title: Fluid stimulation elicits hearing in the absence of air and bone conduction--An animal study.
abstract: Conclusion Cochlea can be directly excited by fluid (soft-tissue) stimulation. Objective To determine whether there is no difference in auditory-nerve-brainstem evoked response (ABR) thresholds to fluid stimulation between normal and animal models of post radical-mastoidectomy, as seen in a previous human study. Background It has been shown in humans that hearing can be elicited with stimulation to fluid in the external auditory meatus (EAM), and radical-mastoidectomy cavity. These groups differed in age, initial hearing, and drilling exposure. To overcome this difference, experiments were conducted in sand-rats, first intact, and after inducing a radical-mastoidectomy. Methods The EAM of five sand-rats was filled with 0.3 ml saline. ABR thresholds were determined in response to vibratory stimulation by a clinical bone-vibrator with a plastic rod, applied to the saline in the EAM. Then the tympanic membrane was removed, and malleus dislocated (radical-mastoidectomy model). The cavity was filled with 0.45 ml saline and the ABR threshold was determined in response to vibratory stimulation to the cavity fluid. Results There was no difference in ABR fluid thresholds to EAM and mastoidectomy cavity stimulation. Air-conduction stimulation from the bone-vibrator was not involved (conductive loss due to fluid). Bone-conduction stimulation was not involved (large difference in acoustic impedance between fluid and bone).
authors.affiliation: a Department of Otolaryngology/Head & Neck Surgery , Shaare Zedek Medical Center Affiliated with the Hebrew University Medical School , Jerusalem , Israel ;
authors.forename: Ronen
authors.initials: R
authors.lastname: Perez
authors.affiliation: b Speech & Hearing Center, Hebrew University School of Medicine - Hadassah Medical Center , Jerusalem , Israel ;|c Department of Communication Disorders , Hadassah Academic College , Jerusalem , Israel ;
authors.forename: Cahtia
authors.initials: C
authors.lastname: Adelman
authors.affiliation: d Department of Medical Neurobiology (Physiology) , Institute for Medical Research - Israel-Canada, Hebrew University-Hadassah Medical School , Jerusalem , Israel.
authors.forename: Haim
authors.initials: H
authors.lastname: Sohmer
mesh_terms: D000818:Animals; D003051:Cochlea / Q000502:physiology*; D005849:Gerbillinae; D006309:Hearing / Q000502:physiology*; D008416:Mastoid / Q000601:surgery
keywords: Soft tissue conduction; cartilage conduction; fat sand rat; fetal hearing; fluid stimulation; liquid test; mastoidectomy; non-osseous bone conduction; scratch test