Occipital condyle fracture in a patient with occipitalisation of the atlas

Resolution of retro-odontoid cyst in a patient with atlanto-occipital assimilation after occipitocervical fixation

Background:

Fusion of the atlas with the lower part of the occiput is clinically known as atlanto-occipital assimilation (AOA) or atlas occipitalization. This can be either partial or complete depending on the extent of fusion. AOA is one of the most common congenital anomalies of the craniovertebral junction and is usually asymptomatic.

Case Description:

An 80-year-old female presented with a retro-odontoid cyst in conjunction with AOA. Following posterior occipitocervical fixation without resection of the cyst, the patient improved, and the postoperative MR documented cyst resolution.

Conclusion:

Patients with AOA and a retro-odontoid cyst may be successfully managed with occipitocervical fixation without resection of the cyst. However, we would recommend preoperative computed tomography angiography to document whether the vertebral artery follows an anomalous course to avoid an intraoperative neurovascular injury.

Traumatic Craniocervical Dissociation in Patients with Congenital Assimilation of the Atlas to the Occiput

Traumatic atlantooccipital dissociation (AOD) is a severe and usually fatal injury. Patients with assimilation of the atlas to the skull are exposed to a higher risk of injury and delay diagnosis due to the abnormal anatomy. We report two cases of acute traumatic craniocervical dislocation in patients with baseline congenital assimilation of the atlas to the skull. Computer tomography (CT) was used to identify the injury. Computer tomography angiography (CTA) showed variations of the vertebral arteries' location on both patients. Assimilation of the atlas was complete in patient one and partial in patient two. Emergent surgical instrumentation and fusion were performed with a very careful and meticulous posterior dissection. As general rule, most of the patients with CCD will undergo occiput to C2 posterior segmental instrumentation and fusion. In the presented cases, a more extensive fusion was necessary based on the type and severity of the CCJ injury and the anatomical anomalies associated. Postoperatively, patient one remained neurologically intact and patient two died. Alternative fixation techniques should be used to minimize risk of VA injury during the surgical procedures.

Immobilisation in occipital condyle fractures: A systematic review

OBJECTIVES

The objectives of this review are to determine the level of evidence for the management of OCF, compare outcomes of different immobilisation, and to review the prognosis.

PATIENTS AND METHODS

A literature search was conducted using 3 databases (MEDLINE, PubMed and EMBASE). All papers between 1940 and July 2017 were screened using PRISMA guidelines. Inclusion criteria were patients with a confirmed diagnosis of occipital condyle fracture(s) on CT managed with any form of immobilisation with no age restriction. Primary outcome was clinical improvement in symptoms or Neck Disability Index. MINORS and OCEBM level was assigned to each study.

RESULTS

25 studies met the inclusion criteria. Most studies used a single form of C-spine immobilisation support (58%) with a semi rigid collar and halo device being the most common. From these studies, the average length of time for immobilisation was 11.7 weeks, 9 weeks and 8.3 weeks for halo, semi-rigid and rigid cervical collars respectively. Neuro deficit was found in 20.3% of patients. OCEBM level of evidence and MINORS score was low.

CONCLUSION

Management of OCF is associated with low level of evidence. Further studies are needed to determine optimal management of these under-diagnosed fractures.