Spasmodic Dysphonia uncommon type of focal laryngeal dystonia

Spasmodic dysphonia (SD) is a relatively uncommon type of focal laryngeal dystonia. It is distinguished by task-specific vocal dysfluency caused by selective intrinsic laryngeal musculature hyperfunction. A sensory trick may help to alleviate symptoms. Although SD can be seen in generalized dystonia syndromes, it is usually a sporadic occurrence. The involvement of the laryngeal adductor muscles is more common than the involvement of the abductor's muscles. The standard treatment for this disorder is botulinum toxin injection, which is usually guided by electromyography and must be repeated as the toxin wears off. To alleviate the symptoms, several non-reversible surgical procedures have been described. Other treatment options are being researched, such as implantable electrical stimulation devices and deep brain stimulation.

Botulinum toxin treatment of spasmodic dysphonia

Spasmodic dysphonia is a type of dystonia known as focal laryngeal dystonia. Videostroboscopy, acoustic analysis, computerized voice analysis, and overall electrophysiological analysis allow for the investigation of the various muscles involved in dysphonia. Spasmodic dysphonia is classified into 

Two Types  Spasmodic Dysphonia

1. adductor spasmodic dysphonia and 

2. abductor spasmodic dysphonia. 

Botulinum toxin injection into the thyroarytenoid muscle under fiberoptic visualization is the most effective treatment nowadays. We present six cases of spasmodic dysphonia that we have been treating for approximately two years with direct injections of botulinum toxin into the vocal cords.

Chapter II Cells and Cell Theory

Following botulinum toxin injection, airflow became more stable.

Objectives

The goal of this study was to see if botulinum toxin injections to the laryngeal and extra laryngeal muscles increased airflow stability and mean airflow in people with spasmodic dysphonia (SD), some of whom had associated vocal tremor (VT).

Design of the study

In a crossover study, aerodynamic data were collected from five subjects before, 2, 4, and 8 weeks after they received treatment by each of two different arms in an injection protocol. Only the thyroarytenoid muscles were treated in one arm of the protocol. The other arm included therapy for both the thyroarytenoid and strap muscles.

Methods

During phonation, mean airflow and coefficient of variation (COV) of airflow were measured. A decrease in the COV of airflow would indicate increased phonatory airflow stability.

Results

Prior to treatment, all subjects with SD/VT had mean airflows comparable to controls. The COV of the airflow ranged from normal to significantly elevated. Following botulinum injection, mean airflow increased while COV of airflow decreased.

Conclusions

This finding suggests that after botulinum toxin injection, there is a change in the type and level of activity in the muscles of speech production. The observed increase in airflow stability could be attributed to improved laryngeal and possibly respiratory system stability.