OBJECTIVE: To report intraoperative round window cochlear microphonic potential test (CM) in patients with profound sensorineural deafness. METHOD: Intraoperative round window CM test were performed on 40 cases with profound sensorineural deafness during cochlear implantation surgery under general anesthesia in the standard operating room. CM were compared with their reliable preoperation distortion product otoacoustic emission (DPOAE). RESULT: The CM were found in 40 patients. The rate at 0.5, 1.0, 2.0, 4.0. kHz was respectively 90%, 97.5%, 100%, 92.5%. The preoperation DPOAE were found in some frequency in 9 cases. The rate at 0.5, 1.0, 2.0, 4.0 kHz was respectively was 2.5%, 2.5%, 17.5%, 2.5%. CONCLUSION The elicited rate of CM was obviously higher than the one of DPOAE in the same patient with profound sensorineural deafness. The intraoperative round window CM may objectively and accurately estimate the part of cochlear function in patients with profound sensorineural deafness.
Adolescent ; Adult ; Child ; Child, Preschool ; Cochlear Implantation ; methods ; Cochlear Microphonic Potentials ; Female ; Hearing Loss, Sensorineural ; physiopathology ; Humans ; Infant ; Male ; Young Adult

Stimulation of the round window (RW) for coupling an implantable hearing system to the cochlea has gained increasing clinical importance. To compare the vibration transfer to the cochlear fluids and partition in response to normal acoustic stimulation and to mechanical stimulation of the RW, we carried out an acoustic-structure coupled finite element analysis using a recently developed finite element (FE) model in our laboratory, which consisted of external ear canal, middle ear and cochlea. Intracochlear pressures were derived during normal forward sound stimulation as well as reverse RW stimulation. A model was utilized to calculate the force required of an actuator at the RW to produce a differential intracochlear pressure that is equivalent to a stimulus produced in normal ear by a given external ear-canal pressure. The current results provided further information to support the optimization of the actuators and adapt existing prostheses for RW stimulation in order to insure sufficient acoustic output.
Acoustic Stimulation ; Cochlea ; physiology ; Cochlear Microphonic Potentials ; physiology ; Ear Canal ; physiology ; Finite Element Analysis ; Hearing Aids ; Humans ; Ossicular Prosthesis ; Pressure ; Round Window, Ear ; physiology ; Vibration

BACKGROUND AND OBJECTIVES: Cochlear microphonic (CM) is an electrical potential generated by outer hair cells in response to acoustic stimulation. The aim of this study is to evaluate the significance of CM in neonatal hearing loss. SUBJECTS AND METHOD: From April 2013 to April 2014, 64 neonates hospitalized in neonatal intensive care unit were enrolled. Subjects underwent transient evoked otoacoustic emission (TEOAE), auditory brain stem response (ABR) and CM. We analyzed the results of hearing tests and the correlation between CM and the other test modalities. RESULTS: Ninety two ears showed normal ABR waves whereas the other 36 ears had abnormal ABR. There were two neonates who were suspected of auditory neuropathy because of the presence of TEOAE and CM. Among 14 ears who showed abnormal OAE results, 12 ears (86%) were identified as having CM. The amplitudes of CMs were correlated with the reproducibility of TEOAE (p<0.005). Between the ears with positive TEOAE and others with negative TEOAE, the amplitudes of CMs were significantly different (p<0.005). CONCLUSION: Many ears were identified with the presence of CM without TEOAE response because of the the vulnerability of OAE from middle ear status and environment. We suppose that CM might provide information on outer hair cell function to complement the OAE in neonatal hearing test.
Acoustic Stimulation ; Cochlear Microphonic Potentials ; Complement System Proteins ; Ear ; Ear, Middle ; Evoked Potentials, Auditory, Brain Stem ; Hair ; Hearing Loss ; Hearing Tests* ; Humans ; Infant, Newborn* ; Intensive Care, Neonatal ; Neonatal Screening

OBJECTIVETo investigate the effect of nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway on cochlear sensitivity. Methods Ten groups of guinea pigs were treated with the following solutions by whole cochlear perfusion for 2 hours: (1) Artificial perilymph; (2) L-arginine; 93) Ca(2+)-ATPase inhibitor; (4) Ca(2+)-ATPase inhibitor + L-arginine; (5) Ca(2+)-ATPase inhibitor + cGMP; (6) Ca 2+ ATPase inhibitor + L-arginine + Non-selective NOS inhibitor; (7) eNOS inhibitor; (8) eNOS inhibitor + Ca(2+)-ATPase inhibitor; (9) eNOS inhibitor + Ca(2+)-ATPase inhibitor + L-arginine; (10) eNOS inhibitor + Ca(2+)-ATPase inhibitor + L-arginine + nNOS inhibitor. The compound action potential (CAP) and cochlea microphonics (CM) were measured to assess the changes of cochlear sensitivity. After the perfusion, the cochleae were harvested and prepared for transmission electron microscopy.

RESULTSThe average threshold shift of CAP after perfusion Ca(2+)-ATPase inhibitor was 28.5 dB, and it was improved in group 4 with 9 dB by L-arginine, similar with group 5. The threshold shift of CAP in group 8 was 42.5 dB, and it decreased in group 9 by L-arginine, on this foundation nNOS inhibitor was added, increased threshold shift of CAP was 6.5 dB, similar with group 8. The results indicated that L-arginine could rivalry the role of Ca(2+)-ATPase inhibitor through the path of NO-cGMP. Transmission electron microscopy showed that Ca(2+)-ATPase inhibitor + L-arginine combined administration resulted in less vacuolization in out hair cell than that treated with Ca(2+)-ATPase inhibitor only.

CONCLUSIONSThe NO-cGMP pathway could regulate cochlear sensitivity; L-arginine may improve the function of Corti's organ via nNOS, and they indicate an important role of supporting cells in the modulation of cochlear function.

Action Potentials ; Animals ; Cochlea ; metabolism ; physiology ; Cochlear Microphonic Potentials ; Cyclic GMP ; metabolism ; Enzyme Inhibitors ; pharmacology ; Guinea Pigs ; Hair Cells, Auditory ; metabolism ; Nitric Oxide ; metabolism ; Nitric Oxide Synthase ; antagonists & inhibitors

OBJECTIVE: To investigate incidents and clinical features of auditory neuropathy in Nanjing deaf school students. METHOD: Three hundred and fifty-eight deaf students in the school accepted the first examination including otoscopic examination, tympanometry and transiently evoked otoacoustic emissions (TEOAE) screening. Detailed audiological and vestibular evaluations including pure-tone audiometry, immittance audiometry and acoustic reflex measures, transiently evoked otoacoustic emissions (TEOAE), distortion product otoacoustic emissions (DPOAE), auditory brain stem response (ABR), electronystagmography (ENG) and vestibular evoked myogenic potential (VEMP) were given to whom had positive TEOAE screening. RESULT: Three hundred and twenty-three students entered the program of screening for auditory neuropathy. One student had positive TEOAE in single ear while the other two had positive TEOAE in both ears. In the screening stage,there were strong evidences in these three students with auditory neuropathy in the detailed audiological procedures. CONCLUSION Auditory neuropathy, which can also be found in deaf schools, is not as rare as we thought before. Early identification and intervention may help those children to avoid entering the deaf school and to return to normal society.
Adolescent ; Adult ; Audiometry, Pure-Tone ; Child ; China ; epidemiology ; Cochlear Microphonic Potentials ; Deafness ; epidemiology ; physiopathology ; Evoked Potentials, Auditory, Brain Stem ; Female ; Hearing Loss, Central ; epidemiology ; physiopathology ; Humans ; Male ; Otoacoustic Emissions, Spontaneous ; Students ; Young Adult