The role of imaging in the pre- and postoperative evaluation of posterior occipito-cervical fusion

Abstract

Occipitocervical fusion is required when the occipitoatlantal joint is unstable. The purpose of this paper is to discuss the role of imaging in the pre- and postoperative evaluation of posterior occipitocervical fusion (POCF), focusing on contoured loop fixation by Hartshill and Songer instrumentation. We studied 21 patients (eight males, 12 females; age range 6-70 years; mean age 32.6 years) with craniocervical instability who underwent POCF with Hartshill U-shaped rod and Songer sublaminar wires. Pre- and postoperative radiographic, computed tomography (CT) and magnetic resonance (MR) imaging examinations were performed in all patients. A 3- to 6-month period of external orthosis with halo vest, sterno-occipitalmandibular immobiliser (SOMI) brace or Philadelphia collar followed surgery. Follow-up was 12-96 (mean 53.1) months. Clinical assessment using the Frankel scale revealed improvement or deterioration arrest in all but two patients: one with C3 failure and halo destabilisation; the other, who had exhibited myelopathy signs on preoperative MR imaging and persistent basilar impression, showed increasing and progressive neurological deficits despite successful POCF. Pre- and postoperative imaging is extremely useful in patients scheduled to undergo POCF. Preoperative MR screening of basilar impression associated with possible spinal cord lesions appears mandatory to predict possible deterioration and prevent undesired failure of the operation and it may suggest the need for an alternative surgical approach, such as the transoral approach.