It is the lateral head tilt, not head rotation, causing an asymmetry of the odontoid-lateral mass interspace

Three-dimensional computed tomography analysis of the atlanto-dental interval in a healthy Karachi population: a single-center retrospective cross-sectional study

Background

The atlantoaxial joint has a complex anatomical configuration and has a wide range of mobility. Traumatic, inflammatory, and neoplastic joint pathologies frequently affect this joint. The aim of this retrospective cross-sectional study was to evaluate the atlanto-dental intervals (ADI) in patients who underwent computed tomography (CT) scans of the neck and cervical spine in at a Tertiary Care Hospital in Karachi, Pakistan.

Methods

This was a retrospective cross-sectional study conducted at a tertiary care hospital in Karachi between 1 January 2021 and 31 December 2021, following approval from the hospital ethical review committee. Patients above the age of 15 who underwent CT scans were included, while individuals with a history of cervical trauma, infection, rheumatoid arthritis, or congenital anomalies, as well as those younger than 15 years old, were excluded. CT scans were performed using a multidetector scanner utilizing a standardized protocol. Sagittal and coronal images were reconstructed. ADI measurements, including anterior ADI (AADI), posterior ADI (PADI), and lateral ADI (LADI) on both sides, were determined using appropriate bone window settings. A radiologist with a minimum of 3 years of experience analyzed the CT scans.

Results

The mean age of the patients was 49.3±17.7 years (age range: 16-85 years). The mean AADI was 1.4±0.4 mm, with a range of 0.0-2.1 mm. The mean PADI was 19.1±1.9 mm, with a range of 13.8-24.6 mm. The mean left LADI measurement was 3.3±1.2 mm with a range of 1.2-10.0 mm, and the mean right LADI measurement was 3.2±1.1 mm with a range of 1.2-6.3 mm.

Conclusion

Our study examined the ADI in patients who underwent CT scans of the neck and cervical spine in Karachi. The findings provide valuable insights into the relationship between ADI measurements, age, and sex. These results contribute to our understanding of the anatomical variations in this region, which may aid in the diagnosis and management of cervical spine disorders.

Diagnostic Benefit of MRI for Exclusion of Ligamentous Injury in Patients with Lateral Atlantodental Interval Asymmetry at Initial Trauma CT

Background Cervical spine CT is regularly performed to exclude cervical spine injury during the initial evaluation of trauma patients. Patients with asymmetry of the lateral atlantodental interval (LADI) often undergo subsequent MRI to rule out ligamentous injuries. The clinical relevance of an asymmetric LADI and the benefit of additional MRI remain unclear. Purpose To evaluate the diagnostic benefit of additional MRI in patients with blunt trauma who have asymmetry of the LADI and no other cervical injuries. Materials and Methods Patients who underwent cervical spine CT during initial trauma evaluation between March 2017 and August 2019 were retrospectively evaluated. Those who underwent subsequent MRI because of LADI asymmetry of 1 mm or greater with no other signs of cervical injury were identified and reevaluated by two readers blinded to clinical data and initial study reports regarding possible ligamentous injuries. Results Among 1553 patients, 146 (9%) had LADI asymmetry of 1 mm or greater. Of these, 46 patients (mean age ± standard deviation, 39 years ± 22; 28 men; median LADI asymmetry, 2.4 mm [interquartile range, 1.8-3.1 mm]) underwent supplementary MRI with no other signs of cervical injury at initial CT. Ten of the 46 patients (22%) showed cervical tenderness at clinical examination, and 36 patients (78%) were asymptomatic. In two of the 46 patients (4%), MRI revealed alar ligament injury; both of these patients showed LADI asymmetry greater than 3 mm, along with cervical tenderness at clinical examination, and underwent treatment for ligamentous injury. In 13 of the 46 patients (28%), signal intensity alterations of alar ligaments without signs of rupture were observed. Four of these 13 patients (31%) were subsequently treated for ligamentous injury despite being asymptomatic. Conclusion Subsequent MRI following CT of the cervical spine in trauma patients with lateral atlantodental interval asymmetry may have diagnostic benefit only in symptomatic patients. In asymptomatic patients without proven cervical injuries, subsequent MRI showed no diagnostic benefit and may even lead to overtreatment. © RSNA, 2021 Online supplemental material is available for this article.