidities, operative courses, complications, and imaging of these patients were recorded.

RESULTS

Diagnoses were neuromuscular disorders in five patients and syndromic disorders in three patients. Mean ages were 9.7 ± 4.1 years at index surgery and 16.8 ± 4.6 years at completion of O-P arthrodesis. Patients underwent a mean of three operations (range, two to five). Occipitocervical arthrodesis was the final operation in six of eight patients (all but the two patients with Loeys-Dietz syndrome). Mean follow-up after the last procedure was 8.5 ± 7.1 years. Two patients underwent revision for protruding occipital implants, and one patient underwent revision for thoracic pseudarthrosis. No patients developed postoperative infections or new neurologic deficits. At final follow-up, Scoliosis Research Society-22r questionnaire scores were lowest for Function (2.6 ± 1.0 of 5 possible points) and highest for Satisfaction (4.1 ± 1.4).

CONCLUSIONS

O-P arthrodesis can benefit patients with extensive spine deformity from neuromuscular or syndromic causes. Patients were young at first operation, which may suggest that younger patients are at higher risk than older patients of major progression of deformity in other spinal regions after deformity correction. Health-related quality of life and radiographic outcomes suggest that patients who underwent O-P arthrodesis had satisfactory outcomes and maintenance of correction during a mean of 8.5 years of follow-up.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Anatomical study of the ventral neurovascular structures and hypoglossal canal for the surgery of the upper cervical spine

The aim of this study is to evaluate the anatomical relationship between the bony structures and ventral neurovascular structures around craniovertebral junction (CVJ). Eleven fresh-frozen cadaveric specimens were dissected around CVJ. The anatomical relationships were evaluated between C1 bony structures (midline, lateral margin of the C1 lateral mass (LM) and C1 transverse process (TP)) and ventral neurovascular structure such as ICA and HN. Morphometric evaluation of occipital condyle was also performed. The diameter of the HN and the ICA was 2.4 ± 0.5 mm and 5.1 ± 0.2 mm. The ICA was located lateral to the C1 LM in 44.4% (ICA Group 1) and in front of lateral half of the C1 LM in 55.6% (ICA Group 2). The HN was located lateral to the C1 LM in 85% (HN Group 1) and in front of lateral half of the C1 LM in 15% (HN Group 2). HN Group 2 was significantly more common in ICA Group 2 (p < 0.05, OR = 2.00, 95% CI: 1.07-3.71). There was significant correlation between ICA and HN in terms of the distance from the midline, C1 LM and TP (r = 0.67, 0.87 and 0.76 respectively, P < 0.01). In conclusion, the HN location is related with ICA location and the medially located ICA is a risk factor of the HN located ventral to the C1 LM. These results demonstrate the vulnerability of the neurovascular structures during CVJ surgery and suggest that preoperative 3D-CTA or enhanced CT scan can be useful in guiding surgical technique.

Occipitocervical Fusion: An Updated Review

Occipitocervical fusion (OCF) is indicated for instability at the craniocervical junction (CCJ). Numerous surgical techniques, which evolved over 90 years, as well as unique anatomic and kinematic relationships of this region present a challenge to the neurosurgeon. The current standard involves internal rigid fixation by polyaxial screws in cervical spine, contoured rods and occipital plate. Such approach precludes the need of postoperative external stabilization, lesser number of involved spinal segments, and provides 95-100% fusion rates. New surgical techniques such as occipital condyle screw or transarticular occipito-condylar screws address limitations of occipital fixation such as variable lateral occipital bone thickness and dural sinus anatomy. As the C0-C1-C2 complex is the most mobile portion of the cervical spine (40% of flexion-extension, 60% of rotation and 10% of lateral bending) stabilization leads to substantial reduction of neck movements. Preoperative assessment of vertebral artery anatomical variations and feasibility of screw insertion as well as visualization with intraoperative fluoroscopy are necessary. Placement of structural and supplemental bone graft around the decorticated bony elements is an essential step of every OCF procedure as the ultimate goal of stabilization with implants is to provide immobilization until bony fusion can develop.

Traumatic Occipitocervical Distraction Injuries in Children: A Systematic Review

BACKGROUND

Occipitocervical distraction injuries (OCDI) in children occur on a wide spectrum of severity, and decisions about treatment suffer from a lack of rigorous guidelines and significant inter-institutional variability. While clear cases of frank atlanto-occipital dislocation (AOD) are treated with surgical stabilization, the approach for less severe cases of OCDI is not standardized. These patients require a careful assessment of both radiographic and clinical criteria, as part of a complex risk-benefit analysis, to establish whether occipitocervical fusion (OCF) is indicated. Here, we performed a systematic review of the literature that describes traumatic OCDI in children < 18 years of age.

SUMMARY

We performed a systematic review, according to PRISMA guidelines, of children < 18 years of age presenting with traumatic etiologies of OCDI. We searched PubMed to identify papers congruent with these criteria. Exclusion criteria included (1) reports on atraumatic causes of OCDI and (2) studies with insufficient clinical and radiographic details on individual patients. We identified 16 reports describing a total of 144 patients treated for pediatric traumatic OCDI. Based on the synthesis of these findings and the collective experience of the authors, we present the demographic, clinical, and radiographic factors that underlie OC instability, which we hope will serve as components of a grading system in the future. We considered various clinical and radiographic findings including: (1) the mechanism of injury, (2) the patient's age, (3) CT/CT angiography of head and neck findings and parameters, (4) MRI findings, and (5) neurological exam, for the purpose of determining the severity of the OCDI and offering treatment guidelines based on the summative risk of underlying OC instability. Key Messages: OCDI is a potentially devastating injury, especially in children. Although missing the diagnosis can have potentially catastrophic consequences, reverting to surgical fixation in less severe cases can subject children to unnecessary operative risk and permanently reduce their range of motion. After reviewing all the available reports of pediatric traumatic OCDI in the neurosurgical literature, we propose an outline of clinical and radiographic factors influencing underlying OC instability that could be incorporated into a grading scale to guide treatment. We hope this study stimulates discussion on the standardization of treatment for pediatric OCDI.

Influence of Postoperative O-C2 Angle on the Development of Dysphagia After Occipitocervical Fusion Surgery: Results from a Retrospective Analysis and Prospective Validation

BACKGROUND

Postoperative dysphagia is a known complication of anterior cervical surgery, but its incidence and possible mechanisms are seldom reported after occipitocervical fusion (OCF). Our objective was to study the relationship between craniocervical alignment and the development of dysphagia after OCF for the treatment of basilar invagination with atlantoaxial instability.

METHODS

The study consisted of a retrospective series and a prospective series. Seventy-eight patients who underwent OCF (30 male, 48 female) were reviewed in the retrospective series. The presence and duration of postoperative dysphagia were recorded with an in-person questionnaire or telephone interview. Sagittal reconstructed computed tomography images before and after the procedure were collected. The O-C2 angle and C2-C7 angle were measured. The relationship of these parameters and their influence to the incidence of dysphagia were analyzed. The patients were grouped according to whether they developed postoperative dysphagia (group A) or not (group B). A prospective case series of 27 patients (group C) were reported to verify the influence of O-C2 angle on postoperative dysphagia.

RESULTS

In the retrospective case series, 19 patients (24.4%) complained of postoperative dysphagia after OCF. The change in the O-C2 angle was significantly lower in group A than in group B (P < 0.001). In the prospective case series, only 1 patient (3.7%) complained of postoperative dysphagia.

CONCLUSIONS

O-C2 angle plays an important role in the development of postoperative dysphagia after OCF procedure. Careful intraoperative alignment of the O-C2 angle may help to reduce the incidence and severity of postoperative dysphagia after OCF.

Craniovertebral fixation … a new technique of occipital - cervical fixation

BACKGROUND

Craniovertebral instability following transoral odontoid excision is usually treated by posterior occipital-cervical fixation using occipital plate and cervical lateral mass fixation with screw rod construct. A patient previously operated for basilar invagination had postoperative infection of both the transoral wound and the posterior implant site which needed removal of the posterior implant earlier.

CLINICAL PRESENTATION

The patient presented with severe neck pain, myelopathy, and chronic discharging sinus in the posterior lower aspect the previous neck surgery wound. Reimaging revealed incomplete odontoid excision. He underwent repeat transoral odontoid excision. Treatment of the instability needed occipitocervical fixation avoiding, the atlas, axis (weakened by infection and previous implants), and the infected posterior cervical wound. A new technique using a customized plate rod construct, fixed anteriorly to the mid cervical vertebrae (by a standard mid cervical exposure) with the rods contoured to reach posteriorly through the safe paraspinal corridor and connected with domino connectors to occipital plate rods fixed on either side of midline by additional posterior exposure avoiding the midline scar was planned and executed successfully.

CONCLUSION

This construct transfers the weight of the cranium to the cervical vertebral bodies along the physiological line of weight transmission and can be considered for distraction and reduction of basilar invagination with atlantoaxial dislocation. The technique seems to be safe and reproducible, but will need to tested over time with more cases.