title: Effects of cerebellar retraction on brainstem auditory evoked potentials in an experimental animal model of cerebellopontine angle tumor.
abstract: The effects of cerebellar retraction on brainstem auditory evoked potentials (BAEPs) were studied in 15 New Zealand rabbits. In the first series, a Fogarty catheter was placed in the cerebellopontine angle of 5 rabbits. When a balloon volume of 0.2 mL was produced, only the latencies of waves III-V of the ipsilateral side increased. With a volume of 0.4 mL the ipsilateral BAEPs were irreversibly lost and the contralateral one reversibly changed. A volume of 0.6 mL caused loss of the BAEP on both sides and death of the animal. In another series, the cerebellum of 10 rabbits was retracted by a self-retaining retractor laterally to medially, so an approach to the cerebellopontine angle was simulated. With a retraction of up to 36 power units (p) the ipsilateral BAEPs were reversibly changed. A retraction of 54 p caused irreversible loss of wave V on both sides. With 84 p ipsilateral and contralateral waves III-V were immediately lost. The animals died within 7 minutes. Our experimental investigation shows that not only a defined volume in the cerebellopontine angle can cause irreversible impairment of brainstem function, but also uncontrolled retraction of the cerebellum.
authors.affiliation: Department of Neurosurgery, University of Düsseldorf, Federal Republic of Germany.
authors.forename: C
authors.initials: C
authors.lastname: Lumenta
authors.forename: K
authors.initials: K
authors.lastname: Reschofsky
authors.forename: W
authors.initials: W
authors.lastname: Bock
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000502:physiology*; D002404:Catheterization; D002528:Cerebellar Neoplasms / Q000503:physiopathology*; D002530:Cerebellopontine Angle; D002531:Cerebellum / Q000473:pathology / Q000502:physiology*; D004195:Disease Models, Animal; D005072:Evoked Potentials, Auditory; D009336:Necrosis; D011817:Rabbits