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

Filemon C Tan; Jeffrey A Strakowski; Faye Y Chiou-Tan

doi:10.4103/jisprm.JISPRM-000138

ORIGINAL ARTICLE

Year : 2022 | Volume : 5 | Issue : 1 | Page : 16-20

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

Filemon C Tan¹, Jeffrey A Strakowski², Faye Y Chiou-Tan³
¹ Department of Bioscience, Rice University, Houston, Texas, USA
² Department of Physical Medicine and Rehabilitation, The Ohio State University; Department of Physical Medicine and Rehabilitation, OhioHealth Riverside Methodist Hospital, Columbus, OH, USA
³ Department of Physical Medicine and Rehabilitation, Baylor College of Medicine, Center for Trauma Rehabilitation Research, Harris Health System, Houston, Texas, USA

Date of Submission	01-Jun-2021
Date of Decision	01-Dec-2021
Date of Acceptance	02-Dec-2021
Date of Web Publication	16-Feb-2022

Correspondence Address:
Dr. Faye Y Chiou-Tan
Department of PMR/EMG, Suite #5203, 2525A Holly Hall, Smith Clinic, Houston, TX 77054
USA

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/jisprm.JISPRM-000138

Abstract

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.

Keywords: Anatomy, botulinum toxin, cervical, dystonia, injection, neck, torsion, torticollis, ultrasound

How to cite this article:
Tan FC, Strakowski JA, Chiou-Tan FY. Ultrasound visualization of torsional anatomic changes in the neck: Applications to cervical rotational torticollis. J Int Soc Phys Rehabil Med 2022;5:16-20

How to cite this URL:
Tan FC, Strakowski JA, Chiou-Tan FY. Ultrasound visualization of torsional anatomic changes in the neck: Applications to cervical rotational torticollis. J Int Soc Phys Rehabil Med [serial online] 2022 [cited 2023 May 29];5:16-20. Available from: https://www.jisprm.org/text.asp?2022/5/1/16/337796

Introduction

Ultrasound is an effective modality for performing both diagnostic evaluation of soft-tissue structures about the neck as well as for use with real-time guidance for interventional procedures. Ultrasound guidance of injections for cervical dystonia (CD) allows precise delivery while avoiding vunerable anatomical structures. Thus guided injections are recommended to reduce adverse events while increasing safety and efficacy.^[1] Recently, Fietzek et al. provided recommendations for use of ultrasound for prescanning and use with electromyography (EMG) to enhance outcome.^[2]

Conventional anatomic descriptions typically demonstrate the structures of interest in an anatomic neutral position. Prior studies have documented sonographic changes with internal rotation in spastic hemiparesis of the upper and lower limbs specifically for the purpose of injection.^{[3],[4],[5],[6],[7]} Identification of the alterations of anatomic relationships from torsion related to CD and torticollis is particularly valuable in light of implications of misdirection with ultrasound guided procedures around vital neurovascular structures. Torsional influence on the soft tissue with cervical rotation occurs when the origin and insertion move at different rates.^[3] Familiarity with that pattern can improve understanding of the sonographic appearance in spastic conditions.

Review of torsional concepts

The concepts of torsional anatomy introduced in the previous papers^{[3],[4],[5],[6],[7]} and supported in this study can be summarized as:

Structures previously seen in cross-section when in anatomic position can appear oblique or inconspicuous with torsional stress. Anisotropic artifacts also can distort the clarity of the anatomic structure
Different anatomic structures are influenced by rotational movement to varying degrees. An example is compression of some muscles with simultaneous elongation of others. This can be compared to an accordion instrument being compressed on one side and distended on the other. In addition, there is typically a varying degree of movement of most structures with a larger amount of excursion in the portion furthest from the origin of movement.

Focus on rotational torticollis

Rotational torticollis, which is characterized by cervical rotational deformity, is the emphasis of this paper. Antero-, latero-, and retrocollis are not depicted in these images. CD, or spasmodic torticollis, affects an estimated 20–4100 individuals per million globally.^[8] Many studies have confirmed that CD can be treated effectively by botulinum toxin A (BTA) injections of spasmodic muscles.^{[9],[10],[11],[12]} Understanding the torsional anatomy of the neck can help prevent inadvertent injury to the neurovascular structures in the neck during ultrasound-guided procedures. Prior studies have demonstrated the efficacy of ultrasound-guided injections;^[13],[14] however, most literature only illustrates an anatomic neutral position and not torsional soft-tissue images typical of CD. This paper reports ultrasound images of muscles commonly injected for CD, in positions of rotation in a healthy subject. Localization of injection for CD treatment can be potentially improved with understanding of the differences between neutral and torsional positions.

Methods

The project was approved by the local institutional review board of the academic medical school. Before beginning the study, informed consent was obtained from the subject, a healthy, 56-year-old female. Ultrasound images were acquired by an American Registry for Diagnostic Medical Ultrasonography Musculoskeletal (ARDMS-MSK) certified ultrasonographer, full professor physician with 12-year ultrasound experience under guidance of the middle author. The middle author is an ARDMS-MSK and American Association of Neuromuscular and Electrodiagnostic Medicine Neuromuscular Ultrasound certified internationally known ultrasonographer. He has written multiple ultrasound textbooks and is a full professor physician with 16-year ultrasound experience. Prescanning was done for optimal gain, focus, elimination of anisotropy, and the most optimal image was chosen. Settings for images were frequency 11.0 MHz, gain 52, depth 2.0–2.50 cm, compound/harmonic imaging, and focus position were used to optimize image quality. Instrument used was GE Logiq P9 with 12-8 MHz 12 L-RS linear transducer. Muscles imaged were those commonly injected for spasticity: descending cranial and caudal trapezius, anterior and middle scalenes, contralateral sternocleidomastoid (SCM), ipsilateral splenius capitis, ipsilateral splenius cervicis, and ipsilateral levator scapulae.^[10] For each muscle, an anatomic neutral and torsional image were taken. In addition, a cine loop video recording was used to track muscles throughout torsional stress. For each site, the subject rotated her head fully to the right, such that the right side was ipsilateral, and left side was contralateral in all images.

Results

Ipsilateral muscles

Trapezius muscle

As the neck rotates from the neutral to right torsional position, the right (ipsilateral), cranial descending trapezius shifts medially and increases in thickness [Figure 1]a. Rotation also obscures the bony landmark of the cervical spine. In contrast, the caudal trapezius does not change significantly upon rotation [Figure 1]b.

Figure 1: Ipsilateral cervical changes in anatomic neutral and right torsion. (a) Descending trapezius: As the neck rotates from the neutral to right torsion, the cranial descending trapezius shifts medially and increases in thickness. Rotation also obscures the bony landmark of the cervical spine. (b) Caudal trapezius: In contrast, the caudal trapezius does not change significantly upon rotation. (c) Anterior and Middle Scalenes: anterior and middle scalenes move more anteriorly when the neck rotates from neutral to torsion. The brachial plexus, which appears as a “traffic light” in neutral position (displaying three circles of the superior, middle, and inferior portions of the brachial plexus in cross section) becomes less recognizable and distorted with torsional stress due to the obliquity and anisotropy. (d) Right Splenius Capitis and Cervicis Muscles: The right splenius capitis and splenius cervicis flatten. The sternocleidomastoid slides over the splenius capitis in the cine loop. (e) Right Levator Scapulae: The right levator scapulae increases in cross-sectional area when in torsion

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Anterior and middle scalenes

Scanning in short axis with the neck rotating from neutral to torsional position, the right (ipsilateral) anterior and middle scalenes move slightly more anteriorly. The brachial plexus, which appears as a “traffic light” in neutral position (displaying three circles of the superior, middle, and inferior portions of the brachial plexus in cross section) becomes less recognizable and distorted with torsional stress due to the obliquity and anisotropy [Figure 1]c.

Right splenius capitis and cervicis muscles

In short-axis views, the right splenius capitis and splenius cervicis were flattened. The SCM slides over the splenius capitis in the cine loop [Figure 1]d.

Right levator scapulae

Scanning in short axis, the right levator scapulae increases in cross-sectional area when in torsion [Figure 1]e.

Contralateral muscles:

Trapezius muscle

As the neck rotates from the neutral to right torsional position, the left (contralateral) descending and caudal portions of the trapezius do not change significantly upon rotation [Figure 2]a and [Figure 2]b.

Figure 2: Contralateral cervical changes in anatomic neutral and torsion. (a and b) Trapezius muscle: as the neck rotates from the neutral to right torsional position, the left (contralateral) descending and caudal portions of the trapezius do not change significantly upon rotation. (c) Anterior and Middle Scalenes: The contralateral middle and anterior scalene flatten and decrease in thickness with torsion. The left brachial plexus becomes less conspicuous due to the obliquity and anisotropic artifact. (d) Left Sternocleidomastoid: as the neck rotates to the torsional position, the sternocleidomastoid moves laterally over the carotid artery. In addition, the jugular veins distend and become more prominent

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Anterior and middle scalenes

On the left (contralateral) side, the middle and anterior scalene flatten and decrease in thickness. The left brachial plexus becomes less conspicuous due to the obliquity and anisotropic artifact [Figure 2]c.

Left sternocleidomastoid

With short-axis views, as the neck rotates from neutral to right torsional position, the SCM moves laterally over the carotid artery. In addition, the jugular veins distend and become more prominent [Figure 2]d.

Discussion

Events associated with botulinum toxin A injection

Review of the literature has demonstrated that botulinum toxin therapy is generally safe and tolerable, with a low incidence of serious adverse events.^[15] However, there is the potential for severe side effects. Between 2001 and 2002, the United States' Food and Drug Administration reported 217 serious adverse events associated with therapeutic BTA.^[16] This was recorded during a time before high-resolution ultrasound and other guidance procedures were readily available, however, complications can include difficulties with breathing, swallowing, and speaking.^[17] Methods for enhancing accuracy of injections in the neck region are particularly important for improving safety.

Advantages of ultrasound-guided injections

Ultrasound technology provides real-time imaging of muscles, other structures (bony landmarks, vessels, and nerves), as well as the needle itself. Ultrasound guidance can increase effectiveness and lower adverse events of BTA therapy by improving localization.^[1],[2] In a small sample, ultrasound-guided injections were able to eliminate incidences of adverse dysphagia, as compared to a 34.7% rate for injections guided by EMG alone.^[18] Randomized, controlled trials have also verified the effectiveness of ultrasound-guided injection.^[13],[14] Finally, a systematic review of randomized, controlled trials have also found level 1 evidence that injections guided by ultrasound and other techniques are superior to manual needle placement without guidance.^[19]

Applications to medical education

The reasons for selecting a healthy volunteer for this study are multiple. Recognition and mapping of muscles in rotation assist in learning new positions of healthy anatomic structures to avoid concluding that they are pathologic. Another reason is that a healthy subject can turn their head easily to positions that allow tracking structures from anatomic neutral to torsion with cine loop, which is challenging in patients with CD. In addition, muscle fibrosis and atrophy, frequently present in individuals with CD, could inhibit reliable distinction between the normal anatomic positional changes being studied and the limitations of the dystonia.

Applications to cervical torticollis

Our previous studies have shown anatomic relocation of structures in the upper and lower limbs when moved from anatomically neutral positions.^{[3],[4],[5],[6],[7]} This study demonstrates the effect of placing the neck in positions of torsion on the ultrasound images typically used for guiding injections. The summary of important points demonstrated in this exercise includes (1) localization of the anterior and middle scalene becomes more challenging due to the loss of conspicuity of the neural echotexture of the brachial plexus both ipsilaterally and contralaterally with torsion. The torsional rotation creates more obliquity and anisotropic artifact. (2) The jugular vein becomes significantly more distended near the contralateral SCM injection site. Inadvertent injection due to unrecognized position change could create an undesired effect from chemodenervation. (3) In contrast, the descending trapezius and levator scapulae position, as they relates to injection strategy, do not change significantly with rotational torsion.

Limitations

This study examined torsional changes in a healthy volunteer rather than a dystonic patient. The use of a healthy patient allowed reconstruction of common patterns in anatomical neutral position and how those changed in right torsional rotation. Individuals with long-standing dystonia can also display muscle echotecture abnormalities beyond just positional changes such as muscle hypertrophy and fibrosis.^[2]

Conclusion

Cervical rotation changes the position and relative relationship of many of the soft-tissue structures about the neck. The effect of torsion on these tissues can be demonstrated with dynamic ultrasound. Knowledge of these alterations with cervical rotation can improve localization for ultrasound-guided cervical injections for CD.

Acknowledgments

The authors wish to acknowledge Michelle Tan for contributions with data acquisition for this article.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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