Functional Voice Disorders

Etiology

Prolonged and frequent vocal abuse is a significant risk for developing anatomical lesions of the larynx, such as nodules (also known as "singer's nodes") and hematomas and their sequelae. Functional voice disorders also result from vocal misuse or abuse as well as from behavioral health pathology. FVDs may be more easily recognized than other psychosomatic disorders because the clinician can visualize the laryngeal structure and function using a mirror or a flexible fiberoptic endoscopy, and therefore rule out organic disease. Both organic and functional voice disorders can affect multiple vocal parameters, including quality, pitch, and loudness, which can all be very problematic for patients.

Common causes of functional voice disorders include:

• Phonotrauma, which is caused by misuse, abuse, and overuse of the voice (yelling, screaming, excessive throat-clearing, and talking with increased loudness).
• Psychogenic aphonia and dysphonia, which are most commonly encountered in patients with underlying behavioral health issues, such as anxiety, depression, and conversion disorder. Associated symptoms may include blindness, paralysis, and other apparent neurological symptoms.[3]

Epidemiology

Voice disorders have an estimated prevalence of 20 million (0.98%) in the United States.[4][5] Vocal abuse is the most common etiology among adults and children. Among adults, teachers represent the most at-risk population.[6][7][8] A 2008 case-control study was conducted with 905 teachers in Spain in order to calculate the prevalence of voice disorders among educators and determine the associated risk factors.[7] All the teachers were given a questionnaire to fill out, followed by a complete head and neck examination and videolaryngostroboscopy. The study concluded that 57% of the teachers suffered from voice disorders, including vocal overstrain, which was the most prevalent (18%). Another study compared voice disorders between daycare center teachers and nursing staff, demonstrating a higher risk of voice disorders in teachers relative to the nursing staff.[8] The prevalence of voice disorders among teachers was 11.6%, but it was only 7.5% in the nonteacher population. Teachers also reported current and past voice disorder symptoms in higher numbers compared to nonteachers.

Pathophysiology

Thus far, no consensus on nomenclature for specific voice disorder pathology has been adopted in the literature.[9] That said, most voice pathologies appear to result from aberrant vocal use, particularly poor vocal technique (straining the voice, inadequate hydration, failing to rest when necessary), poor oral care and hygiene, repeated laryngeal infection, and excessive throat clearing.[10] Patients with chronic vocal problems frequently complain of a "lump in the throat," technically known as globus hystericus, which often indicates laryngopharyngeal reflux that may present even in the absence of noticeable heartburn.[11]

History and Physical

Taking a patient history to help diagnose voice disorders requires determining the frequency, duration, and severity of symptoms as well as any exacerbating or alleviating factors. Environmental factors are important to elicit as well, and these may include low humidity, alcohol use, cigarette smoke, and other airborne particulates like dust or chemical agents. Achieving an understanding of a patient's vocal habits and needs is likewise crucial to developing a working diagnosis and an individualized treatment plan. Including an evaluation of the patient's medical, surgical, psychological, traumatic, and pharmaceutical history can also be very informative in many cases.

The physical examination should include a standard head and neck evaluation as well as palpation of the larynx and trachea and videostroboscopic evaluation of phonation.

Evaluation

A systematic and thorough evaluation of the laryngeal structures and the patient's voice is vital in order to determine an effective strategy for vocal therapy exercises. Clinical evaluation for dysphonic patients is carried out in three steps:

1. History Taking
2. Physical Evaluation
3. Examination

The history-taking involves ascertaining medical, surgical, psychological, or traumatic information that leads to diagnosing and tailoring treatment to the patient. Part of this process is the vocal evaluation, which requires understanding the anomaly and how it affects activities of daily life, such as professional commitments or personal communication. Listening to the pitch, volume, and quality of the voice will help the clinician determine the type of problem. Detailed vocal evaluation leads to a better understanding of the underlying pathology and, therefore, a more appropriate intervention.[12]

Physical examination includes a complete ear, nose, and throat examination after assessing voice quality, loudness, and range. The purpose of the assessment is to focus on nasal airway patency, pharyngeal function, and velopharyngeal competency. Some patients may need pulmonary function studies if they exhibit insufficient expiratory force or volume that leads to an alteration of the voice, compromising the normal pattern of synchronized respiration and phonation. Hearing evaluation may also be important, as hearing loss can influence a patient's perception of their own voice and therefore alter its production.

Laryngoscopy is the most important step in the diagnosis of vocal dysfunction. There are multiple methods of visualizing the larynx, including mirror laryngoscopy, flexible fiberoptic laryngoscopy, distal chip laryngoscopy, digital transoral laryngoscopy, and stroboscopy. Stroboscopy provides the greatest amount of information when evaluating the mucosal wave of the vocal cords.[13][14]

Due to the heterogeneity of functional voice disorders, assessment should also be evaluated for psychogenic and muscle tension pathologies. Psychogenic voice disorders and muscle tension voice disorders are treated by speech-language pathologists (SLPs) who use symptomatic behavioral voice therapy along with counseling and, potentially, psychotherapy.[15]

The presentation of functional voice disorders can take many forms (dysphonia, stuttering, or prosodic abnormalities) and may mimic organic disorders, such that diagnosis can be difficult. A thorough examination, correct diagnosis, and proper treatment are critical. Functional or psychogenic disorders and behavioral movement disorders can be challenging to differentiate based solely on observable speech and voice disturbances; many behavioral and neurological conditions can mimic symptoms of organic voice conditions.[1]

Treatment / Management

The first step in FVD management is determining the correct diagnosis, and treatment may require multiple modalities depending on the cause, type, and severity of the disorder. Most problems can be managed simply by identifying the etiology and modifying patient behavior to avoid it.

As a general rule, there are three primary treatment strategies:

1. Medical Treatment
2. Surgical Treatment
3. Voice Therapy

Speech-language pathologists employ a holistic approach to treatment, striving to balance respiration, phonation, and resonance instead of directly addressing the symptoms of voice problems. Multiple rehabilitative strategies, such as auditory masking, the accent method, conversation training therapy (CTT), Lax Vox speech therapy, expiratory muscle strength training, phonation resistance training, chant speech, and confidential voice are used to manage FVDs. Multiple facilitative techniques are leveraged by SLPs to restore a normal voice, depending on the type of voice disorder, while also trying to determine the underlying causality.[16] Correct positioning, relaxation, hydration, vocal functioning exercises, counseling, patient education, and behavioral modification may all play roles in achieving optimal outcomes. 

In some cases, vocal fold nodules are successfully treated with voice therapy alone. However, many other types of lesions (laryngeal webs, polyps, contact ulcers, and papilloma) require surgical management. Identification of the cause of the dysfunction is the key to a successful treatment. Voice therapy is the standard of care for many of the nearly 140 million people in the United States who suffer from voice disorders; unfortunately, current therapies are not always effective for a number of reasons: incorrect diagnosis, patient noncompliance, and severity of the pathology being chief among them.

Differential Diagnosis

The following clinical entities should be considered potential diagnoses in patients with dysphonia:[17][18]

• Somatoform disorder
• Conversion disorder
• Abuse
• Anxiety disorder
• Depression
• Munchausen syndrome
• Malingering
• Allergic and environmental asthma
• Anaphylaxis
• Bilateral vocal fold paralysis
• Exercise-induced asthma
• Foreign body obstruction
• Laryngeal abnormalities (e.g., neoplasm, polyps, cyst)

Prognosis

Good prognostic indicators include acute onset of symptoms, absence of underlying organic pathology, ability to eliminate the trigger (particularly if it is a life stressor), male gender, young age, and good general health status. Poor prognostic indicators include personality disorders, poor perception of the patient's own wellbeing, associated motor symptoms, and psychogenic nonepileptic seizures.

To optimize outcomes, it is essential to arrive at the correct diagnosis through thorough evaluation and careful consideration. Unless the treatment is tailored to the underlying pathology, the results will not be satisfactory for either the patient or the clinician; voice therapy, for example, will not significantly help a patient with a glottic mass that requires surgical excision. A multidisciplinary approach, typically involving an otorhinolaryngologist or fellowship-trained laryngologist and an SLP, is likely to be most effective at alleviating symptoms and improving quality of life.[19]

Complications

The primary complications associated with FVD relate to the barriers to communication and social isolation that ineffective phonation may produce. When speaking is difficult or results in ineffective communication, frustration, low self-esteem, anxiety, and depression may result. In psychogenic FVD, the longer the FVD exists, the worse the underlying behavioral health problem may become, which can further exacerbate the FVD.[20]