Abstract
Introduction:
Development of new computer technologies, better and more precise imaging, and audiological diagnostics result in faster diagnosis of patients with cerebellopontine angle tumors (CPAT) in such a stage of this pathology in which hearing is still relatively well preserved. Therefore, animal experiments enable us to develop and check new concepts of intraoperative monitoring of the hearing organ and, then, to apply them in clinical practice in patients with CPAT.
Material and Methods:
The authors presented data collected in animal experiments in which the cochlear and the eight nerve function were monitored during induced cochlear reversible ischemic episodes. In all cases laser Doppler cochlear blood flow techniques (LD-CBF), distortion product otoacoustic emission (DPOAE), and evoked auditory potentials (AEP) (i.e., cochlear microphonics [CM] and compound action potentials [CAP]) were measured using the otic probe placed into the RW niche. Hearing organ activity was assessed by stimulating the basis, middle, and apex of the cochlea.
Results:
An animal model of prevention of intraoperative hearing damage was developed and then applied to clinical situations occurring during CPAT surgery. Included and excluded criteria for intraoperative monitoring were presented with some principles of intraoperative monitoring in patients based on data collected during animal experiments.
Conclusions:
Intraoperative monitoring by AEP was found to be more complex and useful to distinguish between cochlear and retrocochlear damage occurring intraoperatively. DPOAE is a better method from the aspect of monitoring in real time. AEP was found to be a more complex response reflecting changes in cochlear and retrocochlear structures as a result of different manipulations of the surgeon, but the average procedure took more time.