Auditory evoked potentials as yardstick for tinnitus

<p class="abstract"><strong>Background:</strong> Aiming to evaluate the recent theoretical postulates on tinnitus underscoring the role of thalamocortical neural tracts, the present study: explores middle latency response (MLR) as a possible physiological measure of tinnitus: thus investigates the predicted exaggeration of P_a-N_a, N_a-P_b interpeak amplitudes in tinnitus patients and; explores middle latency response (MLR) as a prognostic indicator of tinnitus retraining therapy (TRT), thus evaluates possible decrease in P_a-N_a and N_a-P_b amplitude after 2 weeks exposure to tinnitus retraining therapy.</p><p class="abstract"><strong>Methods:</strong> An experimental group was constructed by randomly assigning 30 patients with mean age 38.5 years and complaining of debilitating tinnitus but with normal hearing for the study. MLR was administered on patients with normal auditory brainstem response (ABR) and otoacoustic emission (OAE) both pre- and post-tinnitus retraining therapy. </p><p class="abstract"><strong>Results:</strong> Results demonstrated no significant effect on P_a, N_a and N_b absolute and interpeak latencies. However, significantly exaggerated P_a-N_a and N_a-P_b interpeak amplitudes between experimental and control groups as well as pre and post therapeutic groups were found.</p><p class="abstract"><strong>Conclusions:</strong> This proves that MLR may adequately reflect thalamocortical hyperactivity in cases with distressing tinnitus and demonstrable improvement post TRT warrants the use of MLR as its prognostic indicator.</p>

The Use of Middle Latency Auditory Evoked Potentials (MLAEP) as Methodology for Evaluating Sedation Level in Propofol-Drug Induced Sleep Endoscopy (DISE) Procedure

To analyze the middle latency auditory evoked potential index (MLAEPi), compared to the standard bispectral index (BIS), as a method for evaluating the sedation level in drug-induced sleep endoscopy (DISE). In this controlled clinical study on a sample of 99 obstructive sleep apnea (OSA) or snoring patients, we compared the MLAEPi with the BIS after propofol infusion during the standard DISE technique in order to define the MLAEPi values within the observational window of the procedure. The DISE procedure was divided into eight steps, and we collected both MLAEPi and BIS data values from the same patient in every step. The MLAEPi showed a faster response than the BIS after propofol infusion during DISE. Therefore, the clinical use of the MLAEPi in evaluating the sedation level seems to be a good alternative to the current technological standards.

Target detection in healthy 4-week old piglets from a passive two-tone auditory oddball paradigm

Background Passive auditory oddball tests are effort independent assessments that evaluate auditory processing and are suitable for paediatric patient groups. Our goal was to develop a two-tone auditory oddball test protocol and use this clinical assessment in an immature large animal model. Event-related potentials captured middle latency P1, N1, and P2 responses in 4-week old (N = 16, female) piglets using a custom piglet 32- electrode array on 3 non-consecutive days. The effect of target tone frequency (250 Hz and 4000 Hz) on middle latency responses were tested in a subset of animals. Results Results show that infrequent target tone pulses elicit greater N1 amplitudes than frequent standard tone pulses. There was no effect of day. Electrodes covering the front of the head tend to elicit greater waveform responses. P2 amplitudes increased for higher frequency target tones (4000 Hz) than the regular 1000 Hz target tones (p < 0.05). Conclusions Two-tone auditory oddball tests produced consistent responses day-to-day. This clinical assessment was successful in the immature large animal model.

Auditory Evoked Potentials P50: Pure-tones vs Clicks. There is a Similar Supression?

Objective: Clinical application of middle-latency auditory evoked potential (MLAEPs) has been increasing, highlighting the importance of understanding the nature of P50, a component of middle-latency auditory evoked potential. We manipulated stimulus frequency bands in auditory stimuli in order to investigate the nature of P50 in human auditory evoked potentials. Methods: Two paradigms have been used to obtain P50: one is a conditioning /testing paradigm in which paired of pure tone (1000Hz) are delivered, and the other was presented paired of clicks, both with an intensity of 60 dB sound pressure level above the auditory threshold. A total of 30 healthy volunteers were recruited for this study among Center of genetic engineering (fifteen man and fifteen women, mean age of 36, 5). All without consumption of caffeine, cigarettes and drugs. Results: No statistically significant differences occurred between the P50 amplitudes and latencies for the pure tone and those for the clicks. Conclusions: Our present results indicate that P50 in humans may reflect a feed-forward mechanism of the brain where a preceding stimulus drives sensory gating mechanisms in preparation for a second stimulus, but the contained frequency doesn't influence on the P50. Both types (tones or clicks) can be used in the exploration of patient with this evoked potential.

Effect of Music Training on Auditory Brainstem and Middle Latency Responses

Purpose: The auditory system has potentials to reorganize its structure and function in response to environmental changes such as training, experience, learning, injury, and disease. This is called neuroplasticity. A typical example of neuroplasticity is the music training, which demands cognitive and neural challenges resulting in enhanced auditory perception. This study investigated the effect of music training on auditory evoked responses, particularly auditory brainstem and middle latency responses. Methods: Forty college students consisting of twenty students with music training (musicians) and twenty students without music training (non-musicians) participated in the study. All participants have normal ranges in terms of pure tone audiometry, speech audiometry, and tympanometry. Auditory brainstem response (ABR) and auditory middle latency response (AMLR) from both ears were tested. Absolute latencies and amplitudes of waves in ABR and AMLR were obtained and analyzed.Results: The absolute latencies of wave I and V significantly differed between musicians and non-musicians. They were shorter for musicians than for non-musicians. Significant differences were found in the interpeak latencies of wave III-V and I-V between musicians and non-musicians. They were also shorter in musicians than for non-musicians. In addition, there were only significant differences in the latency of Na in AMLR between musicians and non-musicians. It was shorter for a musician than for non-musician.Conclusion: ABR was more sensitive to the efficacy of the music training.