Transotic Approach for Microsurgical Resection of Expansile Endolymphatic SAC Tumor

Introduction: Endolymphatic sac tumors (ELST) are rare and indolent tumors that arise from the endolymphatic sac or duct in the posterior petrous ridge. We present the case of an especially expansile ELST with subsequent microsurgical management with a transotic approach.

Case Report: A healthy 25-year-old male presented to the otolaryngology clinic with a 5-year history of left-sided hearing loss and 1-year history of progressively worsening vertigo and headaches. Neurologic examination revealed decreased left-sided hearing and a Weber test demonstrated lateralization to the right side. An otoscopic examination revealed a dark red mass behind an intact tympanic membrane. Audiologic evaluation demonstrated near-complete sensorineural hearing loss on the left side and video nystagmography confirmed left-sided peripheral vestibular dysfunction. Thin-cut CT imaging revealed a large, locally aggressive mass centered in the posterior portion of the petrous temporal bone with curvilinear areas of calcification. Thin-cut MRI demonstrated a lobulated, heterogeneously enhancing 2.4 × 3.1 × 2.4 cm mass with extension into the cerebellopontine angle, posterolateral jugular foramen, tympanic cavity, and internal auditory canal. Differential diagnosis included an ELST with consideration of an atypical glomus jugulotympanicum tumor or a chondroid tumor. Surgery was offered as a consideration due to the patient’s age, debilitating symptomatology, and the locally aggressive nature of the tumor with proximity to vital cranial structures. Given the near-complete hearing loss and expansive tumor size, a transotic approach for microsurgical resection was deemed most appropriate. The patient was referred for endovascular consultation and subsequent angiography revealed arterial supply via the ascending pharyngeal and exclusive venous drainage into the left-dominant sigmoid sinus; he ultimately underwent successful tumor embolization with Onyx.

Surgical Management: The patient was placed in supine position and general anesthesia was administered. Neurophysiologic monitoring was performed for cranial nerves VII, IX, X, and XI in conjunction with SSEPs. The surgical area was prepped and draped and a C-shaped postauricular incision was used for initial bony exposure. The external auditory canal was transected and the skin of the ear canal was everted and then closed with 4–0 nylon suture. The tympanic membrane and malleus were exposed and removed and the incostapedial joint was transected. A mastoidectomy and subtotal petrosectomy was performed for partial tumor exposure. The facial canal, sigmoid sinus, and internal auditory canal were then carefully skeletonized and labyrinthectomy was performed, exposing the tumor from the sinodural angle to the jugular bulb. The eustachian orifice was packed the cochlea was drilled, completing tumor exposure. The tumor was then debulked and resected using a combination of bipolar cautery and blunt and sharp dissection with complete decompression of all vital cranial structures. A small portion of tumor remained near the distal sigmoid sinus. A left lower abdominal fat graft was used for closure with sequential closure of all skin layers. Histopathologic analysis revealed an ELST.

Discussion: Endolymphatic sac tumors (ELST) are rare and locally aggressive tumors that may sometimes present with significant extension outside of the middle ear. The transotic approach is a viable solution that offers wide-exposure and facilitates tumor removal.

Fig. 1 Axial T2 FIESTA and coronal postcontrast high-resolution preoperative MRI.

Fig. 2 Microsurgical resection via transotic approach allowing generous exposure.

Fig. 3 Axial and coronal postcontrast postoperative MRI with gross-total resection without residual nodural enhancement.