thesis
Auditieve hersenstampotentialen bij de mens : een studie van enkele fundamentele eigenschappen en hun klinische toepassing
- Publication date
- 1 July 1983
- Publisher
- The aim of the author's research described in this thesis was to obtain abetter understanding of a number of the fundamental characteristics of brainstem
potentials and to establish normal values. This aim is described in chapter
I, following a discussion of the possibilities and limitations of objective and
subjective audiometry, an outline of the development of electroaudiometry
and a description of the regions of origin of brain stem potentials and their
nomenclature.
The experimental set-up is discussed in chapter II, where the signal-tonoise
ratio receives special attention.
The description of the clinical application of brain stem audiometry in
chapter VIII is based on both the literature and personal research.
Chapter IX gives some practical suggestions for the application of brainstem audiometry.
The author's own research, which is described in chapter III-VII, deals
with the following subjects:
1. The aceurenee of and normal values for brain stem potentials. The occurrence
of brain stem potentials and their normal values were investigated in 20 healthy
subjects, 19 men and 1 woman, with normal hearing and ages varying from
20-53 years.
The stimulus used had a wide frequency spectrum, with an intensity of 70
dB HL and a repetition rate of 10 Hz. The responses were filtered with a
high-pass filter, cut-off frequency 300 Hz, 24 dB/oct., and a !ow-pass filter,
cut-offfrequency 3000Hz, 24 dB/oct.
After averaging 16,000 responses to binaural stimulation it was possible to
identify the peaks P2 to P5 inclusive, for 75, 70, 85 and 100°/o of the test subjects
respectively, while after averaging 4,000 responses to manaural stimulation
the proportions were 65, 63, 78 and 98% respectively.
The amplitudes of the responses were highly variable. The latendes were
constant within narrow limits (table 3.1). The average latency for peak P5 was
7.0 ms with a standard deviation of0.35 ms. The interaurallatency difference
averaged 0.02 ms and had a standard deviation of0.27 ms.
2. The distribution of brainstem potentials over the scalp. The distribution of
brainstem potentials over the scalp was investigated to establish whether there
are any electrode positions where the response originates primarily from the
left or the right half of the brain stem. In order to do this the responses were
recorded at 5 points on the nasion-vertex-inion line and the vertex-mastoid
process line. The responses on the latter were obtained after ipsi- and contralateral
stimulation with respect to the active electrode.