Variations of en Bloc Resection for Advanced External Auditory Canal Squamous Cell Carcinoma: Detailed Anatomical Considerations

Abstract

Currently, only lateral temporal bone resection (LTBR) and subtotal temporal bone resection (STBR) are widely utilized for the surgical treatment of advanced squamous cell carcinoma of the external auditory canal (EAC-SCC). However, there are few descriptions of variations on these surgical approaches. This study aimed to elucidate the variations of en bloc resection for advanced EAC-SCC. We dissected the four sides of cadaveric heads to reveal the anatomical structures related to temporal bone resection. From the viewpoint of surgical anatomy, surgical patterns of temporal bone cutting can be divided into four categories: conventional LTBR, extended LTBR, conventional STBR, and modified STBR. Extended LTBR is divided into four types: superior, inferior, anterior, and posterior extensions. Several extension procedures can be combined based on the extension of the tumor. Furthermore, en bloc resection with the temporomandibular joint or glenoid fossa increases the technical difficulty of a surgical procedure because the exposure and manipulation of the petrous segment of the internal carotid artery are limited from the middle cranial fossa. Surgical approaches for advanced SCC of the temporal bone are diverse. They require accurate preoperative evaluation of the tumor extension and preoperative consideration of the exact line of resection to achieve marginal negative resection.

Treatment outcome and prognostic factors of external auditory canal squamous cell carcinoma: A retrospective study in a tertiary center

“…When a tumor extends posteriorly into the mastoid cavity, it can further invade the sigmoid sinus through the posterior cranial fossa. During STBR and TTBR procedures, the sigmoid sinus and jugular bulb are routinely exposed 19 . Intraoperative closure of the sigmoid sinus and jugular bulb has been shown to be generally safe with rare clinical consequences, likely due to the system of collateral drainage and emissary veins that compensate for sigmoid sinus closure 20 .…”

“…During STBR and TTBR procedures, the sigmoid sinus and jugular bulb are routinely exposed. 19 Intraoperative closure of the sigmoid sinus and jugular bulb has been shown to be generally safe with rare clinical consequences, likely due to the system of collateral drainage and emissary veins that compensate for sigmoid sinus closure. 20 However, some authors classified tumor‐invading sigmoid sinus as an unresectable disease.…”

Clinical manifestations and treatment strategies for congenital aural atresia with temporomandibular joint retroposition: A retrospective study of 30 patients

“…Meanwhile, some EAC diseases, such as cholesteatoma and malignancies, can directly destroy the anterior wall of the EAC and invade the TMJ [15][16][17][18].…”

Impact of Positive-Margin Resection of External Auditory Canal Squamous Cell Carcinoma

“…We carefully assessed the extent of tumor extension preoperatively. (Table 2) All surgical procedures were determined based on the direction of tumor extension and included conventional LTBR (cLTBR), extended LTBR (eLTBR) [13], modified STBR (mSTBR) [10], and conventional STBR (cSTBR) [13]. The eLTBR was defined as the cLTBR with superior, inferior, anterior, or posterior extension, as previously reported [13].…”

“…(Table 2) All surgical procedures were determined based on the direction of tumor extension and included conventional LTBR (cLTBR), extended LTBR (eLTBR) [13], modified STBR (mSTBR) [10], and conventional STBR (cSTBR) [13]. The eLTBR was defined as the cLTBR with superior, inferior, anterior, or posterior extension, as previously reported [13]. The mSTBR was composed of temporal craniotomy rather than temporooccipital craniotomy, and limited posterior mastoidectomy [10].…”