Endolymphatic sac tumours: surgical management

BACKGROUND Endolymphatic sac tumours (ELSTs) have been known as an individual tumour entity only since 1984. ELSTs may occur either solitarily and sporadically or as a hereditary manifestation associated with von Hippel-Lindau (VHL) disease. The latter association was first observed in 1992 and confirmed by molecular genetic analysis of the VHL gene. No consensual diagnostic and treatment strategy of ELST exists at present. METHODS Based on imaging criteria in computed tomography, magnetic resonance imaging (MRI), and magnetic resonance angiography, we developed a staging system to classify ELST in a series of seven consecutive patients in an attempt to custom-tailor the surgical approach. Type A referred to tumours that were locally confined without temporal bone erosion or infiltration of the dura (n = 2); type B tumours showed evidence of bone infiltration of the osseous labyrinth and sensorineural hearing loss (n = 2); and in type C, the tumour further invaded the sigmoid sinus and jugular bulb (n = 3). Two patients suffered from VHL disease. RESULTS In all patients, the tumour was completely removed. Stage-adapted surgical approaches included various transpetrosal procedures, from the translabyrinthine to the infratemporal approaches. The functional integrity of the facial nerve was maintained in all tumour stages, whereas the vestibulocochlear nerve could be preserved only in patients with type A tumours. Follow-up MRI demonstrated no local tumour recurrence during a postoperative observation period ranging from 4 to 38 months. CONCLUSION Stage-based surgical strategy enables the complete removal of ELST with minor morbidity. Transmastoid approaches are most efficient for resection of the tumour matrix to prevent local recurrence.