Ear Reconstruction. Clinical and physiological evaluations.

Abstract: Microtia is a congenital malformation where the auricle is not fully developed. In some cases the malformation is complete and the auricle is absent. In Sweden the incidence of microtia is about 2 per 10,000 births. Reconstruction of the external ear is possible by using autologous rib cartilage in three surgical steps: rib cartilage transplantation, ear elevation and final adjustments. Although the aesthetic result is most essential, there are also functional aspects of a reconstruction of the outer ear. To keep the ear free from injury, the skin depends on a functioning alert system: sensitivity to touch, heat and cold. However, the process of ear reconstruction necessarily includes surgical trauma that endangers these protective systems. The blood supply of the skin cover is also impaired during the different reconstructive stages. Little is known about the level and time scale of recovery of sensitivity and blood supply to the reconstructed ear after surgical bisection of nerves and vessels. Symmetry is important in ear reconstruction and the new ear should match the normal ear at the time of reconstruction as well as in the adult life. The potential growth of the ear is a subject of debate. We decided to investigate the precision of today’s tools for size measurements. With this knowledge the issue of growth hopefully can be elucidated. A total of 54 patients with unilateral ear reconstruction, and 30 individuals with normal ears, were included in the studies. We evaluated sensitivity to heat, cold and touch in the reconstructed and normal ear. We also assessed blood flow before and after body heating to investigate the pathophysiological dynamics in the reconstructed ear. Digital morphometry for measuring ear size was compared to the manual methods: compass & ruler and callipers. Measurements were performed on individuals with normal ears. In digital morphometry we also measured reconstructed ears. Our findings show that there is a high degree of restoration of thermosensitivity in the reconstructed ear but the upper parts of the ear still show signs of reduced sensitivity to heat. Tactile sensitivity followed that of thermal sensitivity, with a high degree of restoration in combination with elevated thresholds in the upper parts. The basal blood flow in the reconstructed ear is compatible with that of the normal ear and its dynamic response to indirect heating is also similar. Digital morphometry shows a similar reproducibility as compass & ruler and callipers for measurement of normal ears. Digital morphometry can show great precision in measurements of reconstructed ears but there is high inter-individual variation between different assessors.