Overview of Laryngeal Botulinum Toxin Injection
Botulinum toxin, better known as Botox, is a substance produced from a type of bacteria called Clostridium botulinum. This substance has a unique property – when it’s injected into a muscle, it temporarily stops the muscle from working. It can also decrease the amount of fluid produced by a gland if it’s injected there.
Although Botox is famously used for cosmetic purposes like smoothing wrinkles on the face, it’s also useful in treating certain conditions of the voice box, or larynx. Before Botox was available, these conditions were treated with psychotherapy and speech therapy. Unfortunately, these methods were not very effective.
Botox can be used to manage a number of issues related to the larynx. It’s particularly useful in treating laryngeal dystonia or spasmodic dysphonia (SD), a condition where the voice box muscles spasm, affecting the voice. It also helps in managing conditions like vocal tremors (shaking of the voice box), vocal process granuloma (a type of benign growth), and cricopharyngeal muscle dysfunction (problem with a specific muscle in the throat). By precisely targeting and ‘turning off’ certain muscles in the larynx, doctors can successfully treat these problems.
Most people with spasmodic dysphonia are women, making up 65% of patients. The average age at which it starts is 45 and it affects approximately 1 in every 100,000 people. In one type of spasmodic dysphonia, known as adductor spasmodic dysphonia (ADSD), a specific muscle in the voice box is targeted with Botox to stop its spasms. This use of Botox was pioneered in the 1980s and is now considered the best treatment for this condition.
Anatomy and Physiology of Laryngeal Botulinum Toxin Injection
Botulinum toxin, commonly known for its use in Botox treatments, can actually be used to help treat muscle issues. It works by causing temporary paralysis in certain muscles. It does this by blocking the release of a chemical called acetylcholine, which is needed for muscles to contract. Without acetylcholine, the muscle can’t move, which can be helpful in treating specific medical conditions.
Often, it’s used to treat issues in the muscles inside the voice box. These muscles are essential for speaking, swallowing, and breathing. Some of these muscles are controlled by a nerve called the recurrent laryngeal nerve, while one special muscle, the cricothyroid muscle, is controlled by a different nerve called the superior laryngeal nerve.
Botulinum toxin can be used to treat a condition called laryngeal dystonia, also known as spasmodic dysphonia, which causes people to lose control of their voice because the muscles in their voice box are contracting or relaxing at the wrong times. This can result in a range of voice issues, from sounding strangled or choppy to having a weak or breathy voice.
This treatment can also help with a condition called vocal process granuloma, which is a non-cancerous lump that can form in the voice box. It’s usually caused by acid reflux, not taking care of your voice, or from having a breathing tube in for a long time. The lump can lead to symptoms like feeling like you need to clear your throat a lot, coughing, feeling a lump in your throat, and changes in your voice. Botulinum toxin is used in such cases by injecting it into specific muscles in the voice box.
The botulinum toxin can also be used to help with swallowing problems caused by a muscle in the throat called the cricopharyngeus muscle, which helps us to swallow by relaxing to let food pass into the esophagus. Issues occur when this muscle doesn’t relax properly, but, the toxin can relax it, allowing normal swallowing to occur.
Why do People Need Laryngeal Botulinum Toxin Injection
Spasmodic dysphonia, a condition that affects the voice, is usually identified by its unique symptoms and certain tests rather than a specific diagnostic test. A person with this condition usually has a history of voice breaks and breathiness, which tend to disappear during emotional sounds, like laughing or crying. During physical exams, spasmodic dysphonia can be spotted when the patient says words starting with vowels, counts from 80 to 89, or when saying certain phrases such as “we eat eggs every day.”
There’s another form of dysphonia which becomes more noticeable after voiceless consonants, when counting from 60 to 69, or with certain sentences like “the puppy bit the tape”.
At first, a person might try voice therapy before resorting to botulinum toxin therapy. However, once the condition is identified, botulinum toxin therapy can be used to diagnose and treat it. Some patients who have had surgeries for this condition, like selective laryngeal adductor denervation and reinnervation (SLAD-R), might need to use botulinum toxin to manage symptoms that come back after surgery.
It’s worth noting that botulinum toxin is not only used for spasmodic dysphonia, but it’s also used to treat spasmodic dysphonia with and without vocal tremors, isolated vocal tremors, vocal process granuloma, and dysfunction of the cricopharyngeal muscle, which is a muscle in the throat.
When a Person Should Avoid Laryngeal Botulinum Toxin Injection
The only situations in which a person should not receive botulinum toxin injections, also known as Botox, are if they have neuromuscular disorders or if they are allergic to the ingredients in the toxin. Neuromuscular disorders are conditions that affect the nerves that control your voluntary muscles. If you have a known allergy to Botox or any of its components, the injection could cause a severe allergic reaction.
Equipment used for Laryngeal Botulinum Toxin Injection
When performing a botulinum toxin injection in the voice box (or larynx), the doctor may need different tools depending on the specific issue and the best way to address it. The favored toxin for most voice box movement issues is known as ‘botulinum toxin type A’.
The doctor might use a high-quality flexible video endoscope, which is a thin tube with a tiny camera on the end that allows them to visualize the voice box. This scope may or may not have an operating channel, which is a track that allows the passage of other instruments, but if it does, it is best if it is at least 2.2 mm wide. Sometimes, the doctor may also use equipment known as an EMG to measure muscle response.
Additional supplies typically include solutions of lidocaine (a numbing medication) and naphazoline nitrate (a drug that shrinks swollen blood vessels), an injection device with a flexible needle that is 4 mm long and 23 gauge (a measure of the needle’s thickness), or a slightly thinner 27 gauge needle if the injection is given through the skin.
Who is needed to perform Laryngeal Botulinum Toxin Injection?
In a medical operation, there are several people involved who each play specific roles. The team is typically made up of a main doctor or surgeon, who is the individual trained and skilled in carrying out surgical procedures. Along with the surgeon, there is a nurse or a surgical assistant, who help the surgeon during the procedure.
Another key member of the team is a speech-language pathologist. This professional works to assess, diagnose, and treat communication and swallowing disorders. They often play a critical role in cases where the patient’s ability to speak or swallow may be affected by the surgical procedure.
The team may also include a neurologist, they’re specialized doctors who focus on diagnosing and treating brain and nervous system diseases. They’re particularly important when the operation involves the brain or nerves, to ensure everything in the nervous system is functioning correctly.
All these professionals work together to ensure the operation is successful and that you’re well taken care of.
Preparing for Laryngeal Botulinum Toxin Injection
The doctor uses local anesthetics and clears the nasal passage for clear viewing during the medical procedure. The solution used for this contains 5% lidocaine and 0.02% naphazoline nitrate. This helps make the procedure more comfortable for the patient. They also anesthetize the voice box using a solution of lidocaine or a local painkiller. This is done regardless of the procedure used, to improve the patient’s comfort level during the operation.
For certain techniques, a local anesthetic is also applied through the cricothyroid membrane or the trachea (the windpipe). This involves using 2 ml of 4% lidocaine. The cricothyroid membrane is a thin, round piece of cartilage located in the throat, and the trachea is the tube that carries air from the mouth and nose to the lungs. Using a local anesthetic in these spots helps make the procedure easier and more comfortable for the patient.
How is Laryngeal Botulinum Toxin Injection performed
For treating voice disorders, doctors typically use three main techniques that allow them to access the voice box muscles. These include direct visualization, a method using a tool called a laryngoscope, and a technique that uses a technology called electromyography (EMG).
In the direct visualization technique, the doctor first applies a local anesthetic (a numbing medication) to your nasal cavity. Then, they insert a thin, flexible instrument with a camera, called an endoscope, through your nose and guide it down the passageways leading to the voice box. They use a solution containing the anesthetic Lidocaine which is applied onto the vocal cords. The tool used to deliver this solution is advanced through the channel of the endoscope while being protected by a plastic sheath. The doctor then injects a tiny amount of a medicine called botulinum toxin into the target area of the voice box. This helps relax the muscles and reduce symptoms. The needle is left in place for a few seconds post-injection to reduce any chances of medication leakage.
Different voice disorders require targeting different muscles. For example, in a condition called adductor spasmodic dysphonia, the muscles that bring the vocal cords together are injected. While in abductor spasmodic dysphonia, a muscle that pulls the vocal folds apart is treated. In the case of voice box granuloma, a group of cells that form on the vocal cords, the muscles between the two artytenoids (small cartilages in the voice box) or the thyroarytenoid muscles (muscles in the vocal folds) are injected.
The EMG-guided injection is another technique which uses an EMG needle. This needle is used to target specific muscles depending on the voice disorder. What’s unique about this technique is it doesn’t require visual guidance like the first method. For adductor spasmodic dysphonia, the needle is inserted through the skin and directed towards the muscle responsible for tense vocal cord control. This position is identified by a distinct sound pattern noted on the EMG machine guiding the doctor. For the disorder called abductor spasmodic dysphonia, the needle is directed towards the muscle responsible for voice box relaxation. Patient movements that suggest brisk recruitment such as sniffing confirm the correct placement.
The third technique involves using a laryngoscope, a tool that helps doctors see your voice box, while accessing your throat through a needle. Anesthetic is first applied to your throat and nose. The doctor then uses a thin, flexible camera, called a nasolaryngoscope, which is inserted through your nose and positioned just above the vocal cords. For adductor spasmodic dysphonia, the needle is directed towards the back one third of both the vocal cords.
The method used in treating voice box tremors will depend on the accompanying symptoms and can be achieved using any of the previously mentioned methods. For voice box granuloma, first, the nostrils and airway are numbed. The laryngoscope is then used to visualize as the injection is given into the interarytenoid region (the space between the two small pieces of cartilage at the base of the voice box).
When treating cricopharyngeal muscle dysfunction, a condition where a muscle in the throat does not relax, different amounts of botulinum toxin can be used. Several methods can be employed for the injection including using rigid endoscopy with EMG for location guidance under general anesthesia, using EMG-guided injection with live imaging for location guidance, using an EMG-guided injection through the skin, and using computerized tomography (CT) for location guidance. Each of these methods has its own set of benefits and the choice depends on the specific situation.
Possible Complications of Laryngeal Botulinum Toxin Injection
When doctors treat a voice disorder called spasmodic dysphonia with injections of a substance known as botulinum toxin, some people might have complications. They might face difficulties swallowing (a condition called dysphagia), have a breathy voice, or accidentally inhale fluids into their lungs (a situation known as aspiration).
There are also other downsides to this treatment. It usually has to be done more than once and there isn’t a one-size-fits-all dose that works for everyone. Some people might need more or less of the toxin for it to work properly.
What Else Should I Know About Laryngeal Botulinum Toxin Injection?
People with laryngeal dystonia, a condition that affects the nerves controlling the muscles in the voice box, can find relief with botulinum toxin injections. These injections have been seen to lessen the severity of their voice problems by almost 10%. When the symptoms improve after injecting the affected muscles, it helps verify that the condition is indeed laryngeal dystonia. With a confirmed diagnosis, the patients can then consider suitable treatment options. These might include periodic botulinum toxin injections or more permanent procedures.
Botulinum toxin injections have also been used successfully to treat vocal process granuloma, a noncancerous growth that occurs on the back parts of the voice box. These injections administered to the thyroarytenoid, a muscle of the voice box, have been effective in 77% to 100% of such cases, although some people might experience breathiness post-injection. Another injection approach targeting a pair of muscles in the voice box (interarytenoid injections) has shown good results as well and has a lower chance of causing breathiness. One study showed that this method resulted in complete resolution of the symptoms in 55% of the patients.
Botulinum toxin is also useful in diagnosing and treating cricopharyngeal muscle dysfunction— a condition that causes swallowing difficulties due to a muscle in the throat not relaxing properly. A study showed that it worked well in 5 out of 7 patients who faced mild to severe swallowing problems; their symptoms showed a significant decrease.
