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Flaccid laryngeal nerve paralysis may be treated by vocal fold augmentation with Teflon injection, which is successful to various degrees depending on the subjective interpretation of the patient or clinician. A new material, Phonogel, consisting of cross-linked bovine collagen, is available but not approved for human use in this area. Ten dogs were submitted to videostroboscopy, photoglottography, electroglottography, and acoustic analysis in the normal state, with stimulated recurrent laryngeal nerve paralysis, and with injection of either Teflon or Phonogel. A statistical comparison and the advantages and disadvantages of each material are discussed in relation to this study and its clinical use.

Photoglottography and electroglottography are relatively noninvasive techniques that provide detailed information about vocal fold vibration. However, few significant clinical applications have been made by correlating photoelectric waveforms to specific pathologic changes in laryngeal vibration. Videostroboscopy has recently been used to document vibratory patterns of laryngeal paralyses in a canine model of phonation. A study of PGG and EGG waveforms correlated with videostroboscopy in an in-vivo canine model of phonation with simulated unilateral recurrent or superior laryngeal nerve paralysis is presented. The shift quotient--a new glottographic parameter which identifies flaccid laryngeal paralyses--is presented.

Recent reports have suggested that blood flow to the vocal fold decreases during phonation. However, these studies relied on indirect measures of blood flow, such as tissue oxygen tension. Among the differing methods of measuring blood flow, one of the most sensitive is the microsphere surface technique. This technique has been effective in assessing the overall and regional blood flow to a number of different organs, including the cochlea. Employing an in vivo canine model, we injected microspheres into the left atrium. From there, they were distributed and became entrapped in the tissues in proportion to blood flow. We measured the blood flow to the entire vocal fold, as well as the lamina propria and muscularis layers. The results revealed a statistically significant (p less than .002) increase in blood flow on phonation. The increase, however, was due to increased flow to the muscularis layer. The flow to the lamina propria remained unchanged during phonation.