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|Year : 2018 | Volume
| Issue : 1 | Page : 151-152
“Fusing the appropriate” in complex craniovertebral junction anomalies
Department of Neurosurgery, Postgraduate Institute of Medical Education and Research, Chandigarh, India
|Date of Web Publication||11-Jan-2018|
Dr. Pravin Salunke
Department of Neurosurgery, PGIMER, Sector 12, Chandigarh - 160 012
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Salunke P. “Fusing the appropriate” in complex craniovertebral junction anomalies. Neurol India 2018;66:151-2
The authors have described rare yet complex cases of pan-cervical fusion with atlantoaxial dislocation (AAD). Undoubtedly, the management of these cases is challenging and requires expertise. AAD may be a result of excessive stress at the C1-2 level due to block cervical vertebrae or congenitally deformed C1-2 joints. The authors have elucidated the presence of a bifid arch of Atlas More Details in combination with such pan-cervical fusion. The proposed idea of a bifid arch of atlas as a natural laminotomy providing space for the compressed cervicomedullary junction is quite intriguing.
Congenital AAD is often multiplanar and the deformity of C1-2 joints decides the plane of dislocation. The combination of abnormal sagittal and coronal inclination leads to anteroposterior and vertical dislocation of C1 and C2. The asymmetry of joints on either side adds angular/rotational component to the dislocation. Coronal asymmetry of the joints coupled with a bifid atlas leads to severe lateral angular dislocation. It is important to study the preoperative radiology in coronal, sagittal, and axial planes to understand the multiplanar C1-2 dislocation and to plan surgical intervention. The management of AAD usually is manipulation of the C1-2 joints with fusion in realigned position., The block cervical vertebrae or pan-cervical fusion is often associated with a bifid atlas apart from AAD. A bifid atlas was seen in 3 out of 4 cases described by the authors. The lateral masses of such bipartite atlas are small and peg like. A noteworthy aspect, which the authors have subtly described, is fusing the C1-2 vertebrae and not the occipital squama to the cervical spine. It is important to preserve mobility at the atlanto-occipital joint (OC1), which is relatively stable despite the bifid C1. Fusing the occipital squama to the already fused cervical spine would lead to severe movement restrictions. In addition, there are delayed complications of such a procedure. However, the peg-like small lateral masses in bipartite atlas makes insertion of C1 screws relatively difficult. Despite the challenges, C1-2 fusion is desirable.
The presence of bifid atlas is usually associated with each hemi-ring moving separately. The two halves have a tendency to splay. This cannot be countered by fusing the C1-2 far away from the point where the forces act (using long screws- long lever arms) or by fusing the occipital squama to the cervical spine. Converting the C1-2 into a single unit by fusing the C1-2 lateral masses close to the point where the forces act even prevents splaying of the hemi-rings of the bifid atlas. Goel's plate and screws fixation technique is most appropriate method to achieve such a fusion because it realigns C1-2 and acts as a compression plate as well. An alternative method is by inserting the screws so that tulips/screw heads are in close contact with the lateral masses. Some amount of compression is necessary prior to fastening the rod to prevent any play between the polyaxial screws.
Reaching up to the joints may pose a challenge, especially if the vertebral artery is anomalous. A preoperative CT angiogram is helpful.,,, An anomalous artery is not a contraindication for fusion of C1-2 using facetal screws. The artery can be dissected, mobilized, and safeguarded during drilling and manipulation of the C1-2 joint.,,,
The decision making in such complex cases of AAD is as important as the operative nuances. It requires skill and considerable experience to decide the need and level of fusion. Fusing too much adversely affects the patient's mobility. This manuscript acts as a reference for young surgeons to strike the right balance between the use of implants for fusion and preserving the patient's quality of life.
| » References|| |
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