Reliability and head-loading effects in imaging diagnosis of vertical subluxation in patients with rheumatoid arthritis

OBJECTIVES

The purpose of this study was to examine the reproducibility of vertical subluxation (VS) parameters using X-ray, computed tomography (CT), and tomosynthesis (TS) while comparing the head-loading effects.

METHODS

The VS parameters of 26 patients (retrospective review) were evaluated. Using the intra-class correlation coefficient, we statistically examined the intra-rater and inter-rater reliabilities of the parameters. Head-loaded and -unloaded imagings were compared using a Wilcoxon signed-rank test.

RESULTS

The intra-rater reliability of TS and CT showed intra-class correlation coefficients of ≥0.8 (X-ray range: 0.6-0.8), with similar results for the inter-rater reliabilities. Furthermore, in head-loading imaging, the TS had significantly higher VS scores than that of CT (P < .05).

CONCLUSIONS

In comparison with the X-ray, TS and CT were more accurate and reproducible. In terms of head loading, the VS values for TS were worse than those for CT, indicating that TS was more effective than CT in diagnosing VS.

C2 Superior Facetal Osteotomy: A Novel Technique in Complex Craniovertebral Junction Surgery for C1 Lateral Mass Screw Placement

Complex craniovertebral junction (CVJ) defects account for a considerable proportion of CVJ diseases. Given the heavily assimilated C1, an unfavorable C1-C2 joint orientation, an overriding C2 superior facet, a low-hanging occiput, and an abnormal vertebral artery course with a high-riding vertebral artery, placement of C1 lateral mass screws might be difficult. To address this, a novel technique for placing C1 lateral mass screws that avoid vertebral artery injury, low-hanging occiput, and overriding C2 superior facet was developed in this study. This approach enables firm fixation of C1-C2 even in difficult situations where the placement of the C1 lateral mass is challenging.

Anterior Transarticular Crossing Screw Fixation for Atlantoaxial Joint Instability: A Biomechanical Study

OBJECTIVE

To evaluate the biomechanical stability of anterior transarticular crossing screw (ATCS) and compare it with anterior transarticular screw (ATS) which may provide basic evidence for clinical application.

METHODS

Eight human fresh cadaveric specimens (occiput-C4) were tested with 5 conditions including the intact status, the injury status (type II odontoid fracture), the injury+ATS fixation status (traditional bilateral ATS fixation); the injury+unilateral ATCS fixation status; and the injury+bilateral ATCS fixation status. Specimens were applied to a pure moment of 1.5 Nm in flexion-extension, lateral bending, and axial rotation, respectively. The range of motions (ROMs) and the neutral zones (NZs) of C1 to C2 segment were calculated and compared between 5 status.

RESULTS

ATS and ATCS fixations significantly reduced the motions in all directions when compared with the intact and injury statues (p < 0.05). In flexion-extension, the ROMs of ATS, unilateral ATCS, and bilateral ATCS were 4.7° ± 2.5°, 4.1° ± 1.9°, and 3.2° ± 1.2°, respectively. Bilateral ATCS resulted in a significant decrease in ROM in flexion-extension when compared with ATS and unilateral ATCS (p = 0.035 and p = 0.023). In lateral bending and axial rotation, there was no significant difference in ROM between the 3 fixations (p > 0.05). Three fixations resulted in similar NZs in all directions (p > 0.05).

CONCLUSION

ATCS is a biomechanically effective alternative or supplemental method for atlantoaxial instability.

Iatrogenic atlantoaxial rotatory subluxation after thyroidectomy in a pediatric patient: A case report

BACKGROUND

Atlantoaxial rotatory subluxation (AARS) is an uncommon disease with a greater prevalence among children than adults, and it is mostly associated with trauma. Iatrogenic spinal injury accounts for a low percentage of injuries. However, in AARS, 20%-40% of cases are associated with surgery, and 48% are caused by infection. Here, we describe our experience with a case of iatrogenic AARS after general anesthesia.

CASE SUMMARY

A 12-year-old girl presented with right-sided torticollis and cervical motion limit. The patient had undergone thyroidectomy 2 mo ago. Computed tomography revealed AARS with bilateral locked facets. Following the failure of repeated external reduction under general anesthesia, the patient underwent an open surgical reduction. The patient gained atlantoaxial alignment without any complications. Follow-up radiographs showed a normal appearance without instability. The cervical spine of children is more predisposed to injury due to anatomical and biomechanical differences. AARS secondary to infection and surgery is known as Grisel’s syndrome, which involves non-traumatic AARS. Several cases of AARS after surgery and other procedures with no evidence of inflammation have been reported. Our experience shows that surgery requiring hyperextension of the neck after general anesthesia should also be included as a risk factor.

CONCLUSION

Surgeons and anesthesiologists should be careful not to excessively extend the neck during pediatric surgery. Moreover, clinicians caring for pediatric patients with recent head and neck procedures must be aware of common AARS presentations.

Clinical features of atlantoaxial involvement in patients with rheumatoid arthritis using 18F-fluorodeoxyglucose-positron emission tomography with computed tomography

INTRODUCTION/OBJECTIVES

Cervical spine involvement is one of the most serious complications in rheumatoid arthritis (RA). The study aim was to assess the clinical significance of atlantoaxial (AA) joint involvement detected by ¹⁸F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) with computed tomography (CT) in patients with RA.

METHOD

A prospective cross-sectional study was conducted to evaluate AA joint involvement detected by FDG-PET/CT in consecutive RA patients from December 2017 to February 2022. We investigated the relationship between AA joint involvement and clinical data, including disease activity and patients' cervical symptoms.

RESULTS

Among 48 patients enrolled, abnormal FDG uptake at AA joint was detected in 13 (27%). Rheumatoid factor titre, initial disease activity score 28-erythrocyte sedimentation rate and total standardized uptake value were significantly higher in the 13 patients than in the others (P = 0.004, P < 0.001 and P = 0.001, respectively). All patients with abnormal FDG uptake at AA joint had some cervical symptoms regardless of cervical spine X-ray abnormalities. Neck pain on movement and at rest were more frequent in the 13 patients than in the others (P = 0.001 and P = 0.004, respectively). The most sensitive symptom associated with AA joint involvement was neck pain on movement (sensitivity, 69%), and the most specific symptom was neck pain at rest (specificity, 100%).

CONCLUSIONS

AA joint involvement was commonly observed by FDG-PET/CT in patients with active RA, independent of radiographic findings. Specific cervical symptoms can be important surrogate markers for detection of potential AA synovitis associated with active RA. Key Points • AA joint involvement was frequently seen in RA with high disease activity independent of radiographic findings. • Neck pain was a hallmark of AA joint involvement reflecting disease activity, and resting pain was highly specific.

Posterior C1-C2 fusion for atlantoaxial rotatory fixation after posterior fossa craniotomy in a 4-year old: a case report

INTRODUCTION

This study aimed to highlight that atlantoaxial rotatory fixation (AARF) can be related to neurosurgery procedures in children, with an afterward demonstration of good results after halo-gravity traction and C1-C2 stabilization using the Harms technique.

CASE DESCRIPTION

To the best of our knowledge, this is the first case to report a 4-year-old boy who presented with AARF after a posterior fossa craniotomy to treat a cerebellar astrocytoma. At our medical facility, AARF was diagnosed using plain radiography and computed tomography imaging. The patient was treated with continuous cranial traction for 14 days. Initially, we detected that the patient had no C1 posterior arch or C2 spinous process; therefore, the best option was to perform the Harms technique. Postoperatively, the patient was placed in a cervical collar for 4 weeks. At the 4-year postoperative follow-up, the patient was doing well and had not developed any complications.

CONCLUSION

Herein, we report a case in which AARF can be developed after neurosurgical procedure. Surgical techniques used for atlantoaxial subluxation should be carefully selected. In our case, the Harms technique after cranial traction was an excellent option for correcting and stabilizing the abnormal neck position. However, further studies are required to determine the best technique to use in the pediatric population.

Appropriateness of Cervical Magnetic Resonance Imaging in the Evaluation and Management of C1 Jefferson Fractures

BACKGROUND

Traditionally, C1 fractures have been designated as stable or unstable based on the inherent integrity of the transverse altantal ligament. The purpose of our study was to identify adult trauma patients with C1 fractures on cervical computed tomography and evaluate whether C1-C2 alignment differed in patients with and without an associated transverse atlantal ligament injury on follow-up cervical magnetic resonance imaging.

METHODS

Adult trauma patients who suffered a C1 fracture were identified retrospectively. The cervical computed tomography examinations for these patients were reviewed for the following: C1 fracture classification, anterior atlantodens interval (ADI) widening, asymmetry in the lateral atlantodens interval, C1 lateral mass offset, and atlantoaxial rotation.

RESULTS

Acute C1 fractures were grouped into those with an unequivocal transverse atlantal ligament injury (n = 12), and patients with an unequivocally intact transverse atlantal ligament (n = 20). Three patients were classified as indeterminate for transverse atlantal ligament injury. Statistically significant increases in lateral ADI asymmetry and combined C1 lateral mass offset were identified in patients with transverse atlantal ligament tears.

CONCLUSIONS

Lateral ADI asymmetry (using a cutoff of >3 mm), combined C1 lateral mass offset, and anterior ADI demonstrate robust specificity to "rule in" transverse atlantal ligament injury. Atlantoaxial alignment was overall relatively insensitive as a screening test although sensitivity can be improved using a cutoff of >2 mm for lateral ADI asymmetry. Our findings reinforce the role of cervical magnetic resonance imaging in the diagnostic workup and clinical management of trauma patients with an acute burst fracture of the C1 vertebra.

Factors Associated with Retro-Odontoid Pseudotumor in Long-Term Hemodialysis Patients

OBJECTIVE

Hemodialysis has been reported to be associated with retro-odontoid pseudotumor (ROP), but its clinical characteristics have not been well described. The purpose of the present study was to investigate the factors associated with ROP in hemodialysis patients.

METHODS

A retrospective clinical study of hemodialysis patients was conducted with the evaluation of computed tomography and magnetic resonance imaging of cervical spinal lesions at a single institution from 2012 to 2020. The patients' characteristics and radiographic findings were assessed. A case-control analysis was performed between patients with ROP (ROP group) and patients without ROP (control group).

RESULTS

We analyzed 46 patients. The mean duration of hemodialysis (± standard deviation) was 21.5 ± 11.8 years. The mean retro-odontoid soft tissue thickness was 4.3 ± 0.3 mm and was correlated with the duration of hemodialysis (r = 0.46, P < 0.01). Thirty patients (65.2%) were included in the ROP group. The ROP group showed a significantly longer duration of hemodialysis (24.9 ± 11.2 years vs. 15.2 ± 10.3 years, P < 0.01) and a higher incidence of osteolytic lesions in the atlantoaxial joint compared with the control group (60.0% vs. 18.8%, P < 0.01). Logistic regression analysis revealed the atlantoaxial osteolytic lesions are associated with retro-odontoid pseudotumor in hemodialysis patients (odds ratio, 5.1; 95% confidence interval, 1.1-24.2; P = 0.04).

CONCLUSIONS

The existence of ROP in hemodialysis patients was associated with osteolytic lesions in the atlantoaxial joint. The finding of atlantoaxial erosive lesions in long-term hemodialysis patients requires spine surgeons to carefully evaluate the presence of ROP.

An Intraoperative Trajectory-Determined Strategy of Patient-Specific Drill Template for C2 Transoral Pedicle Insertion in Incomplete Reduction of Atlantoaxial Dislocation: An In Vitro Study

Objectives

This study aims to explore a novel intraoperative trajectory‐determined strategy of grouped patient‐specific drill templates (PDTs) for transoral C₂ pedicle screw insertion (C₂TOPI) for atlantoaxial dislocation (AAD) with incomplete reduction and to evaluate its efficiency and accuracy.

Methods

Ten cadaveric C₂ specimens were scanned by computed tomography (CT) and randomly divided into two groups (the PDT and freehand groups). A novel intraoperative trajectory‐determined strategy of grouped PDTs was created for AAD with incomplete reduction. C₂TOPI was performed by use of the PDT technique and the fluoroscopy‐guided freehand technique. After surgery, the screw deviations from the centroid of the cross‐section at the midpoint of the pedicle and screw position grades were assessed in both groups.

Results

Compared to the freehand group, the PDT group had a significantly shorter surgery time than the freehand group (47.7 vs 61.9 min, P < 0.001). The absolute deviations from the centroids between the preoperative designs and postoperative measurements on the axial plane of the pedicle were 1.19 ± 0.25 mm in the PDT group and 1.82 ± 0.51 mm in the freehand group. On the sagittal plane of the pedicle, the corresponding values were 1.10 ± 0.33 mm in the PDT group and 1.70 ± 0.49 mm in the freehand group. The absolute deviations of the free‐hand group on both the axial and sagittal planes were higher than that of the freehand group (P < 0.05 and P < 0.05, respectively). For the grade of screw insertion position, nine (90%) were observed in type I and one (10%) in type II in the PDT group, whereas five (50%) were in type I, three (30%) were in type II, and two (20%) in type III in the freehand group. Statistical differences could not be found between the groups in terms of the screw positions (P > 0.05).

Conclusion

The novel intraoperative trajectory‐determined strategy of grouped PDTs can be used as an accurate and feasible method for C₂TOPI for AAD with incomplete reduction.

Tophaceous gout of the atlantoaxial joint: a case report

Background

To report the occurrence of tophaceous gout in the cervical spine and to review the literature on spinal gout.

Case presentation

This report details the occurrence of a large and clinically significant finding of tophaceous gout in the atlantoaxial joint of the cervical spine in an 82-year-old Caucasian man with a 40-year history of crystal-proven gout and a 3-month history of new-onset progressive myelopathy. The patient's American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) criteria score was 15.0.

Conclusion

Spinal gout is more common than previously thought, and it should be considered in patients who present with symptoms of myelopathy. Diagnosis can be made without a tissue sample of the affected joint(s) with tools like the ACR/EULAR criteria and the use of the “diagnostic clinical rule” for determining the likelihood of gout. Early conservative management with neck immobilization and medical management can avoid the need for surgical intervention.

Rotational dislocation C1-C2 after otoplasty under local anesthesia

Non-traumatic rotational atlantoaxial subluxation (NTARS) is rare and mostly reported after infection of the upper respiratory tract and named Grisel's syndrome. NTARS has also been reported after head-and-neck surgery, but it is extremely rare after otoplasty. A case of NTARS after bilateral otoplasty is reported under local anesthesia, a 15-year-old female being presented with painful torticollis. The diagnosis of atlantoaxial rotatory subluxation was performed using radiographs and computed tomography 2 weeks after the surgery. Closed reduction was performed by traction of the head and transoral direct pressure over an anterior dislocated C1 mass. The reposition of the joint was achieved, but it was very unstable, and it was not possible to keep the reduction. Open posterior reduction and posterior C1–C2 arthrodesis were performed followed by the use of a soft collar during 3 months.

Management of post-traumatic craniovertebral junction dislocation: A PRISMA-compliant systematic review and meta-analysis of casereports

Although historically considered fatal, with the advent of improved pre-hospital care, traumatic dislocation of the craniovertebral junction (CVJ) has been increasing in prevalence in neurosurgical centers. As more survivors are reported each year, a timely review with meta-analysis of their management seems necessary. PRISMA checklist was followed step by step. PubMed and Web of Science databases were searched using words “craniovertebral junction dislocation” and their corresponding synonyms. Study eligibility criteria included research studies from 2015 onwards that delineated adult and pediatric patients with confirmed post-traumatic atlantooccipital dislocation (AOD) or atlantoaxial dislocation (AAD) who survived until proper treatment. Of 1475 initial records, 46 articles met eligibility criteria with a total of 141 patients with traumatic CVJ dislocation. Of the patients, 90 were male (63.8%). Mean age of the cohort was 33.3 years (range 1–99 years). Trauma that most often led to this injury was road traffic accident (70.9%) followed by falls (24.6%). The majority of authors support posterior instrumentation of C1-C2 (45.2%) especially by means of Goel-Harms method. At mean follow-up of 15.4 months (range 0.5–60 months), 27.2% of treated patients remained neurologically intact. Of initially symptomatic, 59% improved, 37% were stable, and 4% deteriorated. Instrumenting the occiput in cases of pure AAD was associated with lower chance of neurological improvement in chi-square test (p = 0.0013) as well as in multiple linear regression (β = − 0.3; p = 0.023). The Goel-Harms C1-C2 fusion is currently the most frequently employed treatment. Many survivors remain with no deficits or improve, rarely deteriorate. Involving the occiput in stabilization in cases of AAD without AOD might be related with worse neurological prognosis.

Plausible impact of forward head posture on upper cervical spine stability

The cervical spine is responsible for allowing mobility and stability to the head and neck. Any deviation to the center of gravity of the head results in an increase in cantilever loads, which can be particularly damaging to the upper cervical joints. Excessive neck bending also exaggerates stretching through the cervical spine and all of the spinal structures below. It has been reported that forward head posture (FHP) can cause a multitude of disorders including cervical radiculopathy, cervicogenic headaches and cervicogenic dizziness. Most of these conditions manifest with clusters of painful symptoms and spine dysfunctions. The purpose of this case study is to describe the radiographic imaging considerations and to illustrate the potential impacts in symptomatic adults with FHP. We randomly selected radiographs of three individuals with FHP who had undergone cervical adjustment for cervical pain. The occipito-axial (C0-C2) and atlanto-axial (C1-C2) joints were assessed via the C0-2 distance from the C2 base to the McGregor line (Redlund-Johnell criterion) and the Ranawat C1-2 index, in addition to subjective radiographic parameters. By comparing the radiographs of before-and-after intervention of each patient, a regressive joint spacing was observed from both indices. Such a long-lasting stretching concordant with FHP was assumed to be hazardous to joint stability. A definite conclusion, however, cannot be drawn due to the small sample size and a lack of convincing measurements.

Intradural synovial cyst of the upper cervical spine: A rare cause of symptomatic cord compression

Background:

Synovial cysts are commonly observed soft-tissue masses of the spine, typically extradural and located in the lumbar region. We describe a very rare symptomatic case of a C1-C2 intradural synovial cyst.

Case Description:

A 78-year-old female presented with progressive left side weakness, paresthesia, and hyperreflexia. The magnetic resonance imaging revealed a well-circumscribed, subtly enhancing lesion medial to the C1-2 facet, causing cord compression and edema. Using neurophysiological monitoring, surgery included a modified laminectomy of C2 with the removal of the C1 posterior arch. When the dura was opened, a sizable intradural extramedullary lesion was encountered, the cyst was successfully drained and partially resected. The histopathological diagnosis was consistent with a synovial cyst. Postoperatively, the patient’s strength on the left side improved gradually until she was fully ambulatory. Postoperative imaging showed no recurrence at 8 months follow-up.

Conclusion:

Synovial cysts should be considered among the differential diagnose of C1-2 cysts. They can occur intradurally and compress the spinal cord resulting in a significant neurological deficit. Cyst excision may be accomplished utilizing a limited laminectomy for cyst identification and drainage, accompanied by partial resection of the cyst wall. Such intervention can lead to good clinical outcomes.

One-Stage Anteroposterior Extensive Atlantoaxial Osteotomy Correction With 16 Months Follow-up: Technical Case Report

BACKGROUND AND IMPORTANCE

Patients with severe thoracic or lumbar deformities can achieve satisfactory correction through appropriate osteotomies. However, patients with multiple craniocervical malformations commonly undergo conservative or finite surgical therapy mainly because of the involvement of the vertebral artery. Anterior oral meningocele is an extremely rare pathology that has not been previously reported. Here, we provide the first report of complex craniocervical anomalies combined with oral meningocele treated with a 1-stage anteroposterior atlantoaxial osteotomy correction surgery, with outcomes after 16 mo follow-up.

CLINICAL PRESENTATION

A 10-yr-old boy presented with recurrent dyspnea, cyanosis, and progressive torticollis. Imaging studies revealed complicated bony abnormalities accompanied by an anterior oral meningocele. A 1-stage extensive atlantoaxial osteotomy through anterior and posterior approaches was performed with an innovatively designed vertebral artery exclusion technique. Lumbar cistern drainage and ceftazidime were used to address the leakage of cerebrospinal fluid and intracranial infection.

CONCLUSION

The satisfactory outcome demonstrates the feasibility of extensive atlantoaxial osteotomy via a vertebral artery exclusion technique that might also be applicable to osteotomy in segments of C3-C6.

Unilateral atlantoaxial pseudoarticulation: A case report, literature review, and proposed mechanism

Background

Atlantoaxial pseudoarticulation rarely involves the cervical spine, and its etiology is unclear. In theory, pseudoarticulation is comparable to Bertolotti's syndrome in the lumbar spine or may be attributed to an aberrant focal fusion between C0-C1-C2 that occurs during the gastrulation of embryologic development.

Case Description

A 39-year-old female presented with neck pain and upper extremity weakness. Magnetic resonance/computed tomography studies documented a left-sided unilateral pseudoarticulation between the lamina of C1 and C2 causing compression of the dorsal spinal cord. Following resection of the accessory C1/C2 joint utilizing a C1 hemilaminectomy and partial C2 laminectomy, the patient's neck pain and weakness resolved. Histologically, the tissue showed benign osteocartilaginous tissue with no synovial capsule.

Conclusion

Here, the authors present a case of occiput-C1-C2 pseudojoint formation, leading to clinical and radiographic findings of cord compression due to boney outgrowth.

Anterior Transoral Débridement Combined with Posterior Fixation and Fusion for Atlantoaxial Tuberculosis

BACKGROUND

Atlantoaxial tuberculosis (TB) is rare in clinical practice, accounting for only about 0.3%-1% of spinal TB. An anterior-only surgical approach cannot provide strong fixation, whereas a posterior approach cannot achieve complete removal of lesions. A method combining anterior and posterior approaches to treat atlantoaxial TB is advisable. The aim of this study was to evaluate the effectiveness of anterior transoral débridement combined with posterior fixation and fusion for atlantoaxial TB.

METHODS

Clinical data of 20 patients with atlantoaxial TB who underwent anterior transoral débridement combined with posterior fixation and fusion in our hospital were retrospectively analyzed. Antituberculosis drugs were administered for 18 months after surgery. Neurologic status, clinical symptoms, fusion, reduction, and complications were evaluated.

RESULTS

Surgeries were performed successfully in all 20 cases with no injuries to spinal cord, nerves, or blood vessels. Clinical symptoms were relieved in all 20 patients (100%). Postoperative Japanese Orthopaedic Association score, occipitocervical visual analog scale score, and atlantodental interval were significantly improved (P < 0.05). Average follow-up duration was 33 months (range, 24-48 months). Bony fusion was achieved in all 20 cases. No serious complications were documented during follow-up.

CONCLUSIONS

Anterior transoral débridement combined with posterior fixation and fusion is an effective treatment for atlantoaxial TB, achieving removal of lesions and stability.

Radiologic Characteristics of Anterior Transarticular Crossing Screw Placement for Atlantoaxial Joint Instability

OBJECTIVE

The feasibility of anterior transarticular crossing screws (ATCS) was confirmed in cadaveric specimens and it has been used in clinic. However, no study has documented the morphometric characteristics of ATCS. This study seeks to determine the morphometric characteristics of ATCS in C1-C2 fixation.

METHODS

A total of 100 patients without abnormality of C1-2 were enrolled. The range of screw lateral angles (LAs) and the screw lengths of ATCS on coronal images were measured on multiplanar computed tomography images, as well as the screw incline angles (IAs) in the sagittal plane. The ideal trajectory was designed as toward to the posterosuperior points of the opposite C1 lateral mass, which had the longest screw.

RESULTS

The LAs were relatively small in men (31.4°-45.3°) compared with women (32.6°-46.0°). In the sagittal plane, the IAs were ranged from 41.0° to 68.4° in men and from 44.4° to 68.1° in women. The overall screw lengths were longer in men (34.7-44.8 mm) than in women (32.2-39.6 mm). In the ideal path, the LA and IA were 38.4° and 41.0° in men and 39.6° and 44.4° in women, and the screw lengths were 44.8 mm in men and 39.6 mm in women.

CONCLUSIONS

This study provides the range of screw angles and lengths of ATCS, which will help surgeons to perform ATCS safely and accurately.

Morphometric and functional study of the canine atlantoaxial joint

The atlantoaxial joint can be affected by instability, in most cases a congenital pathology in young small breed dogs. Causes of atlantoaxial instability (AAI) are variable but are usually attributed to a lack of ligamentous support. The purpose of the present study was to specify the role of the ligamentous structures in the stabilisation of the atlantoaxial joint and to find possible adaptations of the ligaments' internal structure to their specific function. Five Beagle cadavers were included in this study. Each dog was subjected to a computed tomography (CT) and a magnetic resonance imaging (MRI) examination of the upper cervical region. This region was then dissected and the ligamentous structures stabilising the atlantoaxial joint were measured and removed for histological analysis. A ligament to dens ratio (LDR) was established in order to provide a basis for comparison with the measurements taken in other dog breeds. MRI and gross anatomical measurements were very similar, confirming the validity of the results. MRI thus seems reliable for evaluating the ligamentous structures of the canine occipitoatlantoaxial region. The movement exerting the greatest stress on the atlantoaxial ligaments and inducing the greatest distension of the alar ligaments was a head flexion combined with a rotation. A clear adaptation of the ligamentous shape and internal structure to their specific function was observed. Histologically, alar ligaments consisted of wavy collagen fibres and a high proportion of elastic fibres, providing them with a remarkable elasticity compared to the transverse ligament structure which was much more rigid.

Treatment of Atlantoaxial Tuberculosis with Neurological Impairment: A Systematic Review

BACKGROUND

Tuberculosis (TB) in the atlantoaxial joint is a rare disease. However, the treatment of atlantoaxial TB with neurologic impairment is controversial. The aim of this review is to provide clinical outcomes of surgical and nonsurgical management of atlantoaxial TB.

METHODS

Databases including PubMed, Embase, and the Cochrane Central Register of Controlled Trials were searched for English literature describing the treatment of atlantoaxial TB with neurologic deficits. The outcomes of conservative and surgical treatment approaches, including treatment failure, death, changes in neurologic impairment, and complications, were compared by performing odds ratio (OR) analysis.

RESULTS

Overall, 24 studies (247 patients) meeting the inclusion criteria were analyzed. Ninety-four patients (38%) were treated conservatively and 153 (62%) patients were treated surgically. The rate of poor outcomes was greater in the conservative group (14.89%) than in the surgery group (1.3%) (OR, 0.081; 95% confidence interval [CI], 0.016-0.39).There was no significant difference in mortality between the conservative (1.06%) and surgery (3.27%) groups (OR, 3.28; 95% CI, 0.494-27.381). There was no significant difference in muscle power improvement between the 2 treatments (conservative, 95.7%; surgery:, 94.8%; OR, 1.353; 95% CI, 0.291-4.925).

CONCLUSIONS

Conservative and surgical treatments both significantly improved neurologic deficits in most patients. Compared with conservative treatment, surgical treatment reduced treatment failures without significantly increasing the rates of neurologic deficit improvement or mortality.

Endoscopic single stage trans-oral decompression and anterior C1 lateral mass and C2 pedicle stabilization for atlanto-axial dislocation

Although most of the cases of atlanto-axial dislocation (AAD) and basilar invasion can be managed by posterior approaches in the recent times, anterior decompression with stabilization is required in selected patients who persist with irreducible AAD even after manipulation of the C1-C2 facet joint under general anesthesia. A single stage endoscopic trans-oral decompression and stabilization can be used in such patients. It has not been described so far to the best of authors' knowledge. This is indicated in irreducible AAD with the mandibular angle lying below the C2-C3 disc space. It is not a proper choice when the mandibular angle is above the C2-C3 disc space, there is involvement of the facet joint by trauma or any other pathologies, and if a posterior compression at the cervicomedullary junction persists. All patients should undergo pre-operative radiographs, computed tomography (CT) scan and magnetic resonance imaging with angiogram of the cranio-vertebral region. Utilizing this technique, an intra-operative satisfactory reduction of the dislocation with C1-C2 stabilization could be achieved in 3 patients, and 7 required an additional odontoid excision. Post- operative plain radiographs should be performed to assess for C1- C2 alignment and fusion at 3 and 12 months after surgery. All 10 patients of our series had an irreducible AAD and two had an additional basilar invasion. All patients improved from the pre-operative Ranawat grade 3A (n = 8) and 3B (n = 2) to post-operative grade 1 (n = 9) and 2 (n = 1) at a 3-12- month follow-up assessment. The average duration of the procedure and blood loss was 145 minutes and 75 ml, respectively. Endoscopic trans-oral single stage decompression and stabilization seems to be an effective and safe alternative in selected patients with AAD and basilar invasion.

Quantitative magnetic resonance imaging assessment of lateral atlantoaxial joint meniscoid composition: a validation study

PURPOSE

Lateral atlantoaxial (LAA) joint meniscoid composition may have clinical significance in patients following neck trauma. However, the existing method of radiologically assessing meniscoid composition has an inherent element of subjectivity, which could contribute to measurement variability. The present study sought to investigate the accuracy of two-point Dixon fat/water separation MRI as a quantitative assessment of LAA joint meniscoid composition.

METHODS

Sixteen LAA joint meniscoids were excised from four cadavers (mean [SD] age 79.5 [3.7] years; one female) following cervical spine MRI (two-point Dixon, T1-weighted VIBE and T2-weighted SPACE sequences). Composition of LAA joint meniscoids was undertaken by (1) histological examination by light microscopy, (2) calculation of fat fraction by Dixon MRI (both in-phase/opposed-phase and fat/water methods), and (3) the existing method of considering VIBE and SPACE signal intensities. Analysis was performed using the kappa statistic with linear weighting.

RESULTS

Microscopy revealed three, five, and eight meniscoids to be composed of adipose, fibroadipose, and fibrous tissues, respectively. Dixon sequence MRI classified 11 of these meniscoids correctly, with 'substantial' level of agreement (In-phase/Opp-phase kappa statistic = 0.78 [95% CI 0.38, 1.17]; fat/water kappa statistic = 0.72 [95% CI 0.32, 1.11]). Level of agreement between microscopy and the VIBE and SPACE method was 'slight' (kappa statistic = 0.02 [95% CI - 0.34, 0.38]).

CONCLUSIONS

Findings suggest that Dixon fat/water separation MRI may have superior utility in the assessment of LAA joint meniscoid composition than the existing method of considering VIBE and SPACE signal intensities. These slides can be retrieved under Electronic Supplementary Material.

[The simple posterior operation for different types of malformations in the craniocervical junction with atlantoaxial dislocation]

Objective: To explore the therapeutic effect of simple posterior reduction and decompression technique for different types of malformations in the craniocervical junction with atlantoaxial dislocation. Methods: The clinical data of 34 cases of different malformations in the craniocervical junction who were treated by the simple posterior internal fixation and decompression surgery in the department of neurosurgery of the first affiliated hospital of Nanchang University from March 2014 to March 2017 were analyzed retrospectively.In 34 cases, including 26 cases of basilar invagination with atlantoaxial dislocation (19 cases with atlanto occipital fusion, 12 cases with Chiari malformation, 13 cases with syringomyelia), 8 cases of odontoid malformation with atlantoaxial dislocation (2 cases with Chiari malformation, 1 case with flat skull base, 1 case with malformation of atlas). All the cases were performed Dynamic position X-ray film, CT scan and Three-dimensional reconstruction, and craniocervical MRI scan before the operation.The enlarged decompression of the occipital foramen, the fixation and fusion of the occipitocervical were performed during the operation, and the patients with cerebellar tonsillar hernia were performed decompression of the occipital small bone window. Results: All patients were followed up after the operation.The symptoms were obviously improved in 29 cases (85.3%), stability and no change in 5 cases (14.7%) and none postoperative neurological deterioration cases. Conclusion: The treatment of craniocervical junction malformation using simple posterior reduction and decompression technique is effective and has few complications, which can obviously improve the life quality of the patients.

Complex congenital atlantoaxial dislocation in an infant: case report

The authors report the case of congenital atlantoaxial dislocation in a 9-month-old female infant, who presented with progressive quadriparesis and respiratory failure. The problems in management due to such an early age of presentation, including atypical clinical presentation, unique radiological findings, limited management options, and variable clinical outcomes discussed. This is the youngest case of non-syndromic congenital atlantoaxial dislocation, reported to date, and is a unique combination of lateral, rotatory, and antero-posterior atlantoaxial dislocation.

Brown-Sequard syndrome caused by hyperextension in a patient with atlantoaxial subluxation due to an os odontoideum

Brown-Sequard syndrome is an uncommon complication of atlantoaxial arthrodesis. A 50-year-old female visited our emergency department after falling from a ladder. Radiologic evaluations revealed chronic C1-2 instability with acute spinal cord injury. The day after atlantoaxial fusion was performed, she developed left-sided motor weakness and the loss of right-sided pain and temperature sensation. Based on physical examination and radiologic findings, we diagnosed her as having Brown-Sequard syndrome. Spine surgeons performing this procedure should therefore consider Brown-Sequard syndrome if a patient displays signs of postoperative hemiplegia.

Sagittal Atlantoaxial Joint Inclination and Reduction Index Values for Diagnosis and Treatment of Irreducible Atlantoaxial Dislocation

BACKGROUND

Irreducible atlantoaxial dislocation (IAAD) is a disorder of atlantoaxial joint instability with various causes. The diagnostic criteria for IAAD are variable. The diagnosis of IAAD is mainly based on preoperative and intraoperative traction results, as well as the physician's experience, with no relatively uniform guidelines for the selection of treatment. This study evaluates sagittal atlantoaxial joint inclination (SAAJI) and reduction index (RI) values for diagnosis and treatment of IAAD.

MATERIALS AND METHODS

24 IAAD patients treated in our hospital from January 2008 to July 2014 were retrospectively analysed. Patients included were 13 males and 11 females, with a mean age of 43 years. The various causes for IAAD were atlantoaxial transverse ligament rupture (n=3), old dens fracture (n=15), occipitalization of the atlas (n=6). The patients were divided into two groups. group A underwent anterior release with posterior reduction and fixation; Group B underwent posterior reduction and fixation; 12 healthy individuals served as controls. SAAJI and atlas-dens interval (ADI) values before and after traction were measured, and RI was calculated. Imaging data were analyzed.

RESULTS

The mean SAAJI values were as follows: left, 5.6 ± 1.9° and right, 5.1 ± 2.1° in the control group; right, 39.5 ± 6.0° and left, 38.8 ± 5.8° in Group A; and right, 23.1 ± 7.0° and left, 23.9 ± 6.1° in Group B. There was no significant difference in the SAAJI values of the three groups (P < 0.05). The mean RIs in Groups A and B were 17.6 ± 9.3% and 34.4 ± 5.2%, respectively, and the difference was statistically significant (P < 0.05). There were obvious negative correlations between the SAAJI and RI values in Groups A and B.

CONCLUSIONS

SAAJI and RI can be used as important imaging indicators to determine the reversibility of IAAD. If the RI value is >27.9% and SAAJI value is <32.5°, reduction and fixation can be achieved by the posterior approach alone; otherwise, a combination of anterior and posterior approaches would be necessary.

Basilar impression as complication of Grisel's syndrome

Grisel's syndrome presents a rare disease. Here, we present a peculiar case of Grisel's syndrome with an unfavorable course developing a basilar impression. This highlights the importance of close clinical and radiological follow‐up even in cases where the course seems uncomplicated.

Steinmann Pins for C1 Lateral Mass Screw Placement During Atlantoaxial Stabilization

OBJECTIVE

The authors describe a modified technique for placement of the C1 lateral mass screw using a Steinmann pin as a guide. This technique minimizes dissection and provides atlantoaxial stabilization during arthrodesis.

METHODS

In our technique, a nonthreaded 1.6-mm spade-tip Steinmann pin is placed into the lateral mass of C1 to serve as a guide over which a powered drill is used for screw insertion. Perioperative data were collected for consecutive patients who underwent a C1-2 arthrodesis that involved the modified technique between March 2010 and July 2016. Data included blood loss, operative times, and C2 nerve root injury.

RESULTS

The data for 93 patients were reviewed. Most (91.4%) patients presented with a fracture from an acute trauma. A mean of 1.97 levels was fused in these patients, with a mean blood loss of 76 mL and a mean operative time of 144 minutes. The overall morbidity and mortality rate was 10.7%. The morbidity rate of 7.5% included 30-day postoperative complications of respiratory failure and dysphasia. There were no postoperative vertebral artery injuries, hardware failures, or instances of occipital neuralgia.

CONCLUSIONS

The use of Steinmann pins to guide the placement of C1 lateral mass screws is safe and effective in C1-2 arthrodesis. Limiting dissection minimizes blood loss and injury, maintains efficient operative time, and assists in accurate placement of the screws. Furthermore, with less manipulation and retraction of the C2 nerve root, postoperative occipital neuralgia and the need for C2 root transection are avoided.

Effectiveness of a specific manual approach to the suboccipital region in patients with chronic mechanical neck pain and rotation deficit in the upper cervical spine: study protocol for a randomized controlled trial

Background

Mechanical neck pain is a highly prevalent problem in primary healthcare settings. Many of these patients have restricted mobility of the cervical spine. Several manual techniques have been recommended for restoring cervical mobility, but their effectiveness in these patients is unknown. The aim of the present study is to compare the effectiveness of two types of specific techniques of the upper neck region: the pressure maintained suboccipital inhibition technique (PMSIT) and the translatory dorsal glide mobilization (TDGM) C0-C1 technique, as adjuncts to a protocolized physiotherapy treatment of the neck region in subjects with chronic mechanical neck pain and rotation deficit in the upper cervical spine.

Methods

A randomized, prospective, double-blind (patient and evaluator) clinical trial. The participants (n = 78) will be randomly distributed into three groups. The Control Group will receive a protocolized treatment for 3 weeks, the Mobilization Group will receive the same protocolized treatment and 6 sessions (2 per week) of the TDGM C0-C1 technique, and the Pressure Group will receive the same protocolized treatment and 6 sessions (2 per week) of the PMSIT technique. The intensity of pain (VAS), neck disability (NDI), the cervical range of motion (CROM), headache intensity (HIT-6) and the rating of clinical change (GROC scale) will be measured. The measurements will be performed at baseline, post-treatment and 3 months after the end of treatment, by the same physiotherapist blinded to the group assigned to the subject.

Discussion

We believe that an approach including manual treatment to upper cervical dysfunction will be more effective in these patients. Furthermore, the PMSIT technique acts mostly on the musculature, while the TDGM technique acts on the joint. We expect to clarify which component is more effective in improving the upper cervical mobility.

Trial registration

ClinicalTrials.gov NCT02832232. Registered on July 13th, 2016.

Sublaminar wire migration into the medulla oblongata: a case report

Atlantoaxial procedures have been developed in an effort to ensure solid C1-C2 fusion. However, techniques that involve sublaminar wiring have the potential for neural structure injury. We present the management of a patient who previously underwent Gallie fusion 10 years ago and is presenting with a dislodged titanium wire that has migrated into the medulla oblongata. A 52-year-old female patient known with rheumatoid arthritis presented with truncal ataxia and food regurgitation 10 years after undergoing a C1-C2 Gallie fusion. A computerized tomography (CT) scan revealed that a wire from her Gallie fusion procedure migrated into the medulla oblongata. The patient underwent foramen magnum decompression with C1 bilateral laminectomy, instrumentation, and removal of a migrated wire. Six months later, a CT scan showed that all occipital screws were pulled out. In the revision surgery, new occipital screws were placed with a resultant significant improvement in patient's gait postoperatively. Wire migration as a differential diagnosis should be considered in patients presenting with neurological dysfunction who underwent surgical treatment with sublaminar wire fusion techniques.

Traumatic atlantoaxial rotatory fixation in an adult patient

INTRODUCTION

Atlantoaxial rotational fixation (AARF) is a rare entity in adults, with only a few cases reported in the English literature and often associated with a traumatic mechanism. It is an underdiagnosed condition that must be taken into account in the initial assessment of all craniocervical trauma. Both diagnostic and therapeutic delay may be a potential cause of severe neurological damage or even death of the patient. The therapeutic management is controversial given the difficulty of achieving optimum stability and permanent reduction.

METHODS AND RESULTS

A 28-year-old woman was involved in a traffic accident a week before coming to the emergency with rotation and irreducible cervical flexion from trauma and severe neck pain. CT and MRI column were performed and showed a cervical spinal AARF with transverse and alar ligaments intact and preserved atlantoaxial distance (Fielding I). The patient was treated by progressive cervical traction with 5 kg and manual reduction was completed in 24 h. Subsequently, an external immobilization was performed by cervical rigid collar for 16 weeks. The clinical course was good, with the patient regaining full mobility with cervical neck pain improvement.

CONCLUSIONS

The purpose of this paper is to show a case of a young woman with a posttraumatic AARF successfully treated conservatively. This case delineates the difficulties in diagnosing this pathology, as well as the challenges encountered in its management.

Immunohistochemical investigation of nerve fiber presence and morphology in elderly cervical spine meniscoids

BACKGROUND CONTEXT

Innervation of anatomical structures is fundamental to their capacity to generate nociceptive impulses. Cervical spine meniscoids are hypothesized to be contributors to neck pain; however, their innervation is not comprehensively understood.

PURPOSE

This study aimed to examine the presence and morphology of nerve fibers within cervical spine meniscoids and adjacent joint capsules.

STUDY DESIGN

This is a cross-sectional study.

PATIENT SAMPLE

The sample consists of cervical hemispines of 12 embalmed cadavers (mean [standard deviation] age 82.9 [6.5] years, six female, six left). Either the right or the left half of the cervical spine (hemispine) of each cadaver was included in the sample. So six left sides and six right sides of the cadaver cervical spines made up the 12 hemispines that formed the sample.

METHODS

Cervical spine meniscoids and adjacent joint capsules were excised from lateral atlantoaxial and cervical zygapophyseal (C2-C3 to C6-C7) joints (n=67), then paraffin embedded. Meniscoids were sectioned sagittally (5 µm), slide mounted, and immunohistochemistry was performed using primary antibodies to neurofilament heavy (NF-H) and pan-neurofilament (Pan-NF) to identify nerve tissue. The study was supported by institutional graduate student funding. The authors have no conflicts of interest to declare.

RESULTS

Seventy-seven meniscoids (23 lateral atlantoaxial, 54 cervical zygapophyseal) were extracted and processed (154 sections in total). Sixty-four individual nerve fiber bundles were identified (26 NF-H positive, 38 Pan-NF positive) from 14 meniscoids. Nerves immunoreactive to both NF-H and Pan-NF were identified in 13 of 77 meniscoids (10 of 14 lateral atlantoaxial joint) from 11 joints (eight cadavers). Nerves were always located in joint capsules except three exclusively Pan-NF immunoreactive nerve fiber bundles from two adipose meniscoids.

CONCLUSIONS

The low nerve prevalence in elderly cervical spine meniscoids, with nerves only found in two adipose type meniscoids, suggests these structures may play a minimal role in cervical nociception generation in this demographic. The joint capsules, which were more frequently innervated, appear to be more likely generators of nociception in the elderly. Joint capsule nerves were mostly NF-H positive, indicating potential Aδ-fiber presence.

Canine atlantoaxial optimal safe implantation corridors - description and validation of a novel 3D presurgical planning method using OsiriX™

Background

Canine ventral atlantoaxial (AA) stabilization is most commonly performed in very small dogs and is technically challenging due to extremely narrow bone corridors. Multiple implantation sites have been suggested but detailed anatomical studies investigating these sites are lacking and therefore current surgical guidelines are based upon approximate anatomical landmarks. In order to study AA optimal safe implantation corridors (OSICs), we developed a method based on computed tomography (CT) and semi-automated three-dimensional (3D) mathematical modelling using OsiriX™ and Microsoft®Excel software. The objectives of this study were 1- to provide a detailed description of the bone corridor analysis method and 2- to assess the reproducibility of the method. CT images of the craniocervical junction were prospectively obtained in 27 dogs and our method of OSIC analysis was applied in all dogs. For each dog, 13 optimal implant sites were simulated via geometrical simplification of the bone corridors. Each implant 3D position was then defined with respect to anatomical axes using 2 projected angles (ProjA). The safety margins around each implant were also estimated with angles (SafA) measured in 4 orthogonal directions. A sample of 12 simulated implants was randomly selected and each mathematically calculated angle was compared to direct measurements obtained within OsiriX™ from 2 observers repeated twice. The landmarks simulating anatomical axes were also positioned 4 times to determine their effect on ProjA reproducibility.

Results

OsiriX could be used successfully to simulate optimal implant positions in all cases. There was excellent agreement between the calculated and measured values for both ProjA (ρ_c = 0.9986) and SafA (ρ_c = 0.9996). Absolute differences between calculated and measured values were respectively [ProjA = 0.44 ± 0.53°; SafA = 0.27 ± 0.25°] and [ProjA = 0.26 ± 0.21°; SafA = 0.18 ± 0.18°] for each observer. The 95 % tolerance interval comparing ProjA obtained with 4 different sets of anatomical axis landmarks was [−1.62°, 1.61°] which was considered appropriate for clinical use.

Conclusions

A new method for determination of optimal implant placement is provided. Semi-automated calculation of optimal implant 3D positions could be further developed to facilitate preoperative planning and to generate large descriptive anatomical datasets.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-016-0824-3) contains supplementary material, which is available to authorized users.

Clinical Presentation of Cervical Myelopathy at C1-2 Level

STUDY DESIGN

Single-center retrospective study.

PURPOSE

To clarify the clinical features of cervical myelopathy at the C1-2 level.

OVERVIEW OF LITERATURE

Methods for distinguishing the affected level based on myelomere symptoms or dysfunction of the conducting pathway were established. However, no symptoms have been identified as being specific to the C1-2 level segment.

METHODS

We evaluated 24 patients with cervical myelopathy due to spinal cord compression at the C1-2 level. Preoperative neurological assessment were investigated and compared with the rate and site of compression of the spinal cord using computed tomography-myelography.

RESULTS

Impaired temperature and pain sensation were confirmed in 18 of the 24 patients with that localized to the upper arms (n=3), forearm (n=9), both (n=2), and whole body (n=4). Muscle weakness was observed in 18 patients, muscle weakness extended from the biceps brachii to the abductor digiti minimi in 10 patients, and in the whole body in 8 patients. Deep tendon reflexes were normal in 10 patients, whereas hyperactive deep tendon reflexes were noted in 14 patients. The rate of spinal cord compression was significantly higher in patients with perceptual dysfunction and muscle weakness compared with those with no dysfunction. However, no significant difference in the rate and site of compression was identified in those with dysfunction.

CONCLUSIONS

Perceptual dysfunction and muscle weakness localized to the upper limbs was observed in 58% and 42% of patients, respectively. Neurological abnormalities, such as perceptual dysfunction and muscle weakness, were visualized in patients with marked compression.

Intradural synovial cyst of the atlantoaxial joint: a case report

BACKGROUND

Intradural synovial cysts of the cervical spine represent a rare disease entity, causing stenosis of the spinal canal and thereby leading to progressive myelopathy. In particular, at the cranio-cervical junction early intervention is necessary to prevent permanent neurological dysfunction. We present the case of a 74-year-old man who presented with moderate cervicogenic headache, gait disturbance and progressive left-sided weakness. Magnetic resonance imaging (MRI) of the cervical spine confirmed a left-sided cystic mass located anteriorly at the craniovertebral junction compressing the surrounding structures.

METHOD

Surgical decompression was performed by means of a minimal left-sided laminectomy of C1. Postoperatively, the patients symptoms slowly improved, albeit a persistent ataxic gait.

RESULTS

Intraoperatively, a large intradural cyst was removed via a minimal suboccipital craniectomy combined with laminectomy of C1. Histopathological evaluation revealed a synovial cyst without any features of neoplasia. Despite not using craniocervical instrumentation, no clinical or radiological signs of atlantoaxial instability were observed up to 2 years after surgery.

CONCLUSIONS

Cystic lesions located at the atlanto-axial joint are a rare cause of cervical myelopathy. Preoperative imaging of the cervical spine should include not only MRI and computerised tomography (CT) but also dynamic imaging. Dorsal decompression without instrumentation prevents progressive neurological decline and may allow cord function to recover. If there is additional preoperative instability, instrumentation and fusion may be necessary.

Irreducible Atlanto-Axial Dislocation in Neglected Odontoid Fracture Treated with Single Stage Anterior Release and Posterior Instrumented Fusion

It is a well-know fact that type 2 odontoid fractures frequently go into nonunion. If left untreated, patients may develop irreducible atlantoaxial dislocation (AAD). We describe the surgical management of two patients with neglected odontoid fractures and irreducible AAD treated with single stage anterior release followed by posterior instrumented fusion. Both patients presented with history of neglected trauma and progressive myelopathy. Traction under anesthesia failed to achieve reduction of AAD. Anterior release was done by trans-oral approach in one patient and retrophayngeal approach in the other. Posterior fixation was performed with transarticular screws in both the patients. Both patients had full neurological recovery and demonstrated fusion at follow-up. Anterior release followed by posterior instrumented correction may be an effective alternative to the traditional means of treating irreducible dislocations associated with neglected odontoid fractures.

Morphology and morphometry of lateral atlantoaxial joint meniscoids

The lateral atlantoaxial joints contain folds of synovium termed meniscoids that may potentially contribute to cervical spine pain; however, the anatomy of these structures has not been comprehensively investigated. The purpose of this study was to explore the morphology and morphometry of lateral atlantoaxial joint meniscoids. Twelve cadaveric hemi-spines (6 female; 6 left; mean 81.5 years, SD 7.3) were obtained for dissection and disarticulation of the lateral atlantoaxial joints. Meniscoids were identified and measurements made of surface area, length, and surrounding articular cartilage degeneration. Tissue was sectioned sagittally, stained with hematoxylin and eosin, and examined by light microscopy. Data were analyzed descriptively and using nonparametric techniques. Ventral and dorsal meniscoids (24 in total) were found in each joint, and could be classified histologically into adipose (32%), fibrous (41%), and fibroadipose (27%) meniscoids. No significant associations were found between meniscoid size and age, histology, cartilage degeneration, or joint position. Meniscoid length in males was significantly greater than in females (P = 0.04). Fibrous meniscoids were noted to be associated with articular cartilage degeneration, and adipose and fibroadipose meniscoids with intact cartilage (P = 0.05). Fibrous meniscoids tended to be located dorsally (78%), whereas adipose meniscoids were mostly located ventrally (86%). Distinct patterns in lateral atlantoaxial joint meniscoid morphology were observed, including the association of fibrous meniscoid composition with dorsal joint position and articular cartilage degeneration. The clinical significance of these patterns remains uncertain, and further research is needed to examine these structures across the lifespan and in cervical pathology.

Recurrent atlantoaxial synovial cyst resection via a navigation-guided, endoscope-assisted posterior approach

Background:

Atlantoaxial cysts are rare, and only 46 histologically confirmed cases have been reported.

Case Description:

A 75-year-old male presented 2 years ago with headache, neck pain, loss of balance, and episodic dysphagia, for which he had undergone posterior cervical drainage of a left-sided atlantoaxial cyst. Although his original symptoms resolved, they recurred 2 years later and were correlated with an enhanced MR that showed a recurrent left C1-C2 synovial cyst causing marked cervical cord compression. It was successfully resected through a navigation-guided, endoscope-assisted posterior approach. The patient's symptoms/signs resolved completely, and he has remained symptom-free for over 30 months postoperatively, with no evidence of recurrence on MR or craniocervical instability.

Conclusions:

A patient who successfully underwent resection of a recurrent synovial cervical cyst using a navigation-guided, endoscope-assisted posterior approach has been reported here.

Late complication of surgically treated atlantoaxial instability: occipital bone erosion induced by protruded fixed titanium rod: a case report

OBJECTIVE

Polyaxial screw-rod fixation of C1-C2 is a relatively new technique to treat atlantoaxial instability, and there have been few reports in the literature outlining all possible complications. The purpose of this case report is to present the occurrence and management of occipital bone erosion induced by the protruded rostral part of a posterior atlantoaxial screw-rod construct causing headache.

CLINICAL FEATURES

A 70-year-old Asian man with rheumatoid arthritis initially presented to our institution with atlantoaxial instability causing progressive quadraparesis and neck pain.

INTERVENTION AND OUTCOME

Posterior atlantoaxial instrumented fixation using C1 lateral mass screws in conjunction with C2 pedicle screws was performed to stabilize these segments. Postoperatively, the patient regained the ability to independently walk and had no radiographic evidence of instrumentation hardware failure and excellent sagittal alignment. However, despite a well-stabilized fusion, the patient began to complain of headache during neck extension. Follow-up imaging studies revealed left occipital bone erosion induced by a protruded titanium rod fixed with setscrews. During revision surgery, the rod protrusion was modified and the headaches diminished.

CONCLUSION

This case demonstrates that occipital bone erosion after posterior atlantoaxial fixation causing headache may occur. The principal cause of bone erosion in this case was rod protrusion. Although posterior atlantoaxial fixation using the screw-rod system was selected to manage atlantoaxial instability because it has less complications than other procedures, surgeons should pay attention that the length of the rod protrusion should not exceed 2 mm.

Grisel syndrome: pathophysiological evidence from magnetic resonance imaging findings

Grisel syndrome is a condition of uncertain etiology characterized by a non-traumatic atlantoaxial subluxation following an infection in the head and neck region. Although first described in 1830, the exact pathophysiology of Grisel syndrome remains unclear. We present a case of atlantoaxial subluxation after acute lymphadenitis diagnosed with a dynamic computed tomography (CT) and magnetic resonance imaging (MRI). A previously healthy 9-year-old male patient presented with torticollis of sudden onset. Dynamic CT and MR imaging showed rotary atlantoaxial subluxation and inflammation surrounding the cervical spinal ligaments. A follow-up MRI of the cervical spine, taken 3 weeks after the onset of symptoms, showed a complete resolution of subluxation and inflammation surrounding the cervical spinal ligaments. In this case report, we support the hypothesis that an inflammation-induced laxity of the cervical ligaments is the pathologic key to Grisel syndrome using radiologic findings.

Computer-assisted C1-C2 Transarticular Screw Fixation "Magerl Technique" for Atlantoaxial Instability

STUDY DESIGN

A retrospective study.

PURPOSE

To evaluate the surgical results of computer-assisted C1-C2 transarticular screw fixation for atlantoaxial instability and the usefulness of the navigation system.

OVERVIEW OF LITERATURE

We used a computed tomography (CT)-based computer navigation system in planning and screw insertion in Magerl's procedure, which provides the most rigid atlantoaxial fusion, to avoid risk of vertebral artery (VA) tear by avoiding high-riding VA during screw insertion.

METHODS

Twenty patients who underwent atlantoaxial fusion under the CT-based navigation system were studied. The mean observation period was 33.5 months. The evaluated items included the existence of VA stenosis by preoperative magnetic resonance angiography, surgical time, blood loss volume, Japanese Orthopaedic Association (JOA) score and Ranawat's pain criteria before surgery and at final follow-up, postoperative screw position evaluated by CT, and bony fusion.

RESULTS

The mean operation time was 205 minutes, with the mean blood loss volume of 242 ml. The mean JOA score was 11.6 points before surgery and 13.7 at final follow-up. Occipital and/or cervical pain presented before operation was remitted or resolved in all patients. Evaluation of screw insertion by CT revealed correct penetration to atlantoaxial joints, with a perforation rate of 2.6%. There was no complication, including VA tear, and all patients who were followed-up during one year or more after surgery achieved bony fusion. Some subjects who appeared inappropriate for surgery from CT images were assessed as eligible for surgery based on the evaluation results obtained using the navigation system.

CONCLUSIONS

It was demonstrated that the CT-based navigation system is an effective support device for Magerl's procedure.