TAILIEUCHUNG - Chapter 030. Disorders of Smell, Taste, and Hearing (Part 13)

Evoked Responses Electrocochleography measures the earliest evoked potentials generated in the cochlea and the auditory nerve. Receptor potentials recorded include the cochlear microphonic, generated by the outer hair cells of the organ of Corti, and the summating potential, generated by the inner hair cells in response to sound. The whole nerve action potential representing the composite firing of the firstorder neurons can also be recorded during electrocochleography. Clinically, the test is useful in the diagnosis of Ménière's disease, where an elevation of the ratio of summating potential to action potential is seen. Brainstem auditory evoked responses (BAERs) are useful in. | Chapter 030. Disorders of Smell Taste and Hearing Part 13 Evoked Responses Electrocochleography measures the earliest evoked potentials generated in the cochlea and the auditory nerve. Receptor potentials recorded include the cochlear microphonic generated by the outer hair cells of the organ of Corti and the summating potential generated by the inner hair cells in response to sound. The whole nerve action potential representing the composite firing of the firstorder neurons can also be recorded during electrocochleography. Clinically the test is useful in the diagnosis of Meniere s disease where an elevation of the ratio of summating potential to action potential is seen. Brainstem auditory evoked responses BAERs are useful in differentiating the site of sensorineural hearing loss. In response to sound five distinct electrical potentials arising from different stations along the peripheral and central auditory pathway can be identified using computer averaging from scalp surface electrodes. BAERs are valuable in situations in which patients cannot or will not give reliable voluntary thresholds. They are also used to assess the integrity of the auditory nerve and brainstem in various clinical situations including intraoperative monitoring and in determination of brain death. The vestibular-evoked myogenic potential VEMP test elicits a vestibulocollic reflex whose afferent limb arises from acoustically sensitive cells in the saccule with signals conducted via the inferior vestibular nerve. VEMP is a biphasic short-latency response recorded from the tonically contracted sternocleidomastoid muscle in response to loud auditory clicks or tones. VEMPs may be diminished or absent in patients with early and late Meniere s disease vestibular neuritis benign paroxysmal positional vertigo and vestibular schwannoma. On the other hand the threshold for VEMPs may be lower in cases of superior canal dehiscence and perilymphatic fistula. Imaging Studies The choice of radiologic .

• Y học thường thức
• Disorders of Smell
• Taste
• Hearing
• bệnh học và điều trị
• bài giảng bệnh học
• tài liệu học ngành y
• Harrisons Internal Medicine
• Taste disorders
• Smell and taste disorders
• Non neurodegenerative disorders
• Neurodegenerative chemosensory disorders
• Chemosensory disorders
• Medicolegal aspects
• Physiology of olfaction
• Anatomy and physiology of gustation
• Measurement of gustation
• Measurement of olfaction
• medical books
• pharmacology
• epidemiologic
• Obstetrics
• anatomy
• Preventing Morbidity
• Multidisciplinary Care