Overview of Videostroboscopy
Video endoscopy with stroboscopy, or simply “stroboscopy,” is a key tool often used to check the health of the vocal cords. It helps doctors see how the vocal cords vibrate, showing how healthy and flexible the surface and deeper layers of these cords are. The name “stroboscopy” comes from Greek words meaning “whirling” and “to look at”. This technique was first used way back in the 1800s with a rotating wheel to create the illusion of movement. It was first used to observe the vocal cords moving by a medical researcher named Oertel in 1895.
When we speak or sing, our vocal cords vibrate very fast – too fast for the naked eye to see! Stroboscopy uses a specially designed tube called an endoscope, a microphone, and a light that flashes (strobe light) to help the eye view these motions. The microphone is placed near the voice box, also known as the larynx, and estimates the voice’s basic frequency. The strobe light is then set up to flash, or strobe, slightly slower than the basic frequency of the voice box. This helps capture the different parts of the voice box’s movement cycle.
These captured images are then played back in order to show what looks like a slow motion video clip of the vocal cords in action. This is sort of like how a flipbook works, with a series of quickly changing images making it look like movement is happening.
Although watching these images may look like slow motion, this isn’t because of the time your eye keeps an image (called image retention) or because of how we see brightness over time. Instead, it’s because of how we perceive moving images when the strobe light flashes quickly, allowing us to see movement where it would normally be too fast to see.
Despite being a cost-effective option when compared to high-speed video (which needs a special camera and tons of data storage), stroboscopy does have its limitations. For instances when the vocal cord movements aren’t regular or repeatable, stroboscopy may not work as well. For instances when the voice produces two pitches at the same time, called diplophonia, stroboscopy also doesn’t do too well as it disrupts the microphone’s ability to measure and causes irregular images. In these cases, methods like high-speed video or high-speed single-line video scanning (videokymography) may be more useful.
Anatomy and Physiology of Videostroboscopy
Making sound involves three parts: a power source, something to vibrate and create sound waves, and something to amplify these sound waves. In humans, this is how we make vocal sounds. We use air that we push out from our lungs as the power source. This air is pushed by our diaphragm (the muscle underneath your lungs) and the muscles that are in between our ribs.
The thing that vibrates in our system is the vocal folds in our throat (larynx). The upper part of our air passage and the inside of our mouth act as the amplifier for the sound waves.
The way the vocal folds move when we make sound is often called the “mucosal wave.” This is because the way they move reminds us of how waves move in water. This complex movement in three dimensions is a result of how the air pressure interacts with the structure of the throat. The process starts when the air we breathe out pushes up on the vocal folds that have been brought together. When the pressure beneath the vocal folds becomes high enough, air can escape between the folds. The folds then separate from bottom to top, creating an opening between them that moves upwards until they’re fully open at the top.
As this wave moves upwards and across the vocal folds, there is an interaction between the two main parts of the folds – the cover and the body. Each of these parts is made up of two or more layers. The cover includes the outermost layer of cells and the layer beneath it, while the body includes a middle layer, a deep layer, and a muscle layer. When the vocal folds are fully open, air rushes between them, creating an area of low pressure which makes them close again. So, the bottom edge of the vocal fold starts to close while the top edge is still opening.
Why do People Need Videostroboscopy
If you’re having issues with your voice like hoarseness, breathiness, a tired voice, limited vocal range, discomfort in your voice box, tightness, a need to cough or clear your throat all the time, or changes in sensation, you might need a procedure called videostroboscopy. This procedure might also be suggested to people who recently had surgery on their voice box or neck, those who are doing voice therapy or need regular checks for cancer.
Videostroboscopy is usually suggested after a flexible nasolaryngoscopy – a scope examination of the throat and voice box. This process allows doctors to watch and record in real time how your vocal cords are moving when you speak.
When a Person Should Avoid Videostroboscopy
Videostroboscopy is generally a safe procedure with a few exceptions. This process involves using a flexible or rigid camera to examine your voice box, which can be inserted through your mouth or nose. In order for the examination to be effective, the patient must be able to make a sustained sound that allows the voice box to vibrate. However, the patient’s comfort and ability to follow instructions play a crucial role in the procedure’s success.
Some patients might find it challenging due to anxiety, discomfort, or a powerful gag reflex. People who have a history of fainting during medical procedures, those who are afraid of medical procedures, or those with airborne diseases may not be suitable for this examination. Similarly, patients with disorders that affect blood clotting or those on blood-thinning medication should be careful, as the camera’s passage through the nose can potentially cause minor damage and bleeding. However, such bleeding is infrequent and usually heals on its own.
Equipment used for Videostroboscopy
Videostroboscopy, a procedure used to look at your voice box, involves the same tools that are used in a flexible nasolaryngoscopy, which is a process to examine the inside of your nose and throat. In addition to these, the doctor uses a videostroboscopic unit. Here’s what’s involved:
– A flexible tool with a tiny light and camera at the end, known as a fiberoptic or digital chip-on-the-tip nasolaryngoscope, or a rigid device used for looking inside your body, called a 70-degree endoscope.
– A special microphone that is made for examining the voice box (larynx), which is to be positioned on your throat.
– A high-tech tool called a stroboscopy apparatus takes the sound from the microphone and uses it to accurately match the flashing speed of the light source, allowing the doctor to see in great detail.
– A recording device, used to document the examination process. This allows your doctor to review the exam in slow motion or picture by picture, giving them a better understanding of what’s happening.
Who is needed to perform Videostroboscopy?
A special kind of procedure called ‘videostroboscopy’ is typically done and assessed by certain health professionals such as an ear-nose-throat doctor (also known as an otolaryngologist), a voice box specialist (also known as a laryngologist), or a speech-language therapist. These professionals are trained to perform and understand this procedure.
Preparing for Videostroboscopy
Preparing for a medical procedure called videostroboscopy involves several steps:
1. This procedure is usually done in an outpatient clinic, which means you can go home afterwards.
2. It usually takes about 2 to 3 minutes to complete.
3. A special microphone is placed on your neck, over an area called the thyroid cartilage. This is done to measure the pitch and loudness of your voice.
4. A numbing medication (1% lidocaine) and a decongestant, usually 0.05% oxymetazoline hydrochloride, is sprayed or spread into your nose (for a method called transasal laryngoscopy) or on your tongue and throat (for a method called transoral approach).
5. You will be instructed to lean forward with your lower neck bent forward and your upper neck flexed as if you were sniffing something.
6. The laryngoscope, a tool used to view your throat, is warmed or cleared of fog.
7. The scope is then carefully moved into your nose and past your nasopharynx (the upper part of your throat behind your nose) to help your doctor see your voice box and throat area.
After the steps are completed, your doctor will ask you to make a sound like “ee” at different volumes and pitches. This will help your doctor better understand the health and function of your voice box and voice.
How is Videostroboscopy performed
To examine your voice and throat health, we start by getting a clear view of your voice box, extending from the front to the back. This is important for assessing the movement of the tissues in your voice box. To help us with this assessment, we will ask you to make an ‘i’ sound at different pitches and volumes. You will have to hold these sounds for a little while so we can match them to our special stroboscopic light source, a device that helps us see the motion of your vocal cords better.
We often ask you to do things like sniffing quickly or for a long time, or say ‘i’ between breaths. This helps us evaluate the movements and symmetry of your vocal cords. Other useful tasks might include making an ‘i’ sound in different ways (at different volumes, pitches, or in a rising or falling pattern), counting from 1-10, or repeating specific phrases, such as the days of the week or the months of the year.
Once we’ve done these exercises, we take out the instrument we used to view your voice box and you can rest. We’ll then review the video recording of your voice box movements. We often use a rating form to assess different parts of the voice box and rate your vocal cord movements. We look at things like the size of the movements, the movement pattern of the tissue, any areas that aren’t moving as they should be, the extent of voice box compression, the smoothness and straightness of the vocal cords, whether the vocal cords touch properly, and the symmetry and regularity of these movements, as well as what the voice box looks like when it is closed.
Possible Complications of Videostroboscopy
The problems that can come up with a procedure known as videostroboscopy, are similar to those you might experience with any form of nasolaryngoscopy. This procedure involves looking at your nasal passages and larynx – the part of the throat involving your vocal cords – using a special instrument. Common issues people might face after these procedures can include a nosebleed (epistaxis), discomfort, a reflex to vomit or cough, and responses involving your vagus nerve, which helps control your heart rate, digestion and other body functions (referred to “vagal episodes”).
But it’s important to note that adding stroboscopy (a technique that uses flashing light to capture slow-motion video of vocal cord vibrations) to a nasolaryngoscopy procedure doesn’t make it riskier. Videostroboscopy, which combines both techniques, is generally considered safe.
What Else Should I Know About Videostroboscopy?
Videostroboscopy is considered the best method for capturing images of the larynx, which is your voice box. It is cost-effective, simple to use, and provides real-time sound and visual feedback. This makes videostroboscopy a very useful tool for diagnosing problems with the voice. However, the analysis of the data it provides can vary and often depends on the individual interpreting the results.
There’s also advanced technology that can provide even more information about how your vocal cords vibrate and how they look in detail. Laser-based high-speed videoendoscopy and videokymography are examples of this, but they are usually only used for research purposes or at large voice centers.
Videostroboscopy not only helps to evaluate voice disorders but also plays a part in monitoring voice box health in relation to cancer. For example, if the mucosal wave (a wave-like motion on the surface of your vocal cords) is reduced or missing, it may indicate issues like early throat cancer, scarring, severe skin thickening, or inflammation. Moreover, videostroboscopy can be used to check how the voice box is functioning before and after surgery, see how effective voice therapies are, and monitor the results of surgical treatments.
