Reversible deafness as model of pressure damage to the VIIIth nerve.

Frequency-specific compound action potentials (CAP) of the VIIIth nerve were registered in patients in which surgery confirmed retrocochlear pathology. A different pathologic behaviour of threshold latency was encountered for 2 and 4 kHz CAP, respectively. This was due to the question of whether transmission of neural information by the acoustic nerve's fibres was blocked completely by retrocochlear pathology or not. A totally reversible hearing loss in a case of cystic arachnitis can offer a reasonable explanation.