Purpose of surgery
Reinnervation of a branch of the recurrent laryngeal nerve may restore some lost function to the larynx. It is useful to redirect timing of muscle contraction and block nerve input from inappropriate branches that cause inappropriate timing of muscle contraction. It can block input from central nervous system induced spasms.
Technical name of surgery
Selective denervation of the anterior branch of the recurrent laryngeal nerve followed by reinnervation with the ansa cervicalis nerve.
- Permanent treatment for reducing or eliminating spasms in adductor spasmodic dysphonia
- Reinnervate the anterior branch of the recurrent laryngeal nerve for vocal cord paresis or paralysis.
- Block inappropriate innervation of the larynx causing laryngospasm
- Block inappropriate innervation of the larynx causing dyspnea or stridor
The nerve branch that I typically selectively cut, in order to denervate the larynx, is the anterior branch of the recurrent laryngeal nerve. This branch supplies first the lateral cricoarytenoid muscle and the more distal portion of it supplies the thyroarytenoid muscle. Together, these two muscles close the larynx.
Lateral Cricoarytenoid muscle
The lateral cricoarytenoid muscle rotates the vocal process, adducting the membranous vocal cord toward the midline.
This closing function by the lateral cricoarytenoid muscle allows:
- sound generation by adding pressure beneath the vocal cords,
- during breathing out (expiration) it adds positive end expiratory pressure internally, improving ventilation by keeping the lungs more inflated
- protects the airway during swallowing.
But if the vocal process is rotated medially at the wrong time, it creates sound during breathing in - stridor. If rotated medially for a prolonged time, it creates the sensation of laryngospasm
The thyroarytenoid muscle tenses the vocal cord, which also aids in maintaining vocal cord closure, as well as adjusting the pitch.
The donor nerve that I typically utilize to supply new nerve input is the omohyoid branch of the ansa cervicalis, although a lower branch can also be used if a longer length is needed. The omohyoid muscle typically contracts at the same time as the adductor muscles of the larynx and proves to be a good substitute for adductor nerve problems. I'm aware of some colleagues who use a branch of the thyrohyoid muscle for a similar purpose.
The denervation - reinnervation surgery was originally developed by Dr. Gerald Burke as a permanent surgical treatment for adductor spasmodic dysphonia. Nerve grafting seems to work equally well for inappropriate synkinetic reinnervation of the larynx where there is too much input into the adductor muscles on one side as well as persistent vocal paresis or paralysis where there is inadequate input into the adductor muscles on one side of the larynx.
Bilateral denervation-reinnervation surgery is useful for the treatment of Adductor spasmodic dysphonia.
Unilateral denervation-reinnervation surgery is useful for the treatment of laryngospasm or laryngeal dyskinesis.