Overview

The voice has a significant role in oral communication and is important as an expression of our health, emotion, gender, and age. It forms part of one’s individual identity and personality. In children, this organ is developing in physical structure along with the rest of the speech mechanism. At the same time, the neurocognitive, behavioral growth and maturation of the child occurs. The larynx has highly developed neural connections, so it is not surprising that the voice is sensitive to neural input and control. This includes input derived from emotional centers in the brain. The larynx has been labeled “the valve of emotion” [1]. It is highly responsive to emotional state and stress at all ages.

Studies of voice disorders in children have suggested that the majority of dysphonias are due to vocal overuse and misuse. The common manifestation of these is vocal nodules [2, 3]. This disorder may be viewed as “functional” because underlying dysfunction is the cause of tissue trauma that creates the nodules. Dysphonias also arise in children with no identifiable structural or physical pathologic changes to the vocal folds. In this chapter, we define a functional voice disorder as a voice disturbance that occurs in the absence of structural or neurologic laryngeal pathology. In adult voice clinics, these disorders may account for up to 40% of cases [4]. In pediatric patients, functional voice disorders occur less frequently. A series of 427 children referred to a tertiary pediatric voice disorders clinic reported that 7% of cases had a functional etiology [2]. In another recent series, only 4% of 136 children with voice disorder were labeled as functional or neurogenic [3]. In this review, the major manifestations of functional voice disorders in children are discussed. These include muscle tension dysphonia (MTD) and aphonia and puberphonia or mutational falsetto.

MTD has gained common usage as a diagnostic label for functional dysphonia thought to be due to dysregulated or imbalanced laryngeal and paralaryngeal activity [4]. A variety of glottic and supraglottic patterns of laryngeal closure have been described [5, 6]. Their diagnostic utility has come into question because these closure patterns are not unique to MTD, and do not reliably distinguish them from normal speakers, or other voice disorders [7].

The predominant auditory-perceptual feature of MTD is a strained voice quality, disordered pitch (usually pitch elevation), and reduced loudness. These features may lead to diagnostic confusion with spasmodic dysphonia [8]. Periods of aphonia may also be present. These may be intermittent or persistent. Another feature that may be present in MTD is that periods of normal voice may occur in between the dysphonic intervals. On physical examination, exquisite tenderness to palpation in the thyrohyoid space and narrowing of the thyrohyoid space are frequently identified.

There have been a variety of explanations offered for MTD, including technical misuse due to excessive vocal demands, altered adaptation following upper respiratory infection, increased laryngeal tone due to local irritative conditions such as gastroesophageal reflux, compensation for underlying glottic insufficiency, and psychological or personality traits that express excess laryngeal tension [4].

The psychological traits of adult MTD patients have been studied in some depth. In the most extensive studies by Roy et al., personality profiles were obtained in large groups of patients with MTD, SD, vocal fold paralysis, vocal nodules, and normal controls [9–11]. MTD subjects scored high on dimensions of introversion, anxiety, depression, and emotionalism. Vocal nodule patients scored similarly on anxiety and emotionalism scales; however, instead of introversion (quiet, unsociable, passive, careful), they demonstrated extroversion (dominant, sociable, active). MTD is described as muscularly inhibited voice production in the context of individuals with personality traits of introversion and neuroticism. In response to certain environmental cues or triggers, elevated laryngeal tension creates incomplete or disordered vocal production in a structurally and neurologically intact larynx [4]. The psychological traits of children with functional voice disorders have not been similarly studied.

Despite the above issues that involve the cause of MTD, successful treatment of MTD through behavioral management has been demonstrated in a number of reports [5, 12, 13]. This focuses on the proximate causes of the dysphonia and rebalancing the laryngeal mechanism to produce normal voice. The most effective technique in our experience is manual circumlaryngeal massage and laryngeal reposturing to lower the larynx [5, 12, 14]. This can yield remarkable improvement, with two-thirds of patients achieving normal voice return from a single treatment session. Successful treatment with behavioral therapy in nearly all patients is expected. Recalcitrant or resistant cases may respond after several sessions of therapy. In a case series of pediatric patients treated for “muscle tension dysphonia” recently published, seven of the eight children had vocal nodules with supraglottic hyperfunction seen on laryngoscopy [15]. One patient had aphonia without lesions. All patients improved with voice therapy. As an adjunct treatment for severe MTD, Dworkin et al. reported the use of topical lidocaine spray to the larynx followed by voice therapy [16]. We have found this to be effective in selected pediatric patients. We also used lidocaine block of the recurrent laryngeal nerve to facilitate phonation in a case of recalcitrant functional aphonia in an adolescent [17]. Sensory or motor perturbation of the laryngeal mechanism may relax excessive laryngeal muscle tension and help the patient gain confidence that they have the capacity to produce normal voice.

The voice of adolescence is characterized by pitch instability. This is true for both males and females but more so in males. In a study of children aged 10–17 without and with vocal complaints, acoustic measures of pitch stability on sustained vowel phonation were not found to statistically distinguish the normal from several disordered voice groups [18]. However, the group diagnosed with puberphonia had the most variability of frequency and amplitude. Puberphonia is a voice disorder of adolescent males. It has also been labeled mutational falsetto, adolescent male transitional dysphonia, incomplete mutation, and persistent falsetto. It can be seen in early adolescence or can persist into late adolescence or adulthood. The voice does not successfully accomplish pitch change during puberty, between 12 and 14 years of age. The voice has been described as weak, thin, breathy, and hoarse in quality [6, 12]. A recent study in a large patient group with puberphonia measured the average speaking F₀ at 241 Hz [19]. It is frequently accompanied by downward pitch breaks into chest register. Coughing sound is also in chest register [6]. The voice of puberphonia may be described as a habituated use of falsetto register accompanied by pitch breaks rather than maintenance of the preadolescent voice. This pattern is commonly seen in MTD, so in our view, puberphonia is considered a variation of MTD seen in adolescent males. The larynx is generally positioned high in the neck, and excessive thyrohyoid tenderness and a narrow thyrohyoid space are found on palpation. Laryngeal lowering maneuvers, including head dorsiflexion, depression of the mandible, hyoid pushback, and laryngeal pulldown, are combined with vocalization [12]. This may create a surprised patient and his mother when his normal deep chest register voice is produced for the first time.

The first-line treatment of puberphonia is behavioral voice therapy [6, 12]. The same techniques of laryngeal lowering and reposturing combined with vocal cues that are used for MTD apply to the treatment of puberphonia. Ideally, this is conducted by a speech pathologist experienced in this approach. These techniques facilitate lowering of the laryngeal to engage the chest register and thyroarytenoid muscle activity to lower the pitch of the voice to the patient’s normal male range. A recent study of 45 patients with puberphonia included 16 patients aged 11–15 years and 29 patients aged 16–40 years. All patients were treated successfully with behavioral therapy techniques with maintenance of improvement documented at 6 months [19]. A recent study from our institution documented the successful resolution of puberphonic voice in 12 consecutive patients, with the voice outcome documented by perceptual listener ratings and acoustic measures [20].

For recalcitrant cases of puberphonia, novel approaches have been tried including botulinum toxin injection to relax cricothyroid muscle function [21], pitch-lowering phonosurgical procedures including type III thyroplasty [22], hyoid detachment/laryngeal lowering laryngoplasty [23], and injection medialization laryngoplasty [24, 25]. The reasons for failure of behavioral voice therapy in these cases are unknown. These circumstances should be unusual and are not considered in most cases. The remarkable success of manual reposturing techniques, now documented in several reports, point to this as the first-line approach to treatment of puberphonia [19, 20].

The negative impact of functional voice disorders in children can be substantial. It may affect their ability to form and maintain social relationships with peers and adults, to communicate in school and home environments, and to enter the world of work. Although they are labeled “functional” because no underlying disease process involving the organs of voice and speech is found, the significance of the problem should not be minimized. The organs of voice and speech are neurally controlled, and this neural control is profoundly influenced by central nervous system controls involving emotional state, personality, and stress response as described above. The impact of voice disorders in children on their social, emotional, and physical function is just beginning to be investigated [26]. Voice-related quality of life instruments that are validated and age-appropriate for children and adolescents are greatly needed. Providers caring for these children need to aggressively advocate for needed services, such as voice and speech therapy provided by experienced clinicians. Documentation by video and audio recordings, patient-based quality of life measures, and references from peer-reviewed publications may all be needed in making appeals to insurance providers to cover speech therapy services for these patients.

Role of the Speech-Language Pathologist

The speech-language pathologist (SLP) has the role of restoring the voice back to the patient’s previous normal/baseline (in the case of MTD) or producing and maintaining voice quality and pitch that is expected of patient’s age and gender (in the case of puberphonia). In addition to maneuvers/techniques used to interfere with abnormal muscle contraction patterns to stimulate a normal voice, it is our experience that skilled clinicians apply an art of therapy that is more challenging to quantify and easier to describe. It involves quickly establishing rapport/trust and being able to encourage, coach, and guide the individual to normal voice production. The clinician must also have the knowledge and expectation of the patient’s potential for the functional voice disorder to resolve quickly with proper application of the appropriate therapy techniques to coach and guide the patient to normal voicing. This is certainly the case when the patient has failed numerous medical and behavioral treatment approaches. The child and parent may both feel skeptical that his/her dysphonia may be effectively treated with voice therapy, particularly in a single session.

Following auditory-perceptual evaluation, acoustic and/or aerodynamic recording, laryngeal imaging (if not already performed by the otolaryngologist or available for review), and an anterior neck examination with palpation of the perilaryngeal region to access for as described by Aronson [12], the patient undergoes stimulability testing/trial therapy. In our experience, the vast majority of patients with severe MTD/aphonia and puberphonia are restored to normal in a single treatment session as have been reported in functional dysphonia studies [4, 5, 20]. Various therapy techniques may be used in an attempt to stimulate normal voice production. We favor laryngeal reposturing maneuvers as a primary treatment approach. Laryngeal reposturing is combined with sustained voicing. Transient moments of improved or normal voicing is immediately identified and reinforced. After sustained vowels or voiced consonants are produced consistently accurately the improvement in voicing is extended across the speech hierarchy as manual techniques are faded. Negative practice is used to increase awareness of voice production patterns, increase control, and increase likelihood of generalization and maintenance [20]. In negative practice, the patient is encouraged to return and/or simulate the disordered voice during rote and other speech tasks and then quickly alternate back to the normal voicing patterns based on the clinician’s verbal cues to “switch.” Negative practice in the presence of a parent or other family member and having the patient converse with parent or family member after normal voicing has returned as a generalization activity can be very powerful for the patient’s self-efficacy and setting the bar and expectation of the patient maintaining the normal voice and being able to improve his/her voice immediately if disordered voicing patterns return. The patient quickly developing the self-efficacy and ownership of the voice production during the therapy session is key for sustained improvement. To reinforce patient self-efficacy and ownership while simultaneously following the patient’s progress, the SLP may ask the patient to telephone him or her later that day or the next day as well as in 1–2 weeks to report progress/maintenance without necessarily scheduling an additional therapy session with reinforcing that the patient is in control and he/she has the tools to improve his/her voice by “switching” or course correcting as he/she performed during negative practice if fluctuations occur.

The patient may have apprehension regarding possible questions by family, friends, and schoolmates following sudden change/normalizing in voice after their voice disturbance had been severe and chronic. In these situations where patients may have difficulties rationalizing how they are going to explain to others what happened to their voice, the patient is encouraged to explain that they saw a speech pathologist who specializes in voice and that the clinician performed laryngeal manipulation like a chiropractor or physical therapist that allowed for normal voicing. An individual with puberphonia may have some difficulty accepting “the new voice.” The individual may need to be reassured that it is a “normal” voice that is compatible with his age, gender, and laryngeal size. Although the voice may be much clearer, smoother, stronger, and lower in pitch, the patient may be concerned about drawing more attention to his voice and consequently may be tempted to revert to the disordered voice production pattern. Playing pre- and posttreatment audio recordings for these individuals may be beneficial for the patient to agree that the new voice is more age- and gender-appropriate and will garner less attention than the disordered voice as well as reassuring the patient that after a few days of use, the voice will feel and sound more natural and comfortable. Positive feedback from parents, family members, and friends is also very beneficial in reducing apprehension and increasing comfort and confidence in the new, normal voice.

Role of the Otolaryngologist

By the time children present to the pediatric otolaryngologist with a suspected functional voice disorder, they have often had the problem for many months. They may have missed a lot of school, had many doctor visits, and had an inordinate number of frustrating and unproductive speech therapy sessions. The frustration level of the family is high. The ideal setting to see these children is in a multidisciplinary voice clinic. However, the problem is so uncommon that these patients often present to physician or physician-extender clinics at a time when the speech pathologist is not present or readily available.

It is important for the pediatric otolaryngologist to identify a functional voice disorder and initiate a referral for voice therapy promptly. Since a fast resolution of the problem is possible with effective therapy, it is important to get the patient seen quickly. The pediatric otolaryngologist’s role involves accurately identifying the problem with a medical diagnosis (muscle tension dysphonia ICD-10 code R49.0, puberphonia or mutational falsetto R49.8), explaining it to the patient and family in a way that does not assign blame or guilt, and explaining the necessity of voice therapy. This will usually require an explanation of the necessity of referral to a particular speech-language pathologist who is experienced in functional voice disorder treatment. General pediatric speech-language pathologists usually do not have experience with this patient population. Since children with functional voice disorders are usually older pre-teens or adolescents, we refer them to speech pathologists at adult voice disorders clinics, although they could also be referred to a speech pathologist who specializes in pediatric voice. Since the child may have already had prior speech therapy with unsuccessful outcomes, the pediatric otolaryngologist must be knowledgeable in why therapy with an experienced clinician is likely to be successful. They should provide encouragement, hope, and optimism for the patient and family to resolve the voice problem. Communication with the primary care provider and school may also be necessary to explain the uncommon nature of the problem and the recommended treatment.