Du et al. reviewed 32 patients with basilar invagination and atlantoaxial dislocation who were misdiagnosed as a simple Chiari malformation and received a suboccipital decompression surgery before admission. All patients underwent atlantoaxial facet joint reduction, fixation and atlantoaxial fusion (AFRF) as revision surgery. The separating, fusing, opacifying and false-coloring-volume rendering (SFOF-VR) technique was used to identify the course of the vertebral artery. Clinical and radiological outcomes were assessed after revision surgeries.
Clinical symptoms improved in all patients. The postoperative atlantodens interval, Wackenheim line and clivus-canal angle significantly improved (all P < 0.01). Intraoperative dural tear and cerebrospinal fluid leakage occurred in 3 patients and were managed by suture repair and lumbar drain. Abnormal VA was identified in 7 patients and no VA injury occurred with the aid of SFOF-VR technique. The average follow-up was 19.1 months and atlantoaxial bone fusion was confirmed in 31 patients.
For BI and AAD patients with failed suboccipital decompression, revision surgery is challenging. Occipitocervical fixation and posterior midline bone grafting are rather difficult due to the large occipital bone defect. The current study demonstrated that the posterior AFRF is a simple, safe and highly effective technique in revision surgery for such cases. For VA variations, the SFOF-VR technique is an effective tool to delineate the course VA 1).
A study included all patients with atlantoaxial dislocation and basilar invagination (BI) with occipitalized C1 arch. Study techniques included Nurick grading, computed tomography scan to study atlanto-dental interval, BI, hyper-lordosis, and neck tilt. Sagittal inclination (SI), coronal inclination (CI), cranio-cervical tilt, presence of pseudo-joints, and anomalous vertebral artery were also noted. Patients underwent DCER with/without joint remodeling or extra-articular distraction (EAD) based on the SI being <100°, 100°-160°, or >160° respectively. In cases with pseudo-joints, joint remodeling was performed in type I and EAD in type II. Customized 'bullet shaped' PSC spacers (n=124) and prototype of the universal craniovertebral junction reducer (UCVJR, n=36) were useful.
A total of 148 patients with average age 27.25±17.43 years, ranging from 3 to 71 years (87 males) were operated. Nurick's grading improved from 3.14±1.872 to 1.22±1.17 (p<0.0001). Fifty-two percent of total joints (n=154/296 joints) were either type I (19%)/type II (33%) pseudo-j oints. All traditional indices such as Chamberlein line, McRae line, atlanto-dental interval, and Ranawat line improved (p<at least 0.001). BI, SI, and CI values correlated with type of pseudo-joints (p<0.0001). Side of neck tilt correlated with the type of pseudo-joint (p<0.0001). Cervical hyperlordosis improved significantly (p<0.0001).
Occipito-C2 pseudo-joints are important in determining the severity of BI. Asymmetrical pseudo-joint causes coronal/neck tilt. Type of pseudo-joint can strategize by DCER. Customized instruments and implants make technique safe, effective and easier 2).