Multidetector Computed Tomography and Magnetic Resonance Imaging Evaluation of Craniovertebral junction Abnormalities

Revealing an Uncommon Presentation of Chiari I Malformation With Diverse Craniovertebral Anomalies in the Absence of Syringomyelia and Atlanto-Occipital Subluxation: A Case Report

A Chiari I malformation is a frequently encountered anomaly of the posterior fossa, occurring in a notable percentage of the population. It often coexists with various other craniovertebral junction abnormalities, albeit less frequently with Klippel-Feil syndrome. Interestingly, the majority of individuals with Chiari I malformation do not exhibit any symptoms. We present a rare case of a 25-year-old male with chronic neck and occipital pain, along with progressive weakness and sensory disturbances in all four limbs, urinary urgency, and elevated left shoulder. Examination unveiled spasticity, weakness, and brisk reflexes. On extensive radiological evaluation (X-ray, CT, and MRI), findings revealed various anomalies in the craniovertebral junction, including complete atlanto-occipital assimilation, basilar invagination, and platybasia. Furthermore, cervical segmentation abnormalities indicative of Klippel-Feil syndrome were observed, along with Sprengel's deformity. MRI confirmed Chiari I malformation with tonsillar herniation and myelomalacia, as well as compression at the cervico-medullary junction. This patient underwent a surgical procedure that included transoral odontoidectomy combined with occipito-cervical fixation, after which a good clinical response was observed. It emphasizes the necessity of radiological imaging for the diagnosis of Chiari and other associated abnormalities in the craniovertebral junction.

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.