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@#Alar ligament is one of the most important craniocervical junction (CCJ) ligaments; acting as stabilizer of CCJ and limiting axial rotation. It may be involved in various pathological processes including trauma. Magnetic resonance imaging (MRI) is increasingly being used in cervical spine trauma as a supplement to conventional radiography and computed tomography (CT) to detect a wide range of severe cervical spine injuries. MR depiction of alar ligament requires special sequences despite no known established MR sequence is available. However, the role of MRI in minor or moderate trauma, including whiplash injuries, has long been debated, particularly when neurological dysfunction is absent, because no anatomical disruption other than degenerative disc disease have been reported. In this review, we provide detailed account on the current knowledge of MR visualization of normal alar ligament; outlining the variations in its signal intensity, dimension, shape and orientation.
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@#Introduction: Alar ligament is a paired craniocervical junction ligaments which stabilizes the atlantooccipital and atlantoaxial joints. The main purpose of the study was to compare the normal anatomy of alar ligament on MRI between male and female. The prevalence of alar ligament visualized on MRI and its characteristics were also studied apart from determining the association between the heights of respondents with alar ligament signal intensity and dimensions. Methods: Fifty healthy volunteers were studied using 3.0T MR scanner (Siemens Magnetom Spectra) by 2-mm proton density, T2 and fat-suppression sequences. Alar ligament visualization, dimensions and variability of the ligament courses, shapes and signal intensity characteristics were determined. Results: The orientation of the ligament was laterally ascending in most of the subjects (60%), predominantly oval in shaped (54%) and 67% showed inhomogenous signal. Females are 70% less likely to exhibit alar ligament signal inhomogeneity than males. There were positive correlation between height and the craniocaudal diameter of the alar ligament as well as the anteroposterior diameter, which were statistically significant (r = 0.25, n = 100, p = 0.01 and r = 0.201, n = 100, p = 0.045 respectively). Conclusion: Tremendous variability of alar ligament shows that clinical and multimodality correlation needs to be exercised, especially in evaluating alar ligament MR signal in male. Taller individuals otherwise tend to have longer and thicker ligaments. Future studies with larger samples of alar ligaments including trauma cases are also recommended to supplant a new classification system of alar ligament injury.
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Objective To investigate the imaging features of alar ligament and its extent, and provide the basis forclinical treatment.Methods 3.0 T superconducting MRI was used to scan the alar ligament with high resolution PDWI sequence (Proton density weighted imaging, PDWI)in 109 patients of emergency admissions due to head and neck trauma. Based on imaging features, ligamentous injury was classified into three degrees(Ⅰ to Ⅲ degrees).Patients with Ⅰ degree ligamentous injury were treated conservatively, andⅡtoⅢdegree injury patients were treated with surgery, then follow-up was performed with MRI for the recovery of ligaments and clinical evaluation for symptoms (6 months follow-up period). Results High-resolution PDWI showed 78 patients with no ligament injury.On follow-up, patients recovered well (atlantoaxial joint motor function and clinical symptoms). Thirty one patients had alar ligament injury in varying degrees, of which 18 patients had grade Ⅰ injury, nine patients had degree Ⅱinjury, and four patients had degreeⅢinjury .All gradeⅠinjury patients received conservative treatment. Follow-up of patients showed good recovery, MR revealed the lesions shrank in varying degrees or disappear. Six gradeⅡinjury patients had surgical treatment, and three received conservative treatment. On follow-up, seven patients had a good recovery, two patients underwent surgical treatment within 3 months after injury and recovered well.Three gradeⅢpatients treated by surgery, and all with good recovery postoperative, and a patient died of respiratory failure. Conclusions High resolution PDWI is an effective tool to evaluate the extent of the alar ligament injury. Grade Ⅰ ligamentous injury patients treated conservatively can achieve good results, GradeⅡandⅢligamentous injury patients should receive surgical treatment early.
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Introduction: Odontoid process is a bony projection of axis around which the atlas rotates. It measures 1 to 1.25 cms in length and projects upwards from the body of Axis. An elongated odontoid process may narrow the foramen magnum causing compressive neurological symptoms. It can cause cervical stiffness, serious restrictions of neck movement, and even a bone-derived torticollis. Observation: During routine osteology classes, we encountered an Axis vertebra with an elongated odontoid process. The measurements of the elongated odontoid process were taken using digital Vernier slide calipers. Conclusion: Elongated odontoid process can be mistaken for fracture of dens in radiological images; hence the knowledge of elongated odontoid process is useful for the radiologists, neurosurgeons and orthopaedicians for accurate diagnosis and treatment involving cranio-vertebral junctions.