Videostroboscopy of human vocal fold paralysis

Area of Science:

• Otolaryngology
• Neurology
• Speech Science

Background:

• Laryngeal paralysis diagnosis is challenging due to infrequent stroboscopic studies and lack of lesion site documentation.
• Understanding vocal fold vibration dynamics is crucial for diagnosing laryngeal paralysis.

Purpose of the Study:

• To investigate the characteristics of vocal fold vibration in human laryngeal paralysis using stroboscopy and glottography.
• To identify objective diagnostic markers for laryngeal paralysis, differentiating between superior and recurrent laryngeal nerve involvement.

Main Methods:

• Unilateral infiltration of recurrent and superior laryngeal nerves with lidocaine in volunteers to simulate paralysis.
• Videostroboscopic analysis, photoglottography, and electroglottography synchronized to assess vocal fold motion.
• Studied 20 patients with untreated laryngeal paralysis.

Main Results:

• The primary finding was significant asymmetry in traveling wave motion on stroboscopy of the paralyzed larynx.
• Normal vocal folds exhibited faster wave velocity and greater mucosal wave distance compared to paralyzed folds.
• No symmetric traveling wave was observed in any patient or volunteer with laryngeal paralysis.

Conclusions:

• Asymmetric traveling wave motion is a consistent finding in human laryngeal paralysis, regardless of nerve involvement.
• Synchronized glottography provides valuable timing information for asymmetric laryngeal vibrations.
• These findings enhance diagnostic capabilities for laryngeal paralysis.