Nidia Patricia Cedeño Ortiz

Speech-Language Pathologist, Therapy Laser PG, ORCID: 0000-0001-8325-6113

 

ABSTRACT

Background

Voice and swallowing disorders are common functional sequelae following thyroidectomy. Although these impairments have traditionally been attributed to laryngeal nerve injury, growing evidence suggests that muscular, fascial, scar-related, and biomechanical factors also play a substantial role in laryngeal and swallowing dysfunction. Photobiomodulation (PBM) has emerged as a complementary therapeutic approach with potential benefits for tissue repair and functional recovery through bioenergetic modulation, inflammatory regulation, and neuromuscular optimization.

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Objective

To retrospectively describe functional outcomes in post-thyroidectomy patients with medically diagnosed vocal fold paralysis who underwent photobiomodulation integrated into a speech-language rehabilitation program.

 

Methods

A retrospective descriptive study was conducted through the review of medical records from 72 patients treated between 2016 and 2026 at a specialized rehabilitation center. All participants had undergone thyroidectomy and had a medical diagnosis of vocal fold paralysis. The therapeutic protocol consisted of 12 photobiomodulation sessions using a Class IIIA laser (650 nm, 100 mW) applied for 90 seconds per treatment point, combined with speech-language rehabilitation. Variables related to laryngeal mobility, vocal quality, swallowing function, scar characteristics, and cervical muscular performance were analyzed. Objective measurements derived from acoustic voice and swallowing analyses were also included.

 

Results

All participants met the predefined criteria for functional voice and swallowing recovery at the completion of rehabilitation. Improvements were also observed in laryngeal mobility, cervical tissue mobility, and acoustic voice and swallowing parameters.

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Conclusions

The findings suggest that photobiomodulation may represent a valuable complementary intervention within rehabilitation programs for post-thyroidectomy patients with vocal fold paralysis. Prospective controlled studies are required to confirm these findings and establish standardized therapeutic protocols.

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Keywords: Photobiomodulation; Vocal Fold Paralysis; Thyroidectomy; Dysphagia; Dysphonia; Speech-Language Rehabilitation.

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INTRODUCTION

Thyroidectomy is one of the most commonly performed surgical procedures for the treatment of benign and malignant thyroid disorders. Despite advances in surgical techniques and intraoperative nerve monitoring systems, voice disorders remain among the most significant functional complications following thyroid surgery, substantially affecting quality of life, occupational performance, and daily communication (Pace-Asciak et al., 2022).

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Clinical manifestations following thyroidectomy include dysphonia, vocal fatigue, reduced maximum phonation time, impaired vocal projection, ineffective cough, and swallowing difficulties. These impairments may result from temporary or permanent injury to the recurrent laryngeal nerve or superior laryngeal nerve. However, biomechanical, myofascial, and scar-related mechanisms affecting hyolaryngeal mobility have also been described (Pace-Asciak et al., 2022; Wen & Wang, 2022).

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Vocal fold paralysis is one of the most extensively studied complications of thyroid surgery because of its impact on both voice and swallowing. In addition to glottal insufficiency, patients may develop supraglottic compensatory behaviors, increased phonatory effort, and impaired airway protection mechanisms, increasing the risk of penetration and aspiration (Ruoppolo et al., 2021; Wen & Wang, 2022).

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More recently, it has become evident that functional recovery following thyroid surgery is not exclusively dependent on neural integrity. Persistent inflammation, fibrosis, cervical adhesions, and fascial restrictions may compromise the mobility of tissues involved in phonation and swallowing, thereby limiting recovery even in patients with partial neural restoration (Morrissey et al., 2025).

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Photobiomodulation has emerged as a complementary therapeutic strategy capable of inducing biological responses through the application of low-intensity light at specific wavelengths. Its mechanism of action is associated with cytochrome c oxidase activation, increased ATP synthesis, oxidative stress modulation, and regulation of inflammatory cascades involved in tissue repair (Khan, 2016; Khalkhal, 2020).

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Several investigations have reported favorable effects of photobiomodulation on scar healing, peripheral nerve regeneration, muscular recovery, and modulation of fibrotic processes in different clinical contexts (Er-Rouassi et al., 2022; Kazemikhoo, 2022; Kim et al., 2022). In patients undergoing thyroid surgery, these effects may contribute to the functional recovery of structures affected by surgical intervention.

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Furthermore, objective assessment tools such as acoustic voice analysis and acoustic swallowing analysis provide quantifiable indicators that complement clinical evaluation and contribute to a more precise characterization of therapeutic outcomes.

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Therefore, the aim of this study was to retrospectively describe the functional outcomes observed in post-thyroidectomy patients with medically diagnosed vocal fold paralysis who underwent photobiomodulation integrated into a speech-language rehabilitation program.

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METHODS

Study Design

A retrospective descriptive study was conducted through the review of medical records from patients treated between 2016 and 2026 within a specialized speech-language rehabilitation program.

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Participants

The study sample consisted of 72 patients with a history of thyroidectomy and a medical diagnosis of vocal fold paralysis who were referred for functional rehabilitation.

Table 1

Demographic and Clinical Characteristics of the Study Population (N = 72)

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Note. Participants were treated between 2016 and 2026. Age range: 27-65 years.

Inclusion Criteria

• History of total or partial thyroidectomy.

• Medical diagnosis of vocal fold paralysis.

• Availability of complete medical records.

• Documented speech-language follow-up.

• Participation in the photobiomodulation protocol.

Exclusion Criteria

• Incomplete medical records.

• Lack of functional follow-up documentation.

• Patients who did not complete the therapeutic protocol.

• Progressive neurological disorders that could interfere with the interpretation of functional outcomes.

 

Therapeutic Procedure

All patients received a comprehensive traditional speech-language rehabilitation program combined with photobiomodulation therapy.

Photobiomodulation was delivered using a Class IIIA laser with a wavelength of 650 nm and an output power of 100 mW. The treatment protocol consisted of 12 therapeutic sessions, with an application time of 90 seconds per treatment point.

Photobiomodulation was applied to anatomical structures associated with vocal function, swallowing function, and postsurgical tissue recovery. Treatment areas included:

• The anatomical course of the recurrent laryngeal nerve, aiming to support tissues associated with neuromuscular function involved in vocal fold paralysis.

• Suprahyoid musculature, involved in hyolaryngeal elevation and airway protection during swallowing.

• Infrahyoid musculature, associated with stabilization and functional positioning of the larynx.

• The laryngeal region corresponding to the anatomical projection of the vocal folds, intended to support tissue function related to phonation and minimize muscular changes associated with vocal fold immobility.

• The pericicatricial cervical region, aiming to promote tissue healing, improve scar mobility, and reduce biomechanical restrictions associated with scar formation.

• Areas presenting clinically identified myofascial restrictions.

The distribution of treatment points was individualized according to findings obtained during the initial speech-language evaluation.

Selection of treatment areas was based on the involvement of these structures in the pathophysiology of voice and swallowing disorders associated with post-thyroidectomy vocal fold paralysis, as well as on the potential effects of photobiomodulation on tissue repair, inflammatory modulation, and functional recovery described in the literature.

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Variables and Outcomes

Information was obtained from clinical records and acoustic analyses performed during therapeutic follow-up.

Primary Outcomes

The primary outcomes of the study were:

Functional Voice Recovery

Defined as the restoration of a voice that allowed effective oral communication during daily activities, characterized by reduced phonatory effort, improved vocal stability, and decreased functional limitations compared with the initial assessment.

Functional Swallowing Recovery

Defined as the ability to safely and efficiently perform oral feeding with adequate airway protection and without clinically significant swallowing limitations compared with baseline evaluation.

 

Secondary Outcomes

Voice Variables

• Vocal quality.

• Vocal fatigue.

• Maximum phonation time.

• Laryngeal mobility.

• Phonorespiratory efficiency.

Swallowing Variables

• Swallowing-respiratory coordination.

• Swallowing safety.

• Functional feeding efficiency.

Tissue and Biomechanical Variables

• Cervical fibrosis.

• Scar-related restrictions.

• Cervical tissue mobility.

• Associated muscular tension.

 

Instrumental Variables

Objective measures obtained through acoustic voice analysis and acoustic swallowing analysis were included as complementary tools to evaluate functional progression.

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Acoustic Voice Analysis

Acoustic voice assessment included the analysis of total vocal energy and formant structures to evaluate changes in vocal intensity and resonance gain. Fundamental frequency (F0) was analyzed as an indicator of habitual vocal pitch, and the presence of vocal fry was recorded as a complementary marker of phonatory organization.

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Acoustic Swallowing Analysis

Acoustic swallowing assessment included evaluation of the three characteristic swallowing acoustic curves, the presence of post-swallow expiratory airflow, and the measurement of swallowing latencies, according to the acoustic swallowing analysis protocol routinely used within the rehabilitation program. These variables were used as objective indicators of swallowing function throughout clinical follow-up.

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Outcome Analysis

Clinical evolution was categorized according to information documented at the completion of the rehabilitation process. A favorable outcome was defined as the recovery of functional voice and/or functional swallowing documented in the medical record and supported by speech-language evaluation and follow-up acoustic analyses.

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Statistical Analysis

A descriptive analysis of information contained in the medical records was performed. Categorical variables were summarized using frequencies and percentages, whereas continuous variables were described using means and standard deviations when appropriate.

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RESULTS

Participants

Between 2016 and 2026, a total of 121 medical records from patients with vocal disorders were reviewed. Following application of eligibility criteria, 49 records were excluded due to incomplete clinical information, insufficient follow-up documentation, or failure to meet inclusion criteria.

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The final sample consisted of 72 post-thyroidectomy patients with a medical diagnosis of vocal fold paralysis.

The study population was predominantly female (n = 63, 87.5%), while males represented 12.5% of the sample (n = 9). Participants ranged in age from 27 to 65 years.

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Regarding the surgical procedure, 70 patients (97.2%) had undergone total thyroidectomy, whereas 2 patients (2.8%) had undergone partial thyroidectomy.

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Concerning the distribution of laryngeal impairment, 45 patients (62.5%) presented left vocal fold paralysis, 3 patients (4.2%) presented right vocal fold paralysis, and 24 patients (33.3%) presented bilateral vocal fold paralysis.

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All participants presented dysphonia and dysphagia at baseline. Additionally, 37 patients (51.4%) exhibited clinical signs of cervical fibrosis or scar-related restriction (Table 2).

Table 2

Baseline Clinical Characteristics (N = 72)

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Clinical Outcomes

Clinical records documented functional voice recovery and functional swallowing recovery in all patients included in the study.

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Regarding voice function, improvements were documented in vocal quality, reduced phonatory effort, and enhanced communicative performance. Furthermore, clinical records indicated improved functional mobility of laryngeal structures throughout rehabilitation.

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With respect to swallowing, all participants showed favorable clinical progression characterized by improved feeding efficiency and progressive reduction of swallowing-related difficulties reported at baseline.

Table 3

Clinical and Instrumental Outcomes Following Rehabilitation

Note. Outcomes were determined through clinical assessment, acoustic voice analysis, and acoustic swallowing analysis conducted during follow-up. Improvements in resonance gain, vocal intensity, and F0 organization were determined through comparative qualitative analysis of acoustic voice recordings obtained before and after rehabilitation.

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Instrumental Findings

Acoustic voice analysis demonstrated improved organization of vocal energy, increased resonance gain, enhanced vocal intensity, and a more functional configuration of fundamental frequency (F0), accompanied by a reduction in vocal fry patterns.

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Acoustic swallowing analysis revealed improved organization of swallowing acoustic curves, consistent post-swallow expiratory airflow, and swallowing latency patterns compatible with functional swallowing performance.

Among the patients presenting cervical fibrosis or scar-related restriction, clinical records documented improved cervical tissue mobilityand reduced biomechanical limitations associated with postoperative scar formation.

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DISCUSSION

The present retrospective study demonstrated functional voice recovery and functional swallowing recovery in all patients who participated in a comprehensive speech-language rehabilitation program combined with photobiomodulation therapy. These findings are particularly relevant given that all participants presented dysphonia and dysphagia associated with post-thyroidectomy vocal fold paralysis at baseline.

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Functional recovery in this patient population should be interpreted within the multifactorial pathophysiology underlying post-thyroidectomy dysfunction. Although vocal fold paralysis is commonly associated with recurrent laryngeal nerve injury, postoperative impairments are also influenced by tissue fibrosis, scar formation, myofascial restrictions, and biomechanical alterations affecting hyolaryngeal mobility (Pace-Asciak et al., 2022; Wen & Wang, 2022). From this perspective, restoration of voice and swallowing function cannot be attributed solely to neural recovery but must also be understood as the result of structural and functional adaptations involving the entire laryngeal and cervical system.

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The favorable outcomes documented in this cohort are consistent with previous reports describing the biological effects of photobiomodulation on inflammatory modulation, tissue repair, collagen remodeling, and functional recovery of surgically affected tissues (Kim et al., 2022). These mechanisms may have contributed to improved cervical tissue mobility, reduced scar-related restrictions, and enhanced performance of structures involved in phonation and swallowing.

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The recovery of functional voice observed in the present study is in agreement with previous investigations emphasizing the clinical relevance of early and individualized rehabilitation programs in patients with vocal fold paralysis following thyroid surgery (Ruoppolo et al., 2021; Wen & Wang, 2022). Likewise, The recovery of functional swallowing may be associated with improvements in the biomechanical mechanisms involved in hyolaryngeal elevation, airway protection, and bolus transport.

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An additional contribution of this study was the incorporation of acoustic voice and swallowing analyses as objective outcome measures. Improvements in vocal energy organization, resonance gain, vocal intensity, functional F0 configuration, and reduction of vocal fry patterns were accompanied by more organized swallowing acoustic curves, consistent post-swallow expiratory airflow, and latency patterns consistent with clinically functional swallowing. Together, these findings provided instrumental support for the clinical improvements documented throughout rehabilitation.

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The findings also support a broader clinical perspective in which post-thyroidectomy rehabilitation should be understood as a process involving neural, muscular, fascial, and biomechanical factors. From this standpoint, successful restoration of voice and swallowing function may depend not only on vocal fold mobility but also on the functional reorganization of the hyolaryngeal complex and the cervical tissues involved in phonation and swallowing.

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Strengths and Limitations

A major strength of this study was the integration of both clinical and instrumental outcome measures, including acoustic voice and swallowing analyses, which provided objective documentation of functional changes throughout rehabilitation. Furthermore, the study reflects ten years of clinical experience and includes a relatively large cohort of post-thyroidectomy patients with vocal fold paralysis treated within a standardized rehabilitation framework.

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Acoustic measures were primarily interpreted within a clinical framework and were not complemented by standardized instrumental examinations such as videofluoroscopy, fiberoptic endoscopic evaluation of swallowing, or laryngeal. Finally, only patients who completed the rehabilitation program and had adequate follow-up documentation were included in the analysis, which may have influenced the favorable outcomes reported.

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Despite these limitations, the present study provides clinically relevant evidence derived from a decade of rehabilitation practice and identifies photobiomodulation as a promising complementary intervention that warrants further investigation through prospective controlled studies.

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Clinical Implications

The results suggest that photobiomodulation may be incorporated as an adjunctive therapeutic resource within rehabilitation programs for post-thyroidectomy patients presenting voice and swallowing disorders associated with vocal fold paralysis. The observed improvements support the potential value of combining tissue-oriented interventions with conventional speech-language rehabilitation to address both functional and biomechanical components of recovery.

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CONCLUSIONS

The retrospective review of 72 post-thyroidectomy patients with medically diagnosed vocal fold paralysis demonstrated the recovery of functional voice and functional swallowing following participation in a comprehensive speech-language rehabilitation program combined with photobiomodulation therapy.

Clinical and instrumental findings revealed improvements in laryngeal mobility, cervical tissue mobility, resonance-related vocal parameters, vocal intensity, swallowing acoustic patterns, and scar-related restrictions. These results suggest that photobiomodulation may represent a valuable complementary intervention within rehabilitation programs targeting voice and swallowing dysfunction after thyroid surgery.

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Given the retrospective observational nature of this study, the findings should be interpreted as descriptive clinical outcomes rather than evidence of direct therapeutic efficacy. Future prospective controlled studies are required to determine the magnitude of the therapeutic effects observed, identify the specific contribution of photobiomodulation, and establish evidence-based treatment protocols for this population.

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Ethical Considerations

This study was conducted in accordance with the ethical principles established in the Declaration of Helsinki for research involving human participants and with applicable health research regulations. Due to its retrospective design, based on the review of medical records, no interventions beyond routine clinical practice were performed. Confidentiality was ensured through the anonymization of all personal and clinical data included in the analysis.

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Informed Consent

All patients enrolled in the rehabilitation program provided informed consent for the therapeutic procedures and for the academic and scientific use of their clinical information. Principles of confidentiality and data protection were strictly maintained throughout the study. During the document review process, participant identity was protected through coding and anonymization of all analyzed records.

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Funding

This study was self-funded by the author. No external funding was received from public, private, commercial, or non-profit organizations for the conduct of the study, data analysis, or manuscript preparation.

 

Conflict of Interest Statement

The author declares no financial, academic, professional, or personal conflicts of interest that could have influenced the interpretation of the results or the preparation of this manuscript.

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Artificial Intelligence Statement

The author used Microsoft 365 Copilot solely to support language refinement, text organization, and manuscript editing. Artificial intelligence was not used for study design, data generation, data analysis, interpretation of results, or scientific decision-making. The author takes full responsibility for the accuracy, integrity, and originality of the content presented in this manuscript.

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Author Contributions (CRediT)

Nidia Patricia Cedeño Ortiz: Conceptualization, Methodology, Investigation, Data Curation, Formal Analysis, Resources, Validation, Writing – Original Draft, Writing – Review & Editing, Supervision, and Project Administration.

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