Overview of Videostroboscopy
Stroboscopy (also known as “videostroboscopy” or “video endoscopy with stroboscopy”) is a widely used technique that lets us visualize how your vocal cords move. It’s a vital tool to assess the health of your voice.
The word “stroboscopy” comes from Greek, meaning “to look at something spinning.” The method has been around since the early 1800s when it was developed to watch pictures on a rotating wheel, creating an illusion of movement. This same idea was later applied to see how vocal cords vibrate, back in 1895.
When we speak, our vocal cords vibrate very fast, too quick for our eyes to see. Stroboscopy helps us “slow down” this movement and examine it. The process uses a special telescope (endoscope), a microphone, and a flashing light. The microphone is put near the voice box (the larynx) and helps gauge the voice’s main pitch. The flashing light then syncs to a slightly slower rate than this pitch, capturing the phases of the voice box’s cycle. This makes a slow-motion video clip of the vocal cords as they work, much like flipping through a flipbook to create motion.
There’s been some confusion about how stroboscopy works, mainly around how it achieves the “slow-motion” effect. This isn’t due to things like Talbot’s Law (a principle about the perceived brightness of objects) or persistence of vision (the idea that humans retain images for a fraction of a second). Instead, the effect comes from how our eyes perceive a series of flicker-free images when the frequency of the flashing light goes above a certain rate.
While stroboscopy is a more affordable option compared to other techniques like high-speed video, it has some limitations. It can’t monitor non-regular or wavering movements of the vocal cords. It struggles with a condition called diplophonia, where two different pitches occur at the same time, that interferes with the microphone calculating the main pitch and leads to irregular, inconsistent images. Plus, if the cycles of the voice box differ from one to the next, stroboscopy may not accurately show a single cycle. In these situations, it might be better to use videokymography (high-speed video scanning along a single line) or high-speed videolaryngoscopy.
Anatomy and Physiology of Videostroboscopy
To make sound, our bodies use three parts: a power source, something that vibrates to make noise, and something to amplify it (make it louder). Our bodies use the air we breathe out as the power source. This air is pushed from our lungs by the diaphragm and muscles between our ribs. The sound is made by something called the vocal folds located in our voice box or larynx. The upper part of our airway and our mouth amplify the sound.
When the vocal folds vibrate, it’s like waves moving in water. This vibration is moving in different directions and is complicated. It starts when the air we breathe out pushes against the closed vocal folds from below. When there’s enough pressure, the air can get through the folds. The vocal folds then start to open from the bottom up, creating a gap that moves upwards until it’s fully opened at the top.
As this ‘wave’ moves up and sideways across the vocal folds, two parts of the vocal folds interact: the cover and the body. They are both made up of multiple layers. The upper part, or cover, is made of a layer of cells (squamous epithelium) and an inner layer (Reinke’s space). The body is underneath and is made of the intermediate layer, the deep layer, and the voice muscle. When air flows quickly between the open vocal folds, it creates a lower pressure (Bernoulli’s effect) and closes the gap in the folds from bottom to top. So, the bottom edge of the vocal fold starts closing as the upper edge is opening.
Why do People Need Videostroboscopy
If you’re dealing with voice issues like hoarseness, breathlessness, getting tired from talking, losing your range of voice pitch, discomfort in your voice box, feeling tightness, irritation leading to frequent coughing or need to clear your throat, or strange sensation, you may benefit from a procedure called videostroboscopy. This procedure can also be useful if you’ve recently had surgery on your voice box or neck, are currently in voice therapy, or need to be monitored for cancer.
Videostroboscopy is often carried out after a doctor has used a special flexible camera (nasolaryngoscopy) to take a look at your throat and voice box. The advantage of videostroboscopy is that it shows and records how your vocal cords vibrate in real time. This allows your doctor to better understand what might be causing your voice problems.
When a Person Should Avoid Videostroboscopy
Videostroboscopy is a medical procedure that is generally safe and doesn’t pose much discomfort to the patient. It involves the use of a small device called a laryngoscope that goes through the mouth or nose, or a different kind of device that goes into the mouth. The patient usually finds the procedure quite manageable with some preparation and guidance from the doctor.
The procedure helps doctors see the vocal cords in a slow-motion effect. However, the patient should be able to make a steady sound over a period of time for the procedure to work effectively. The success of the examination could be affected if the patient is anxious or uncomfortable as they may not be able to follow the instructions correctly during the process.
However, not all the patients might be suitable for videostroboscopy. If a patient has a strong sense of gagging, a history of fainting spells, severe nervousness about medical procedures, or airborne diseases that can spread to others, the procedure might not be the best option for them. Also, patients with blood disorders or those taking anti-blood clotting medications might not be ideal candidates for this procedure because the laryngoscope can potentially damage the lining of the nose and cause a nosebleed. However, such bleeding occurrences are rare in clinical practice and usually heal on their own.
Equipment used for Videostroboscopy
Videostroboscopy, a technique to examine your throat and voice, needs the same resources as a flexible nasolaryngoscopy, an easy procedure to check your throat and voice box. However, videostroboscopy also uses a few extra pieces of equipment:
1. A flexible fiberoptic instrument or a digital chip-on-the-tip nasolaryngoscope, these are small tube-like devices used to look inside your throat.
2. A specialized laryngeal or throat microphone, this is a particular type of microphone that is placed on your neck.
3. A stroboscopy device – this piece of equipment analyses signals from the microphone. It uses this information to adjust the frequency of the light source, used by the doctor to get a good view inside your throat.
4. A recording device to store images or videos from the exam. This enables the doctor to review them in slow motion or image by image, which allows them to make a thorough examination of your condition.
Who is needed to perform Videostroboscopy?
Videostroboscopy is a medical procedure often carried out and analyzed by certain types of doctors and therapists. These professionals could be an otolaryngologist (a doctor who specializes in ear, nose, and throat issues), a laryngologist (a doctor who focuses on diseases and disorders of the voice box, or larynx), or a speech-language pathologist (a therapist who treats speech and communication problems). These specialists have the training and knowledge to properly conduct and understand the results of the videostroboscopy procedure.
Preparing for Videostroboscopy
Videostroboscopy is a test done at a doctor’s clinic, typically lasting around 2 to 3 minutes. This helps doctors see how your vocal cords move when you talk. Before this test begins, the doctor places a specialized microphone on your neck to better hear your voice’s pitch and loudness.
To prepare for the test, the doctor will apply a numbing medicine and a decongestant, usually 0.05% oxymetazoline hydrochloride, into your nose (for a nose-related approach) or on your tongue and the back of your mouth (for a mouth-related approach). These medications will make you more comfortable during the procedure.
Next, you’ll be asked to lean forward, like if you were sniffing something. This position helps the doctor better see your throat. The doctor then warms up or defogs a special instrument called a laryngoscope. This tool is carefully inserted through your nose and moved past the back of your throat to get a clear view of your vocal cords.
Once the laryngoscope is positioned correctly, the doctor will ask you to make an “ee” sound at various pitches and volumes. This way, the doctor can see and understand how your vocal cords are functioning.
How is Videostroboscopy performed
For doctors to study your vocal cords and how they move, they need to be able to see a full image of the voice box, which is also known as the larynx. This should include a view from the front of the box, all the way to the back, where there are two small cartilages shaped like pyramids, called arytenoids. Sometimes the epiglottis, a flap that covers your windpipe when you swallow, can get in the way but doctors will try to get around it to get a view.
During the examination, you will be asked to make different sounds, like /i/, at different pitches and volumes. These sounds need to be sustained for a period to allow the doctor to align the strobe light being used to examine the voice box. Once you have produced these sounds, the doctor will remove the examination tool known as a laryngoscope, and you can rest.
Some common tasks used for evaluation might include rapidly sniffing, creating an /i/ sound between breaths, and repeating sounds at different volumes and pitches. The doctor might also ask you to glide from low to high and high to low pitches and to repeat phrases like counting from 1 to 10, or naming days of the week or months of the year. All these help to evaluate your vocal fold mobility and symmetry.
After the examination, the doctor will review a video recording of your vocal cords in action. They use an evaluation form to rate different aspects of the vocal cords and their movements. They will look at several factors including the width and pattern of vocal cord movements, any areas where the vocal cords don’t vibrate, and the level of compression in your voice box during sound creation.
They’ll also look at the smoothness and straightness of your vocal folds and whether they are in alignment when your voice box closes. Other factors include the duration your vocal folds stay open and closed during sound creation, the symmetry of your left and right vocal fold movements, and the regularity and shape of your vocal cords when they close.
All these observations give the doctor a comprehensive understanding of the health and function of your vocal cords.
Possible Complications of Videostroboscopy
Videostroboscopy, a test used to look at your voice box, can have some side effects. These can be similar to those experienced with nasolaryngoscopy, which is another type of test done using a thin tube to view the inside of your nose and throat. Common side effects can include nosebleeds (epistaxis), discomfort, feeling an urge to gag or throw up, sneezing, coughing, and fainting-like episodes linked to the vagus nerve (vagal episodes). However, adding stroboscopy – which uses flashing light to capture video of vocal cord vibration – to the procedure doesn’t increase these risks. So, overall videostroboscopy is considered a safe procedure.
What Else Should I Know About Videostroboscopy?
Videostroboscopy is a state-of-the-art method used for viewing the throat, specifically the larynx or voice box. This tool has gained reputation for its cost-effectiveness and user-friendly features. Videostroboscopy offers instant audio and video feedback and is particularly handy for identifying voice problems. However, results can vary as they largely depend on the person interpreting the data.
More advanced technologies can deliver extra functional information about the vocal cords’ vibration and appearance. Tools such as high-speed laser videoendoscopy and videokymography can be used to analyze how the vocal cords vibrate, but they are primarily used for research purposes and in specialized voice centers.
Videostroboscopy also helps in monitoring for cancer. If the waves on the mucous membrane are decreased or absent, it might suggest issues with the vocal cord’s health and flexibility. This condition could hint at problems like dysplasia (abnormal cell growth), scarring, early signs of glottic cancer (cancer of the vocal cords), serious skin thickening or inflammation. Videostroboscopy is also used in determining the functioning of the voice box before and after surgery, evaluating how effective voice therapies are, and keeping track of surgical results.