Effects of temperature and elevated intracranial pressure on peripheral and brain stem auditory responses in dogs. 1986

T A Jones, and W J Weidner

Far-field recordings of central (P2 through P4) and peripheral (cochlear microphonic; and compound action potential of the eighth nerve) auditory responses were used to assess changes in auditory function resulting from elevated intracranial pressure. Normative data for eight dogs were obtained. The relationship between response latency and core temperature was examined. A mean slope of -0.17 ms/degrees C resulted for the temperature range of 35.0 to 40.0 degrees C. Systemic arterial pressure was measured in order to identify the cerebral ischemic response. Responses were not altered significantly unless the intracranial pressure approached within 15 to 30 mm Hg of mean systemic arterial pressure. Changes in the response consisted of both enhancement and deterioration during intracranial pressure elevation and were accompanied by increases in systemic arterial pressure during that elevation. Supernormal amplitudes of the action potential also occurred during recovery periods. Results suggest that: (i) during elevated intracranial pressure, changes in both central and peripheral auditory function result from ischemia rather than pressure-induced distortion of the cochlea or central neural assemblies. (ii) Far-field auditory responses may include an O2-dependent cochlear microphonic. (iii) An unknown process causing enhancement of central and peripheral neural responses exists and operates in connection with intracranial hypertension. Possible mechanisms underlying enhancement of response components are discussed.

UI MeSH Term Description Entries
D007427 Intracranial Pressure Pressure within the cranial cavity. It is influenced by brain mass, the circulatory system, CSF dynamics, and skull rigidity. Intracerebral Pressure,Subarachnoid Pressure,Intracerebral Pressures,Intracranial Pressures,Pressure, Intracerebral,Pressure, Intracranial,Pressure, Subarachnoid,Pressures, Intracerebral,Pressures, Intracranial,Pressures, Subarachnoid,Subarachnoid Pressures
D001933 Brain Stem The part of the brain that connects the CEREBRAL HEMISPHERES with the SPINAL CORD. It consists of the MESENCEPHALON; PONS; and MEDULLA OBLONGATA. Brainstem,Truncus Cerebri,Brain Stems,Brainstems,Cerebri, Truncus,Cerebrus, Truncus,Truncus Cerebrus
D003056 Cochlear Nerve The cochlear part of the 8th cranial nerve (VESTIBULOCOCHLEAR NERVE). The cochlear nerve fibers originate from neurons of the SPIRAL GANGLION and project peripherally to cochlear hair cells and centrally to the cochlear nuclei (COCHLEAR NUCLEUS) of the BRAIN STEM. They mediate the sense of hearing. Acoustic Nerve,Auditory Nerve,Acoustic Nerves,Auditory Nerves,Cochlear Nerves,Nerve, Acoustic,Nerve, Auditory,Nerve, Cochlear,Nerves, Acoustic,Nerves, Auditory,Nerves, Cochlear
D004285 Dogs The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065) Canis familiaris,Dog
D005072 Evoked Potentials, Auditory The electric response evoked in the CEREBRAL CORTEX by ACOUSTIC STIMULATION or stimulation of the AUDITORY PATHWAYS. Auditory Evoked Potentials,Auditory Evoked Response,Auditory Evoked Potential,Auditory Evoked Responses,Evoked Potential, Auditory,Evoked Response, Auditory,Evoked Responses, Auditory,Potentials, Auditory Evoked
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D013696 Temperature The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms. Temperatures

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