Atlanto-axial dislocation in rheumatoid arthritis--diagnostic and therapeutic aspects

Adult cervical spine deformity: a state-of-the-art review

Adult cervical deformity is a structural malalignment of the cervical spine that may present with variety of significant symptomatology for patients. There are clear and substantial negative impacts of cervical spine deformity, including the increased burden of pain, limited mobility and functionality, and interference with patients' ability to work and perform everyday tasks. Primary cervical deformities develop as the result of a multitude of different etiologies, changing the normal mechanics and structure of the cervical region. In particular, degeneration of the cervical spine, inflammatory arthritides and neuromuscular changes are significant players in the development of disease. Additionally, cervical deformities, sometimes iatrogenically, may present secondary to malalignment or correction of the thoracic, lumbar or sacropelvic spine. Previously, classification systems were developed to help quantify disease burden and influence management of thoracic and lumbar spine deformities. Following up on these works and based on the relationship between the cervical and distal spine, Ames-ISSG developed a framework for a standardized tool for characterizing and quantifying cervical spine deformities. When surgical intervention is required to correct a cervical deformity, there are advantages and disadvantages to both anterior and posterior approaches. A stepwise approach may minimize the drawbacks of either an anterior or posterior approach alone, and patients should have a surgical plan tailored specifically to their cervical deformity based upon symptomatic and radiographic indications. This state-of-the-art review is based upon a comprehensive overview of literature seeking to highlight the normal cervical spine, etiologies of cervical deformity, current classification systems, and key surgical techniques.

Effect of modified clivoaxial angle on surgical decision making and treatment outcomes in patients with Chiari malformation type 1

Introduction

Chiari malformation type 1 (CM1), a complex pathological developmental disorder of the craniovertebral junction, is typically characterized by herniation of the cerebellar tonsils from the foramen magnum. Treatment using posterior fossa decompression alone without taking the ventral cervico-medullary compression into consideration may lead to unsatisfactory treatment outcomes. The current study evaluated the utility of the modified clivoaxial angle (MCAA) in assessing ventral compression and also examined its effect on treatment outcomes.

Method

This retrospective study included 215 adult patients who underwent surgical treatment for CM1 at one medical center over a 10-year period. The following surgical techniques were used to decompress the posterior fossa: (a) PFD: bone removal only; (b) PFDwD: bone removal with duraplasty; and (c) CTR: cerebellar tonsil resection. The morphometric measurements of the craniovertebral junction (including MCAA) were recorded using preoperative images, and the postoperative clinical status was evaluated using the Chicago Chiari outcome scale (CCOS).

Results

MCAA was positively correlated with the CCOS score and also independently predicted treatment outcome. To enable Receiver operating characteristic (ROC) curve analysis of CCOS scores, the patients were divided into three groups based on the MCAA cut-off values, as follows: (a) severe (n = 43): MCAA ≤ 126; (b) moderate (n = 86): 126 < MCAA ≤ 138; and (c) mild (n = 86): MCAA > 138. Group a exhibited severe ventral cervico-medullary compression (VCMC), and their CCOS scores for the PFD, PFDwD, and CTR groups were 11.01 ± 1.2, 11.24 ± 1.3, and 13.01 ± 1.2, respectively (p < 0.05). The CCOS scores increased with widening of the MCAA angle in all surgical groups (p < 0.05). Furthermore, patients with mild MCAA (>138°) exhibited 78% regression of syringomyelia, and this was significantly greater than that observed in the other groups.

Discussion

MCAA can be used in the selection of appropriate surgical techniques and prediction of treatment outcomes, highlighting the importance of preoperative evaluation of ventral clivoaxial compression in patients with CM1.

Evaluation of Soft Tissue Hypertrophy at the Retro-Odontoid Space in Patients with Chiari Malformation Type I on Magnetic Resonance Imaging

INTRODUCTION

Chiari malformation type I (CM-I) is a well-known hindbrain disorder in which the cerebellar tonsils protrude through the foramen magnum. The soft tissues, including the transverse ligament and the tectorial membrane at the retro-odontoid space, can compress the cervicomedullary junction if they become hypertrophic.

METHODS

Twenty-two symptomatic patients with CM-I (aged 5-19 years) were treated between 2007 and 2017 at our institute. The retro-odontoid soft tissue was evaluated using T2-weighted magnetic resonance imaging. Anteroposterior (AP) distances and craniocaudal distances of the soft tissue were measured in patients with CM-I and 48 normal control children. Modified clivoaxial angles were also evaluated as the index of ventral compression of the cervicomedullary junction.

RESULTS

Of the 18 patients treated with foramen magnum decompression, 16 patients improved postoperatively, whereas the condition of 2 remained unchanged. The AP distances in the CM-I group (6.0 mm) were significantly larger than those in the control group (3.5 mm), whereas there were no apparent differences in the craniocaudal distances. Modified clivoaxial angles were obviously smaller in the CM-I group (131.5°) than in the control group (146.9°). Moreover, the AP distances were significantly reduced postoperatively (5.5 mm), although the other parameters did not change significantly.

CONCLUSIONS

The retro-odontoid soft tissue in symptomatic patients with CM-I can be hypertrophic enough to compress the cervicomedullary junction ventrally even if there are no combined osseous anomalies. Foramen magnum decompression works to reduce the hypertrophic changes significantly, suggesting that downward tonsil movement might participate in hypertrophic soft tissue formation at the retro-odontoid space.

Posterior atlantoaxial facet screw fixation in rheumatoid arthritis

OBJECT

This retrospective review was conducted to determine the efficacy of transarticular screw fixation in a group of patients who were treated for rheumatoid atlantoaxial instability.

METHODS

Thirty-six patients (mean age 63 years) with rheumatoid atlantoaxial instability were treated with posterior atlantoaxial transarticular screw fixation supplemented with an interspinous C1-2 strut graft-cable construct to provide immediate three-point fixation to facilitate bone fusion. Previous attempts at fusions by using bone grafting with wire fixation at other institutions had failed in six of these patients. Six patients underwent transoral odontoid resections for removal of large irreducible pannus as a first-stage procedure, which was followed within 2 to 3 days by the posterior procedure. Postoperatively, 33 patients were placed in hard cervical collars and three required halo vests because of severe osteoporosis. Of eight patients categorized as Ranawat Class II preoperatively, all eight returned to normal after surgery; of eight patients in Ranawat Class III-A preoperatively, four improved to Class II and four remained unchanged. All 20 patients classified as Ranawat Class I preoperatively recovered completely. Pain decreased or resolved in all patients, and there were no complications related to instrumentation. At follow-up review (mean 2 years), 33 patients (92%) had solid bone fusions, and three (8%) had stable fibrous unions.

CONCLUSIONS

Posterior atlantoaxial transarticular screw fixation provides a good surgical alternative for the management of patients with rheumatoid atlantoaxial instability. This technique provides immediate three-point rigid fixation of the C1-2 region, thus obviating the need for halo vest immobilization in most cases.

Atlantoaxial degenerative articular cysts

Cysts associated with spinal joints are not a common cause of neurological symptoms. The authors report a series of five patients with cysts of the atlantodental articulation and review five additional cases from the literature. The patients ranged from 60 to 85 years of age and included three men and seven women. No patient had evidence of rheumatoid arthritis or previous trauma. The cysts caused ventral cervicomedullary compression, did not enhance on magnetic resonance imaging, and were not associated with widening of the anterior atlantodental interval or osseous degeneration of the dens. All patients improved postsurgery. Fusion was required if a transoral procedure was performed. Patients undergoing posterior decompressions were clinically and radiographically stable after operation.

Stabilization of the unstable upper cervical spine in rheumatoid arthritis

We present our clinical experience and the results of surgical treatment of 13 patients with rheumatoid involvement of the cervical spine, namely severe atlanto-axial dislocation. A posterior fusion was carried out using a bicortical H-shaped iliac crest bone graft and steel wire. Postoperatively all patients were immobilized for 8 weeks in a Halo cast. There were no postoperative complications and all patients showed a stable fusion confirmed by radiography. Complete pain relief was obtained in 9 patients, partial in 4.