Direct Vocal Fold Testosterone Injection for Treatment of Sulcus Vocalis: A Case Report

Abstract

This case report describes the use of targeted vocal fold testosterone injection as a novel, minimally invasive treatment for sulcus vocalis in a 28‐year‐old cisgender male with long‐standing voice difficulties unresponsive to conventional therapies. He underwent two intramuscular testosterone injections into the thyroarytenoid muscle. Post‐treatment, he demonstrated significant vocal improvements, including enhanced glottal competence, increased phonation time, and improved patient‐reported outcomes, suggesting that androgen receptor stimulation may promote vocal fold remodeling as a potential alternative to surgical intervention.

1. Introduction

Sulcus vocalis is an abnormality of the true vocal fold characterized by a depression of the epithelium along its free edge adherent to the underlying lamina propria or even extending into deeper layers. Its incidence ranges from 0.4% to 48%. While occasionally asymptomatic, symptoms may include hoarseness, breathiness, vocal strain, fatigue, instability, and even a higher‐pitched voice [1]. These are thought to occur secondary to inadequate apposition of the true vocal folds during phonation, causing disruption to mucosal wave propagation. The exact mechanism of action by which sulcus vocalis arises is debated, and several theories have been proposed, including phonotrauma and inflammation versus embryological and congenital irregular development.

Traditional management strategies for sulcus vocalis focus on addressing vocal fold apposition and optimizing mucosal wave propagation. Non‐procedural techniques to address this include voice therapy. Procedural techniques include clinic‐based vocal fold augmentation and operative Type‐1 thyroplasty or epithelial reconstruction, though many patients seek to avoid more invasive procedures.

We previously explored the role of targeted vocal fold testosterone injections for voice modulation in a select group of female‐to‐male transgender patients with durable response [2]. Testosterone is believed to act on androgen receptors in the larynx to elongate and thicken the vocal folds, which can then secondarily lead to downstream improvement in glottal closure and vocal projection with less breathiness [3]. It has also been shown in animal models to increase the bulk of the vocalis muscle and thicken the lamina propria and epithelium [4]. This avenue may provide a novel non‐surgical therapeutic option in select dysphonic patients and inspired our application in this case to treat sulcus vocalis.

Herein, we describe targeted vocal fold testosterone therapy for a young cisgender male patient with long‐standing dysphonia from sulcus vocalis who sought to avoid surgical intervention after inadequate response to voice therapy. Given his treatment goals and normal systemic testosterone levels, targeted androgen therapy was pursued as a tailored, minimally invasive approach to improve vocal function.

2. Case Report

UCSD Institutional Review Board (IRB) approved this study (IRB #801712). Under the following protocol, one patient underwent injection of testosterone cypionate (200 mg/mL) into the thyroarytenoid muscle of the vocal folds. Two injections of 25 mg testosterone cypionate were administered into the RIGHT vocal fold spaced 5 days apart. A third injection was then administered 19 weeks later. Point‐touch trans‐cricothyroid approach was used while directly visualizing the vocal fold with laryngoscopy during administration to confirm expansion of the target region (Figure 1). Twenty‐five milligrams (0.125 cc) of stock testosterone cypionate was drawn into a 1 cc syringe and diluted with preservative‐free saline to an injectable volume of 0.3 cc. Blood testosterone levels before and after the treatment period were checked. Acoustic measures and videostroboscopy were performed. Voice therapy was not performed concurrently. Laryngoscopy, Voice handicap index (VHI‐10) and Voice‐related quality of life (V‐RQOL) were obtained before treatment, 11 and 34 weeks after treatment.

FIGURE 1.

Side by side comparison of the true vocal folds at baseline, post‐injection #1, post‐injection #2, 11‐weeks post, and 34‐weeks post.

This patient is a 28‐year‐old male with long‐standing dysphonia that first began around age 12. He specifically had concerns pertaining to vocal strain, high pitch, notably with the absence of voice deepening with puberty and poor vocal projection. He trialed voice therapy with a speech‐language pathologist multiple times since puberty and injection laryngoplasty with standard hyaluronic‐acid‐based filler without meaningful improvement in his subjective voice quality. At 11 weeks after completion of two injections, the patient reported a subjective increase in volume, decreased breathiness, and reduced effort (see Audio S1). VHI‐10 was reduced from 32 to 14 while V‐RQOL went from 35 to 15 compared to baseline measurements. He underwent a 3rd injection at 19 weeks with follow‐up at 34 weeks. VHI‐10 and V‐RQOL further improved to 5 and 12, respectively, while acoustic changes demonstrated improved access to a lower pitch range, increased maximum phonation time, and normalization of the S/Z ratio (Table 1). Further, the patient exhibited anatomic changes that reflect his voice improvement with remarkable right vocal fold fullness and reduction of the sulcus vocalis sustained at 34 weeks after treatment (Figure 1).

TABLE 1.

Acoustic and quality measures before and after treatment.

	Baseline	11 weeks post	34 weeks post
F0 (Hz)	190	180	191
Range [min, max]	160, 410	137, 294	130, 313
MPT (s)	17	21	18
S/Z (normal 1.0–1.4)	0.78	1.25	1.125
VHI‐10	32	14	5
V‐RQOL	35	15	12

Abbreviations: F0, fundamental frequency; MPT, maximum phonation time; V‐RQOL, voice related quality of life; VHI‐10, voice handicap index 10.

3. Discussion

Current minimally‐invasive sulcus vocalis treatment options are limited. While voice therapy or hyaluronic acid injection can provide improvements for some, it may not be effective or long‐lasting. We demonstrate a novel, minimally‐invasive technique to improve voice outcomes using targeted testosterone injections. This technique has proven durable in voice masculinization in transgender men [2]. This patient was pleased with the durability of his voice improvements after 3 injections and gained an increase in confidence and QoL following treatment, which was not achieved with years of prior conservative approaches, most evident with his V‐RQOL going from poor (35) to excellent (15) following this novel treatment. Objectively, he achieved his desired access to a lower pitch range. With improved glottal competence, he achieved a longer maximum phonation time and a s/z ratio suggesting he had more normal laryngeal function (Table 1). Figure 1 shows improvement in the contour of the right true vocal fold after the series of injections and sustained at 34 weeks.

Androgen receptors have been described in the macula flava, a region shown to be a stem cell niche, and stimulation of this region with targeted testosterone may provide a uniquely well‐suited treatment for sulcus vocalis. Through stimulation of the macula flava, it is possible that one might be able to expand the lamina propria to fill in these defects with the true building blocks of the multi‐layered complex anatomy of the vocal fold. This hypothesis inspired this novel approach [5].

Targeted vocal fold testosterone therapy provides an ability to tailor treatments to each patient's needs. This patient achieved his desired outcome after 3 injections. Throughout treatment, the patient's testosterone levels stayed within normal limits without any adverse reactions.

4. Conclusion

Targeted, minimally invasive administration of testosterone directly into the vocal fold for treatment of sulcus vocalis achieved an expeditious and improved outcome for our young patient with chronic dysphonia. The short exposure to testosterone required with this approach potentially reduces its risk profile (i.e., cardiovascular effects, polycythemia, venous thromboembolic events) while providing the possibility of permanent voice quality change.

Conflicts of Interest

The authors declare no conflicts of interest.

Supporting information

Audio S1. A comparison of phonation at baseline and at 11 weeks post injection.

Voora R. S., Tenggara M. K., Schiedermayer B., and Vahabzadeh‐Hagh A. M., “Direct Vocal Fold Testosterone Injection for Treatment of Sulcus Vocalis: A Case Report,” The Laryngoscope 136, no. 2 (2026): 915–917, 10.1002/lary.70129.