Anatomical Variations of the Levator Scapulae Muscle - an MR Imaging Study

Transcription

1 Anatomical Variations of the Levator Scapulae Muscle - an MR Imaging Study Poster No.: R-0016 Congress: 2015 ASM Type: Scientific Exhibit Authors: J. Au, A. Webb, G. Buirski, P. Smith, M. Pickering, D. Perriman; Canberra/AU Keywords: Normal variants, MR, Musculoskeletal system, Head and neck, Anatomy, Education and training DOI: /ranzcr2015/R-0016 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 10

2 Purpose Anatomical variations of the levator scapulae muscle are scarcely described in the current literature. However, knowledge of levator scapulae morphology and variants is important in many clinical settings. In clinical radiology, recognition of normal variants in neck muscles is important in preventing the misinterpretation of the muscle as other anatomical structures such as a lymph node or blood vessel [1]. In addition, knowledge of this muscle is also important in surgery when it is used as a muscle flap in head and neck reconstructions [2]. Furthermore, anatomical variations of this muscle may give rise to myofascial pain syndromes and can have important implications in the medical management of patients with cervical dystonia [3, 4]. The purpose of this study was to explore the prevalence and range of anatomical variations of the levator scapulae muscle visible on MR images. Page 2 of 10

3 Methods and materials Thirty-seven subjects (13 males, 24 females) aged 18 to 36 years were enrolled and consented for a larger prospective study from which this data was derived. T1-weighted spin echo axial images (TE/TR = 15/957 milliseconds, 4 mm slice thickness with no interslice gap) of the cervical spine of each subject were acquired using a 3 Tesla MR scanner. The MR images were systematically reviewed. The levator scapulae muscle was identified attaching between the C1-C4 transverse processes and the superior angle of the scapula. Variations in levator scapulae morphology were recorded, described and categorised on the basis of their accessory attachment site. Page 3 of 10

4 Results Levator scapulae variations were identified in 16 of the 37 subjects (4 right, 6 left, 6 bilateral). In 10 subjects, the levator scapulae had an accessory attachment unilaterally to either the serratus anterior (SA) or serratus posterior superior (SPS) muscles or to the first/second rib. 4 subjects demonstrated bilateral accessory attachments to SA, 1 had bilateral accessory attachments to SPS and unilateral accessory attachment to SA, and 1 subject had bilateral attachments to both. The details of the accessory attachments identified in the 16 subjects are summarised in Table 1. Figure 1 contains MR images from superior (a) to inferior (h) obtained from a subject with bilateral accessory attachments to the SPS muscles. The accessory attachments (aa) can be seen arising from the medial aspect of the levator scapulae (LS) on both sides. The accessory muscles then course inferiorly and medially, eventually attaching to the SPS muscles. Figure 2 contains MR images from superior (a) to inferior (h) obtained from a subject with a unilateral accessory attachment to the SA muscle on the right side. The accessory attachment (aa) can be seen arising from the anterior aspect of the levator scapulae (LS) on the right side. The accessory muscle then courses inferiorly and laterally, eventually attaching to the right SA muscle. Page 4 of 10

5 Images for this section: Table 1: Levator scapulae accessory attachments identified in the 16 subjects Trauma and Orthopaedic Research Unit, ACT Health - Canberra/AU Page 5 of 10

6 Fig. 1: MR images from superior (a) to inferior (h) obtained from a subject with bilateral accessory attachments to the serratus posterior superior muscles Trauma and Orthopaedic Research Unit, ACT Health - Canberra/AU Page 6 of 10

7 Fig. 2: MR images from superior (a) to inferior (h) obtained from a subject with a unilateral accessory attachment to the serratus anterior muscle on the right side Trauma and Orthopaedic Research Unit, ACT Health - Canberra/AU Page 7 of 10

8 Conclusion Considerable variations in the attachments of the levator scapulae muscle were evident on MR images in this cohort. The findings of this study have implications for the interpretation of cervical spine MR images in clinical radiology. Recognition of levator scapulae accessory attachments will prevent the misinterpretation of these normal variants as adenopathy or a thrombosed vein. Also, this study's findings have further implications in the field of head and neck surgery, and the management of patients with myofascial neck pain and cervical dystonia. Page 8 of 10

9 Personal information Dr John Au Intern, Canberra Hospital Dr Alexandra Webb Senior Lecturer, Australian National University Medical School Professor Graham Buirski Section Head, MusculoSkeletal Imaging, Sidra Medical and Research Center, Doha Professor Paul Smith Director of Orthopaedic Surgery, Canberra Hospital Associate Professor Mark Pickering ADFA School of Engineering and Information Technology, UNSW Dr Diana Perriman Clinical Research Co-ordinator, Trauma and Orthopaedic Research Unit Page 9 of 10

10 References Page 10 of 10