Accessory Inspiratory Muscles in Chronic Neck Pain (AIM-CNP)

August 21, 2026 updated by: Sena Çınarlı, Kocaeli Sağlık ve Teknoloji Üniversitesi

Ultrasonographic Characteristics of Accessory Inspiratory Muscles and Their Relationship With Respiratory Function in Individuals With Chronic Non-Specific Neck Pain: A Cross-Sectional Case-Control Study

This cross-sectional case-control study aims to investigate the ultrasonographic structural and functional characteristics of accessory inspiratory muscles in individuals with chronic non-specific neck pain and compare them with healthy controls. In addition, the relationships between accessory inspiratory muscle characteristics, diaphragm function, respiratory muscle strength, and pulmonary function parameters will be examined. The findings may improve understanding of the respiratory involvement associated with chronic neck pain and contribute to more comprehensive assessment strategies.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Chronic non-specific neck pain is a prevalent musculoskeletal disorder associated with pain, disability, and reduced quality of life. Emerging evidence suggests that its effects may extend beyond the cervical region and involve respiratory dysfunction. Previous studies have reported reductions in respiratory muscle strength, pulmonary function, and diaphragm function in individuals with chronic neck pain.

The diaphragm plays an important role not only in respiration but also in postural control and spinal stabilization. Ultrasonographic studies have demonstrated alterations in diaphragm thickness and mobility in individuals with chronic neck pain. However, little is known about potential compensatory adaptations occurring in accessory inspiratory muscles, including the sternocleidomastoid, anterior scalene, and upper trapezius muscles.

The purpose of this observational case-control study is to investigate the ultrasonographic characteristics of accessory inspiratory muscles in individuals with chronic non-specific neck pain and to compare these characteristics with those of healthy controls. Additionally, the relationships between accessory inspiratory muscle characteristics, diaphragm function, respiratory muscle strength, and pulmonary function will be examined.

Participants with chronic non-specific neck pain and age-matched healthy controls will undergo ultrasonographic assessment of the diaphragm and accessory inspiratory muscles, pulmonary function testing, and respiratory muscle strength evaluation. Associations among ultrasonographic, respiratory, and functional variables will be analyzed to improve understanding of respiratory involvement in chronic neck pain and to identify potential clinical assessment targets.

Study Type

Observational

Enrollment (Estimated)

10

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

The study population will consist of adults aged 18 to 65 years. The case group will include individuals with chronic non-specific neck pain lasting at least 3 months, while the control group will consist of age-matched healthy volunteers without neck pain during the previous 3 months. Participants will be recruited from the Physical Medicine and Rehabilitation outpatient clinic and the surrounding community.

Description

Inclusion Criteria

Chronic Non-Specific Neck Pain Group:

  • Age between 18 and 65 years
  • Presence of chronic non-specific neck pain for at least 3 months
  • Non-traumatic origin of neck pain
  • Pain intensity ≥ 3 on the Numeric Pain Rating Scale (NPRS) or Visual Analog Scale (VAS)
  • Neck Disability Index (NDI) score ≥ 15
  • Willingness to participate and provide informed consent

Healthy Control Group:

  • Age between 18 and 65 years
  • No neck pain during the previous 3 months
  • Not receiving any treatment related to the cervical region
  • Willingness to participate and provide informed consent

Exclusion Criteria (Both Groups):

  • History of whiplash injury or cervical trauma
  • Previous cervical spine surgery
  • Cervical radiculopathy or neurological deficits
  • Chronic respiratory diseases (e.g., COPD, asthma)
  • Active respiratory tract infection
  • Thoracic or abdominal surgery within the previous 6 months
  • Rheumatologic, neuromuscular, or systemic inflammatory disorders
  • Pregnancy
  • Physiotherapy treatment for neck pain within the previous 3 months
  • Regular respiratory muscle training or breathing exercises within the previous 3 months
  • Inability to comply with study procedures or assessments

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Chronic Non-Specific Neck Pain
Participants aged 18-65 years with chronic non-specific neck pain lasting at least 3 months.
Diaphragm thickness was assessed by ultrasonography while the participant was in a standardized position. Measurements were obtained at the end of expiration and during maximal inspiration.
Anterior scalene muscle thickness was assessed by ultrasonography while the participant was in a standardized position. Measurements were obtained at rest and during maximal inspiratory effort.
Upper trapezius muscle thickness was assessed by ultrasonography while the participant was in a standardized position. Measurements were obtained at rest and during maximal inspiratory effort.
Maximal inspiratory pressure was measured using a respiratory pressure measurement device. The participant performed a maximal inspiratory effort against an occluded airway after complete expiration. Repeated measurements were performed with appropriate rest intervals.
Maximal expiratory pressure was measured using a respiratory pressure measurement device. The participant performed a maximal expiratory effort against an occluded airway after maximal inspiration. Repeated measurements were performed with appropriate rest intervals.
Pulmonary function testing was performed using spirometry while the participant was in a standardized seated position. The participant completed maximal forced expiratory maneuvers following standardized instructions, and technically acceptable measurements were recorded.
Healthy Control
Age-matched healthy individuals without neck pain during the previous 3 months.
Diaphragm thickness was assessed by ultrasonography while the participant was in a standardized position. Measurements were obtained at the end of expiration and during maximal inspiration.
Anterior scalene muscle thickness was assessed by ultrasonography while the participant was in a standardized position. Measurements were obtained at rest and during maximal inspiratory effort.
Upper trapezius muscle thickness was assessed by ultrasonography while the participant was in a standardized position. Measurements were obtained at rest and during maximal inspiratory effort.
Maximal inspiratory pressure was measured using a respiratory pressure measurement device. The participant performed a maximal inspiratory effort against an occluded airway after complete expiration. Repeated measurements were performed with appropriate rest intervals.
Maximal expiratory pressure was measured using a respiratory pressure measurement device. The participant performed a maximal expiratory effort against an occluded airway after maximal inspiration. Repeated measurements were performed with appropriate rest intervals.
Pulmonary function testing was performed using spirometry while the participant was in a standardized seated position. The participant completed maximal forced expiratory maneuvers following standardized instructions, and technically acceptable measurements were recorded.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Diaphragm Thickening Ratio
Time Frame: Baseline
Diaphragm thickening ratio measured using ultrasonography.
Baseline
Sternocleidomastoid Muscle Thickness
Time Frame: Baseline
Sternocleidomastoid muscle thickness measured using ultrasonography.
Baseline

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Anterior Scalene Muscle Thickness
Time Frame: Baseline
Anterior scalene muscle thickness measured using ultrasonography.
Baseline
Upper Trapezius Muscle Thickness
Time Frame: Baseline
Upper trapezius muscle thickness measured using ultrasonography.
Baseline
Maximal Inspiratory Pressure (MIP)
Time Frame: Baseline
Maximal inspiratory pressure will be measured using a respiratory pressure measurement device. Participants will perform a maximal inspiratory effort against an occluded airway after complete expiration. The highest technically acceptable value will be recorded in cmH₂O. Higher values indicate greater inspiratory muscle strength.
Baseline
Forced Vital Capacity (L)
Time Frame: Baseline
Forced vital capacity will be measured using spirometry during a maximal forced expiratory maneuver performed after maximal inspiration.
Baseline
Maximal Expiratory Pressure (MEP)
Time Frame: Baseline
Maximal expiratory pressure will be measured using a respiratory pressure measurement device. Participants will perform a maximal expiratory effort against an occluded airway after maximal inspiration. The highest technically acceptable value will be recorded in cmH₂O. Higher values indicate greater expiratory muscle strength.
Baseline
Forced Expiratory Volume in 1 Second (L)
Time Frame: Baseline
Forced expiratory volume in the first second will be measured using spirometry during a maximal forced expiratory maneuver performed after maximal inspiration.
Baseline
FEV1/FVC Ratio (%)
Time Frame: Baseline
The ratio of forced expiratory volume in the first second to forced vital capacity will be determined from spirometry measurements.
Baseline
Peak Expiratory Flow (L/sn)
Time Frame: Baseline
Peak expiratory flow will be measured using spirometry during a maximal forced expiratory maneuver performed after maximal inspiration.
Baseline
Forced Expiratory Flow at 25-75%
Time Frame: Baseline
Forced expiratory flow during the middle 50% of the forced vital capacity maneuver will be measured using spirometry.
Baseline

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

June 10, 2026

Primary Completion (Estimated)

September 1, 2026

Study Completion (Estimated)

December 1, 2026

Study Registration Dates

First Submitted

June 20, 2026

First Submitted That Met QC Criteria

August 21, 2026

First Posted (Actual)

August 24, 2026

Study Record Updates

Last Update Posted (Actual)

August 24, 2026

Last Update Submitted That Met QC Criteria

August 21, 2026

Last Verified

July 1, 2026

More Information

Terms related to this study

Other Study ID Numbers

  • KOSTU-26-USG

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data will not be made publicly available because the study involves sensitive health-related information and participant confidentiality cannot be fully guaranteed despite de-identification procedures. Aggregate study findings will be reported in scientific publications.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

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