Injection Laryngoplasty in Patients with Vocal Cord Paralysis After Thyroid Surgery

Vocal cord paralysis is one of the most distressing complications after thyroid surgery. It can lead to breathing problems if bilateral and hoarseness and aspiration if unilateral. Approaches after vocal cord paralysis include waiting in the hope of recovery, reinnervation surgery, laryngeal frame surgery and injection laryngoplasty. Among these options, injection laryngoplasty stands out due to its low cost, low morbidity rate and the ability to avoid open surgery.

Injection Laryngoplasty

Injection laryngoplasty can utilize short-term or long-term materials. It is reported that injections using short-term materials reduce the necessity for open surgery and yield favorable results regarding the final status of the vocal cords. This way, optimal synkinetic reinnervation can be achieved.

A study by Jang et al. [Jang JY et al, Eur Arch Otorhinolaryngol, online publication July 16, 2015] compared vocal findings of patients who underwent early and late injections. ArteSense (20% polymethylmethacrylate, 80% bovine collagen 3.5% solution), which shows relatively long-lasting effects, was injected into the patients. Those who received injections in the first 3 months post-thyroid surgery were termed the early injection group, while those injected after 3 months were termed the late injection group. In this study conducted in Seoul, there were 24 cases in the early group and 31 in the late group. The average injection duration in the early group was 39 days postoperatively, while in the late group, it was 334 days. In both groups, an average of 0.6 ml of material was injected. All injections were performed percutaneously under local anesthesia via thecricothyroid approach. Objective and subjective voice assessments were conducted before and 3 months after the injection.

In all parameters tested in the early group (maximum phonation time [MPT], jitter, shimmer, noise-harmonic ratio [NHR], GRBAS assessment, and voice handicap index [SHE] 30), statistically significant improvement was observed. In the late group, subjective parameters GRBAS and SHE 30, along with MPT showed significant improvement; however, improvements in jitter, shimmer, and NHR were limited.

When comparing the results of the early and late groups, it was observed that the values for jitter, shimmer, and breathiness were statistically different.

Vocal cord paralysis is a known complication of thyroid surgeries. The incidence of vocal cord paralysis after thyroid surgery ranges from 1% to 11%. It is also possible to encounter vocal cord paralysis at lower rates after other neck and chest surgeries. This condition occurs due to damage or trauma to the recurrent laryngeal nerve, which innervates the vocal cords. Vocal cord paralysis can lead to hoarseness, shortness of breath, vocal fatigue, aspiration (food and liquids entering the trachea), and difficulty swallowing. Injection laryngoplasty has gained popularity as a minimally invasive treatment option that provides significant improvements in voice quality and swallowing function.

The recurrent laryngeal nerve, responsible for the movement of the vocal cords, can be damaged during thyroid surgeries due to its anatomical proximity to the thyroid gland. Possible causes of vocal cord paralysis following thyroid surgeries include direct nerve injury, thermal damage from electrocautery, nerve traction or stretch, and pressure from hematoma or edema. Understanding the etiology of vocal cord paralysis is important for determining an appropriate treatment strategy.

Injection Laryngoplasty Procedure

During injection laryngoplasty, a biocompatible substance is injected into the paralyzed vocal cord. The material used strengthens the position of the vocal cord and enhances its vibratory capabilities. The procedure can be performed under local anesthesia or general anesthesia for patient comfort. The most commonly used injectable materials include hyaluronic acid, calcium hydroxylapatite, and autologous fat. Factors considered in selecting the material for injection include the duration of the paralysis, the longevity of the material in the body, the desired vocal cord position, and factors related to the patient.

Positive Effects of Injection Laryngoplasty

Improvement in Voice Quality: Injection laryngoplasty helps to increase voice quality by restoring the tension and position of the vocal cord. Patients often report relaxation in breathing, increased voice intensity and sustainability, and improvement in pitch control. These positive effects contribute to better voice use, intelligibility, and overall communication skills.

Improvement in Swallowing Function: Vocal cord paralysis can negatively affect quality of life by leading to difficulty swallowing and aspiration. Injection laryngoplasty helps restore glottic closure, reducing the risk of aspiration and facilitating normal swallowing function. Patients frequently report a decrease in coughing during meals, improved food intake, and normalization of eating and drinking skills.

Psychological Benefits: Difficulties with voice and swallowing caused by vocal cord paralysis can significantly impact an individual's emotional state and social interactions. Successful results achieved with injection laryngoplasty have been shown to alleviate anxiety, depression, and social isolation, resulting in rapid positive changes in interpersonal communication.

Patient Satisfaction and Functional Outcomes: Numerous studies have reported high rates of patient satisfaction following injection laryngoplasty. Patients often express significant improvements in voice quality, increased ease of communication, and a reduction in voice-related limitations in daily activities. Functional outcomes such as increased vocal range and endurance also contribute to overall patient satisfaction and the ability to return to preoperative vocal function levels.

In addition to the early benefits of injection laryngoplasty, which aims to fill the space between the vocal cords, it is known to positively affect the healing of the microscopic nerves involved, increase the tension of the muscles that make up the vocal cords and thus have a positive effect on the patient's quality of life.