Transcription
Spasmodic dysphonia is a condition characterized by vocal breaks during speech due to spasms of the vocal cord muscles. The most common type of spasmodic dysphonia is adductor spasmodic dysphonia, where the vocal cords suddenly and forcibly come together, causing a person's voice to suddenly cut off or catch. The standard treatment for adductor spasmodic dysphonia is botulinum toxin injection into the thyroarytenoid muscle under EMG guidance. Although the exact positioning and steps may vary between healthcare providers, the basic steps in performing an EMG-guided botulinum toxin injection into the vocal cords are as follows.
The patient is placed in a comfortable position with their head hyperextended. A lidocaine injection is given in the sublingual space via the cricothyroid space, located directly below the larynx. Over the next few minutes, the local anesthetic will numb the larynx, making the subsequent botulinum toxin injection much easier for patients to tolerate. While waiting for the anesthesia to take effect, the EMG machine can be turned on and leads applied to the neck. Two leads applied to the patient include the patient's green signal and a red positive lead.
An appropriate amount of botulinum toxin is prepared within a 1cc syringe and an attached electrode needle. This, in turn, is connected to the black EMG connector. The syringe containing the botulinum toxin and electrode needle is inserted into the cricothyroid space and directed both superiorly and horizontally to where the vocal cord muscle is located. When the needle electrode enters the muscle, the EMG machine provides an auditory and visual confirmation of muscle activity to indicate proper placement. An appropriate amount of botulinum toxin is then injected. The same procedure is then repeated on the other side before the needle is completely removed and the procedure is concluded.