Botox Treatment and the Nervous System
When a nerve gets the signal from the brain to fire, chemicals called neurotransmitters are released from the nerve into the muscle fibers, causing the muscle to contract. Botox works by preventing the release of the neurotransmitters. This prevents the contraction of the muscle. Actually, the Botox is injected in such small amounts that it only affects the muscle fibers near the injection site, not the entire muscle. Therefore, the muscle contraction is weakened, but not entirely eliminated.
In the case of Botox injections for Benign Essential Tremor, the action of the Botox does not stop the tremor, but weakens the severity of the tremor. The Botox is injected into the thyroarytenoid muscle within the vocal fold. The thyroarytenoid muscle is responsible for the strength of the staccato, hiccuping effect of the tremor.
We talk about the Botox wearing off, but that is not quite what happens. The tiny ends of the nerve fibers near the injection site eventually die off from the Botox. However, new nerve endings grow, much like the roots of a plant. The regrowth of active nerve endings allows the release of neurotransmitters again, so that the muscle contraction is no longer weakened. The gradual
strengthening of muscle contraction makes it feel as if the Botox effect is wearing off.
Botox can be used to treat a number of voice disorders including Spasmodic Dysphonia (aka Laryngeal Dystonia), Benign Essential Tremor, and severe Muscle Tension Dysphonia.
If you're going to receive Botox injections...
How long does it take?
The injection process will only take a few minutes. Then we'll ask you to wait a few minutes after your injection, to make sure you feel OK.
Does it hurt?
Most people say it's a little painful for a short time, like getting a tetanus shot. No anesthesia is used, because most people prefer avoiding additional injection. It's helpful if you relax, just like that tetanus shot. It's fine if you want to have someone come with you and hold your hand.
How do we know the needle is in the right muscle?
At the Lions Voice Clinic, we use EMG (electromyographic) guidance. That means the needle is attached to a tiny wire that sends a signal to the electromyograph machine, which in turns gives a signal about the activity of the muscle. When the needle is in place, we will have you activate the muscle by performing a specific task such as saying "eee" or sniffing. Electrical energy caused by the contraction is sent through the wire to the electromyograph, and a "crackling" sound confirms that the needle is in the correct muscle. Before your injection, a round disc called an electrode will be applied to your forehead and another strapped around your left wrist. These provide grounding and reference for the electrical signal. In the case of adductor Spasmodic Dysphonia when the thyroarytenoid muscle is injected, there will be two injections, one for each side. In the case of abductor SD, only one side at a time is injected. This is because the injection is going into the muscle that pulls the vocal folds apart and allows you to breathe. If both sides are weakened at the same time, breathing could be impaired (you wouldn't like that!). After several injections, often a dose is found that allows for simultaneous injections on both sides, without compromising breathing. When the injections are for Benign Essential Tremor, usually both sides are injected in the same visit.
How soon does the injection take effect?
Usually in the next three days. Sometimes people can feel a difference the next morning, but more often it takes a day or two. If you don't feel any effect within a week, call us. Sometimes the strongest effect is felt first, and other times the effect builds over the first week. Individual reactions are hard to predict.
What are the side effects?
Side effects are minimal, because the amount of Botox is so small, and the area it affects is very small. Both side effects are related to the intended purpose of the Botox, to weaken the vocal folds.
In the first week, a few people notice choking or coughing when they drink thin liquids like water. It is the same effect when you get water "down the wrong pipe." To avoid this, sip carefully; don't chug-a-lug. Many people cough a little when they first take a drink after the injection takes effect, and then they remember to sip more slowly. It is rarely a problem, and rarely lasts more than a week.
The other, more common side effect is that your voice may become weak and breathy for some period of time after the injection. This is because the vocal folds are weak and cannot come together strongly to provide a strong vibration. This is what prevents the spasm. In time the breathiness resolves and the voice becomes stronger, but still does not spasm. The degree of breathiness and the length of time the voice stays breathy are related to the dose of Botox, and to the individual reaction. In general, the larger the dose, the longer the voice stays breathy, but also, the longer the spasms are prevented after the breathiness resolves.
Some people cannot tolerate any breathiness or weakness in their voice, and therefore they have frequent, small doses of Botox. Others can tolerate several weeks of breathiness, but in exchange they get more months of improved voice quality. It may take a few injections before you know your best dose and timing schedule.
How will I know when I should get another injection?
In the case of Spasmodic Dysphonia, the spasms will return gradually, and at first they will not be as strong as they were before the injection. Spasms typically get worse over a period of weeks or months. During that time, techniques you learned in voice therapy are the most helpful. Patients learn their pattern, and call to schedule their next injection before the spasms become too severe.
In the case of tremor, the tremor gradually becomes stronger over a period of weeks or months. During that time, techniques you learned in voice therapy are the most helpful. With repeated injections, patients learn their best pattern of dose and timing, and call to schedule their next injection in time to prevent severe worsening of symptoms.