1. Computer Architecture and Networks Lab. 컴퓨터 구조 및 네트워크 연구실 Middle-Latency Auditory Evoked Potentials : Basic Issues and Potentials Applications(3/3) 2009. 5. 6 이창호

2. Computer Architecture and Networks Lab. Contents Stimulus Considerations CLINICAL USE OF MIDDEL-LATENCY POTENTIALS Threshold Estimation and Effects of Hearing Loss on MLAEPs Site-of-Lesion Testing and Assessment of Central Auditory Disorders Cochlear Implants Central Auditory Processing Disorders –Case study Central Deafness Are MLAEPs Modality Specific CAN Lab. INHA University.

3. Computer Architecture and Networks Lab. Stimulus Considerations Middle-latency responses can be affectd by changes in various stimulus parameters. Middle-latency components(Pa, Nb, Pb,Nc, Pc) An inverse relationship was found between latency and frequency. Consequence, certain tradeoffs become necessary in the context of stimulus generation, and these physical limitations have their greatest impact when considering the choice of stimuli for audiomeric purposes. Using evoked potentials, audiogram reconstruction is a more ambitious goal. CAN Lab. INHA University.

4. Computer Architecture and Networks Lab. Threshold Estimation and Effects of Hearing Loss on MLAEPs It was felt that MLAEPs could serve as a means of threshold estimation in the lower-frequency range for audiometric purposes. MLAEPs could potentially be used to detect either peripheral hearing loss of more central auditory disorders. However, the clinical instances in which use of AEPs are most important, such as early identification of peripheral hearing loss in infants and young children, are also those settings in which MLAEP variability is highest. CAN Lab. INHA University.

5. Computer Architecture and Networks Lab. Site-of-Lesion Testing and Assessment of Central Auditory Disorders An analysis of the effects of cerebral lesions on middle- latency responses can provide information about the underlying neural generators. As noted above, issues related to the number of electrodes used in the spatial sampling of MLAEPs become crucial in attempting to determine the effects of CNS lesions on these potentials. In individuals with partial epilepsy, brainstem and middle-latency responses were found to be unaffected, while alterations in later cortical responses, N1/P2 were noted. CAN Lab. INHA University.

6. Computer Architecture and Networks Lab. Cochlear Implants The use of MLAEPs has also been suggested for the evaluation of cochlear implant candidates. In postlingually deafned adults, alterations in middle- latency amplitude and interlatency variation were related to specific speech-perception abilities. CAN Lab. INHA University.

7. Computer Architecture and Networks Lab. Central Auditory Processing Disorders It has been suggested that MLAEPs may be valuable indices of central auditory processing. None of the patients with abnormalities of middle- latency component Pa had cortical lesions. Other related applications in the area of sensory processing have been in psychiatric research concerned with the neurobiology of schizophrenia. They suggest that this measure may be a useful predictor for early identification of central auditory processing disorder(CAPD). CAN Lab. INHA University.

8. Computer Architecture and Networks Lab. Case study of Central Deafness(1) A case of central deafness in a young child with Moyamoya disease. –Normal transient evoked. –Distortion product otoacoustic emisions –ABRs, MLAEPS, LLAEPs CAN Lab. INHA University.

9. Computer Architecture and Networks Lab. Case study of Central Deafness(2) CAN Lab. INHA University.

10. Computer Architecture and Networks Lab. Case study of Central Deafness(3) CAN Lab. INHA University.

11. Computer Architecture and Networks Lab. Case study of Central Deafness(4) CAN Lab. INHA University.

12. Computer Architecture and Networks Lab. Are MLAEPs Modality Specific The first is demonstrating that AEPs are abnormal and potentials evoked by stimulation of other sensory modalities are normal. The second strategy would examine the extent to which MLAEPs serve as predictors of conditions that have been documented to be auditory specific by behavioral measures. Thus, the clinical use of MLAEPs as tests of CAPDs must await further research. CAN Lab. INHA University.