[ENG findings in 47 acoustic neurinomas].

Abstract

ENG examinations still belong to the basic examinations in the diagnosis of acoustic neurinomas. The decisive finding in small and medium-sized tumours is a peripheral involutional vestibular symptomatology on the side of the lesion: vestibular caloric hyporeflexia to areflexia, possibly associated with spontaneous nystagmus towards the sound side. In large or giant tumours on the ENG tracing other symptoms caused by compression and pressure on the brain stem and flocculonodular part of the cerebellum are found: visual paretic nystagmus (its variant is Bruns-Stewart's nystagmus), rebound nystagmus, high fixation suppression index, ocular dysmetria (over- or undershoot) and delaging of the eyes during fixation of a moving target, compensated by corrective saccades in tests of continuous tracing of ocular movements, which all provide unequivocal evidence of the size of the tumour. In this way 13 small and medium sized tumours were diagnosed, as well as large tumours (above 2 cm in diameter) and giant tumours (above 4 cm in diameter) a total of 34. In this respect ENG findings were consistent with surgical ones and CT and if any CT cisternographic findings with contrasting air filling.