A three-dimensional study of the atlantodental interval in a normal Chinese population using reformatted computed tomography

Abstract

The atlantodental interval has been usually used for the evaluation of atlantoaxial instability. However, the asymmetry of the lateral atlantodental interval is occasionally found in healthy individuals. Controversy therefore exists as to the clinical significance of this asymmetry in patients after trauma. The purpose of this study was to determine the normal range of atlantodental intervals in normal individuals using reformatted computed tomography. In this study, C1-C2 vertebrae were imaged in 230 adult patients by a Lightspeed Vct CT (General Electric, CT, USA) with a slice thickness of 0.625 mm. After reformatting the original images, the anterior atlantodental interval (AADI) and lateral atlantodental interval (LADI) were measured. The AADI was found to be 1.83 ± 0.46 mm (0.9-3.4 mm) in males and 1.63 ± 0.43 mm (0.5-3.2 mm) in females. The AADI was significantly greater in males than in females (p < 0.05). The 95% confidence interval for AADI was 1.75-1.90 mm in males and 1.54-1.72 mm in females. No statistically significant differences were found between males and females in the left and right LADI, and LADI asymmetry. The left LADI was found to be 3.38 ± 0.87 mm (1.7-6.0 mm), and the right LADI was 3.42 ± 0.84 mm (1.7-5.9 mm) in males, while the left LADI was 3.30 ± 0.73 mm (1.5-5.3 mm) and the right LADI was 3.37 ± 0.92 mm (1.7-5.9 mm) in females. The 95% confidence interval for left LADI was 3.23-3.52 and 2.94-3.25 mm, and for right LADI was 3.27-3.56 and 3.18-3.56 mm in males and females, respectively. The mean asymmetry of LADI was 0.76 ± 0.66 mm (0.0-3.5 mm) in males and 0.73 ± 0.70 mm (0.0-3.7 mm) in females. The 95% confidence interval for LADI asymmetry was 0.65-0.87 mm in males and 0.59-0.88 mm in females. Most of the population was found to have an asymmetry ranging between 0.1 and 2.0 mm. The current study shows that LADI asymmetry is common in patients without any cervical spine abnormalities. LADI asymmetry may be a normal anatomic variant and there is no evidence to confirm that LADI asymmetry is a sensitive or specific indicator of traumatic atlantoaxial instability. Radiologists and clinicians should be aware of this normal range of asymmetry when interpreting CT scans of the atlantoaxial region.

Cross-sectional study of the neural ossification centers of vertebrae C1–S5 in the human fetus

“…The most conspicuous type of spina bifida is undoubtedly myelomeningocele with the unfused neural processes of the lumbosacral spine. As a result, the spinal cord freely protrudes through an existing opening [7, 11, 15]. In fact, an understanding of the timing of spinal ossification centers is extremely useful in the prenatal detection of skeletal dysplasias (osteochondrodysplasias) resulting in both a delayed appearance of ossification centers and poor mineralization because of osteogenesis imperfecta type II [28], achondrogenesis [26], tanatophoric dysplasia type I [11], and hypophosphatasia [31].…”

New anatomical data on the growing C4 vertebra and its three ossification centers in human fetuses

“…Block vertebrae are the consequence of their mal-segmentation and fusion through neighboring intervertebral discs. Spina bifida is characterized by a midline cleft between the two neural processes [5, 13, 18, 27]. Furthermore, detailed knowledge on the normal growth of spinal ossification centers in fetuses may be helpful in the prenatal diagnosis of skeletal dysplasias (osteochondrodysplasias).…”

Anterior Atlantodental and Posterior Atlantodental Intervals on Plain Radiography, Multidetector CT, and MRI

“…The PADI on plain radiography was higher than on MDCT or MRI (p < 0.05) ( We found our data are in good agreement with previous reports. In the recent literature, AADI on MDCT is reported to be 1.83 ± 0.46 mm in men and 1.63 ± 0.43 in women (22), and AADI on MRI is reported to be 2.29 ± 0.47 mm (23). These results agree with our finding that AADI on MDCT is smaller than Note.-AADI = anterior atlantodental interval, MDCT = multidetector CT, PADI = posterior atlantodental interval PADI of less than 14 mm was associated with the presence of paralysis, and in another study, severe stenosis was defined as a and the average spinal cord diameter was 7.8 ± 0.7 (range of 6.2-9.3) mm.…”

“…AADI was measured from the posteroinferior aspect of the anterior arch of the atlas, to the adjacent anterior surface of despite several studies (21)(22)(23)(24). In the present work, we aimed to determine the normal values of AADI and PADI on plain radiography, MDCT and MRI, as well as the dural sac width and spinal cord diameter at the atlantoaxial joint level on MRI.…”