Brainstem Essay

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It is a far-field response that reflects stimulus-locked, synchronous neural firing from nuclei along the brainstem.(45) The conventional click generated ABR is a robust response, producing five vertex recorded positive peaks (Waves I–V) usually within 6 to 7 milliseconds after very brief duration (0.1 milliseconds), moderately high intensity click stimulation, at rates of roughly 8 to 24/sec. These waves are the result of abrupt activation of auditory neurons from the cochlea to the inferior colliculus. About 2,000 to 4,000 repetitions are averaged from each ear within a 10 to 15 milliseconds recording window representing one trial, and generally two superimposed trials are necessary from each ear. Only Wave V is seen after less intense…show more content…
(47) Generally click ABR is used for threshold estimation and assessment of neural intergrity. The appearance of Wave V generally follows by about 10 to 20 dB the threshold to hear the respective click. (47) The click evoked brainstem auditory evoked potential (BAEP)/brainstem auditory evoked response (BAER)/auditory brainstem response (ABR) has well-established utility in neurology, neurologic surgery, and otology since its introduction to clinical medicine in the 1970s.(51) Routine click ABR interpretation consists of Waves I, III, and V absolute and interpeak interval (IPI) determinations, and comparison with normative data. In neurologic practice, the cornerstone of click ABR interpretation has been the IPIs representing central or brainstem conduction times, often obviating confounding middle ear conductive delay or hearing problems which usually cause a delayed Wave I. It’s elicited by click stimuli delivered to each ear separately, thus it’s sensitive to brainstem lesions from tumors, trauma, hemorrhage, ischemia, demyelination, or metabolic insult. (46) Waveform amplitudes perhaps more dependant on neuronal generators, are more variable between individuals, susceptible to background noise and less reliable than latency conductions, although absence of waves after Wave I or II has
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