[A lidocaine base for surface anesthesia of the tympanic membrane]

An anatomical study was conducted to determine the effects of 10% lidocain base (dissolved in DMSO) on the structure of the tympanic membrane. Survival times ranged from 1 day to 3 months. Membranes were embedded in plastic and cut in semithin sections. Within 1 and 3 days mild swelling of the epithelium was seen; 1 month after treatment the connective tissue layers of the lamina propria were severely hyperplastic. 2 months after lidocain-Base application additional collagen fibres, loosely packed and less regularly, appeared in the submucosal connective tissue layer. However, normal appearance of the drums was noticeable after 3 months survival.