Spasmodic dysphonia is a rare neurological condition that affects a person's speech. Speech requires pushing air from the lungs between the vocal cords in the throat. This causes the vocal cords to vibrate, creating sounds the lips and tongue shape into words. Spasmodic dysphonia affects the muscles in the voice box, the larynx, causing them to spasm involuntarily and affecting a person's ability to produce normal speech. The condition varies in severity from person to person and may become worse over time.
Experts do not know why some people develop spasmodic dysphonia, though it appears to most often develop due to abnormalities in the brain. Research suggests the affected area is one deep inside the brain called the basal ganglia. In some cases, spasmodic dysphonia has a genetic component, meaning a parent passed it onto their child. Medical professionals once believed the cause of the condition was psychological because the voice sometimes sounded normal. Although this is a possible reason for spasmodic dysphonia, it is very rare.
Spasmodic dysphonia causes 'breaks' in the voice that may occur only occasionally in mild cases. However, many people experience frequent breaks, sometimes occurring every other word. This can make their speech very difficult to understand. Spasmodic dysphonia is a chronic condition, which means that the person will usually have lifelong symptoms. Speech problems may gradually worsen over time.
Spasmodic dysphonia is an unusual condition, with around one to four cases occurring per every 100,000 people. Most people first develop symptoms of the condition between the age of 30 and 50. Although anyone can develop it, the condition is more likely to affect women than men.
Adductor spasmodic dysphonia is the most common form of the condition. It causes spasms that stiffen the vocal cords and make them hit one another. This can make it difficult to form vocal sounds and typically causes the voice to sound strained. Words may be cut off part way through or difficult to start. When the person laughs, cries, or shouts, this usually stops the spasms. In these situations, their voice will sound normal. Stress often makes this type more severe.
People with abductor spasmodic dysphonia experience spasms that cause their vocal cords to open inappropriately, preventing normal vibration and allowing air to escape while they are speaking. This can give the voice a 'breathy' quality and cause it to sound weak. As in adductor spasmodic dysphonia, spasms do not usually occur when the person is laughing, crying, or shouting. In very rare cases, people have a combination of both adductor and abductor spasmodic dysphonia. This is known as mixed spasmodic dysphonia.
The risk factors for developing this condition are not fully understood. However, experts believe infections of the upper respiratory tract can increase a person's overall risk. Injuries to the larynx can also make the condition more likely. Overusing the voice persistently can also cause spasmodic dysphonia, as can periods of psychological stress.
Diagnosing spasmodic dysphonia can be difficult because it often presents with symptoms similar to other voice disorders. Reaching a diagnosis usually requires a team of doctors from various areas of expertise including a neurologist, an ear, nose, and throat specialist, and a speech-language pathologist. These experts will examine the person's vocal cords for any signs of abnormality. The patient will speak and carry out other vocal activities while the medical practitioners watch for spasm, and an evaluation of the voice can identify patterns typical of the condition. A neurologist can rule out other causes.
There is no known cure for spasmodic dysphonia. However, symptoms often improve after a physician injects botulinum toxin into the vocal cords. This weakens the muscles and helps to prevent them from spasming. The injections usually work for a few months before the effects wear off, after which time the person will need further injections. This treatment can cause a 'breathy' voice and problems with swallowing, side effects that usually wears off after a few days. This treatment is effective for most people and can improve many cases of abductor spasmodic dysphonia.
Some people with spasmodic dysphonia may benefit from voice therapy to help minimize their symptoms and normalize the sound of their voice as much as possible. This is usually only effective if the condition is relatively mild. Psychological therapy can also help if the condition affects the quality of life.
If spasmodic dysphonia is severe, the individual may have problems communicating because the vocal symptoms make speech difficult to understand. If the person's voice is weak, a device designed to amplify speech may help. Some people use specially-designed software on a device such as a smartphone, which can transform written text into speech.
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