[Impression of the thyroid cartilage lamina--differential diagnosis in hyperplasia of the ventricular fold].

Impression of the thyroid lamina is presented by means of CT examinations of the larynx and in correlation with the clinical features and with serial sections of the larynx in the horizontal plane. This anomaly of the thyroid lamina produces the laryngoscopic aspect of a hyperplastic false vocal cord. Measurements proved that the horizontal extension of the convex thyroid lamina is always longer than the lamina of the other side. The pathogenetic mechanism in the development of this anomaly lies--in our opinion--in the irregular increase in size that probably begins at the onset of puberty. The impression of the thyroid lamina is predominantly found in men and mainly on the left side. In its effects this anomaly must be classified as a dysplastic dysphonia and as such it reduces the capacity of the vocal organ and predisposes to the development of functional dysphonia. There should be careful differentiation between the impression of the thyroid lamina and the "genuine" hyperplastic ventricular fold, because these clinical syndromes are completely different from each other in aetiology, therapy and consequences.