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Neurology India, Vol. 53, No. 2, April-June, 2005, pp. 238-240 Technical Report Atlantoaxial joint distraction for treatment of basilar invagination secondary to rheumatoid arthritis Goel Atul, Pareikh S., Sharma P. Department of Neurosurgery, Seth G. S. Medical College and K. E. M. Hospital, and Lilavati Hospital and Research Centre, Mumbai Correspondence Address: Department of Neurosurgery, KEM Hospital and Seth GS Medical College, Mumbai - 400 012, atulgoel62@hotmail.com Date of Acceptance: 13-Feb-2005 Code Number: ni05075 ABSTRACT We present our experience of treating two cases of rheumatoid arthritis involving the craniovertebral junction and having marked basilar invagination by an alternative treatment method. In both the cases, the facets were osteoporotic and were not suitable for screw implantation. The patients were 66 and 72 years of age and both patients were females. Both the patients presented with complaints of progressively increasing spastic quadriparesis. Surgery involved attempts to reduce the basilar invagination and restore the height of the 'collapsed' lateral mass by manual distraction of the facets of the atlas and axis and forced impaction of titanium spacers in the joint in addition to bone graft harvested from the iliac crest. The procedure also provided stabilization of the region. No other fixation procedure involving wires, screws, plate and rods was carried out simultaneously. Following surgery both the patients showed symptomatic improvement and partial restoration of craniovertebral alignments. Follow-up is of 2 and 24 months. Distraction of the facets of atlas and axis and impaction of metal implant and bone graft in the facet joint can assist in reduction of basilar invagination and fixation of the region in selected cases of rheumatoid arthritis involving the craniovertebral junction.Keywords: Basilar invagination, craniovertebral junction, rheumatoid arthritis Treatment of basilar invagination secondary of rheumatoid arthritis can be a formidable surgical issue. Numerous methods to achieve decompression and stabilization of the region have been described in the literature. We have recently discussed our technique of atlantoaxial joint distraction and simultaneous atlantoaxial plate and screw fixation in the treatment of basilar invagination and fixed atlantoaxial dislocation in congenital, traumatic and infective craniovertebral junction pathology. [1],[2],[3],[4],[5],[6],[7],[8] In this report, we wish to put on record the feasibility of distraction of the facets of atlas and axis using forced impaction of titanium spacers and bone graft as an alternative technique of reduction of the basilar invagination and stabilization of the joint in selected patients having rheumatoid disease of the craniovertebral region. MATERIALS AND METHODS Two 66- and 72-year-old females, seropositive for rheumatoid arthritis, were treated with the above-mentioned technique. The case selection was based on the extent of destruction of the facets of the atlas or axis by the disease process and their nonsuitability for screw implantation. Follow up is of 2 and 24 months. Both the patients were investigated with magnetic resonance imaging (MRI), computerized tomography (CT) scanning and dynamic plain radiology. Both the patients presented with progressively worsening spasticity in the limbs were able to walk with support and could perform routine activities only with considerable difficulty. There was no sensory deficit in both patients. Both the patients were on long-term steroids for the rheumatoid arthritis. Both the patients had severe basilar invagination. The tip of the
odontoid process was 13 and 9 mm above the Chamberlain′s line, 11 and 7 mm above the digastric line and 20 and 15 mm above the Wackenheim′s
clival line, respectively. There was no evidence of any radiographic
presence of mobile subluxation with flexion resulting in an increase
in the atlantodental or clivodental interval, increased compromise of
the canal diameter, or reduction in the girth of the brainstem. The facets
of atlas and axis were osteoporotic in both cases and were not suitable
for screw implantation. There was no retroodontoid pannus in both cases. DISCUSSION The term ′basilar invagination′ in cases with rheumatoid arthritis has been used synonymously with the terms ′cranial settling′ or ′vertical odontoid migration′. [9],[10],[11],[12] Basilar invagination is commonly associated with instability of the region and the complex results in a significant degree of neck pain and myelopathy adding considerably to the disability secondary to affection of other joints. For basilar invagination, transoral decompression and subsequent posterior fixation have been the most accepted treatment protocol. A variety of instrumentation and methods have been adopted to secure the occipitocervical and atlantoaxial fixation. 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.[13],[14] Menezes et al. observed that traction in cases with basilar invagination and atlantoaxial subluxation results in a significant improvement in the craniovertebral alignments.[9]We had described a technique of interarticular plate and screw method of atlantoaxial fixation in the year 1988 and had recently discussed distraction and realignment of the atlantoaxial joint for basilar invagination and fixed atlantoaxial dislocation for cases with congenital malformations of the region and for rheumatoid arthritis. [1],[2],[3],[4],[5],[6],[7],[8] In the latter technique, the atlantoaxial joint was opened widely after sectioning of the C2 ganglion and the two facets were then distracted and the distraction was maintained with metal spacers and bone graft. Plate and screw fixation of the joint was subsequently done by the interarticular plate and screw method. In both our presented patients, the facets of the atlas and axis were strong enough to sustain the impaction of the metal implant but were osteoporotic and were not suitable for screw implantation. The cause of basilar invagination appeared to be a lateral mass ′collapse′ resulting in its reduced height.[9],[10],[15] We observed that the distraction and impaction of the titanium spacer within the joint cavity increased the height of the lateral masses, reduced the basilar invagination and restored the craniovertebral alignments. It was observed that after the impaction of the implant and bone graft within the joint cavity, the region was significantly stable and any kind of fixation procedure could be avoided. Wide removal of atlantoaxial joint capsule and articular cartilage by drilling and subsequent distraction of the joint by manual manipulation provided a unique opportunity to obtain reduction of the basilar invagination and of atlantoaxial dislocation. Multi-holed titanium spacers were chosen in order to allow bone incorporation and fusion across the distracted joint space. Following surgery, the alignment of the odontoid process, anterior arch of the atlas and the clivus and the entire craniovertebral junction improved towards normalcy. The tip of the odontoid process receded in relationship to the Wackenheim′s clival line, Chamberlain′s line and digastric suggesting reduction in the basilar invagination. The stabilization was affected by jamming the motion fulcrum of the region. As no wire, screws, plates and rods were used for fixation, as is conventionally the norm; the extent of stability provided by the implant will have to be assessed by a larger experience over a longer period of time. In the postoperative phase, the patients used a hard cervical collar and were advised to limit activities related to neck movements for a period of three months. During the period of follow-up, both patients had shown neurological recovery and there was no indication of implant failure, suggesting the effectiveness of the operation. The procedure is technically demanding and anatomically precise,[16],[17] but if it is learned adequately and performed successfully, the neurological outcome is extremely gratifying. REFERENCES
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