[Electro-cochleographic findings in posterior fossa tumours (author's transl)].

The different audiometric and electrocochleographic findings in two patients with acoustic neuromas are presented. Significantly different thresholds from the two methods of testing are explained on the basis of the ganglion cells, peripheral axons and hair cells remaining unaffected for some time whilst the central axons are damaged by tumour pressure. Differences of recruitment measured conventionally by ABLB audiometry or by electrocochleography are explained on a neurogenic basis. In cases of acoustic nerve fibre damage, single fibre tuning is altered to a raised threshold and a reduced frequency specificity.