Laryngeal Dystonia: Selective Denervation and Reinnervation
Selective Laryngeal Denervation and Reinnervation
Selective laryngeal adduction denervation and reinnervation (SLAD/R) is a surgical procedure to treat adductor spasmodic dysphonia/laryngeal dystonia by cutting (denervating) selected end branches of the recurrent laryngeal nerve, which is a branch of the vagus cranial nerve.
The first attempts to reduce the spasms of spasmodic dysphonia by severing the laryngeal nerve took place in the 1970s. Cutting the laryngeal nerve paralyzed the muscles controlling one side of the larynx so that the larynx could not contract excessively. Early results were good, but symptoms reappeared in many patients. Subsequent pioneers in the field sought to improve the procedure by varying the method by which the nerve was separated from the muscle. Recurrence of symptoms as well as breathy voice continued to be a problem in many patients.
The element that distinguishes SLAD/R from previous incarnations of the surgery is that, after the recurrent laryngeal nerve is cut away from the thyroarytenoid and lateral cricoarytenoid muscles, the muscle's nerves are hooked up to another nerve (reinnervated), one that is not associated with the dystonia. Supplying the muscle with another nerve prevents the problematic branch of laryngeal nerve from growing back and reconnecting to the muscle. Preventing the laryngeal nerve from communicating to the muscle prevents the spasms from returning and helps to change the closing forces of the larynx. It is important to note that the procedure is performed on both sides of the vocal cords, unlike previous nerve operations performed for adductor SD.
The procedure is accomplished through an incision in the neck and by creating a small window into the laryngeal cartilage to expose the underlying nerves and muscles. An operating microscope is often used to aid in identification and suturing of the tiny nerve branches. The procedure takes three or four hours to complete. Great care is taken to preserve the back part of the cartilage that protects the nerve branches to the breathing muscles.
SLAD/R is best suited for individuals with spasmodic dysphonia without a tremor. It may be an option for persons who are not satisfied with botulinum toxin treatments. Hundreds of people with spasmodic dysphonia have undergone SLAD/R. During the initial recovery period, all patients experience temporary voice breathiness and some experience swallowing difficulty. These issues resolve over a few months and the patient is left with an improved voice. Studies have indicated that as many as 85-90% of patients are very satisfied with the results of surgery, and the results, so far, have been life long.
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