Brainstem Auditory Evoked Responses
Synonyms
Definition
Brainstem auditory evoked responses (BAER) test the function of the auditory nerve and auditory pathways of the brain by measuring the electrophysiologic responses to repeated clicks presented to each ear. The response time of electrical waves generated from different anatomical parts of the brain-ear system are plotted as summarized below (Lew, Lee, Pan, & Chiang, 2007):
Wave I: Cochlear nerve (CN VIII)
Wave II: Cochlear nucleus (CN VIII)
Wave III: Superior olivary complex
Wave IV: Lateral lemniscus
Wave V: Inferior colliculus
Waveform delays may indicate an abnormality in function along the auditory pathway. Unilateral delays suggest a lesion to cranial nerve VIII along its pathway or in the brainstem. BAER may be abnormal in acoustic neuroma, demyelinating disease, migraine...
References and Readings
- Huszar, L. (2006). Clinical utility of evoked potentials. eMedicine. Retrieved July 9, 2007 from http://www.emedicine.com/neuro/topic69.htm
- Lew, H. L., Lee, E. H., Pan, S. S. L., & Chiang, J. Y. P. (2007). Electrophysiologic assessment techniques: evoked potentials and electroencephalography. In N. D. Zasler, D. I. Katz, R. D. Zafonte (Eds.), Brain Injury Medicine (p. 158). New York: Demos.Google Scholar
- Zafonte, R. D., Hammond, F. M., & Peterson, J. (1996). Predicting outcome in the slow to respond traumatically brain-injured patient: Acute and subacute parameters. NeuroRehabilitation, 6, 19–32.PubMedGoogle Scholar