Introduction: Cranial settling that is not reducible with preoperative traction poses considerable difficulties in management.
Methods: A retrospective review of patients who presented with cranial settling and failed preoperative cervical traction. All patients had a preoperative neurologic deficit. Cranial settling was defined as the tip of the dens protruding above McRae line. Patients were managed surgically with posterior instrumented occipto-cervical (OC) fusion with a screw/rod/plate construct. The reduction maneuver involved distraction between C2 screw and the occipital plate allowing the occiput to migrate superior posterior over the pre-contoured rod with simultaneous anterior inferior migration of the dens resulting in restoration of OC alignment. The distance of the odontoid tip in relation to McRae line and Wackenheim line, atlanto-dens interval, Redlund-Johnell criterion, and cervicomedullary angle were measured pre and postoperatively using CT and MRI.
Results: Four patients were available for analysis (3 males, 2 females). Three patients had advanced degenerative changes at the OC junction, 1 had rotatory subluxation, 1 had an infection that resulted in cranial settling. Average follow up was 5 months. Postoperatively the mean Wackenheim value and atlanto-dens distance were reduced 7.39 +/- 3.7 mm and 3.8 +/- 3.2 mm, respectively. Redlund-Johnell criterion and the distance of the odontoid tip in relation to McRae line improved 7.86 +/- 3.9 mm and 7.76 +/- 3.67 mm, respectively. There were no intraoperative changes in neuromonitoring and no neurologic deficits post-operatively. Reduction was maintained in all patients at last follow-up.
Conclusions: Direct posterior distraction technique between occiput and C2 screw safely and effectively restores OC alignment in patients with cranial settling that is not reducible with preoperative traction. Transoral odontoidectomy and cervical traction for the treatment of cranial settling should be reconsidered.
Patient Care: This technique may eliminate the need for cervical traction in a select group of patients.
Learning Objectives: By the conclusion of this session, participants should be able to understand the described basilar invagination reduction technique