Transcanal Endoscopic Assisted Skull Base Endolymphatic Sac Tumour Resection: A Rare Disease with Advanced Technology

By June 7, 2019

Chan, Po Ling1; Chang, Wai Tsz1; Tam, Ka Yue1; Tong, Michael Chi Fai1
1 Department of Otorhinolaryngology, Head and Neck Surgery, The Chinese University of Hong Kong, Hong Kong, China

Endolymphatic sac tumours(ELST) are rare but aggressive, papillary adenomatous tumours arising from the endothelium of the endolymphatic sac. It could cause local destruction of the temporal bone resulting in facial nerve(FN) weakness, tinnitus, hearing loss(HL) or vestibular dysfunction. For its challenging position in lateral skull base, current surgical approaches are invasive, requiring extensive bone drilling with big incisions and sacrificing hearing or FN functions. A new emerging approach – Transcanal endoscopic assisted approach is introduced with a case and step-by-step technique illustration to tackle these disadvantages.

A 52 year-old woman presented with nonspecific yet longstanding vertigo, tinnitus and fluctuating right-sided HL in 2014. Physical examination showed normal neurological and cerebellar functions, and bilateral normal tympanic membranes(TM). Contrast Magnetic Resonance Image revealed a lesion up to 2.1 x 1.3 x 2.2cm deep to posteromedial cortex of right temporal bone, abutting posterior semicircular canal and sigmoid sinus. Despite worsening vertigo and hearing, she refused open surgery via TLA or RSA for the invasiveness and cosmetic concern. Therefore, a transcanal combined endoscopic-microscopic retrolabyrinthine approach was performed for tumour resection.

A complete removal of the lesion is achieved with clear visualisation of the tumour location with surrounding important structures including middle and posterior cranial fossa dura, internal acoustic meatus and jugular bulb, and preservation of hearing and facial nerve functions. Post-operative Computer Tomography showed a clearance of tumor with minimal bone destruction. She recovered with static hearing and a small intra-auricular wound in two weeks with intact TM.

Transcanal endoscopic assisted technique provides a new surgical approach in accessing petrous apex and lateral skull base lesions.