Ultrasound visualization of torsional anatomic changes in the neck: Applications to cervical rotational torticollis

Introduction: The objective of this paper is to demonstrate changes in the sonographic appearance of muscles in region of the neck with cervical movement from neutral anatomic position to right rotational torsion. Methods: Sonographic images were obtained in a 56-year-old healthy female. Muscles selected are common targets for botulinum toxin A injection in treatment for cervical dystonia. Sonographic images were obtained with the transducer placed over the muscle of interest with the neck in both anatomic-neutral and right-rotated positions. Cine loop video was also recorded at each site to track muscles throughout torsion. Results: The results show that in rotational torsion, (1) the brachial plexus becomes difficult to view due to anisotropy when examining the scalenes. The relationship between the anterior and middle scalenes and brachial plexus becomes less distinct with cervical rotation beyond neutral position. (2) The positional relationship of the sternocleidomastoid (SCM) and the ipsilateral splenius capitus is altered. (3) The jugular vein changes from collapsed to distended in the contralateral SCM view. (4) The position of the trapezius is not altered significantly. Conclusion: The sonographic appearance of soft tissue structures about the neck differs significantly with cervical movement from an anatomic neutral position to a position of right torsion. Knowledge of the dynamic positional changes of the muscles in this region in relation to each other, as well as the neurovascular structures, with cervical movement and torsion can potentially improve diagnostic assessment as well as accuracy of interventional procedures.