Aphonia is defined as the inability to produce voiced sound. A primary cause of aphonia is bilateral disruption of the recurrent laryngeal nerve, which supplies nearly all the muscles in the larynx. Damage to the nerve may be the result of surgery (e.g., thyroidectomy) or a tumor.

Aphonia means "no sound". In other words, a person with this disorder has lost his/her voice.

Muteness or mutism () is an inability to speak, often caused by a speech disorder, hearing loss, or surgery. Someone who is mute may be so due to the unwillingness to speak in certain social situations.

Injuries are often the cause of aphonia . Minor injuries can affect the second and third dorsal area in such a manner that the lymph patches concerned with coordination become either atrophic or relatively nonfunctioning. Tracheotomy can also cause aphonia.

Any injury or condition that prevents the vocal cords, the paired bands of muscle tissue positioned over the trachea, from coming together and vibrating will have the potential to make a person unable to speak. When a person prepares to speak, the vocal folds come together over the trachea and vibrate due to the airflow from the lungs. This mechanism produces the sound of the voice. If the vocal folds cannot meet together to vibrate, sound will not be produced. Aphonia can also be caused by and is often accompanied by fear.

Those who are physically mute may have problems with the parts of the human body required for human speech (the esophagus, vocal cords, lungs, mouth, or tongue, etc.).

Trauma or injury to Broca's area, located in the left inferior frontal cortex of the brain, can cause muteness.

In 2006, the U.S. Department of Education indicated that more than 1.4 million students were served in the public schools' special education programs under the speech or language impairment category of IDEA 2004. This estimate does not include children who have speech/language problems secondary to other conditions such as deafness; this means that if all cases of speech or language impairments were included in the estimates, this category of impairment would be the largest. Another source has estimated that communication disorders—a larger category, which also includes hearing disorders—affect one of every 10 people in the United States.

ASHA has cited that 24.1% of children in school in the fall of 2003 received services for speech or language disorders—this amounts to a total of 1,460,583 children between 3 –21 years of age. Again, this estimate does not include children who have speech/language problems secondary to other conditions. Additional ASHA prevalence figures have suggested the following:

- Stuttering affects approximately 4% to 5% of children between the ages of 2 and 4.

- ASHA has indicated that in 2006:

- Almost 69% of SLPs served individuals with fluency problems.

- Almost 29% of SLPs served individuals with voice or resonance disorders.

- Approximately 61% of speech-language pathologists in schools indicated that they served individuals with SLI

- Almost 91% of SLPs in schools indicated that they servedindividuals with phonological/articulation disorder

- Estimates for language difficulty in preschool children range from 2% to 19%.

- Specific Language Impairment (SLI) is extremely common in children, and affects about 7% of the childhood population.

Speech and language impairment are basic categories that might be drawn in issues of communication involve hearing, speech, language, and fluency.

A speech impairment is characterized by difficulty in articulation of words. Examples include stuttering or problems producing particular sounds. Articulation refers to the sounds, syllables, and phonology produced by the individual. Voice, however, may refer to the characteristics of the sounds produced—specifically, the pitch, quality, and intensity of the sound. Often, fluency will also be considered a category under speech, encompassing the characteristics of rhythm, rate, and emphasis of the sound produced

A language impairment is a specific impairment in understanding and sharing thoughts and ideas, i.e. a disorder that involves the processing of linguistic information. Problems that may be experienced can involve the form of language, including grammar, morphology, syntax; and the functional aspects of language, including semantics and pragmatics

An individual can have one or both types of impairment. These impairments/disorders are identified by a speech and language pathologist.

Medical often works in conjunction with behavioral approaches. A pulmonary or ENT (otolaryngologist) specialist will screen for and address any potential underlying pathology that may be associated with VCD. Managing GERD has also been found to relieve laryngospasm, a spasm of the vocal cords that makes breathing and speaking difficult.

Non-invasive positive pressure ventilation can be used if a patient's vocal cords adduct (close) during exhalation. Mild sedatives have also been employed to reduce anxiety as well as reduce acute symptoms of VCD. Benzodiazepines are an example of one such treatment, though they have been linked to a risk of suppression of the respiratory drive. While Ketamine, a dissociative anesthetic, does not suppress respiratory drive, it has been thought to be associated with laryngospasms.

For more severe VCD cases, physicians may inject botulinum toxin into the vocal (thyroarytenoid) muscles to weaken or decrease muscle tension. Nebulized Lignocaine can also been used in acute cases and helium-oxygen inhalation given by face mask has been used in cases of respiratory distress.

Psychological interventions including psychotherapy, cognitive behavioural therapy (CBT), Biofeedback, and teaching self-hypnosis are also suggested to treat VCD. Intervention is generally targeted at making the client aware of stressors that may trigger VCD symptoms, to implement strategies to reduce stress and anxiety, and to teach techniques for coping with their symptoms.

CBT can focus on bringing awareness to negative thought patterns and help reframe them by focusing on problem solving strategies. Psychologists may also use relaxation to reduce distress when a patient is experiencing symptoms. Biofeedback can be a helpful addition to psychotherapy. The aim of Biofeedback is to educate the client on what happens to the vocal cords during breathing and to help them learn to control their symptoms.

Choosing an intervention strategy needs to be assessed by a multidisciplinary team and individualized therapy planned carefully, keeping the characteristics of each patient in mind.

The treatment for post-polio syndrome is generally palliative and consists of rest, analgesia (pain relief) and utilisation of mechanisms to make life easier such as powered wheelchairs. There are no reversive therapies. Fatigue is usually the most disabling symptom; energy conservation can significantly reduce fatigue episodes. Such conservation can be achieved with lifestyle changes, reducing workload and daytime sleeping. Weight loss is also recommended if patients are obese. In some cases, the use of lower limb orthotics can reduce energy usage.

Medications for fatigue, such as amantadine and pyridostigmine, have not been found to be effective in the management of PPS. Muscle strength and endurance training are more important in managing the symptoms of PPS than the ability to perform long aerobic activity. Management should focus on treatments such as hydrotherapy and developing other routines that encourage strength but do not affect fatigue levels. The recent trend is towards use of intravenous immunoglobulin (IVIG) which has yielded promising, albeit modest results, but there is insufficient evidence to recommend it as a treatment.

PPS increases the stress on the musculoskeletal system due to increasing muscular atrophy. A recent study showed that in a review of 539 PPS patients, 80 percent reported pain in muscles and joints and 87 percent had fatigue. Joint instability can cause significant pain in individuals with PPS and should be adequately treated with painkillers. Supervised activity programs and decreasing mechanical stress with braces and adaptive equipment are recommended.

Because PPS can fatigue facial muscles, as well as cause dysphagia (difficulty swallowing), dysarthria (difficulty speaking) or aphonia (inability to produce speech), persons with PPS may become malnourished due to difficulty eating. Compensatory routines can help relieve these symptoms such as eating smaller portions at a time and sitting down whilst eating. PPS with respiratory involvement requires special management such as breathing exercises, chest percussion with a stethoscope on regular occasions for observation of the disease and management of secretions. Failure to properly assess PPS with respiratory involvement can increase the risk of missing aspiration pneumonia (an infection of the lower respiratory tract) in an individual. Severe cases may require permanent ventilation or tracheostomy. Sleep apnoea may also occur. Other management strategies that may lead to improvement include smoking cessation, treatment of other respiratory diseases and vaccination against respiratory infections such as influenza.

There are a number of different treatments that are available to treat and manage conversion syndrome. Treatments for conversion syndrome include hypnosis, psychotherapy, physical therapy, stress management, and transcranial magnetic stimulation. Treatment plans will consider duration and presentation of symptoms and may include one or multiple of the above treatments. This may include the following:

1. Explanation. This must be clear and coherent as attributing physical symptoms to a psychological cause is not accepted by many educated people in western cultures. It must emphasize the genuineness of the condition, that it is common, potentially reversible and does not mean that the sufferer is psychotic. Taking a neutral-cause-based stance by describing the symptoms as functional may be helpful, but further studies are required. Ideally, the patient should be followed up neurologically for a while to ensure that the diagnosis has been understood.

2. Physiotherapy where appropriate;

3. Occupational Therapy to maintain autonomy in activities of daily living;

4. Treatment of comorbid depression or anxiety if present.

There is little evidence-based treatment of conversion disorder. Other treatments such as cognitive behavioral therapy, hypnosis, EMDR, and psychodynamic psychotherapy, EEG brain biofeedback need further trials. Psychoanalytic treatment may possibly be helpful. However, most studies assessing the efficacy of these treatments are of poor quality and larger, better controlled studies are urgently needed. Cognitive Behavioural Therapy is the most common treatment, however boasts a mere 13% improvement rate.

Empirical studies have found that the prognosis for conversion disorder varies widely, with some cases resolving in weeks, and others enduring for years or decades. There is also evidence that there is no cure for Conversion Disorder, and that although patients may go into remission, they can relapse at any point. Furthermore, many patients who are 'cured' continue to have some degree of symptoms indefinitely.

Post-polio syndrome occurs in approximately 25 to 50 percent of people who survive a poliomyelitis infection. On average, it occurs 30–35 years afterwards; however, delays of between 8–71 years have been recorded. The disease occurs sooner in persons with more severe initial infection. Other factors that increase the risk of postpolio syndrome include increasing length of time since acute poliovirus infection, presence of permanent residual impairment after recovery from the acute illness, and being female.

Post-polio syndrome is documented to occur in cases of nonparalytic polio (NPP). One review states late-onset weakness and fatigue occurs in 14 to 42 percent of NPP patients.

Many individuals have mild symptoms, which recur infrequently, while others may have persistent problems that become debilitating or life-threatening.

There are no prospective randomized controlled trials studying therapies for relapsing polychondritis. Evidence for efficacy of treatments is based on case reports and series of small groups of patients.

For mild cases limited to joint pain or arthritis, oral nonsteroidal anti-inflammatory drugs (NSAIDs) may be used. Other treatments typically involve medications to suppress the immune system. Corticosteroids are frequently used for more serious disease. Steroid-sparing medications such as azathioprine or methotrexate may be used to minimize steroid doses and limit the side effects of steroids. For severe disease cyclophosphamide is often given in addition to high dose intravenous steroids.