Ultrasonographic Evaluation of Morphological and Functional Characteristics of Intercostal Muscles in Stroke Patients and Their Relationship With Clinical Parameters

Stroke frequently leads to respiratory muscle dysfunction due to impaired central motor control. Although diaphragm involvement after stroke has been extensively investigated, there is limited evidence regarding the morphological and functional characteristics of extra-diaphragmatic inspiratory muscles, particularly the parasternal intercostal muscles.

The primary objective of this study is to evaluate parasternal intercostal muscle morphology and contractility in individuals with stroke using ultrasonography. Parasternal intercostal muscle thickness will be measured at end-tidal expiration and maximal inspiration, and intercostal muscle thickening fraction (ICTf) will be calculated as an indicator of muscle contractility. Measurements will be obtained bilaterally, allowing comparison between the hemiplegic and non-hemiplegic sides.

In addition, diaphragm thickness and diaphragm thickening fraction will be assessed using ultrasonography. Respiratory muscle strength will be evaluated by maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) measurements according to ATS/ERS recommendations. Pulmonary function tests including forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and FEV1/FVC ratio will also be performed.

Clinical outcomes including motor impairment, balance, functional independence, and stroke-specific quality of life will be assessed using the Fugl-Meyer Assessment, Berg Balance Scale, Functional Independence Measure (FIM), and Stroke-Specific Quality of Life Scale (SS-QoL), respectively.

A healthy control group matched for age, sex, and body mass index will be included to establish reference values for parasternal intercostal muscle ultrasonographic measurements and to allow comparative analyses between stroke patients and healthy individuals.

The study is designed as a single-center, controlled cross-sectional observational study. A minimum of 40 individuals with stroke and 25 healthy volunteers will be enrolled. Associations between ultrasonographic respiratory muscle measurements and clinical parameters will be analyzed to improve understanding of respiratory muscle involvement after stroke and its relationship with functional outcomes.

Inclusion criteria

(Stroke Group):

• Age between 18 and 75 years.
• History of ischemic or hemorrhagic stroke.
• Ability to understand and comply with study procedures.
• Provision of written informed consent.

Exclusion criteria

(Stroke Group):

• Presence of acute or chronic pulmonary disease.
• History of thoracic or abdominal surgery.
• Presence of another neuromuscular disorder.
• Aphasia or cognitive impairment preventing participation in assessments.
• Active malignancy.

Inclusion criteria

(Healthy Control Group):

• Age between 18 and 75 years.
• Willingness to participate in the study.
• Provision of written informed consent.

Exclusion criteria

(Healthy Control Group):

• History of stroke or other neurological disorders.
• History of chronic respiratory disease (e.g., COPD, asthma).
• Chest wall deformity.
• Presence of systemic diseases that may affect muscle function.