MRI assessment of the alar ligaments in the late stage of whiplash injury – a study of structural abnormalities and observer agreement

Abstract

Our aim was to characterise and classify structural changes in the alar ligaments in the late stage of whiplash injuries by use of a new MRI protocol, and to evaluate the reliability and the validity of this classification. We studied 92 whiplash-injured and 30 uninjured individuals who underwent proton density-weighted MRI of the craniovertebral junction in three orthogonal planes. Changes in the alar ligaments (grades 0-3) based on the ratio between the high signal area and the total cross-sectional area were rated twice at a 4-month interval, independently by three radiologists. Inter- and intraobserver statistics were calculated by ordinary and weighted kappa. Cases classified differently were reviewed to identify potential causes for disagreement. The alar ligaments were satisfactorily demonstrated in all cases (244 ligaments in 122 individuals). The lesions, 2-9 years after the injury, varied from small high-signal spots to high signal throughout the cross-sectional area. Signal was highest near the condylar insertion in 82 of 94 ligaments, indicating a lesion near that insertion, and near the dental insertion in eight, indicating a medial lesion. No grade 2 or 3 lesion was found in the control group. At least two observers assigned the same grade to 214 ligaments (87.7%) on the second occasion. In 30 ligaments (12.3%) this agreement was not obtained. Pair-wise interobserver agreement (weighted kappa) was fair to moderate (0.31-0.54) in the first grading, improving to moderate (0.49-0.57) in the second. Intraobserver agreement (weighted kappa) was moderate to good (0.43-0.70). Whiplash trauma can cause permanent damage to the alar ligaments, which can be shown by high-resolution proton density-weighted MRI. Reliability of classification of alar ligament lesions needs to be improved.

Are early MRI findings correlated with long-lasting symptoms following whiplash injury? A prospective trial with 1-year follow-up

“…In one cohort, a considerable part of patients with chronic WAD were observed to have lesions in the upper cervical ligaments as visualised on MRI of the craniovertebral junction [21][22][23]. This study indicated that the alar and transverse ligaments as well as tectorial and posterior atlanto-occipital membranes can be damaged by whiplash injuries.…”

“…A fourth consideration is that having known more recent results demonstrating signs of injury to the upper cervical ligaments in chronic whiplash-associated disorders [15,[21][22][23] when planning this study, we would have focused more upon the upper cervical spine. The importance of upper ligament injuries should be evaluated in future prospective trials.…”

“…To explore the biological component of neck pain following whiplash injuries, studies of magnetic resonance imaging (MRI) have been performed in order to visualise potential damage to the cervical spine [3,4,8,17,[21][22][23]29]. Generally, very few identifications of traumatic lesions have been described in the acute phase after whiplash injuries and findings do not seem to be associated with the prognosis [4,17,29].…”

Magnetic resonance imaging signal changes of alar and transverse ligaments not correlated with whiplash-associated disorders

“…One study was further excluded after detailed screening of full text articles because the comparison was performed in quantitative date of signal alterations of the transverse ligament [32], not qualitative date in other studies. Another two papers by the same authors, evaluating alar and transverse ligaments, respectively, shared the same subjects, thus were combined and considered as one study [20,23]. Because MRI scan protocol and evaluation criteria for ligament changes used in the paper by Lindgren et al [24] (1.5 T dynamic kine MRI and two-point grading scale and movement) was completely different from other six papers (1.5 T fast spin-echo proton density-weighted sequences and four-point grading scale), this paper was excluded in order to minimize clinical bias.…”

“…These structures could be well visualized by magnetic resonance imaging (MRI) [17][18][19]. In recent years, with the development of more detailed MRI techniques morphologic changes of the ligaments and membranes in the craniocervical junction, especially alar and transverse ligaments have been discussed [18,[20][21][22][23][24][25][26][27]. However, most of these studies include relatively small samples of patients and thus their results were inconsistent and lacked statistical strength.…”