caa a22 4500 477108156 CHVBK 20180405111601.0 cr unu---uuuuu 170330e19960801xx s 000 0 eng 10.1007/BF01411288 doi (NATIONALLICENCE)springer-10.1007/BF01411288 Influence of blood supply, thermal and mechanical traumata on hearing function in an animal model [Elektronische Daten] [V. Braun, H. Richter] Summary: Even with modern neurosurgical techniques preservation of functional hearing in acoustic neurinoma surgery is still impossible in a large number of cases. Due to the necessity of averaging the brainstem auditory evoked potentials (BAEP) this monitoring is not a real time measurement. Therefore the surgeon cannot be sure which manipulation during the tumour dissection has caused the loss of the BAEPs. The direct monitoring of the cochlear nerve (CNAP) may warn the surgeon earlier. But it is not able to explain, which manipulation has caused the worsening of the potentials. A loss of the waves after coagulation of a vessel next to the cochlear nerve may be the result of the heat or of the disturbance of the blood supply. Potentially harmful to cochlear nerve function may be the interruption of inner ear blood supply, thermal or mechanical traumta. Experimental studies are rare to nonexistent. We therefore tested selectively each trauma for its influence on the BAEPs in an animal model. In New Zealand rabbits a lateral craniectomy of the posterior fossa was performed. Care was taken not to retract the cerebellum or to open the inner ear system, because both factors might disturb the BAEPs. Each step of the operation was followed by BAEP recording. After reaching the internal auditory canal, the cerebellopontine angle of 6 animals was exposed to heated water with definitive increasing temperature. The BAEPs did not react significantly until 71 °C was reached and protein coagulation started. In the second group, the internal auditory artery of 6 rabbits was compressed with a microdissector for 3 minutes. Subsequently the BAEPs disappeared in all animals. In the last group a constant pressure of 10 g was applied to 6 cochlear nerves for 1 minute consistently causing the loss of the BAEPs. The results are statistically significant (p=0.03). We therefore concluded that the blood supply of the inner ear is of the upmost importance for cochlear nerve function. Mechanical manipulation should be minimized whereas thermal traumatization of the nerve is only critical when the nerve itself is coagulated. Springer-Verlag, 1996 Acoustic neurinoma nationallicence BAEP monitoring nationallicence hearing preservation nationallicence inner ear blood supply nationallicence Braun V. Department of Neurosurgery, University of Ulm, Günzburg, Federal Republic of Germany aut Richter H. Department of Neurosurgery, University of Ulm, Günzburg, Federal Republic of Germany aut Acta Neurochirurgica Springer-Verlag 138/8(1996-08-01), 977-982 0001-6268 138:8<977 1996 138 701 https://doi.org/10.1007/BF01411288 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF01411288 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Braun V. Department of Neurosurgery, University of Ulm, Günzburg, Federal Republic of Germany aut NATIONALLICENCE 700 1- Richter H. Department of Neurosurgery, University of Ulm, Günzburg, Federal Republic of Germany aut NATIONALLICENCE 773 0- Acta Neurochirurgica Springer-Verlag 138/8(1996-08-01), 977-982 0001-6268 138:8<977 1996 138 701 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer