A stroboscopy is a valuable diagnostic test that can be used to detect problems with the voice box. A trained otolaryngologist or speech-language pathologist can administer the painless test in less than half an hour in an outpatient setting. The stroboscopy test involves passing a long, flexible tube down your throat that emits fast, bright pulses of light. The frequency of the strobe light is adjusted to match the frequency of the vocal cord vibrations, allowing the physician to see a clear video image of the vocal cord activity. The procedure can detect problems such as cysts, tumors, especially loose or tight cords, and other abnormalities that would be difficult to recognize with less sophisticated types of tests.
The stroboscopy procedure makes use of a well-known phenomenon of light and human vision to reproduce very fast and subtle movements in a type of slow motion video. The strobe rate is set close to the normal frequency of the vocal cords when a certain tone is produced. As a patient vocalizes, the strobe light illuminates the chords by squeezing, relaxing, rising and falling. The video that is produced shows the average movement of the leads over a set time interval, which doctors use to determine abnormalities in the movement or structure of the leads.
A person who has a chronic sore throat, wheezing, and speech difficulties may be a candidate for a stroboscopy if other diagnostic tests fail to discover an underlying cause. During an initial evaluation, the doctor can explain the procedure in detail and make sure the patient is comfortable with it. The stroboscopy test is minimally invasive, very low risk, and does not cause pain or discomfort for most people.
At the beginning of the procedure, the patient is seated in a comfortable chair with the head tilted back. A topical anesthetic is applied to the back of the tongue and throat to prevent pain and nausea. The strobe is carefully fed through the mouth and down the larynx to the site of the vocal cords. The strobe light turns on and the patient is instructed to hold a long "e" sound at its normal pitch. The strobe rate is adjusted to match, and the doctor begins the recording process.
In most stroboscopy procedures, patients must go through several rounds of testing while making "e" sounds in high, medium, and low tones. Some voice box problems are not easily distinguished on certain tones, so changing the tone and trying several times can uncover a subtle abnormality. Once the test is complete, the doctor and patient can immediately review the video to assess the findings. Based on the results of the stroboscopy, decisions can be made about the need for additional surgical treatment, medications, or tests.