Participants and Methods
Ethic statement
Our study was approved by both ethics review committees of Kyushu University Hospital (permit no. 29-43).
Patient selection and profile
We retrospectively reviewed patient records, as shown in the patient selection flow chart in Figure 1. Applicable patients were treated at the Department of Otorhinolaryngology Head and Neck Surgery, Kyushu University Hospital, from January 1993 to July 2020. The initial dataset of patients with temporal bone malignancies comprised 181 cases, of which a final dataset of 64 cases was selected based on patients treated with en bloc temporal bone resection preserving the auricle. To estimate patient physical functioning, we used the Eastern Cooperative Oncology Group (ECOG) performance status scale. All patients were capable of self-care and their performance status was defined as ≤ 2.
Data collection and statistical analysis
From the final data set, we gathered information related to auricular complications, including sex, age, affected side, clinical stage, presence of pre-/infra-auricular lymph node dissection, history of radiotherapy, surgical procedure, type of skin incision, additional surgical procedures, reconstruction method, and auricular complications. We used a Fisher exact two-sided test to examine the association between auricular complications and categorical variables, namely neck dissection, parotid gland resection, pre-/infra-auricular lymph node metastasis, temporomandibular joint manipulation, and history of radiation therapy at the locoregional site. We used JMP 6.1 software (SAS Institute, Cary, NC, USA) for statistical analysis and selected P < 0.05 to indicate statistical significance.
Cadaveric dissection
Three formalin-perfused adult cadaveric heads were dissected to reveal the vascular structures related to the auricle. The arteries and veins were injected with red or blue silicone rubber (Dow Corning, Midland, MI, USA), Thinner 200 (Dow Corning), and RTV catalyst (Dow Corning), then dissected under 3–40 × magnification.
En bloc surgical procedure for temporal bone malignancies
Two surgical procedures are used globally: 1) lateral temporal bone resection, which involves en bloc removal of the external auditory canal (EAC) along with the tympanic membrane; and 2) subtotal temporal bone resection, which involves en bloc removal of the temporal bone, including (or transecting) the otic capsule. Depending on local progression, these are combined with additional procedures, including parotid gland resection, neck dissection, and manipulating the temporomandibular joint (TMJ).