Evaluation of Swallowing Muscles Using Ultrasonography and Shear Wave Elastography in Patients Receiving Radiotherapy for Nasopharyngeal Carcinoma Diagnosis

The aim of this study is to evaluate the mylohyoid, geniohyoid and digastric muscles in patients with radiotherapy-induced dysphagia due to nasopharynx cancer using ultrasonography and shear wave elastography (SWE).

Post-radiotherapy swallowing dysfunction evaluation was carried out using fibreoptic endoscopic evaluation (FEES), ultrasonography of the swallowing muscles, shear wave elastography and swallowing assessment scale between the dates of 01/01/2023 and 01/06/2023.

All patients were interviewed to obtain detailed medical histories. Following this, standardized swallowing assessments were administered, including the Eating Assessment Tool (EAT-10) and the M.D. Anderson Dysphagia Inventory (MDADI). Head and neck examination, endoscopic examination and fibreoptic endoscopic swallowing assessment were performed at the Otorhinolaryngology, Head and Neck Surgery clinic. Penetration Aspiration Score (PAS) was determined by the experienced faculty member. Afterwards, an experienced radiologist performed neck ultrasonography and shear wave elastography (SWE) using an Aplio 500 Platinium Ultrasonography system (Toshiba Medical Systems, Japan) equipped with high-frequency linear transducer (frequency range = 5-14 MHz). With SWE, the stiffness values of the mylohyoid, geniohyoid and digastric muscles were measured in m/s and kPa, and their thickness was measured in mm. The tissue elasticity was outlined using a colour-coded system ranging from dark blue indicating least stiffness to red representing greatest stiffness, with a default measurement range of 0-120 kPa. The elastic value E (kPa) is calculated using the equation E = 3 ρ (m/s) 2. In the equation, m/s represents the shear wave propagation speed, and ρ represents the tissue density (approximately 1 in humans). All patients receiving radiotherapy were treated in our hospital's radiation oncology clinic for Stage I nasopharyngeal cancer received 70 Gy (2,12 Gy/Gun) gross tumour value (CTV70), with 5-10 mm margin for microscopic spread, delivered according to the International Commission on Radiation Units and Measurements (ICRU) Reports 50 and 62 guidelines. After obtaining the data, comparisons between the groups and correlations between the quantitative data were assessed using appropriate statistical methods.

Eligibility Criteria:
Inclusion Criteria

Patient Group:

* Volunteered for the study.
* Aged 18-65 years.
* Diagnosed with Stage I nasopharynx cancer.
* Completed radiotherapy treatment at least 12 months prior to the study.
* No additional cancer diagnoses.
* No history of chemo-radiotherapy.
* No prior head-neck trauma or surgery.
* No rheumatologic or neuromuscular disorders.
* No pre-existing swallowing disorders.
* Control Group (Healthy Volunteers):

Control group:

* Aged 18-65 years.
* No history of head and neck cancer.
* No prior neck surgery or trauma.
* No radiotherapy to the head and neck region.
* No rheumatologic or neuromuscular disorders.
* No central haemorrhagic or ischemic disease.
* No pre-existing swallowing disorders.

Exclusion Criterias:

* Younger than 18 years or older than 65 years.
* Any history of neck interventions (e.g., for cancer metastasis, cervical spine surgery, trauma).
* Presence of systemic conditions potentially causing dysphagia (e.g., neurological, rheumatological, metabolic, or muscular disorders).
* Previous radiotherapy for reasons other than Stage I nasopharynx cancer (in the patient group).
* Any other cancer diagnosis besides Stage I nasopharynx cancer (in the patient group).