Mutational dysphonia, also known as mutational falsetto or functional falsetto, is a condition in which an individual continuously produces a pre-adolescent voice even after reaching post-adolescence [1]. Diagnosing mutational dysphonia is crucial, as it often accompanies psychological issues. This condition negatively impacts the patient’s personal and professional life [2]. However, once diagnosed, it can usually be treated quite effectively with a few sessions of voice therapy, resulting in high patient satisfaction.

To correctly diagnose mutational dysphonia, it is necessary for the physician to take a thorough social and medical history of the patient as well as to perform an analysis of the patient’s voice. The characteristics of mutational dysphonia include a high-pitched, monotonous, and breathy voice [3], hence the term “falsetto.”

Nonetheless, the authors experienced a case in which the patient’s voice quality was difficult to be diagnosed instantly as mutational falsetto. Rather, the patient presented a voice closer to that of an adolescent who has not gone through puberty just yet, resembling that of a typical female or a pre-adolescent male. This case highlights the importance of thorough differential diagnosis and appropriate treatment, even for patients who do not display typical characteristics of mutational dysphonia. Therefore, we report our treatment experience along with a literature review, with the hope of highlighting the importance of the correct diagnosis of mutational dysphonia, as well as effective treatments that can improve patients’ quality of life.

A 20-year-old male presented to the clinic with a high-pitched voice, without any physical abnormalities or medical conditions. At his first visit, the patient had a typical female or preadolescent male voice without breathiness or hoarseness. He stated that he grew up in a somewhat oppressive environment with a strict father. The patient’s larynx would elevate during phonation, and the tone would get lower when the thyroid cartilage was digitally manipulated post-inferiorly. Stroboscopic examination revealed severe stretching of the bilateral thyroarytenoid muscles (Fig. 1). No evidence of vocal cord paralysis or laryngeal mucosal lesions was found. A computed tomography scan of the neck demonstrated that the patient had a normal anatomical structure of the voice box, thus ruling out the possibility of anatomical causes of the patient’s voice disorder.

Although presented with a rather stable and clear voice (Table 1 and Fig. 2), the patient continuously having had a pre-adolescent voice after puberty suggested the possibility of mutational dysphonia, and we proceeded with voice therapy. The patient had 5 sessions of voice therapy over the course of 8 weeks. Voice therapy started out with evaluating the patients’ psychological status due to one’s current voice, and a thorough explanation on the necessity of voice therapy. After such evaluation, the patient was taught to digitally manipulate one’s thyroid cartilage posteriorly, which shortens the length of the vocal cord and thus lowering one’s tone, also known as the finger method. Another method mainly used was the humming exercise. Humming exercise is when the patient gradually lowers one’s voice through humming, and once a certain pitch is obtained, the patient then starts to speak in vowels with the same pitch. Other methods included voice focus technique and abdominal respiration, and each session of voice therapy was recorded for feedback. The patient was also encouraged to use such obtained voice in his everyday life. The effectiveness of voice therapy was evaluated using voice speech tests pre- and post-voice therapy, which included perceptual evaluation (using the GRBAS score), acoustic analysis, phonatory aerodynamic system, voice handicap index (VHI), reflux symptom index, and voice discomfort scale.

As a result, the patient’s fundamental frequency dropped from 205 Hz to 107 Hz, and the perceptual evaluation score improved from 4 (G1R0B1A1S1) to 0 (G0R0B0A0S0) (Table 1). Stroboscopic findings also showed a loss of stretching of the thyroarytenoid muscles, which was present initially (Figs. 3 and 4). These results show that the patient achieved a proper voice tone for his age, and perceived voice quality improved through voice therapy. After the completion of voice therapy, the patient was very satisfied with his new voice. Although his pitch was initially unstable during everyday conversations (Figs. 5 and 6), he gradually adapted to his new voice and continued with outpatient follow-up visits.

Mutational dysphonia is a condition in which one continues to have a high-pitched, pre-adolescent voice even after puberty. Many possibilities have been suggested as the cause of mutational dysphonia, most of which focus on psychological issues such as difficulty accepting one’s new male voice, male identity problems, or social immaturity [4]. Although the condition is known to be mostly caused by psychological factors, the condition itself can also cause further psychological and emotional distress to the patient, thus highlighting the importance of treatment [5]. Likewise, the patient in this case also confessed of his somewhat introverted and passive personality, along with an oppressed childhood with a strict father. Therefore, we carefully discussed the need for treatment and thoroughly explained the prognosis, along with emotional support and empathy.

Not all mutational dysphonia patients present with a “falsetto” voice, and there have been efforts to classify mutational dysphonia into different categories according to the characteristics of the voice—such as one with diplophonia and a falsetto voice, one without diplophonia but with a falsetto voice, one with diplophonia and a non-falsetto voice, and one without diplophonia and a non-falsetto voice [6]. The study also showed that different voice characteristics would respond to treatments differently, suggesting the importance of voice analysis and the possibility of different treatment options for mutational dysphonia according to voice characteristics. In the case of our patient, there was no evidence of diplophonia or a falsetto voice, and the voice analysis did not show any abnormalities; subjectively, the patient’s voice sounded close to normal. This made the initial diagnosis challenging. However, an indirect diagnosis was made based on the patient’s larynx elevating significantly even during comfortable phonation and the stroboscopy revealing excessive stretching of the vocalis muscles.

The treatment of choice for patients with mutational dysphonia, without physiological or neurological condition, is behavioral management, including voice therapy [4]. However, there are patients who do not respond to voice therapy, especially those who have been suffering from the condition for a longer period of time. For those who do not respond to voice therapy, botulinum toxin injection could also be an alternative treatment option before considering permanent anatomical changes via surgery [7]. Type 3 thyroplasty has also been shown to be successful [8]—a procedure in which a part of the thyroid cartilage is relaxed, causing the vocal cords to be shorter, thus decreasing fundamental frequency. However, surgical approach brings other factors to consider, such as surgical complications, recovery time, psychological burden on the patient, and the possibility of unsatisfactory results despite invasive treatment [9]. In this case, the patient achieved excellent treatment results with voice therapy alone. This success is attributed to the patient’s active participation in the treatment. Although the patient sought treatment for his high-pitched voice, he did not have difficulty with phonation and had a pleasant-sounding voice. In such cases, patients might not feel the necessity for treatment, which could diminish the effectiveness of voice therapy. If a patient is accurately diagnosed but the effectiveness of voice therapy is insufficient, it might be necessary to consult with a psychiatrist to determine if the patient is being psychologically avoidant to his or her current situation before considering invasive treatments.

Although the patient’s fundamental frequency after voice therapy has decreased dramatically, objective measures of his voice quality have worsened, which is evident with increased jitter, shimmer, and noise-to-harmonic ratio. This could be due to the patient not being completely adapted to his new voice, thus producing a poorer quality voice. There have been previous case reports where voice therapy successfully lowered the fundamental frequency yet worsened voice quality [5]. Hammarberg [10] explains that patients receiving voice therapy are similar to those going through puberty, needing time to adjust to their new voice. The VHI also increased from a score of 30 to 41 post-therapy, suggesting that the patient feels more restricted functionally, physically, and emotionally due to his voice. It has been suggested that most mutational dysphonia patients who first go through voice therapy receive negative feedback from their surroundings due to the unfamiliarity of their new voice. The solution to this problem is minimizing such unfamiliarity with continuous exposure of the new voice to their surroundings [5].

The authors had a valuable experience treating a patient with mutational dysphonia that closely resembled a typical female voice, reinforcing the importance of accurate diagnosis and comprehensive treatment. Although the VHI score increased after treatment, the patient subjectively expressed satisfaction with the changed voice, and his mutational dysphonia has been successfully treated via voice therapy. It is important for a physician to remember that mutational dysphonia voice characteristics cannot be generalized, and thus thorough history taking and voice analysis of the patient are necessary for both correct diagnosis and corresponding treatment.