An atlas vertebra with a centrum? A case report of an abnormal atlas and axis

Anatomo-radiological importance and the incidence of os odontoideum in Turkish subjects: a retrospective study

PURPOSE

Os odontoideum is a rare anatomical and morphological variation of the odontoid process and associated with a range of symptoms such as spinal cord and vertebral artery injuries. This study aimed to evaluate the frequency of os odontoideum in Turkish cases by sagittal/coronal cervical magnetic resonance imaging (MRI) and computed tomography (CT) and analyze the relationship with age, gender and related symptoms.

METHODS

The incidence of os odontoideum was retrospectively diagnosed by sagittal/coronal cervical CT and MRI out of 16,122 subjects aged 20-70 years (mean 46) in the period between 2014 and 2018. The relationship of os odontoideum with age, gender, and symptoms was recorded.

RESULTS

The statistical analysis of the study was performed by the χ² test and two-way mixed ANOVA. Os odontoideum was detected in 18 (0.11%) (11 males; 7 females) out of 16,122 patients. The mean age was 47.5 ± 1.4 years in the females and 43.5 ± 2.5 years in the males (p < 0.05). 6 odontoideum were detected out of 6467 (3756 males, mean 48 ± 0.7, 2711 females, mean 46 ± 1.2) subjects by CT and 12 odontoideum were detected out of 9655 patients (5607 males and 4048 females) by MRI.

CONCLUSION

Neck pain was the most frequent symptom. The prevalence of os odontoideum especially round type is more frequent in older male patients over 40 years old with head and neck pain or atlantoaxial instability, and is less common in Turkish subjects when compared to various ethnic groups.

Anomalies of the odontoid process discovered as incidental findings on cephalometric radiographs

Two patients with unusual developmental anomalies of the odontoid process of the axis are presented. These anomalies were discovered as incidental findings on the cephalometric radiographs obtained as part of orthodontic treatment. Both patients had severe instability of the cervical spine at the articulation between the first and second cervical vertebrae that required referral to a medical specialist. When this was discovered, both patients were asymptomatic, with normal neurologic findings. Surgical stabilization of the spine was considered but deferred because the patients had no neurologic signs or symptoms. To protect them from head injury, the patients were advised to refrain from contact sports and strenuous exercise, and follow-up evaluations were recommended. These cases emphasize the need to evaluate head and neck structures shown on cephalometric radiographs, independent of the traditional morphometric analysis.

Congenital anomaly of craniovertebral junction: atlas-dens fusion with C1 anterior arch cleft

A rare case of congenital atlantoaxial block is reported. A 13-year-old boy had a fusion of a non-separated odontoid process with the anterior arch of the atlas, in association with an anterior midline C1 arch cleft.

Vertebral artery pseudoaneurysm complicating posterior C1-2 transarticular screw fixation: case report

BACKGROUND

Vertebral artery injury during posterior C1-2 transarticular screw fixation occurs in approximately 3% of patients and may remain asymptomatic or result in arteriovenous fistulae, occlusion, narrowing, or dissection of the vertebral artery, and lead to transient ischemic attacks, stroke, or death.

CASE DESCRIPTION

This is the first report of a pseudoaneurysm resulting from damage to the vertebral artery during the procedure. This 31-year-old male underwent posterior C1-2 transarticular screw fixation for unstable os odontoideum. Injury to the left vertebral artery occurred while the hole for the left screw was being drilled. Temporary control of bleeding with local pressure was followed by immediate postoperative angiography that revealed a left vertebral artery pseudoaneurysm. Although the patient remained asymptomatic, therapeutic anticoagulation was instituted 6 hours postoperatively. Increasing size of the pseudoaneurysm was noted on routine follow-up angiography 4 weeks later. Endovascular occlusion of the pseudoaneurysm and left vertebral artery, with preservation of vertebrobasilar flow through the right vertebral artery, was accomplished without neurological consequence.

CONCLUSIONS

Vertebral artery pseudoaneurysm complicating posterior C1-2 transarticular screw fixation may be effectively treated with endovascular approaches.