[Tumour staged surgery of endolymphatic sac tumors (ELST)].

BACKGROUND: Endolymphatic sac tumours (ELST) have only been known as own tumour entities since 1984. ELST might occur solitarily and sporadically as well as hereditary connected to von Hippel-Lindau disease (VHL). This connection has been observed in 1992 for the first time and confirmed by molecular genetic analyses of the VHL gen. There is no agreement yet concerning diagnostics and therapy.

METHODS: Our attempt of classifying this type of tumour is the first one. According to our own experience and to literature, we suggest the following classification: ELST type A is locally confined without erosions of the temporal bone nor infiltration of the subarachnoidal area; ELST type B with bony infiltration of the labyrinth block and clinical hearing loss, and ELST type C with additional infiltration of the sigmoid sinus and the vein of jugular bulb. Preoperative diagnostics are performed according to defined radiological criteria in CT and MRI scans including MR-angiography.

RESULTS: In 6 patients, including two with a VHL syndrome, ELST was completely sanitized by stage-compatible surgery, using translabyrintine to infratemporal approaches, according to the tumour classification that we developed. The VII (th) nerve could be saved in all tumour stages, and in stage ELST type A the VIII (th) nerve as well. All patients remained without local recurrence in MRI check during the observation period of 4 to 38 months.

CONCLUSION: Our stage-compatible surgery of ELST allows total tumor removal with minor morbidity. In contrast to the antero-, retrosigmoidal and suboccipital approaches, the tumour matrix can be safely removed via transmastoidal approach to exclude local recurrences.