Descriptive Analysis of the Arterial Supply to the Auricle in Patients with Unilateral Microtia

Anatomic Study of Vascular Supply of the External Ear Using CT Angiography in Congenital Microtia

BACKGROUND

The morphology of the arteries of the external ear on the affected side of congenital microtia differs from normal. The present study aimed to use computed tomography angiography (CTA) to describe the anatomic variations of arteries in microtia and provide theoretical guidance for the first stage of autologous auricular reconstruction by the 2-stage method.

METHODS

Ten patients with unilateral microtia from May 2021 to August 2021 were included. Computed tomography angiography and 3-dimensional reconstruction were used to analyze the supply and branches of the main arteries of the auricle. The number of the superficial temporal artery (STA) and posterior auricular artery (PAA) branches to the auricle, vessel diameter, and the presence or absence of the STA and PAA branches were documented. The skin flap and incision were designed combined with the anatomic of auricular arteries.

RESULTS

The blood supply of the auricle mainly came from the STA and PAA. The STA's preauricular branch and PAA's posterior auricular branch were absent to varying degrees, and the middle branch was more prominent. The average diameter of the STA on the healthy auricle was 3.07±0.96 mm, and the average diameter of the PAA was 1.72±0.50 mm. The average diameter of the STA on the microtia auricle was 2.65±0.42 mm, and the average diameter of the PAA was 1.53±0.67 mm. There was a statistically significant difference in the diameter of STA between the healthy auricle and the microtia auricle (P=0.006). However, there was no significant difference in the diameter of the PAA between the healthy auricle and the microtia auricle (P=0.112). The skin flap and incision were designed and combined with the preoperative CTA images, and no flap necrosis was observed in all patients.

CONCLUSION

The vascular distribution of arteries in microtia patients was clearly and accurately assessed by CTA. In our experience, the data and detailed imaging were useful in designing skin flaps and incisions during the first stage of autologous auricular reconstruction by the 2-stage method.

The role for cochlear implants in microtia and congenital aural atresia: A case report and a review of literature

Sensorineural hearing loss resulting from microtia and aural atresia is rare due to different embryologic origins of the external and inner ear. Consequently, cochlear implants are seldom performed in patients with microtia and/or aural atresia. Herein we discuss an 8 year-old boy with congenital aural atresia and microtia who underwent cochlear implant surgery for profound hearing loss with good results. A literature review was performed and discussed. Pre-operative planning with high resolution computed tomography and facial nerve monitoring are crucial in identification and preservation of the facial nerve due to the high rate of aberrant anatomy. Careful incision placement is required particularly if pinna reconstruction is considered. Literature review highlighted various surgical approaches as well as different modalities used for intra-operative facial nerve monitoring. Only one patient had intra-operative complications. Cochlear implant is a viable solution in patients with external ear malformations and severe-profound sensorineural hearing loss. Adequate planning and counselling are essential due to the challenges that may occur in microtia and aural atresia.

Shape Optimization of Costal Cartilage Framework Fabrication Based on Finite Element Analysis for Reducing Incidence of Auricular Reconstruction Complications

Skin necrosis is the most common complication in total auricular reconstruction, which is mainly induced by vascular compromise and local stress concentration of the overlying skin. Previous studies generally emphasized the increase in the skin flap blood supply, while few reports considered the mechanical factors. However, skin injury is inevitable due to uneasily altered loads generated by the intraoperative continuous negative suction and uneven cartilage framework structure. Herein, this study aims to attain the stable design protocol of the ear cartilage framework to decrease mechanical damage and the incidence of skin necrosis. Finite element analysis was initially utilized to simulate the reconstructive process while the shape optimization technique was then adopted to optimize the three-pretested shape of the hollows inside the scapha and fossa triangularis under negative suction pressure. Finally, the optimal results would be output automatically to meet clinical requirement. Guided by the results of FE-based shape optimization, the optimum framework with the smallest holes inside the scapha and fossa triangularis was derived. Subsequent finite element analysis results also demonstrated the displacement and stress of the post-optimized model were declined 64.9 and 40.1%, respectively. The following clinical study was performed to reveal that this new design reported lower rates of skin necrosis decrease to 5.08%, as well as the cartilage disclosure decreased sharply from 14.2 to 3.39% compared to the conventional method. Both the biomechanical analysis and the clinical study confirmed that the novel design framework could effectively reduce the rates of skin necrosis, which shows important clinical significance for protecting against skin necrosis.