Search

Brainstem auditory evoked potentials (brainstem AEPs) were simultaneously recorded from 13 scalp and earlobe electrodes from normal subjects employing a noncephalic reference. The scalp distributions of the individual components (waves I-V) were presented as isopotential maps with the use of a topographic computer display system. Binaural clicks produced symmetrically distributed brainstem AEPs over the scalp. With monaural stimulation, the topography of the responses differed in locus of maximum amplitude for each of the components, suggesting that different generators are involved in the production of these components (for example, wave V is of maximal amplitude with the shortest peak latency over the contralateral frontal area). Wave I was the only component that reversed its polarity according to electrode locations. Other waves were positive over the scalp and earlobes in confonnity with the concept that they are volume conducted, far field potentials. Brainstem AEPs in subjects with lesions ...

1. Measurements of each of the inner ear sensory areas are reported and compared for various vertebrates. These indicate:a. 5:5 and 6:4 ratios are most common in comparing the total pars superior sensory area of the inner ear with the total pars inferior area;b. 7:3 to 2:8 ratios exist, in comparing the canal type with the macular type areas, which appear to be related to the equilibratory demands made upon the organism;c. that, in comparing cochlear type with saccular type areas, the tailless amphibians exhibit a surprisingly high value for the former;d. that in some forms the crista horizontalis is larger than the average of the two vertical cristae, possibly associated with the mode of locomotion;e. that the macula sacculi, throughout vertebrates, is of considerable size, as is the macula lagenae (where present);f. that there is a great actual and relative variation in the size of the papilla basilaris (organ of Corti), particularly among reptiles;g. that it is the size of the papilla amphibiorum which...

We have been particularly concerned with the large number of patients with confirmed retrocochlear lesions who have demonstrated cochlear test results on audiological evaluation. The literature is replete with information suggesting that the patient with a tumor of the VIIIth nerve will demonstrate the classical signs of significant reduction in auditory speech discrimination, abnormal tone decay, lack of loudness recruitment, negative SISI scored and Bekesy tracings classifiable as either type III or type IV. We feel it is safe to say that one rarely encounters such a clearcut picture.In this paper we discuss the audiologic data for a series of patients recently evaluated in our department. All these patients demonstrated only cochlear findings on audiological evaluation, yet all patients had surgically confirmed VIIIth nerve tumors.