Comparison of the healing mechanisms of human dry and endogenous wet traumatic eardrum perforations

This prospective study aimed to assess the spontaneous healing mechanisms of human dry and endogenous wet traumatic tympanic membrane perforations (TMPs). A total of 106 patients with traumatic TMPs were included. Based on the presence or absence of endogenous bloody or watery exudates on the residual eardrum and/or at perforation margins, 73 perforations were classified as dry perforations and the remaining 33 as endogenous wet perforations. In 65 of the 73 dry perforations, centripetal migration of an epithelial layer was the first event seen during the spontaneous healing process, which was followed by growth and migration of the other two layers (i.e., the fibrous layer and the inner mucous layer). In the remaining eight dry perforation cases, outward epithelial migration was observed on the side of the perforation edge. In the 33 endogenous wet perforations, closure seemed to start with growth of the fibrous layers which were then covered by the migrating epithelium. Within the first week after injury, only 16.3 ± 6.7 % of the perforation area healed in the dry perforation cases, whereas 82.2 ± 13.9 % of the perforation area healed in the wet perforation cases; the difference was significant (P < 0.01). These observations suggest that different mechanisms may be involved in spontaneous healing of dry and wet traumatic TMPs in humans, thereby resulting in differences in healing time and healing outcome.