The Characteristic Of Mismatch Negativity In Presb-Ycusis Patients With Different Stimulus Modes

ObjectivePresbycusis refers to a kind of slowly progressive sensorineural hearing loss,because of the auditory organs growing old and degeneration of binaural symmetry for increasing age, and generally it happens in two ears.Presbycusis is characterized by a factor called attenuation phenomenon,that is to say it can hear voices, but couldn’t understand meaning what to say, especially in noise environment. At present there are subjective method used for determination of presbycusis test including pure tone hearing threshold test, speech audiometry; Objective hearing tests includ distortion product otoacoustic emission (DPOAE), Brainstem evoked potential (ABR), etc. The above means that patients with presbycusis confirm different parts of the auditory pathway lesions. In this paper, the clinical diagnosis of patients with presbycusis difference frequency Mismatch negative wave (Mismatch negativity, MMN) and duration Mismatch negative wave incubation period and amplitude differences of adults with normal hearing and hearing the old compare test results analysis and discussion, in patients with presbycusis, different pathological changes, provide favorable basis for the diagnosis of senile deafness.Methods46patients (30cases of male, female16cases, aged51to75, including500Hz,1000Hz,2000Hz,4000Hz,pure tone hearing threshold for10～30dB、20～65dB、20～75dB、30～80dB)who saw doctors in Department of Otorhinolaryngology Head and Neck Surgery, Tianjin First Center Hospital from December2011to September2012and40stuffs (the male26, female14, aged50to76, including500Hz、1000Hz,2000Hz,4000Hz,pure tone hearing threshold of5～15dB、5～20dB、10～20dB、10-25dB respectively)working in this hospital and their family members and visiting other departments (disease of ear no effect) in this hospital were enrolled in this study as the experimental groups.50youth(32male,18female, aged20～30,500Hz,1000Hz,2000Hz,4000Hz,pure tone hearing threshold of-5～20dB respectively) were voluntary from Tianjin medical university as control group. Requires that all selected objects acoustic immittance tympanum figure are type"A", and had no history of other otology diseases. Application GSI61listening detector to pure tone hearing threshold test of all the subjects, GSI2000Tympstar2middle ear acoustic immittance testing analyzer, Intelligent Hearing Systems SmartEP, detection of frequency difference MMN and duration difference MMN. Test in accord with GB/T16403(1996) acoustic electric shielding room. The MMN amplitude and latent period were compared analysis and came to conclude.Results1. The results of frequency difference MMN with Presbycusis group, youth group and the hearing normal elderly group:The latency of frequency MMN between presbycusis group and normal hearing elderly group is significant difference (P<0.05), but amplitude no significant difference (P>0.05); The latency and amplitude between hearing normal elderly group and young control group are no significant difference (P>0.05); The latency of frequency MMN between presbycusis group and youth control group is significant difference (P<0.05), but amplitude no significant difference (P>0.05).2. The results of duration difference MMN with Presbycusis group, youth group and the hearing normal elderly group:The latency and amplitude of duration MMN between hearing normal elderly group and young control group are significant difference (P<0.05);The latency between presbycusis group and normal hearing elderly group is significant difference (P<0.05), but amplitude no significant difference (P>0.05); The latency between normal hearing elderly group and youth control group is significant difference (P<0.05), but amplitude no significant difference (P>0.05).3. The result of presbycusis group between frequency MMN and duration MMN:the latency is significant difference (P<0.05), amplitude no significant difference (P>0.05).4. The result of normal hearing elderly group between frequency MMN and duration MMN:the latency is significant difference (P<0.05), amplitude no significant difference (P>0.05). 5.The result of youth control group between frequency MMN and duration MMN:the latency and amplitude are no significant difference (P>0.05).ConclusionThere are long latency and small amplitude for frequency and duration MMN with presbycusis, due to the long time of hearing loss, which lead to the auditory cortex plasticity changes;Compared with the frequency difference MMN,duration MMN has long latency,which can explain duration MMN more sensitive frequency difference MMN, can earlier reflect the changes of cortical and subcortical.