In response to The topical use of insulin accelerates the healing of traumatic tympanic membrane perforations.

Traumatic tympanic membrane (TM) perforations heal spontaneously ranging from 78.7% to 88%. Otologists recommend a golden rule, keep the ear dry, as an important factor influencing TM healing. This way, Araujo et al., in their article “The Topical Use of Insulin Accelerates the Healing of Traumatic Tympanic Membrane Perforations,” describe a control group of Wistar rats in which traumatic perforations were made with a standardized needle in the pars tensa of the TMs. The ears were kept dry and spontaneous healing was followed. In the Letter to the Editor, Dr. Zheng-Cai Lou speculates that we should have chosen the saline group to be our control group. We disagree. First, we believe that moist/wet environments may not be better than dry ear for healing of traumatic TM perforation. In the article by Zheng-Cai Lou, it is even stated in the introduction that otologists obey the cardinal principle to keep the ear dry in TM perforations. On the other hand, we understand that if there has been speculation about the use of saline as a control group, new studies are necessary to confirm this. If the use of saline impairs the healing of TM perforation, saline use in TM will not be a good control group. Another discussion point is the comparison between the healing between TM and the skin. The early stages of wound healing in the TM follow the conventional wound-healing stages of hemostasis and inflammation. The proliferative and migratory stages are distinctly different. In cutaneous tissue, a granulation tissue bed forms, which serves as a platform upon which reepithelization occurs. The TM is unique as a wound-healing tissue in that it is suspended in air. The squamous epithelial layer initially forms a bridge across the wound, and only then is followed by the re-formation of fibrous component. Soon, we must be cautious when generalizing speculative treatments between both tissues and must respect their differences.