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Biomedical subjects

R D Battmer

Publications and source records attributed to R D Battmer.

At least 73 records · Page 4Linked to original sources
PubMed1988

Magnetic resonance imaging (MRI) and high resolution computertomography (HRCT) in cochlear implant candidates.

Cochlear implant candidates must be thoroughly tested for their suitability pre-operatively. Electrical and electrophysiological tests as well as a psychological assessment are of fundamental importance in the selection process. The implantation of an intracochlear electrode requires specific information about the anatomy of the petrous bone and the endocochlear space. Such information can be obtained by using high resolution computed tomography (HRCT) or magnetic resonance imaging (MRI) using a surface coil. Over three years 438 patients were evaluated in our clinic as possible implant candidates. Out of these candidates 251 were evaluated using HRCT and 123 using MRI. In 39 (15.5%) cases we found bony abnormalities of the petrous bone using HRCT scans. 17 (13.8%) of the cases evaluated with MRI had no complete fluid filled spaces in the cochlea. Three patients who where identified as having ossified cochleas were subsequently implanted with an extracochlear device. MRI and HRCT have proved to be fundamental tools in determining patients suitable for implantation of an intracochlear electrode array.

Cochlea↗
PubMed1986

[The promontory test and electrocochleography in deafness caused by mumps].

Contradictory histological findings in patients with deafness following mumps led us to conduct electrophysiological investigations. Promontory testing (PT) and measurement of cochlear microphonics (CM) enabled us to distinguish between neural and sensory deafness. On the basis of a careful history and serological tests in 19 cases of unilateral deafness we found that the hearing loss was probably caused by mumps. In all patients except one auditory sensations could be obtained by electric stimulation of the acoustic nerve whereas no CM were detectable even with strong stimuli of 100 dB tonepips. In view of the electrophysiological findings, doubt is cast on the neural genesis of deafness following mumps as assumed by Lehnhardt (1962).

Audiometry, Evoked Response↗
PubMed1986

[The promontory test and electrocochleography with reference to indications for cochlear implant].

A successful cochlear implant demands a functioning auditory nerve. A subjective and qualitative recording can be obtained by promontory testing (PT) whereas cochlear microphonics (CM) give information about the status of the hair-cells in the inner ear. The results of both tests together show different patterns: in sensory deafness in which a cochlear implant is indicated, no CM and no compound action potentials (CAP) can be obtained, whereas the patient reports hearing sensations (PT positive) in response to promontory testing. Deafness caused by lesions close to the second neurone of the auditory pathways can be localized by preserved CM and CAP, but there is no response to promontory testing. A ganglionic deafness ie. of the first neurone can be distinguished by preserved CM, absent CAP and a negative PT. The combined results of electrocochleography and promontory testing help in deciding whether a cochlear implant is indicated, and in localising the origin of the deafness, eg. neural or sensorineural. The possible results are illustrated by examples.

Adult↗
PubMed1986

[Cochlear implants].

Since the middle of 1984, the HNO-Klinik der Medizinischen Hochschule Hannover has provided deaf adults with a 22-channel cochlear implant (CI) device of Clark-NUCLEUS. The digital working system consists of an implantable stimulator/receiver and an externally worn speech processor. Energy and signals are transmitted transcutaneously via a transmitter coil. During the prevailing 26 operations (April 1986) the electrode array could be inserted at least 17 mm into the cochlea. The threshold and comfort levels of all patients were adjusted very quickly; the dynamic range usually grows during the first postoperative weeks. The individual rehabilitation results vary greatly, but all patients show a significant increase of vowel and consonant comprehension while using the speech processor and an improvement of words understood per minute in speech tracking from lip-reading alone to lip-reading with speech processor. Four months after surgery seven of 17 patients (group I) are able to understand on average 42.7 words per minute by speech tracking without lip-reading. Six patients (group II) recognise 69.2% of vowels and 42.5% of consonants by speech processor alone. Four patients (group III) can correctly repeat only vowels (52.3%) without lip-reading, but using the speech processor together with lip reading they have an improvement in consonant understanding of 37.9% and under freefield conditions they are able to understand up to 17.8% numbers of the Freiburg speech test.

Cochlear Implants↗
PubMed1986

[High-resolution computerized tomography as a supplementary examination prior to cochlear implants].

Patients must be thoroughly tested for their suitability for a cochlear implant. Promontory testing and electrocochleography are of fundamental importance. It is possible to distinguish sensory deafness from other forms by combining the results of both tests. The implantation of intracochlear electrodes requires exact information of the anatomy of the cochlea, the tympanic wall of the cochlea and the endocochlear space. This can be assessed by axial high resolution computed tomographic scans. 8 of 70 patients were inoperable because of cochlea lesions (fractures or malformations). The advantage of computer tomography compared to conventional tomography is the fact that radiation exposure is less while the resolution is nearly the same. If computer tomography and conventional tomography do not reveal any fractures an exploratory tympanotomy should precede the cochlear implant operation in patients with a history of cranio-cerebral trauma.

Audiometry, Evoked Response↗
PubMed1984

[Relations between pure-tone threshold and discrimination of monosyllables in inner ear high-frequency hearing disorders].

To prove earlier studies with similar subjects (Lehnhardt 1973, 1977) we examined the report of 613 patients (1046 ears) with inner ear high frequency hearing disorders in order to find a correlation between the pure tone threshold and discrimination for monosyllables. The present data again confirm a close correlation between the pure tone hearing loss above 40 dB (HL) at the frequencies 3,000, 2,000 and 1,000 Hz and the percentage discrimination for monosyllables at 65 dB speech intensity level. Furthermore, in progressive high tone deafness with residual hearing in the low frequency range alone, correlations can be shown between the hearing loss above 40 dB in the frequencies 500 and 250 Hz on one hand and the discrimination for monosyllables at intensity levels of 80 and 95 dB on the other hand. These correlations have been converted into a table to enable a recognition of these connections without further calculation. They should be taken into consideration in routine audiometry and in legal cases especially. Greater differences in results indicate errors in testing or calibration; in individual cases they may be a hint of an uncommon origin of the hearing disease.

Adult↗
PubMed1984

[The validity of various audiometric testing methods in tumor-induced hearing disorders].

In order to study the diagnostic possibilities for detecting acoustic neuromas respectively tumors of the cerebello pontine angle 60 patients with secured tumor (op. confirmed) were preoperatively examined audiologically . The test results were worked out statistically and checked of their validity in respect of the diagnosis. It could be found, that the results of the conventional audiometry, if taken in its entirety, approved a secure diagnosis in most of the cases; though very discretely marked constellations of test results had to be considered. Routine-audiometric failures were essentially restricted to patients which were deaf or had a high-grade hearing loss ( Lehnhardt 1983). The recordings of auditory brain stem responses of them selves showed in all cases a result in the sense of retrocochlear hearing disorder, not only with regard to prolonged absolute latency times of JV/P6 but also of prolonged interpeak latency times between JI and JV. In cases of monaurale deafness, the ERA supplied a secure criterion for a brain stem disorder because of delayed latency times on the not affected side.

Acoustic Impedance Tests↗
PubMed1983

[Data telecommunication in electric response audiometry (ERA)].

Telephone-lines suit for the transmission also of digital data along long distances. In ERA this technique is favourable. --because the application of a computer is necessary anyway and the primarily analogous data have to be transformed to digital ones anyhow and --because the expenses for purchase, maintainance and operation of the complete equipment stress practices and small hospitals disproportionately. To test "ERA via telephone" we established outstations, the peripheral measuring equipment of which was composed of commercially available devices (Digital Equ. Corp.); only the computer controlled stimulator originated from our own construction. The communication software between central and peripheral station was written in a way that the realtime feature of the registration was preserved and, therefore, only about 30 min are necessary to obtain the intensity-latency time-function (P6/JV) of both ears.

Audiometry↗
PubMed1983

[Significance of ERA for differentiating hearing disorders of different origins].

The reliability on audiometric findings in hearing disorders of different genesis has been considerably improved by the ERA. By no means, the ERA can replace the conventional hearing tests, rather it is an additional technique of examination. Apparently it does not reveal specific findings of psychogenic hearing disorders - unless the prolongation of the cortical response as repeatedly seen by us. In case of aggravation ERA renders us possible to detect the kind of hearing defects and the actual threshold - e.g. with respect to high frequency range by brain stem responses, for 500 and 1,000 Hz according to the cortical responses. The neural hearing impairment caused by tumours always exhibits extremely prolonged latencies even at high intensities, eventually concomitant with a response threshold elevated versus the subjective threshold. These reactions, above all, become apparent in the brain stem rather than in the cortex. In contrast to this the sensoric hearing disorders the ERA elucidates even objectively the recruitment: normal latencies at high intensities. The latency of the objective response, thus, corresponds to the sound stimulus is perceived loud, and it is long for stimuli perceived relatively low - even in spite of great intensity. Comprising the ERA the quote of audiometric failures in excluding an acoustic neuroma is reduced to a minimum.

Adolescent↗
PubMed1981

The brain stem response SN10, its frequency selectivity, and its value in classifying neural hearing lesions.

The component P6 of the brain stem is only to be related to the hearing ability in the high tone range of greater than or equal to 2 kHZ, but it can be traced up to the hearing threshold. The cortex response N90, on the other hand, is frequency-specific, but it can hardly be recorded up to the subjective hearing threshold. The slow brain stem response SN10 (Davis and Hirsh 1979), unaffected by medicamented sleep, shall give information about hearing ability in the low and medium frequency range and may thus be an ideal complement to the fast response P6. In a number of normal hearing people and patients with sensorial hearing impairment of different frequency characteristics the brain stem responses P6 and SN10 were simultaneously recorded. As stimuli we used tone pips of a rise and fall time independent of frequency of about 2 ms and with a plateau of 2 ms as well. The mean threshold of the SN10 response is about 10 dB above the subjective hearing threshold. The constancy of the latencies corresponds to that of P6. The frequency selectivity of this relatively slow brain stem response is proved by comparing the P6 and SN10 responses with the course of the subjective hearing threshold. The topodiagnostic significance of the wave SN10 in connection with the brain stem response P6 and the cortical response N90 is shown in a case of neural hearing impairment.

Acoustic Stimulation↗
PubMed1980

The automatic tone decay test as part of dynamic measurement of threshold.

Only dynamic recording of the tone threshold can give information on pathologic adaptation, auditory fatigue, and aggravation. We have therefore automated the tone decay test. This was achieved by modifying the Grason-Stadler audiometer E 800 and, concurrently, by developing a special device with integrated circuits for this purpose. The print-out is made by a commerical x-y-recorder which is also used for recording the impedance test results. During the automatic tone decay test the patient himself increases the intensity of the tone only until he can hear the tone again, the intensity of the tone otherwise remaining constant. Thus, we obtain either a flat (adaptation) or a sharply declining (auditory fatigue) curve which correlates with the Békésy continuous tone curve, but may show a distinctive separation. The tone decay test is - in contrast to all other suprathreshold tests - independent of the amount of hearing loss. It can therefore give information on the kind of hearing impairment for normal short duration thresholds as well.

Audiometry↗
PubMed1980

Storage of audiometric data - online - with a small computer.

For online storage of audiometric measuring data we use an audiometer with serial operating output, a computer (DEC PDP 11/03), and a graphic terminal (DEC VT 55). The data can be controlled at any given time on the display and read like an audiogram. To transmit the data it is mainly only necessary to activate one button on the audiometer in addition. Pure tone and speech audiograms appear on the display in separate diagrams; in addition, beneath the pure tone threshold the results of the suprathreshold tests and the impedance measurements are indicated. For additional observations three lines are left available. If desired, a computer-supported masking aid can be used; independent of this, cross-heard values and applied masking noise intensities are stored. Paper documentations can achieve success as a hardcopy or as a four-coloured plotter print. Statistical groupings are possible without further processing.

Audiometry↗
PubMed1979

Simultaneous recording of fast and slow auditory evoked potentials (slow-fast-simultaneous-ERA, SFS-ERA).

In order to reduce measurement time we have used part of the interstimulus interval of the slow cortical responses to record fast brain stem responses. For this purpose we reconstructed a programmable audiometer and preamplifier which are controlled by a computer. These, with 1/4 ms-click and tone-burst stimulation simultaneously gained fast and slow responses, not only give a frequency-related view of the threshold and the kind of hearing loss--because of amplitude and latency--, but also in some cases--because of differences between both responses--give ideas of the possible location of the hearing impairment through the auditory pathways. The audiological value of this new method is discussed and explained by giving examples of two interesting cases, one central-neural hearing loss and one questionable aggravation.

Acoustic Stimulation↗
PubMed1979

[Behaviour of the fast brain stem response P6 under noise influence, an "objective noise audiometry" (author's transl)].

The fast brain stem response can be recorded even at the threshold; it informs on hearing in the high frequency range of greater than or equal to 2000 cps. Especially in those frequencies often the differentiation between sensorial and neural hearing impairment is of interest--f. e. controlling the pure tone threshold in noise: at sensorial hearing loss tones remain heard within noise of equal loudness unaltered, at neural hearing loss the tone vanishes in noise, e. g. the tone-intensity must be increased to make the tone arise again. This phenomenon known from subjective audiometry mentally can be transferred to the recording of acoustic evoked potentials and can be proved by the behaviour of latency of P6: at sensorial hearing loss the latency is prolonged (corresponding to minus 20 dB) but the response furthermore is recorded in the noise as well as at the click masked threshold; at neural hearing loss, however, the response can be recorded again with a click-intensity, which exceeds that of the noise clearly.

Audiometry↗