Odontoid Resorption After Posterior Occipitocervical Fusion in Rheumatoid Basilar Invagination

Background Context: Inflammatory arthritis of the cervical spine is common and begins early after the onset of rheumatoid arthritis. Atlantoaxial instability is the most common pattern followed by cranial settling or basilar invagination, with subaxial subluxation being least common. Vertical migration of the odontoid (basilar invagination) poses an increased risk of sudden death from compression of the brain stem. A combination of transoral decompression and posterior occipitocervical fusion has been described, although a single posterior approach stabilization may suffice and avoid the associated comorbidities with an anterior/posterior surgery in a high-risk rheumatoid patient. Purpose: To report a case of odontoid resorption and cervicomedullary angle improvement after occipitocervical fusion. Study Design: A retrospective case report. Methods: Radiographic analysis. Results: After posterior occipitocervical fusion alone for basilar invagination there was a reduction of cervicomedullary angle to 127 degrees at 3 years follow up. This was improved from an initial 115 degrees through odontoid remodeling. Conclusions: Basilar invagination treated with posterior alone occipitocervical stabilization may suffice in providing stability and long term decompression of the cervicomedullary junction through resorption and remodeling of the odontoid. This case study supports the viability of avoiding a transoral resection for an irreducible severely migrated odontoid.

Craniovertebral junction anomaly with kissing carotids

Background: “Kissing carotids” typically involves the lower C4-C6 retropharyngeal space. Here, we describe a case of “kissing carotids” observed at the C1-C2 level in conjunction with basilar invagination (BI). Case Description: A 34-year-old-male presented with congenital atlantoaxial dislocation and BI. The initial surgical plan was for a transoral decompression (TOD). However, this approach was abandoned when the preoperative computed tomography angiography (CTA) documented “kissing carotids” lying anteriorly at the C1-C2 level. Conclusion: Obtaining a CTA before performing a TOD for BI is essential to prevent an intraoperative catastrophic hemorrhage due to the laceration of “kissing carotids.”

REDUCTION AND INTERNAL FIXATION OF COMPLEX FRACTURES OF THE ODONTOID BY THE TRANSORAL APPROACH

ABSTRACT Type II odontoid fractures with irreducible posterior displacement are uncommon, and can cause spinal cord compression, respiratory failure and even death. Treatment is usually surgical, with transoral decompression and posterior fusion or with reduction and fusion of C1-C2 by the transoral approach. We describe a case of type II odontoid fracture with irreducible posterior atlantoaxial dislocation that was treated exclusively by the transoral approach with osteosynthesis of the odontoid, thus preserving functional segmental mobility. Level of Evidence III; therapeutic study.

Comprehensive Drilling of C1-2 Facets and Multiplanar Realignment for Atlanto-Axial Dislocation and Basilar Invagination: 2-Dimensional Operative Video

The management for congenital atlantoaxial dislocation (AAD) and basilar invagination (BI) has significantly changed in the last 2 decades. Authors operate these cases through a direct posterior approach by opening and manipulating the C1-2 joints (irrespective of C1 assimilation), modifying Goel's technique. The joints in these cases are often oblique in both sagittal and coronal planes giving rise to anteroposterior and vertical slip of C1 on C2. Asymmetry on either side gives rise to coronal/lateral angular tilt along with rotational component. The authors have described comprehensive drilling of the facets (osteotomies) in sagittal and coronal planes to release the joints. Metallic spacers with graft window packed with bone chips are inserted to compensate for the drilled bone. Screws are inserted in C1 lateral mass and C2 pedicle. A rod is fastened between the screw heads and further multiplanar realignment can be achieved by manipulating the rod. The technique obviates the need for transoral decompression and the C1-2 joints are closely fused. The facetal osteotomies coupled with manipulation for realignment in all planes provides a composite solution for even the extremely complex lateral dislocation or complete spondyloptosis with severely deformed C1-2 joints that may be difficult with techniques described earlier. There is no need to include occipital squama and multiple cervical vertebrae in the construct, irrespective of the C1 assimilation. The authors have operated over 200 cases of irreducible CAAD/BI with good outcome and have illustrated their technique in this video. Proper informed consent was obtained from the patient.

Surgical strategies for the treatment of os odontoideum with atlantoaxial dislocation

OBJECTIVEThis study aimed to compare the clinical results of using posterior fixation and fusion with or without anterior decompression to treat os odontoideum with atlantoaxial dislocation.METHODSTwenty-five consecutive patients with os odontoideum were included in this study. Sixteen patients with reducible atlantoaxial dislocation were treated by single-level posterior fusion and stabilization; the other 9 were treated with posterior fusion and stabilization combined with transoral decompression. Pre- and postoperative CT scans and MR images were obtained.RESULTSTwenty-four patients were followed for 24–54 months (average 36.5 months). Postoperative CT scans indicated that all pedicle screws were placed satisfactorily except in 2 cases, in which the screws slightly penetrated the transverse foramen. Postoperative MR images demonstrated that sufficient decompression of the spinal cord was obtained in all patients. Complications included 1 case each of pedicle screw breakage, pharynx ulcer, and persistent pharynx discomfort. Statistical analysis of all cases revealed that mean Japanese Orthopaedic Association scores improved from a preoperative score of 10.2 (range 7–13) to a postoperative score of 15.6 (range 11–18).CONCLUSIONSPatients who have os odontoideum with a reducible atlantoaxial dislocation can be effectively treated with single-level posterior fusion and stabilization. Combined transoral decompression and posterior fusion and stabilization is recommended for those with irreducible atlantoaxial dislocation.

Evaluating Atlantoaxial Dislocation Based on Cartesian Coordinates: Proposing a New Definition and Its Impact on Assessment of Congenital Torticollis

BACKGROUND Conventional 2-dimensional (2-D) definition of atlantoaxial dislocation (AAD) is inadequate for coexisting 3-D displacements. OBJECTIVE To prospectively classify AAD and its related abnormalities along 3 Cartesian coordinates and assess their association with torticollis. METHODS One hundred and fifty-four patients with congenital AAD were prospectively classified according to their C1-2 displacement along 3 Cartesian coordinates utilizing 3-D multiplanar CT. The impact of this 3-D dislocation on occurrence of clinically manifest torticollis was also evaluated and surgical treatment was planned. RESULTS Three dimensional CT assessment detected the following types of C1-2 dislocations: I:translational dislocation (along Z coordinate, n = 37 [24%]); II: central dislocation (along Y coordinate, n = 10 [6.5%]); III: translational+central dislocation (along Z+Y coordinates, n = 42 [27.3%]); IV: translational dislocation+ rotational dislocation+coronal tilt (along Z+X coordinates, (n = 6 [3.9%]); V: central dislocation (basilar invagination)+rotational dislocation+coronal tilt (along Y+X coordinates, n = 11 [7.1%]); VI: translational dislocation+ central dislocation+ rotational dislocation+ coronal tilt (along all 3 axes, n = 48 [31%]). Assessing degree of relative C1-2 rotation revealed that 27 (37%) of 85 patients with <50 rotation and 54 (78%) of 69 patients with >5° rotation had associated torticollis. Translational dislocation had negative association (odds ratio [OR] 0.1, 95% confidence interval [CI; 0.47-0.32], P = .00), while type VI (OR 5.0, 95% CI [2.2-11.19], P = .00), type V (OR 4.44, 95% CI [0.93-21.26], P = .04), and type IV (OR 1.84, 95% CI [0.32-10.38], P = .48) dislocations had strong positive association with torticollis. Sixty-two (40%) patients improved, 68 (44%) remained unchanged, and 24 (16%) patients worsened postoperatively. Twenty-eight patients required second-stage transoral decompression following posterior distraction–fusion due to neurological nonimprovement. CONCLUSION Three-dimensional assessment of AAD including evaluation of culpable C1-2 facet joints addresses anomalous displacements in 3 Cartesian planes. This provides targets for adequate cervicomedullary decompression-stabilization, and helps in the management of accompanying torticollis.