To the occiput or not? C1-c2 ligamentous laxity in children with down syndrome

Abstract

Study Design Retrospective case review. Objective Atlantoaxial instability with and without basilar invagination poses a considerable challenge in management regarding reduction, surgical approach, decompression, instrumentation choice, and extent of fusion. A variety of strategies have been described to reduce and stabilize cranial settling with basilar invagination. Modern instrumentation options included extension to the occiput, C1-C2 transarticular fixation, and C1 lateral mass-C2 pars among others. Since not all cases of cranial settling are the same, their treatment strategies also differ. Factors such as local vascular anatomy, amount of subluxation, need for distraction, and shape of occipital condyles will dictate level and type of instrumentation. The objective of this study was to outline treatment options and provide a rationale for the surgical plan. Methods Two cases of C1-C2 instability in patients with Down syndrome are described. Case 2 underwent C1-C2 instrumented fusion, whereas case 1 involved posterior instrumented fusion to the occiput. Results Both patients tolerated the procedures well. There were no complications. Minimum follow-up was 1 year. There was no loss of reduction. Solid arthrodesis was achieved in both cases. Conclusion Successful reduction can be achieved with both C1-C2 instrumented fusion as well as O-C instrument fusion. Factors such as local vascular anatomy, amount of subluxation, need for distraction, and shape of occipital condyles will dictate level and type of instrumentation.

Keywords: C1–C2 instability; Down syndrome; basilar invagination; occiput; os odontoideum; pediatric.

Fig. 1

Preoperative lateral X-ray of cervical spine demonstrating posterior displacement of the dens secondary to C1–C2 instability. The atlantodens interval measured 15.8 mm. A component of rotatory subluxation is also present.

Fig. 2

Computed tomography scan demonstration midline sagittal cut of the cervical spine. Basilar invagination is present in addition to significant rotatory component. The distance between the posterior arch of C1 and the dens is severely diminished resulting in significant spinal canal stenosis.

Fig. 3

Axial computed tomography scan demonstrating significant rotatory subluxation with critical spinal stenosis at C1–C2.

Fig. 4

Sagittal T2-weighted magnetic resonance imaging demonstrating severe spinal cord compression between the posteriorly displaced dens and posterior arch of C1.

Fig. 5

(A) Postoperative lateral X-ray of cervical spine demonstrating reduction of C1–C2 instability with posterior O–C1–C2 instrumentation (Harms technique) and fusion. (B) Axial computed tomography at C1–C2 demonstrating reduction of rotatory subluxation. (C) Postoperative sagittal T2-weighted magnetic resonance imaging demonstrating decompression of the spinal cord and reduction of basilar invagination.

Fig. 6

Sagittal T-2 weight magnetic resonance imaging of the craniocervical junction demonstrating severe spinal cord compression secondary to C1–C2 instability.

Fig. 7

Computed tomography scan demonstration midline sagittal cut of the cervical spine. An os odontoideum is visible in addition to posterior displacement of the dens.

Fig. 8

(A) Lateral X-ray of cervical spine demonstrating posterior displacement of the dens secondary to C1–C2 instability. (B) Lateral X-ray of cervical spine in halo traction demonstrating incomplete reduction of posterior displacement.

Fig. 9.

Sagittal computed tomography scan of the (A) left and (B) right occipitocervical joints demonstrating no evidence of diastasis.

Fig. 10

(A) Preoperative lateral X-ray of cervical spine demonstrating posterior displacement of the dens secondary to C1–C2 instability. (B) Postoperative lateral X-ray of cervical spine demonstrating complete reduction of C1–C2 instability with posterior C1–C2 instrumentation (Harms technique) and fusion.