Denervation-reinnervation for treatment of adductor spasmodic dysphonia

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Denervation-reinnervation surgery

Denervation Reinnervation surgery, or DeRe surgery for short, is a procedure designed by Gerald Berke MD from UCLA in California as an alternative to the current standard therapy of botulinum toxin (Blitzer 1998) for ADductor spasmodic dysphonia. The standard treatment is injection of Botox into the vocal cord muscle about four times per year. The DeRe procedure is designed to surgically mimic what goes on during a Botox injection. A branch of the nerve (Anterior branch of the Recurrent Laryngeal Nerve) to the muscle within the vocal cord (thyroarytenoid muscle or vocalis muscle) is cut. The cut stump of the nerve is pointed away from the vocal cord muscle and a different nerve (ANSA cervicalis) from another muscle in the neck is attached to the remaining nerve of the thyroarytenoid muscle. The procedure is also known as Selective Laryngeal Adductor Denervation (or SLAD).

History of the procedure

A little history behind the treatment of spasmodic dysphonia may help put this procedure into perspective. Until the mid 1970's, nearly every scientific article attributed this disorder to psychogenic causes and recommended treatment with psychological interventions (with not much success). Dr. Dedo, in San Francisco, feeling this was a neurologic condition, developed a procedure that cut one of the two nerves (the recurrent laryngeal nerves) to the voice box. This paralyzed one side of the voice box and many people were better. To this day, Dr. Dedo feels this is a very successful surgery. Other people found that, while initally nearly everyone is improved, over the course of time about 2/3 of people had a return of their symptoms and now had one paralzsed or at least immobile vocal fold. Many have returned to Botox injections for treatment of their vocal spasms. Because of the great attraction between a cut nerve and a muscle that lacks a nerve, it is probable that the recurrent laryngeal nerve regrows and reconnects to the thyroarytenoid muscle and thus the spasms return.
 
In the late 1980s, botulinum toxin (Botox) began to be tried on the spasms with remarkable success, though the effects were of limited duration (three to four months before another injection is required). Botulinum toxin  became the standard treatment. Dr. Berke reasoned that cutting only the branch to the thyroarytenoid muscle and then trying to ensure that the nerve didn’t regrow could be accomplished with a nerve transfer graft. Cutting the nerve weakens the vocal cords and alone gives perhaps too breathy a voice. However, when a new (non-spasmodic) nerve grows into the vocal cord muscle (thyroarytenoid), the bulk of the muscle is restored, though it may not move completely normally. This bulk though is adequate to allow the other muscles within the voice box to do their jobs.
 
Dr. Berke first began performing the surgery after some basic science research on patients who were not getting satisfactory results from botulinum toxin.
 
In deciding whether to have this kind of surgery, you will need to weigh several factors. Is botulinum toxin a reasonable treatment for you, given the skill of the person doing the injection, the distance you must travel for the injection, the cost and your willingness to try something new and only starting to be proven effective? Do you want to be on the cutting edge with its potential benefits and its unknown risks and outcomes or do you prefer more certainty?
 
I have found the surgery to be useful in cases of unilateral vocal paralysis with synkinesis. It is actually possible to have a nerve that has recovered from a paralysis and now because of the reinnervation, it is "too tight" or perhaps it could be described as overly sensitive and it can spasm and reduce the airway.

Presurgery

The surgery is designed to ameliorate the symptoms of ADductor spasmodic dysphonia (AD SD). It surgically mimics the treatment of AD SD by botulinum toxin. It weakens the muscle in the vocal cords and then, when the new nerve graft grows in, the muscles gain some bulk, but not their previous function. The surgery does not treat vocal tremor. Presently there is not a satisfactory similar procedure for ABductor spasmodic dysphonia, though some have been proposed.
 
It is beneficial to have enough time lapsed since your last botulinum toxin  injection so that the nerves to the voice box are active (this means that the spasms of your spasmodic dysphonia will probably be bothering you). This nerve activity allows the branches of the nerve to be more easily identified during surgery.
 
Before the surgery, a PARQ conference is held with you. This is an acronym for Procedures, Alternatives, Risks and Questions. It means that your surgeon has discussed with you in full detail the reasons for going to surgery and that you are satisfied with those reasons.

Risks

The main risks of the procedure are anesthesia, a less-than-expected beneficial outcome, bleedinginfection, or a poorer-than-expected voice quality.
  • Anesthesia
    • The risk of anesthesia is that you could have a major life threatening reaction to some medication. This is very uncommon and I would compare it to getting in your car and driving some distance with the risk of an accident and dying. Even though the risk is severe, it is acceptably small, as most of us continue to drive. In the case of surgery, you even have the added benefit of life support equipment and trained personnel standing by. This procedure is performed under general anesthesia and the operation may last four to six hours.
  • Less-than-expected beneficial outcome
    • Relief of effortful speaking and relief from spasms are the expected outcome. Usually the surgery is much like a "large" botulinum toxin injection. Most patients have complete relief from their dystonia or spasms initially. Then both of the nerves begin to regrow. If the new, grafted nerve reaches the muscle first, the patient will have prolonged and probably permanent relief from the spasms. However, if some of the original, cut nerve regrows back into the muscle, the patient may have a partial return of spasms, in one or both sides. Some patients may have a permanent softer voice. Sometimes these unexpected outcomes can be dealt with by further surgery or with additional botulinum toxin injections.
      I have spoken with a number of people who have had the procedure (by myself, by Dr. Berke and by other surgeons), ranging from several months ago to many years out from surgery. Of those with whom I have spoken, the quality of the voice ranged from completely normal to very gravelly. Most were pleased with their voice, though most had lost their upper vocal range. Most had marked relief from the effort or strain of speaking with spasmodic dysphonoia and related that this benefit outweighed any vocal limitations they had. I have corresponded by email with several people who have been severely dissatisifed with the results, though I have not heard the quality of their voices.
  • Bleeding
    • Bleeding is a potential risk anytime a cut is made. This is primarily a problem after the surgery, where, if a blood vessel breaks, a hematoma may form under the skin that could require another surgical procedure to drain it out. If you are on any medication that may thin the blood, that would increase the risk. Examples of medications that might prolong bleeding include Coumadin, aspirin or even vitamin E. You should go over all medications that you take with your physician before surgery. A drain may be left in the wound for blood or fluid to come out. It would typically be removed in one to three days.
  • Infection
    • Any time a skin incision is made, that becomes a route for bacteria to enter into the body. This procedure is performed under sterile conditions and an antibiotic may be given in the operating room.

Surgery

Anesthesia

General anesthesia is utilized with an endotracheal tube down your throat to breathe for you while asleep. The procedure lasts about three to five hours.

Preanesthesia room

In the preanesthesia area, you get to wear that famous "open back" gown. You will be there for about an hour answering many questions for the tenth or perhaps the twentieth time. You learn that you actually lead a very interesting life judging from the thickness of the stack of papers representing you in the medical record. You may be given a sedative, depending on your wishes and your anesthesiologists recommendations. From the preanesthesia room, you leave your family and ride on your back, staring at the ceiling, to the operating room.

The operating room

The operating room table is often pre-chilled (I warned you). The surgery is done with you in a lying down position.

The procedure

After you are asleep, your neck is prepped to be made sterile. Usually a solution of iodine is used unless you are allergic to iodine. Drapes are placed to keep the neck area sterile.
 
About a two to three inch incision is placed in your neck over the voice box. It is placed in or parallel to a skin crease to aid in hiding it later on. A nerve called the Ansa Cervicalis is located on each side of the neck. It is located adjacent to the sternocleidomastoid muscle and the omohyoid muscle. Later in the case, this nerve is cut and routed into the voicebox. The assumption is that this nerve is not affected by the spasms that the nerve to the voice box is.
 
Several layers of muscles are pulled aside and the thyroid cartilage is exposed. The thyroid cartilage is the front of the voice box, and in men it is often known as the Adam’s apple. Some of the muscles attached to the voice box (thyrohoid) are disconnected. The cricothyroid muscle may also be disconnected - as this is the muscle that creates our upper voice; disconnecting this would account for the loss of the higher pitches. A window is created into the voice box and two of the muscles that ADduct or close the vocal folds are visualized. Typically, the branch of the nerve supplying these muscles (anterior branch of the recurrent laryngeal nerve) is visible on their surface. If it is difficult to distinguish the nerve from other tissue, the recurrent laryngeal nerve is stimulated with an electrical pulse and an EMG monitor placed into or on the vocal cord muscles will activate when the nerve branch is found.
 
The anterior branch is cut and the stump tied off with a suture and then angled out of the voice box.(Nerves have a strong tendency to regrow so hopefully the ansa cervicalis nerve will grow into the vocal muscles before this stump finds its way back.) At the surgeons discretion, a portion of the vocal fold muscles may be removed (such as the lateral cricoarytenoid). The ansa cervicalis nerve is now cut and then sutured to the remaining nerve into the thyroarytenoid muscle.
 
For spasms related to vocal cord paralysis, the procedure may be performed on one side only. For ADductor spasmodic dysphonia, the procedure is bilateral - that is, the denervation is repeated on the opposite side during the same case.

Recovery

You wake up typically in the recovery room. You stay in the recovery room until the nurses and anesthesiologist are certain the majority of the anesthetic is gone from your system. You will then return to your room.

Pain

There may be moderate pain after surgery. Since pain varies from person to person, I would typically prescribe Vicodin. Vicodin is essentially Tylenol and a narcotic, hydrocodone. For some, hydrocodone produces less nausea than codeine. This may be used for either throat pain or for a throat tickle or cough. There are extensive options for management of pain.

Instructions during healing

  • First week(s)
    • It is likely that you will have a very weak voice, much like a botulinum toxin injection. It is also likely that you will have initial difficulty swallowing liquids without choking on them. Similar to a strong botulinum toxin injection, these side effects will tend to last longer, perhaps to some degree for one to three months. Drinking through a straw or with your head tucked to your chin may help alleviate some of the choking. Thickening of drinking liquids may also help.
      The incision should be kept dry for at least 48 hours after surgery and if a drain is placed, for 48 hours after the drain is removed. This allows enough time for the skin edges to seal over. At times an antibiotic ointment may be placed on the incision.
      Speaking will also be a bit of work. When the vocal cords don’t occlude tightly (and they won’t after surgery for a while) it takes a lot of air to set them vibrating. This leads to several symptoms. Most people say they are “short of breath”. You will actually be running a lot of air in and out of the lungs. You may feel dizzy or lightheaded from what amounts to hyperventilation. Talking and walking at the same time could be difficult. Additionally, the voice as it recovers may sound a bit high or squeaky. The muscles that create high pitch (cricothyroid) try to kick in and bring the weakened vocal cords together.
      Scars go through a maturation process that takes about a year. During the first half of that time, the scar will tend to be pink and will tend to pigment very easily if exposed to the sun. That will make the scar more visible. I recommend using SPF 40 sunscreen to prevent this pigmentation. I have no opinion on the use of vitamin E on the incision. It certainly does no harm, though I do not know that it helps. Since the voice box elevates when swallowing, the scar can tether to the deeper tissues and move conspicuosly during swallowing. This may correct with time or be corrected later after healing finishes.
  • Six weeks
    • Return for a follow up visit to see how you have healed. Feel free to use your voice as much as you can tolerate.
  • Three months
    • Mid-term evaluation, if possible
  • Six months
    • If you are in the area, I would like to see you
  • One year
    • Long-term evaluation of your surgery.