ABSTRACT
Objective To study the possible mechanism of hearing impairment after noise exposure .Methods Adult SD rats (n=14) were monaurally exposed to a loud noise (16 kHz ,one octave band pass (116 dB SPL)) for 1-hour ,or left as non-exposed controls (n=8) .The ABR was measured before and on the 7th day following unilateral noise exposure .All the Animals were euthanased at 7th day following acoustic trauma .We used Western blots to quantify protein levels of PV ,CR and CB in the inferior colliculus .Results The auditory thresholds in 8 , 12 ,16 ,20 ,24 ,and 32 kHz of all the ears exposed to noise showed a significant increase (P<0 .001) .Compared to the sham -exposed controls ,noise-exposed animals had significantly higher levels of PV and CR and lower levels of CB in both the ipsilateral and contralateral IC than controls (P<0 .05) .Respectively ,all the noise-exposed ani-mals had higher levels of PV and CR in the ipsilateral IC than ipsilateral side (P<0 .05) .Conclusion These studies display a significant threshold shift and changes on the expressions of PV ,CR and CB in IC following acoustic trau-ma ,which may be related to noise deafness ,tinnitus and other series of auditory dysfunction .
ABSTRACT
Objective To assessment the effect of autologous mastoid cortical bone to cover the mastoidetomy defect via transmastoid and posterior tympanotomy approach surgical technique during cochlear implantation in a ‐dults .Methods A total of 58 adults patients with profound sensorineural hearing loss accepted cochlear implantation from January 2010 and June 2014 ,which were using autologous mastoid cortical bone to cover the mastoidetomy de‐fect via transmastoid and posterior tympanotomy approach surgical technique .By observing postoperation complica‐tion the effect of surgery was evaluated .ABR were obtained for each patients at first ,third and sixth month after op‐eration .The patients which were not using autologous mastoid cortical bone to cover the mastoidetomy defect via transmastoid and posterior tympanotomy proach surgical technique acted as control group .Results No depression was found in the postauricuhtr site .None of the patients had experienced any immediate or delayed postoperative in ‐fection complication such as wound infection ,post - auricular abscess ,acute otitis media ,chronic otitis media ,in‐tracranial complication and necrotic of cortical bone .Autologous cortical bone cap had grew together with remnant cortical bone in all cochlear implantation patients .All implanted processor were in a good position ,all patients had good results after turning on the implant .The ABR thresholds were elevated about 70 dB compare to pre - operation values(P 0 .05) .Conclusion The tech‐nique of autologous mastoid cortical bone to cover the mastoidetomy defect in cochlear implantation surgery can pre ‐vent depression of the postauricuhtr site ,remain stability of the implanted processor ,and have a good aided hearing thresholds after operation .