brainstem auditory evoked response

brainstem auditory evoked response (BAER),

the electric activity that may be recorded from the brainstem in the first 10 msec after presentation of an auditory stimulus. In a subject with normal brainstem functioning, seven peaks are observed. A delayed, normally shaped waveform may indicate a hearing loss caused by a middle or inner ear disorder; one or more missing peaks may indicate a neural disorder.

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brainstem

the stemlike portion of the brain connecting the cerebral hemispheres with the spinal cord, and comprising the pons, medulla oblongata and midbrain; considered by some to include the diencephalon. See also reticular activating system, ascending reticular formation, thalamus.

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brainstem auditory evoked response

see brainstem auditory evoked response.

brainstem hemorrhage

results from cranial trauma and characteristically causes unconsciousness with varying types and degrees of motor paralysis and irregularities of respiration, depending on the site.

brainstem reticular formation

see reticular activating system.

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brainstem auditory evoked response

BAER, Brainstem auditory evoked potential Neurophysiology A method for evaluating hearing using clicking sounds and recording the responses–known as auditory evoked potentials with EEG electrodes placed on the scalp; the early responses reflect electrical activity at the cochlea, cranial nerve VIII and brainstem; late responses are due to cortical activity; after each click, 7 consecutive potentials are recorded, designated as waves I through VII, each of which corresponds to a specific relay point in the brainstem; BAER is an objective means of diagnosing and localizing early lesions of the auditory system Indications BAER is used to diagnose acoustic neuroma, intrinsic brainstem lesions–eg, multiple sclerosis, infarction, gliomas, degenerative disease–eg, Charcot-Marie-Tooth disease, Meniere's disease, olivopontocerebellar degeneration, stroke, Wilson's disease, ↑ intracranial pressure, brain death