Review questions

1. How is the association between cervicothoracic junction anatomic variation and neurogenic thoracic outlet syndrome described in the literature?
2. What imaging modalities are used in the assessment of cervicothoracic junction anatomical variations in patients with neurogenic thoracic outlet syndrome?
3. How is imaging used to describe, classify, grade, and assess these anatomical variations in the literature?
4. How is imaging described as contributing to the diagnosis or management of neurogenic thoracic outlet syndrome?
5. Is there a recognized pattern or patterns of field defect in the cervicothoracic transition area that can be identified, and what is their link with C7 costal elements?

Selection Criteria

Concept

The concept for this review is the use of any imaging modality (such as, but not limited to, radiography, computed tomography, magnetic resonance imaging, and ultrasonography) to identify, classify, assess, or report on anatomical variations of the cervicothoracic junction. This includes both osseous variations (e.g., cervical ribs, elongated C7 TPs) and soft tissue variations (e.g., congenital fibrous bands, scalene muscle anomalies, or aberrant vasculature causing neurogenic compression).

We will exclude studies that discuss nTOS diagnosis or management but do not report on specific imaging findings related to anatomical variations. Studies focusing exclusively on vascular imaging (e.g., angiography, arteriography) will also be excluded.

Context

This review will consider evidence from any clinical or research setting where imaging for the investigation or diagnosis of nTOS is performed, including hospital departments, specialist clinics, and private imaging centers. There will be no restrictions based on geographic location or cultural context.

Types of Sources

This scoping review will consider both experimental and quasi-experimental study designs including randomized controlled trials, non-randomized controlled trials, before and after studies and interrupted time-series studies. In addition, analytical observational studies including prospective and retrospective cohort studies, case-control studies and analytical cross-sectional studies will be considered for inclusion. This review will also consider descriptive observational study designs including case series, individual case reports and descriptive cross-sectional studies for inclusion.

Qualitative studies and text and opinion papers will also be considered for inclusion in this scoping review. In addition, systematic and scoping reviews that meet the inclusion criteria will also be considered.

Search strategy

A three-step search strategy will be utilised in this review, developed in consultation with a medical librarian (JH) and refined using best practices. First, an initial limited search of MEDLINE (via Ovid) was undertaken to identify articles on the topic. The text words contained in the titles and abstracts of these articles, along with their associated index terms, were used to develop a comprehensive search strategy (see Appendix 1). The search strategy, including all identified keywords and index terms, will be adapted for each included database and information source. The reference lists of all included sources of evidence will be screened for additional studies (backward citation searching). Additionally, forward citation searching of highly relevant included studies will be performed using appropriate citation indexes.

Studies published in the English language will be included to maintain the accuracy of descriptive and conceptual terms. Studies published from database inception will be included to ensure comprehensive capture of the earliest literature relating to anatomical classifications.

The primary databases to be searched include MEDLINE (via Ovid), PubMed, Embase (Elsevier), Scopus, and CINAHL (EBSCOhost). While MEDLINE and PubMed share substantial overlap, both are included to ensure the exhaustive capture of all ‘ahead-of-print’ and non-indexed biomedical literature. The inevitable duplicate records resulting from this database overlap will be systematically identified and removed prior to screening.

Sources of grey literature will be searched to capture non-peer-reviewed and unpublished studies. For the purposes of this review, this includes academic theses, preprints, conference abstracts, and institutional reports. These sources will be identified using Google Scholar.

Study/Source of evidence selection

Following the search, all identified citations will be collated and uploaded into Zotero 7.0.28 (Digital Scholar, Virginia, USA) and duplicates removed. Following a pilot test, titles and abstracts will then be screened by two independent reviewers (HOHB and GS) for assessment against the inclusion criteria for the review. Potentially relevant sources will be retrieved in full and their citation details imported into Rayyan [23]. The full text of selected citations will be assessed in detail against the inclusion criteria by two independent reviewers. Consistent with the JBI methodology for scoping reviews, critical appraisal of individual sources of evidence will not be performed [21]. Reasons for exclusion of sources of evidence at full text that do not meet the inclusion criteria will be recorded and reported in the scoping review. Any disagreements that arise between the reviewers at each stage of the selection process will be resolved through discussion, or with an additional reviewer. The results of the search and the study inclusion process will be reported in full in the final scoping review and presented in a PRISMA flow diagram [24].

Data extraction

Data will be extracted from papers included in the scoping review by two independent reviewers (HOHB and GS) using a data extraction tool developed by the reviewers. The data extracted will include specific details about the participants, concept, context, study methods and key findings relevant to the review questions.

A draft extraction form is provided (see Appendix 2). The draft data extraction tool will be modified and revised as necessary during the process of extracting data from each included evidence source. Modifications will be detailed in the scoping review. Any disagreements that arise between the reviewers will be resolved through discussion, or with an additional reviewer. If appropriate, authors of papers will be contacted to request missing or additional data, where required.

Data analysis and presentation

Data analysis and presentation will involve a descriptive numerical analysis and a thematic summary, presented in graphical, diagrammatic, and tabular formats to align with the review’s objectives. Descriptive charts will illustrate the distribution of studies by publication year, country of origin, and study design. A main table will detail the characteristics of all included sources. A cross-tabulation matrix will be used to map the anatomical variations against the imaging modalities employed. Further descriptive tables will summarize identified classification systems and the reported role of imaging. A narrative summary will accompany all results, synthesizing the charted and tabulated data to describe how the findings relate to the review’s questions and objectives. This presentation plan may be refined as data are extracted, and the final review will adhere to the PRISMA-ScR guidance [22].

Study status and timeline

At the time of submission (May 2026), preliminary searches have been conducted to inform the search strategy, but no formal data screening or extraction has commenced. The study is scheduled to proceed according to the following timeline:

• Record screening: We anticipate the completion of title and abstract screening, as well as full-text review, by June 2026.
• Data extraction: The data charting process is expected to be completed by July 2026.
• Results: The final synthesis of results and drafting of the review manuscript is expected to be completed by September 2026.