Pitfalls of magnetic resonance imaging of alar ligament

Physical Therapy, 2012

Background The alar ligaments are integral to limiting occipito-atlanto-axial rotation and lateral flexion and enhancing craniocervical stability. Clinical testing of these ligaments is advocated prior to the application of some cervical spine manual therapy procedures. Given the absence of validation of these tests and the potential consequences if manipulation is applied to an unstable upper cervical spine segment, exploration of these tests is necessary. Objective The purpose of this study was to examine the direct effect of the side-bending and rotation stress tests on alar ligaments using magnetic resonance imaging (MRI). Design This was a within-participant experimental study. Methods Sixteen participants underwent MRI in neutral and end-range stress test positions using proton density-weighted sequences in a 3-Tesla system. Measurements followed a standardized protocol relative to the position of the axis. Distances were measured from dens tip to the inferior margin of the fo...

Manual Therapy, 2016

Background: The alar ligament is an essential component of upper cervical stabiltiy and may be injured in whiplash associated mechanisms. It has been advised that the integrity of the alar ligament be tested prior to manual therapy to the cervical spine, although the tests utilized lack validity and reliability. While MRI assessment allows for visualization of the alar ligament, it also produces poor interobserver agreement. Purpose: The purpose of this study was to assess the origin, insertion, and characteristics of the alar ligament in cadaveric models and document observed variations. Methods: The alar ligaments of cadaveric models were exposed and the models positioned prone with the cervical spine in neutral. A series of high quality photos were taken at various positions and angles so that the entire ligament could be visualized. Results: The angle the ligmaent traveled from the dens to the occiput ranged from 41.8 to 69.1 degrees. Additional variations were noted in thickness and location of insertions into the occiput also varied. Conclusion: Manual stress testing of the alar ligament may not be reliable due to anatomical variations in the angle of placement of the alar ligament, as well as variations in its insertion into the occiput. These same variations may explain the differences in MRI interpretations. Implications: Clinicians should rely on patients subjective signs and symptoms as well as clinical presentation to determine possible alar ligament pathology. Manual stress testing and MRI reports should be interpretted knowing that their reliability have not been established. Funding Acknowledgements: No funding was required. Ethics Approval: No ethics approval was needed.

Neuroradiology, 2002

World neurosurgery, 2018

A precise anatomical description of the alar ligaments is important to better understand their biomechanical and pathologic implications. Although there are several studies regarding their anatomy, the literature is inconsistent. To our knowledge, there are no reports that compare cadaveric morphologic findings with computed tomography (CT) images of the alar ligaments. Eight sides from 4 fresh-frozen cadaveric specimens were used in this study. After routine dissection of the craniocervical junction, the alar ligaments were exposed. We carried out measurements of the alar ligaments, their position within the craniovertebral junction, and their relation to the dens and adjacent structures. Fine-cut CT of the specimens was performed, and the measurements were later compared with the original cadaveric dissections. Alar ligaments were attached to the upper half of the lateral surface of the dens and ran laterally to its insertion just medial to the occipital condyle. The ligaments wer...

Spine, 2012

Study Design. A prospective study of healthy volunteers. Objective. To evaluate the infl uence of magnetic resonance imaging (MRI) fi eld strength on the delineation and signal intensity of alar ligaments (AL) in healthy volunteers. Summary of Background Data. The fact that AL physiologically show morphologic variabilities is well established. However, presence and etiology of high-signal intensities within the AL as well as the infl uence of the MRI fi eld strength on the signal characteristics of AL are still not completely understood. Methods. Coronal and sagittal 2-mm proton-density weighted sequences were acquired in 50 healthy volunteers using different MRI fi eld strengths (1 T, 1.5 T, 3 T). Delineation and signal characteristics of AL were evaluated by 2 neuroradiologists independently. Differences concerning delineation and signal intensity between the MRI scanners, inter rater reliability between the 2 readers, and intrarater reliability at different time points were calculated. Results. Delineation of AL was signifi cantly better both on 3 T and 1.5 T than on 1 T ( P = 0.05) in sagittal as well as in coronal view. In coronal view delineation was signifi cantly better on 3 T than on 1.5 T, whereas in sagittal view no signifi cant difference was evident when comparing 1.5 T and 3 T. Concerning signal intensity of AL in sagittal view, there was no signifi cant difference between the 3 different fi eld strengths. Inter-rater and intrarater agreements were fair to moderate with respect to delineation as well as signal intensity of AL. Conclusion. 1.5 T and 3 T signifi cantly improve the delineation of AL when compared with lower fi eld strength (1 T), but signal intensity of the AL in healthy volunteers is not infl uenced by the fi eld

Spine, 2008

Study Design. Case-control study. Objective. To use high-resolution magnetic resonance imaging (MRI) in assessing signal intensity areas in the alar ligaments. Summary of Background Data. Conflicting evidence exists whether areas of high signal intensity in the alar ligament on MRI are more frequent in whiplash patients than in noninjured control subjects. Methods. A case-control designed study of 173 subjects included one group with persistent whiplash associated disorder Grade I-II after a car accident (n ϭ 59), one with chronic nontraumatic neck pain (n ϭ 57) and one group without neck pain or previous neck trauma (n ϭ 57). High-resolution protonweighted MRI in 3 planes was used. The images were independently evaluated by two experienced neuroradiologists who were blinded to patient history and group allocation. The alar ligaments were evaluated according to a 4-point grading scale; 0 ϭ low signal intensity throughout the entire cross section area, 1 ϭ high signal intensity in one third or less, 2 ϭ high signal intensity in one-third to two thirds, and 3 ϭ high signal intensity in two thirds or more of the cross section area. Results. Alar ligament changes Grade 0 to 3 were seen in all 3 diagnostic groups. Areas of high signal intensity (Grade 2-3) were found in at least one alar ligament in 49% of the patients in the whiplash associated disorder Grade I-II group, in 33% of the chronic neck pain group and in 40% of the control group (2 , P ϭ 0.22). Conclusion. The previously reported assumption that these changes are due to a trauma itself is not supported by this study. The diagnostic value and the clinical relevance of magnetic resonance detectable areas of high intensity in the alar ligaments are questionable.

Journal of Biomedical Science and Engineering, 2012

Purpose: The assessment of the morphology and dimensions of the craniocervical ligaments using a 3 Tesla (T) Magnetic Resonance (MR) scanner, the correlatation of our results with those from cadaveric and other MR studies and the detection of the most appropriate sequence for the best imaging of the craniovertebral junction ligaments. Methods: 58 healthy volunteers (mean age 45 years) underwent a Magnetic Resonance Imaging (MRI) of the cervical spine at 3T MR unit. The MRI protocol included axial, coronal and sagittal Proton-Density (PD) sequences and sagittal T1 Fluid Attenuated Inversion Recovery (FLAIR) and T2 sequences. The images were evaluated by two radiologists and the posterior atlantoocipital ligament, the anterior atlantoocipital ligament, the transverse ligament and the apical ligament were anatomically detected, described and measured. Results: The transverse ligament was identified at 93.1%, the apical ligament was identified at 60.34%, the posterior atlantooccipital membrane was identified at 94.8% and the anterior atlantooccipital membrane was identified at 96.5% of the cases. All ligaments appeared with low signal intensity, except the anterior atlantooccipital ligament which appeared with intermediate signal intensity. Their length, width and thickness were measured and, in general, correlated well with other anatomic and MR studies. Conclusion: Reliable assessment of the morphology and signal intensity of the craniocervical ligaments can be achieved with PD sequence at 3T MR imaging. The sagittal plane provides better delineation of the craniocervical (CC) ligaments but the axial and coronal planes are of paramount importance in the assessment of the transverse and apical ligaments.

Journal of …, 1991

t~ Twenty normal human subjects and 14 patients with upper cervical spine pathology were studied with axial high-field magnetic resonance (MR) imaging to examine the transverse atlantal ligament. Gradient-echo MR imaging pulse sequences provided reliable visualization of the transverse ligament, which exhibited low signal intensity and extended behind the dens between the medial portions of the lateral masses of C-I. The MR imaging characteristics of the transverse ligament were verified in clinical studies and in postmortem specimens. The clinical MR examinations defined 27 normal ligaments, three ligament disruptions, and four stretched rheumatoid ligaments. Atlantoaxial instability associated with transverse ligament rupture or ligamentous laxity required internal fixation. In c~mtrast, fractures of C-1 or C-2 or atlantoaxial rotatory dislocations associated with an intact transverse ligament healed without instability or nonunion. The transverse ligament is the primary, stabilizing component of C-I. The treatment of atlantoaxial instability has previously been based on criteria drawn from computerized tomography or plain radiographic studies, which only indirectly assess the probability of rupture of the transverse ligament. It is concluded that MR imaging accurately depicts the anatomical integrity of the transverse ligament. After transverse ligament failure, the remaining ligaments of the craniovertebral junction are inadequate to maintain stability. The presence of ligament disruption should be considered as a criterion for early fusion. KEY WORDS 9 atlantoaxial instability 9 cervical spine 9 spinal fracture 9 transverse atlantal ligament 9 magnetic resonance imaging * Signa MR unit manufactured by General Electric, Milwaukee, Wisconsin.

The Spine Journal, 2007

BACKGROUND CONTEXT: The posterior ligamentous complex (PLC) is thought to contribute significantly to the stability of thoracolumbar spine. Obvious translation or dislocation of an interspace clearly denotes injury to the PLC. A recent survey of the Spine Trauma Study Group indicated that plain radiographic findings, if present, are most helpful in determining PLC injury. However, confusion exists when plain radiography shows injury to the anterior spinal column without significant kyphosis or widening of the posterior interspinous space. PURPOSE: The objective of this study is to identify imaging parameters that may suggest a disruption of the posterior ligamentous complex of the thoracolumbar spine in the setting of normalappearing plain radiographs. This study was performed, in part, as a pilot study to determine critical imaging parameters to be included in a future prospective, randomized, multicenter study. STUDY DESIGN/SETTING: Survey analysis of the Spine Trauma Study Group. PATIENT SAMPLE: None. OUTCOME MEASURES: Compilation and statistical analysis of survey results. METHODS: Based on a systematic review of the English literature from 1949 to present, we identified a series of traits not found on plain X-rays that were consistent with PLC injury. This included five imaging findings on either computed tomography (CT) scans or magnetic resonance imaging (MRI) and several physical examination features. These items were placed on a survey and sent to the members of the Spine Trauma Study Group. They were asked to rank the items from most important to least important in representing an injury to the PLC in the setting of normal-appearing plain radiographs.

Neuroradiology, 2010

Introduction Dysfunctional transverse and alar craniovertebral ligaments can cause instability and osseous destruction in rheumatoid arthritis (RA). This study examined (1) the feasibility of high-resolution magnetic resonance imaging (MRI) of these ligaments in RA and (2) the relation between ligament high-signal changes and atlantoaxial subluxation and RA duration/severity. Methods Consecutive RA patients (n=46) underwent clinical examination, functional radiography, and high-resolution MRI. Two blinded radiologists rated MRI image quality, graded ligament high-signal changes 0-3 on proton-weighted sequences using an existing grading system, and assessed cervical spine rheumatic changes on short tau inversion recovery images. Agreement was analyzed using kappa and relations using multiple logistic regression. Results MRI images had good quality in 42 (91.3%) of 46 patients and were interpretable in 44 (32 women and 12 men, median age/disease duration 60.4/9.1 years). MRI grades 2-3 changes of the transverse and alar ligaments showed moderate and good interobserver agreement (kappa 0.59 and 0.78), respectively, and prevalence 31.8% and 34.1%. Such ligament changes were more frequent with increasing anterior atlantoaxial subluxation (p=0.012 transverse, p=0.028 alar), higher erythrocyte sedimentation rate (p=0.003 transverse), positive rheumatoid factor (p=0.002 alar), and neck pain (p= 0.004 alar). Conclusion This first study of high-resolution MRI of these ligaments in RA showed high feasibility and relations with atlantoaxial subluxation, RA disease activity, and neck pain. The clinical usefulness of such MRI needs further evaluation.