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Background
Vocal cord paralysis is a voice disorder that occurs when one or both of the vocal cords (or vocal folds) do not open or close properly (NIDCD, 1999). Vocal cord paralysis is a common disorder, and symptoms can range from mild to life threatening. Someone who has vocal cord paralysis often has difficulty swallowing and coughing because food or liquids slip into the trachea and lungs. This happens because the paralyzed cord or cords remain open, leaving the airway passage and the lungs unprotected. Vocal cord paralysis may be caused by head trauma, a neurological insult such as a stroke, a neck injury, lung or thyroid cancer, a tumor pressing on a nerve, or a viral infection (NIDCD, 1999). In older people, vocal cord paralysis is a common problem affecting voice production. People with certain neurological conditions, such as multiple sclerosis or Parkinson's disease, or people who have had a stroke may experience vocal cord paralysis. In many cases, however, the cause is unknown. People who have vocal cord paralysis experience abnormal voice changes, changes in voice quality, and discomfort from vocal straining (NIDCD, 1999). For example, if only one vocal cord is damaged, the voice is usually hoarse or breathy. Changes in voice quality, such as loss of volume or pitch, may also be noticeable. Damage to both vocal cords, although rare, usually causes people to have difficulty breathing because the air passage to the trachea is blocked. Vocal cord paralysis is usually diagnosed by an otolaryngologist (NIDCD, 1999). Noting the symptoms the patient has experienced, the otolaryngologist will ask how and when the voice problems started in order to help determine their cause. Next, the otolaryngologist listens carefully to the patient's voice to identify breathiness or harshness. Then, using an endoscope, the otolaryngologist looks directly into the throat at the vocal cords. A speech-language pathologist may also use an acoustic spectrograph, an instrument that measures voice frequency and clarity, to study the patient's voice and document its strengths and weaknesses. There are several methods for treating vocal cord paralysis, among them surgery and voice therapy. In some cases, the voice returns without treatment during the first year after damage (NIDCD, 1999). For that reason, doctors often delay corrective surgery for at least a year to be sure the voice does not recover spontaneously. During this time, the suggested treatment is usually voice therapy, which may involve exercises to strengthen the vocal cords or improve breath control during speech. Sometimes, a speech-language pathologist must teach patients to talk in different ways. For instance, the therapist might suggest that the patient speak more slowly or consciously open the mouth wider when speaking. Surgery involves adding bulk to the paralyzed vocal cord or changing its position (NIDCD, 1999). To add bulk, an otolaryngologist injects a substance, commonly Teflon, into the paralyzed cord. Other substances currently used are collagen, silicone, and body fat. The added bulk reduces the space between the vocal cords so the non-paralyzed cord can make closer contact with the paralyzed cord and thus improve the voice. Sometimes an operation that permanently shifts a paralyzed cord closer to the center of the airway may improve the voice (NIDCD, 1999). Again, this operation allows the non-paralyzed cord to make better contact with the paralyzed cord. Adding bulk to the vocal cord or shifting its position can improve both voice and swallowing. After these operations, patients may also undergo voice therapy, which often helps to fine-tune the voice. Treating people who have two paralyzed vocal cords may involve performing a surgical procedure called a tracheotomy to help breathing (NIDCD, 1999). In a tracheotomy, an incision is made in the front of the patient's neck and a breathing tube (tracheotomy tube) is inserted through a hole, called a stoma, into the trachea. Rather than breathing through the nose and mouth, the patient now breathes through the tube. Following surgery, the patient may need therapy with a speech-language pathologist to learn how to care for the breathing tube properly and how to reuse the voice. Vocal cord nodules (singer's nodules) are small, hard, callus like growths that usually appear singly on the vocal cord (Merck, 1997). Nodules consist of condensations of hyaline connective tissue in the lamina propria at the junction of the anterior 1/3 and posterior 2/3 of the free edges of the true vocal cords. Vocal cord polyps are small, soft growths that usually appear singly on a vocal cord. They are most often caused by vocal abuse or long-term exposure to irritants, such as chemical fumes or cigarette smoke. Vocal cord nodules are caused by chronic voice abuse, such as yelling, shouting, or using an unnaturally low frequency (Merck, 1997). Chronic infections caused by allergies and inhalation of irritants, such as cigarette smoke, may also produce these lesions. Hoarseness and a breathy voice result. Carcinoma should be excluded by biopsy. Treatment for nodules that do not resolve with voice therapy involves surgical removal of the nodules at direct laryngoscopy and correction of the underlying voice abuse. Vocal nodules in children usually regress with voice therapy alone. If nothing is done to change vocal abuse habits, vocal cord nodules can last a lifetime, and may even recur after surgical removal. With proper voice training with a certified therapist, nodules can disappear with 6 to 10 voice therapy sessions over six to 12 weeks. With rest, some vocal cord polyps will go away on their own within a few weeks. Most, however, will require surgical removal. Speech therapists use a variety of techniques to restore a patient's ability to produce speech, including: - Patients are instructed in voice modification and relative voice rest. At its most extreme, relative voice rest involves an initial period of between 4 and 7 days using the voice no more than 15 minutes in each 24-hour period. It is normally undertaken with speech therapist supervision, once its advantages and disadvantages have been explored with the patient.
- Patients are instructed to minimizing voice use. This involves speaking no more than is absolutely necessary. Patients are taught to be succinct when speaking, to avoid any loud use of the voice, to keep phone calls brief and to avoid all non-speech voice use (throat clearing, coughing, “voiced” sneezing, crying, “voiced” laughing, and odd sound-effects).
- Patients are told to avoid any “voice abuse” practices identified by the speech therapist. Patients are instructed to avoid or modify internal (bodily and psychological) and external (environmental) voice-damaging environments as much as possible.
- Patients are instructed in how to engage in a short warm-up period of controlled, soft vocal exercises before using the voice. Patients may also be advised, where appropriate, to keep a supply of drinking water handy, and to massage under their chin if their mouth becomes dry.
- Patients are taught good voice production techniques. Patients may be instructed in optimal breathing patterns, to speak more slowly, to articulate clearly, to speak at a comfortable pitch and loudness level, to use pitch change rather than volume change for emphasis, to monitor their posture, to avoid monotone delivery, and to be aware of muscle tension.
- Patients may be advised to avoid speaking when they are ill or tired. Dehydration, fatigue and other general medical conditions have an effect on the mucosa covering the vocal cords, potentially altering lubrication and vocal efficiency.
Laryngitis due to viral infection usually resolves within one to three weeks. Laryngitis due to vocal abuse will generally go away on its own in a few days with voice rest. Functional voice disorders are characterized by the presence of vocal symptoms without anatomical laryngeal abnormality. Muscle tension dysphonia (MTD) is the most common disorder in this category. Sama et al (2001) stated that the laryngoscopy features commonly associated with FD are frequently prevalent in the non-dysphonic population and fail to distinguish patients with FD from normal subjects. In regards to a multi-dimensional protocol for assessing functional results of voice therapy, Dejonckere (2000) noted that results show that there is a large variation in the inter-individual and inter-dimensional results of the voice therapy (4 to 26 sessions) -- in the same patient, one dimension may be significantly improved while another one is significantly worsened. Furthermore, Roy (2003) stated that while voice therapy by an experienced speech-language pathologist remains an effective short-term treatment for FD in the majority of cases, but less is known regarding the long-term fate of such intervention. Thus, there is insufficient evidence regarding the effectiveness (especially long-term outcomes) of voice therapy for the treatment of muscle tension dysphonia. Voice therapy has been shown to be effective in rehabilitating persons treated for early glottic carcinoma. In a randomized, controlled trial, van Gogh and colleagues (2006) evaluated the effectiveness of voice therapy in patients who experienced voice problems after receiving treatments for early glottic cancer. Of 177 patients, 6 to 120 months after treatment for early glottic carcinoma, 70 patients (40 %) suffered from voice impairment based on a 5-item screening questionnaire. About 60% of those 70 patients were not interested in participating in the study. A total of 23 patients who were willing to participate were randomly assigned either to a voice therapy group (n = 12) or to a control group (n = 11). Multi-dimensional voice analyses (the self-reported Voice Handicap Index [VHI], acoustic and perceptual voice quality analysis, videolaryngostroboscopy, and the Voice Range Profile) were conducted twice: before and after voice therapy or with 3 months in between for the control group. Statistical analyses of the difference in scores (post-measurement minus pre-measurement) showed significant voice improvement after voice therapy on the total VHI score, percent jitter, and noise-to-harmonics ratio in the voice signal and on the perceptual rating of vocal fry. The authors concluded that voice therapy proved to be effective in patients who had voice problems after treatment for early glottic carcinoma. Improvement not only was noticed by the patients (VHI) but also was confirmed by objective voice parameters.
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