Introduction
Laryngeal dystonia is a rare neurological condition affecting the larynx or voice box and may cause breathing difficulties. The disturbance in the voice is known as spasmodic dystonia, whereas the disturbance in breathing is known as respiratory dystonia. Dystonia is a sustained involuntary contraction that causes abnormal posture or movement.
This may be generalized in various diseases of the basal ganglia or focal or segmental, as in spasmodic torticollis when the head involuntarily turns to one side. Other segmental dystonias may cause abnormal disabling postures of a limb to be taken up during certain specific actions, such as writer's cramps or numerous other occupational cramps. Laryngeal dystonia is a focal type that affects only one specific part of the body: the larynx muscles. It is most commonly seen in females than males. The most common type of laryngeal dystonia is spasmodic dysphonia.
What Are the Signs and Symptoms of Laryngeal Dystonia?
The signs and symptoms may vary from person to person. There may be no symptoms with a normal voice to be severely affected. The symptoms may occur on the same day or from day to day. Initially, the individual may suffer from mild symptoms.
The symptoms may progress and stop generally. In very few individuals, the mild symptoms may progress into severe dystonias involving the face and neck. The symptoms may worsen and improve with rest. It is common in individuals who use their voice frequently and may result from straining muscles. It may be associated with tremors.
These are neurological disorders characterized by excessive involuntary rhythmic shaking of a particular part of a body, more specifically, arms or hands. The tremors may range from four to twelve times within one second. It may affect the tongue or the vocal cords, leading to difficulty in speaking or also known as dysarthria. It can also affect the neck muscles leading to shaking of the head.
The most common speech disorder is chronic stuttering, characterized by an abnormal speech pattern composed of a prolonged, repetitive, unusual type of hesitation that may affect the rhythmic flow of speech. It is a self-limiting disorder that may resolve on its own before adolescence.
What Are the Types of Laryngeal Dystonia?
The two most common types of laryngeal dystonia are adductor spasmodic dysphonia and spasmodic abductor dysphonia. Adductor spasmodic dysphonia is mostly prevalent among individuals. The main function of the adductor muscle of the larynx is to bring the vocal cords together.
A strained, harsh-sounding voice characterizes adductor spasmodic dysphonia. The affected individuals may face difficulties speaking vowel sounds such as eat, back, I, olives, or nest. The main function of the abductor muscle of the larynx is to draw the vocal cords apart.
Abductor spasmodic dysphonia is characterized by breathy, whispered speech and loss of voice for a short period. The affected individuals may have difficulty controlling speech after certain sounds like h, s, p, t, or k. Few individuals may suffer from both the type of spasmodic dysphonia and mixed spasmodic dysphonia.
What Are the Causes of Laryngeal Dystonia?
The causes of laryngeal dystonia are unknown or idiopathic. Multiple factors may be involved in the development of the disease. It may be caused by a genetic, environmental, or neurological factor, trauma or surgery, or infection or may be due to certain drugs or toxins. Although genetic susceptibility plays an important role in the development of the disease, the disease may not be expressed until and unless triggered by other genetic or environmental factors.
What Are the Diagnostic Tests to Be Carried Out?
The otolaryngologist, pathologist, and neurologist must carefully evaluate the voice and speaking under different conditions.
The diagnostic test that should be carried out is:
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Laryngoscopy is used to visualize the larynx or the voice box, including the vocal cords and the nearby adjacent structures. It is performed with the help of the laryngoscope, a thin, flexible tube with light, lens, and camera that helps to visualize the voice box more closely. It may be useful to rule out certain structural abnormalities of the vocal cords, such as nodules, polyps, or tumors.
What Is the Treatment Protocol for Laryngeal Dystonia?
There is no specific treatment protocol for laryngeal dystonia. Psychological support and counseling may help individuals to overcome the situation related to anxiety and depression in such patients. Often, botulinum toxin therapy may help to relax the overstrained laryngeal muscles. The drug should be administered every three to four months.
Also, speech therapy may be useful in some mild cases. Therefore botulinum toxin therapy and speech therapy must go hand in hand to obtain effective treatment of laryngeal dystonia. Specific surgical procedures such as thyroplasty and selective laryngeal adductor denervation-innervation may be required in some cases.
Conclusion
Respiratory distress can present as a serious, life-threatening complication of laryngeal dystonia. Clinical advances have led to improvements in recognizing features of dystonia, such as tremors. These discoveries have begun to shape the treatment approaches for laryngeal dystonia, and new treatment modalities such as magnetic resonance imaging-guided focused ultrasound has emerged as excellent diagnostic tools.
