Video Laryngeal Stroboscopy - Indications and the Procedure

Introduction:

The vocal cords vibrate rapidly, making it impossible for the human eye to appreciate the actual vibration. When one is engaged in a conversation, the vocal folds in males vibrate on an average of 100 to 130 times a second, and the vocal folds in females vibrate on an average of 190 to 220 times a second. A video laryngeal stroboscope uses a strobe light that forms a series of images depicting the vocal folds' slow-motion vibration. This enables the physician to examine the vibration of the vocal folds and to detect any problems in the functioning of the vocal cords.

How Is Voice Produced in Human Beings?

The production of sound requires three constituents, namely:

• A power source.

• A vibratory source.

• A resonator.

The expired air in humans, which moves out from the lungs by the diaphragm and intercostal muscles, acts as the power source. The vocal folds that are present within the larynx act as the vibratory source, and the combination of the upper airways and oral cavity make up the resonator chamber. The vibratory pattern of the vocal folds is known as the 'mucosal wave' since the movements of the vocal folds mimic the waves in a fluid medium. The vibration of the vocal folds involves multiple steps and results from the teamwork between the anatomical structures and air pressure. The production of voice in humans is as follows:

• During inhalation, the diaphragm contracts and flattens as the lungs get filled with air.

• During exhalation, the air from the lungs travels up through the trachea (windpipe) and reaches the larynx or voice box.

• The vocal folds in the larynx remain open when one breathes and close when one produces a sound.

• The gushing of air through the vocal cords facilitates the vocal cords' vibration, producing voice.

What Are the Parameters That Are Assessed Using Video Laryngeal Stroboscopy?

The following parameters are assessed using this procedure:

• Vocal Fold Edges: The edges of the vocal folds are assessed to determine whether they are rough, smooth, straight, or irregular.

• Vocal Fold Closure: The vocal cords are examined to determine whether they close entirely or gaps are formed while closing.

• Structural Characteristics: These characteristics include looking for the presence of any abnormal laryngeal structures that hinders the phonation and the presence of any unusual bumps or masses.

• Vibration Characteristics: These include checking whether the vocal cords vibrate symmetrically without any irregularity or stiffness and assessing whether they are sufficiently flexible to permit adequate pitch variation.

When Is a Video Laryngeal Stroboscopy Indicated?

A video laryngeal stroboscopy is indicated in the following conditions:

• Noncancerous (benign) vocal cord lesions or polyps.

• Hoarseness.

• Difficulty breathing.

• Vocal cord paralysis (inability to move one or more vocal cords).

• Dysphagia (difficulty swallowing) and other swallowing disorders.

How Does a Video Laryngeal Stroboscope Function?

The vocal cords vibrate at a rapid rate when singing, yelling, or talking. A long, thin tube accompanied by an attached camera records a video of the vibrations of the vocal cords in slow motion. This slow-motion video helps the healthcare professional to determine if the vocal cords are vibrating normally, and helps to detect the presence of any lesion that hinders the vibration.

How Should One Be Prepared for Video Laryngeal Stroboscopy?

In video laryngeal stroboscopy, there is no requirement for general anesthesia (a medicine that puts one to sleep so that a person does not feel any pain during the procedure). An appointment is made with the healthcare professional, and the procedure is done as an outpatient procedure. If a child is receiving a video laryngeal stroboscopy, then the parent or the guardian can bring a comfort item that would help the child when they are nervous. A young child can sit on the parent's or the guardian's lap during the procedure.

How Is Video Laryngeal Stroboscopy Carried Out?

The procedure is as follows:

• A topical numbing medicine is applied on the inside of the nose. The effect of the numbing medicine will extend to the throat making it numb.

• The physician will tie a tiny microphone around the person’s neck to record the vocal sounds.

• A thin, flexible tube called an endoscope is inserted through the nose to the posterior of the throat. Due to the numbing medicine, the person will not feel any discomfort at this stage.

• The physician will ask the individual to speak or make sounds like ‘eee’ or ‘aah’ and correspondingly record a video of the vibration of the vocal cords. This might take around 15 to 20 minutes.

• Once the necessary range of sounds has been recorded, the physician will carefully pull out the endoscope from the nose and the throat.

• The effect of the numbing medicine might take around one to two hours to fade away. During this period, one can find it difficult to feel the nose and the throat. It is better to avoid eating since swallowing can be difficult when the throat feels numb. Water or clear liquids can be consumed till the throat feels normal.

The diagnosis will be provided shortly following the procedure. The doctor will inform the individual if further tests or treatments are required.

Will Video Laryngeal Stroboscopy Be Painful?

Since topical numbing cream is applied, one does not feel any pain during the procedure. There is usually no pain even after the procedure. Very rarely, there can be minor bleeding from the nose after the procedure. One can seek medical help in such situations.

Who Performs a Video Laryngeal Stroboscopy?

The procedure may be performed by the following:

• A specialized laryngologist who is an expert in diagnosing and treating the disorders of the larynx (voice box) and vocal cords.

• Otolaryngologist or an ENT (ear, nose, and throat specialist) who is an expert in diagnosing and treating the conditions of the ear, nose, and throat.

• A speech-language pathologist (an expert in diagnosing and treating communication and swallowing problems).

• A specialty-trained nurse practitioner who carries out the procedure under the guidance of a laryngologist or an otolaryngologist.

What Are the Challenges and Complications of Video Laryngeal Stroboscopy?

The challenges and complications are as follows:

• Since the slow-motion effect can be obtained only with prolonged phonation, cooperation from the patient is important.

• The procedure's success can be affected by the individual's anxiety, discomfort, and inappropriate compliance with the instructions.

• The procedure might be contraindicated in individuals with strong gagging reflexes, those having airborne contagious infections, and anxiety regarding medical procedures.

• Though bleeding is rare and resolves immediately, video laryngeal stroboscopy is contraindicated in those with bleeding disorders since the insertion of the scope through the nasal passage can sometimes result in mucosal damage and epistaxis (bleeding from the nose).

Conclusion:

Video laryngeal stroboscopy is a procedure that is carried out to examine the vocal cords and is considered the gold standard procedure for laryngeal imaging. The advantages of this procedure are that it is easy to use, cost-effective, and real-time audio and visual feedback can be obtained. Besides diagnosing voice disorders, video laryngeal stroboscopy plays a major role in oncologic surveillance. An absence or decrease in the mucosal wave indicates structural abnormalities and flexibility of the vocal cord, which can be a sign of various health conditions like scarring, early glottic carcinoma (a common laryngeal cancer involving one or both the vocal cords), and so on. It is a painless procedure, and one can continue with their daily activities after the procedure.