BACKGROUND: In clinical routine we have noticed a disagreement of ENT-specialists and phoniatricians in the division of the vocal folds in thirds. To show if there is consensus in this field by the german phoniatricians this study was done.
METHODS: In two parts of a study, a pilot study and a follow up study, we sent twelve different images of the larynx to all german phoniatricians. In six of these images the physicians should set the marks of the ventral and dorsal limitation of the second third of the vocal folds. In six different images a mark should be related to the particular third of the vocal folds. The phoniatricians were asked to assess how certain they were in their valuation. They were asked either, how long they have been working as a physician and how long they have been specialized as a phoniatrician and as an ENT-surgeon. In the follow up study the phoniatricians were requested to first divide up the thirds in a way that the dorsal third corresponds to the cartilaginous part of the vocal folds (scheme 1) and second divide up the thirds in a way that all three thirds correspond to the ligamental part of the vocal folds. DISCUSSION AND FINDINGS: In the pilot study, when no instructions for the division of the thirds were given, the data differed much more than in the follow up study, when the physicians were told to use scheme 1 and scheme 2. That was because some phoniatricians divided up just the ligamental part and others the ligamental plus the cartilaginous part of the vocal folds in thirds. The more the physicians could overlook the membraneous part of the vocal folds the more certain they were in their assessment.
CONCLUSIONS: The assessment of the division of the vocal folds in thirds is more homogeneous when the phoniatricians were requested to divide up the thirds in a way that the dorsal third corresponds to the cartilaginous part of the vocal folds (scheme 1). Therefore we suggest that this way of division should be used further on.