35 Craniovertebral Realignment for Basilar Invagination and Atlantoaxial Dislocation Secondary to Rheumatoid Arthritis

10.1055/b-0034-81412

35 Craniovertebral Realignment for Basilar Invagination and Atlantoaxial Dislocation Secondary to Rheumatoid Arthritis

Goel, Atul

Atlantoaxial dislocation and basilar invagination are both commonly associated with rheumatoid arthritis involving the craniovertebral region. Numerous methods to achieve decompression and stabilization of the region have been described in the literature. We present the feasibility of an alternative technique of craniovertebral bone alignment by distraction of the facets of the atlas and axis with or without the addition of direct lateral mass plate and screw atlantoaxial fixation for management of both basilar invagination and atlantoaxial dislocation secondary to rheumatoid arthritis. We have discussed this technique in our reports on the subject.1–5

Seropositive rheumatoid arthritis has been identified in ∼0.9% of the white adult population of the United States and 1.1% of the adult population in Europe.6,7 Of these, as many as 10% of patients may need an operation for atlantoaxial subluxation and basilar invagination. Such figures are not available from India, as the incidence of rheumatoid arthritis affecting the craniovertebral junction appears to be significantly less, and in our institute, congenital anomalies form the bulk of craniovertebral pathology.

The term basilar invagination has been used synonymously with cranial settling and vertical odontoid migration.8–10 Basilar invagination is commonly associated with atlantoaxial dislocation, and the complex results in a significant degree of neck pain and myelopathy. Occipitocervical fixation has been observed to provide stabilization to the craniovertebral region, and the clinical outcome has been uniformly reported to be satisfactory.3,8,10–12 Different instrumentation and methods have been adopted to secure the occipitocervical fixation. Recently, several authors have reported success after transarticular atlantoaxial fixation.11,12 Some reports have indicated that atlantoaxial fixation is the treatment of choice even in the presence of retro-odontoid pannus. Some authors have reported arrest of the vertical migration of the basilar invagination and regression of the size of the retroodontoid pannus after posterior fixation.10,12 For basilar invagination, transoral decompression and subsequent posterior fixation has been the most accepted treatment protocol. Menezes et al.10 observed that traction in cases with basilar invagination and atlantoaxial subluxation results in a significant improvement in the craniovertebral alignment. They suggested the use of halo traction for maintaining the distracted and reduced state of both basilar invagination and atlantoaxial subluxation during positioning for surgery to avoid cord injury.

Clinical Series

Between November 2001 and January 2008, 15 patients with rheumatoid arthritis involving the craniovertebral junction were treated in our neurosurgery department.4,5 Nine had basilar invagination and “fixed” atlantoaxial dislocation, and six had a retro-odontoid pannus and mobile and incompletely reducible atlantoaxial dislocation. Patients ranged in age from 24 to 78 years. Seven patients were men, and eight were women. Neck pain and spastic quadriparesis were the most prominent symptoms.

Procedures

All patients underwent distraction of the facets of the atlas and axis and attempts toward reduction of both basilar invagination and atlantoaxial dislocation ( Figs. 35.1, 35.2, and 35.3 ) by the techniques described by us earlier.1–5 In 11 patients, distraction of the facets was followed by fixation using lateral mass plate and screws. In four patients, only distraction of the facets using custom-made spiked spacers was performed, and no lateral mass fixation using a plate and screws was done ( Figs. 35.1 and 35.2). No patient underwent anterior transoral decompression or a posterior foramen magnum bony decompression.

Selection Criteria for the Type of Surgery

In general, we feel that distraction and additional fixation using lateral mass plate and screws should be performed wherever feasible. This is particularly true in younger patients and in cases where the lateral mass bones could provide sufficiently strong purchase for the screws. However, when the mobility is subtle, and the lateral masses are either diseased or osteoporotic, only distraction may be suffcient.