As per research, laryngeal dystonia or spasmodic dysphonia is a neurological disorder usually caused because of an abnormal nervous system or a brain disorder. Spasmodic dysphonia most often affects women, particularly between the ages of 30 and 50 years. It may start after a period of stress or illness.
- An imbalance in the chemicals of the nervous system may sometimes cause muscle tremors in our bodies. In patients with laryngeal dystonia, these tremors happen in the vocal folds.
- Structural abnormalities in the brain may also cause laryngeal dystonia. Evidence suggests that the condition starts at the base of the brain in the basal ganglia, which coordinates involuntary muscle movement. There seems to be a problem in the feedback loop between the brain and the voice box. Due to a problem with this feedback loop, there are resultant spasms or overly tight muscle contractions in the muscles of the voice box. The exact reason why the brain delivers these excessive signals is not completely understood.
- Postmortem studies have determined that people with this condition show an increased number of swollen cells in areas of the brain that controls laryngeal behavior.
- In a few patients, increased stressors in life may lead to laryngeal dystonia.
- Spasmodic dysphonia may be inherited. Genetic factors may put some people at a high risk of spasmodic dysphonia, particularly those who have family members with any form of neurological movement disorders that cause twisting, repetitive movements, or abnormal postures. Some genes that predispose patients to developing spasmodic dysphonia have already been identified, and about 12% of individuals with spasmodic dysphonia have a positive family history.
- Infection or inflammation may also have a role in precipitating this disease. Laryngeal dystonia may also start after an upper respiratory infection such as cold or flu.
- It is possible that an accident may also trigger laryngeal dystonia either at the time of intubation, for example, during surgery, or due to injuries to the neck.
- Prolonged voice use may also cause laryngeal dystonia.
- Other causes may include thyroid disorders, antihistamine use, and autoimmune disorders.
What is laryngeal dystonia?
Laryngeal dystonia or spasmodic dysphonia involves involuntary contractions of the vocal cords causing interruptions of speech and voice quality. The larynx is our voice box and is critical to speech. Laryngeal spasms make normal talking difficult, leading to laryngeal dystonia. Symptoms of laryngeal dystonia are generally categorized into two primary forms:
- Adductor spasmodic dysphonia: It is a more common type where speaking causes abnormal, involuntary, excessive contractions of the muscles that bring the vocal cords together. This causes a tight strangled-sounding voice quality, often with abrupt starting and stopping of the voice, resulting in a broken speech pattern and short breaks in speech.
- Abductor spasmodic dysphonia: It is a less common type; there is an over contraction of the muscles that separate the vocal cords, resulting in a breathy, whispering voice pattern. People with this type often describe feeling winded and out-of-breath during the speaking.
Common symptoms may include:
- Voice breaks up
- Voice sounds breathy, whispery, strangled, or tight
- Vocal tremor
- Hoarse voice
- Jerky voice
- Tremulous voice
- Intermittent voice breaks
- The effort required to produce voice
- Failure to maintain voice
- Breathy voice spasms
What are the treatments available for laryngeal dystonia?
Treatment options for laryngeal dystonia may include:
- Compensatory habits or tricks: Patients with laryngeal dystonia have very strained, choked-sounding voices, and they may find that their symptoms are reduced by whispering. The whispery voice may initially sound less common. Humming before speaking or breathing techniques may also be helpful.
- Botulinum neurotoxin injections: These injections weaken the muscles by blocking the nerve impulse to the muscle. Botulinum toxin injections generally improve the voice for a period of 3-4 months, after which the voice symptoms gradually return. Reinjections are necessary to maintain a good speaking voice.
- Speech/voice therapy: It is often incorporated into the treatment plan, especially before and after botulinum neurotoxin injections. Voice therapy can help the fatigue associated with the added effort required to speak. Techniques that focus on controlling the breath and using the breath to make the most of the voice may be helpful. Weeks or months of voice therapy may be required.
- Surgical procedure: The surgical procedure called selective laryngeal adductor denervation and reinnervation may be an option. Botulinum neurotoxin injections may still be needed following the surgery, and the procedure’s benefits may not be permanent.