What is Spasmodic Dysphonia (SD)?

Spasmodic dysphonia (SD) is a neurological disorder that causes “spasms” of the vocal cords and interruptions of speech. It can dramatically affect the ability to speak and can interfere with the patient’s quality of life. Patients describe their voice as broken up or tight, strained, or strangled in quality. The condition is similar to other focal dystonias such as cervical dystonia (torticollis), blepharospasm, musician’s dystonia, and writer’s cramp.

The National Spasmodic Dysphonia Association has an excellent website describing this condition and provides examples of the different kinds of voice problems with SD.

The most common type of SD is Adductor spasmodic dysphonia. This type of SD was successfully treated in the DEBUSSY trial. There is also a rare type of SD called Abductor spasmodic dysphonia. We have recently successfully treated this condition and published our randomized controlled trial in the prestigious peer-reviewed journal Neurosurgery in 2021 (link to paper).

We have also recently submitted our initial excellent results on treating Abductor SD and Mixed SD with deep brain stimulation in the peer-reviewed journal Open Neurosurgery.

TREATMENT OPTIONS

How Have We Treated SD?

Every patient is unique, and every treatment has potential side-effects or complications. It is therefore very important that patients discuss their personal treatment plans with their own physician. This website is only designed to give an overview of the options available for patients with SD so that they are more informed and can discuss their treatments with a better knowledge of what is available.

The National Spasmodic Dysphonia Association has an excellent website highlighting all the potential treatments currently available for spasmodic dysphonia.

Until recently, all the treatments of SD were designed only to weaken the throat muscles and not to correct the underlying neurological problem causing the disorder. Following the discovery that deep brain stimulation (DBS) can block the underlying neurological cause of SD, patients now have a choice to correct the underlying cause of SD rather than to just temporarily cover up the symptoms. Importantly, patients with symptoms that are not improved with the current destructive treatments now have an additional treatment option.

This section provides an overview of the current therapy for SD. Information on deep bran stimulation (DBS) is provided by clicking the drop down menu above labeled “DBS”.

Speech Therapy

Speech therapy can be provided by a speech language pathologist and involves training the patient to change how they use their voice. These techniques do not have any medical or surgical risks and are therefore a very good idea to try. Unfortunately, many patients have symptoms that are too severe to gain significant benefits.

Oral Medications

There are no medications that are designed specifically to correct spasmodic dysphonia. There are medications that can help dystonia in general and occasionally SD patients can also benefit but usually the side-effects (drowsiness) are worse than the benefits. Patients can speak directly to their physician to see if any medications would benefit them. Most often it is impossible to know without ‘a try it and see approach’.

Botulinum Toxin (Botox)

Botulinum toxin (marketed as Botox) is the most powerful poison in the world. In its purified form, a very small amount injected into any muscle will weaken it for several months. The muscles controlling the vocal cords are pathologically tight and in spasm as a result of the neurological disorder of adductor spasmodic dysphonia (SD). One therapy, therefore, is to deliberately weaken the muscles controlling the vocal cords with targeted injections of Botox. The muscles are then weaken for several months and this reduces the severity of the symptoms. The downsides of Botox include (i) a weaken or ‘breathy’ voice, (ii) the effect is only temporary and must be repeated for ever, (iii) the needle injections through the throat are painful, and (iv) it can be very expensive.

Destructive Nerve Surgery

The goal of all of these various types of destructive surgery is similar to that of Botox – weaken or disable the affected throat muscles. They have only been used on a subtype of SD called adductor spasmodic dysphonia.

Thyroplasty is an operation where the vocal cords are moved further apart. That way, when the SD forces them closed, there is still a small space between the vocal folds. A review of this technique reported short-term benefits but unfortunately, two-thirds of patients returned to baseline within one year. Denervation operations involve cutting the nerve(s) to the vocal cords. This produces a ‘hoarseness’ instead of SD but many patients have a return of their symptoms once the nerve regenerates. Selective Laryngeal Adductor Denervation-Rennervation (SLAD-R)is a type of denervation procedure but the cut nerves are attached to different, nearby nerves.

The original report from 1999, described 21 patients who were reported to do well although the outcome was a telephone survey and the opinion of an expert who clearly knew if the patients had received surgery or not. This raised the possibility of bias. Six patients had complications and four required additional surgery or therapy. No measure of the expected complication, voice breathiness, was provided.

A long-term, retrospective follow-up of some of the patients who had this procedure reported chronic breathiness in a third of patients (30%) and continued voice breaks in a quarter of them (26%). This operation has not been widely accepted. Only one other center (Vancouver) has ever reported their experience with SLAD-R and the disappointing results led to this operation being abandoned.

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