Search PubMed⌕ Search

Biomedical subjects

G Gerull

Publications and source records attributed to G Gerull.

At least 37 records · Page 2Linked to original sources
PubMed1981

[Olfactory stimulation and contingent negative variation (CNV) (author's transl)].

In addition to olfactory evoked responses (Fig. 1a) the vertex-negative voltage shift was registered in 20 normal adults. Fig. 2 shows this potential for an olfactory indicative stimulus followed by a tone burst or flash sequence, which are stopped by the test person's manual reaction. In Fig. 3 two alternating odorous stimuli are presented, one of which is followed by the tone. The selective expectancy wave is followed by the tone. The selective expectancy wave is only built up by the marked olfactory stimulus. For the first time CNV can be used as a clinical investigation tool to confirm central perception of odorous stimuli and furthermore to objectivate impaired central odour discrimination (parosmia).

Adult↗
PubMed1981

[Medium-latency acoustically evoked brain potentials used for examination of the auditory pathway (author's transl)].

Potentials of the 10-15 ms latency range evoked by acoustic clicks and Gauss-shaped tone bursts habe been investigated in normal hearing adults, 20 patients with cochlear damages, and 6 cases of temporal lobe processes. Methods and results are compared to those of brain stem audiometry. Mean and standard latency ranges are calculated for the different peaks (Fig. 1). Amplitudes should be used only for side difference evaluation in the same patient, because of their big interindividual variation. In cases of profound high frequency hearing loss (Fig. 2) medium-latency potentials yield true threshold values in the low frequency range, where brainstem potentials are failing. The medium latency potentials show a substantial decrease of amplitude for stimuli contralateral to the damaged side (Fig. 3). So this method can be a functional hearing test to detect or at least suspect temporal damages.

Audiometry↗
PubMed1979

Chronic and acute transtentorial herniation with tumours of the posterior cranial fossa.

In patients with expanding lesions of the posterior fossa general hyper-reflexia (and bilateral latency shifts of auditory evoked brain stem potentials) have been noted as possible symptoms of chronic ascending transtentorial herniation. After ventricular tap, this chronic herniation may evolve into acute herniation with progressive reduction of consciousness which in our experience can only be survived by decompression of the compressed brain stem. The chronic transtentorial herniation is related morphologically to demyelination of the pyramidal tracts and the auditory pathways, whereas the acute transtentorial herniation is related to microcirculatory disturbances in the reticular formation of the mesencephalo-pontine junction.

Auditory Pathways↗
PubMed1979

[Objective diagnosis of recruitment by brainstem audiometry (author's transl)].

The differential diagnosis in cochlear damage with brainstem potentials is easily done by looking for normal latencies that coincide with substantial hearing loss. Further validation can now be achieved with methods representing Fowler and SISI test equivalents. Amplitudes of brainstem potential were compared in 28 patients with marked differences of hearing loss in either ear. Amplitudes are balanced at the stimulus intensity corresponding to subjective loudness balance (Fig. 3). Intersubject comparison of input/output function steepness is not advisable because of the greater interindividual variation of amplitudes (Fig. 2). Amplitude modulation by short Gauss-shaped increments (Fig. 1) or by decrements of a continuous tone evokes clear brainstem potentials at thresholds of about 5dB above subjective detection, but it also depends upon stimulus duration or steepness (Fib. 4), frequency (Fig. 5) and the degree of modulation (Fig. 6). With a cochlear hearing loss of more than 40dB, a 1 dB increment evokes potentials for continuous tone intensities higher than 20 dB above subjective thresholds (Fig. 7). This test is mainly useful for children with retarded language development and lacking a stapedius reflex, for adults, who cannot sufficiently cooperate, and where there is a prolonged latency due to middle ear damage or a steep high frequency loss.

Audiometry↗
PubMed1979

[The complex tympanic membrane impedance in various middle ear disturbances (author's transl)].

Clinical experience with two-component registration (Susceptance and Conductance) of the tympanic membrane impedance at two frequencies (220 and 660 Hz) is reported. More than 1000 results of the last 6 years have been evaluated. The normal tympanometric shape is confirmed by computer simulation. More information about mass and elasticity relations of the middle ear is obtained by the complex registration at 660 Hz. Clinical examples are presented to demonstrate the influence of scars on the ear drum and of a disruption of the ossicular chain. In 77 cases of otosclerosis with stapes fixation, as confirmed by operation, the shape of the pressure-dependent admittance is significantly narrower than in normal hearing ears. For a glomus tumor a pulsation of the oto-admittance following the electro-cardiogram can be shown. In a classification of the tympanometric types the different shapes correspond well to the set of functional finding (normal) ears, otosclerosis, Eustachian tube malfunction, processes of the middle ear cavity, post operation state). The extreme sensitivity of the method, however, produces a small group of unpredictable results for each type. So differential diagnosis is to be done by usual audiometric methods or microscopy of the ear drum.

Acoustic Impedance Tests↗
PubMed1978

[Quantitative results of the brainstem audiometry in middle ear, cochlear, and retrocochlear hearing damage (author's transl)].

After a discussion of the technique and validity of the objective audiometry using acoustically evoked brainstem potentials, we demonstrate the shape of potentials at various locations of the scalp. We compare the objective findings for middle and inner ear hearing losses with the subjective audiogram. Disturbances in the middle ear are marked through a letency shift corresponding to the hearing loss with normal bone conducted reaction. When the cochlea is damaged we notice a quick decrease in amplitude from the loudnesscompensation to the threshold with normal latencies. As examples for retro-cochlear damages we give the cases of a child, retarded after encephalitis, of an infant and of a patient with stato-acoustic neurinoma, whereby also the cochlear, subcortical and cortical potentials are evaluated.

Acoustic Stimulation↗
PubMed1977

[Damages of the auditory pathway at brain stem level investigated by acoustically evoked potentials (author's transl)].

In 57 patients with operated expansive tumors in the postcranial fossa auditory evoked brain stem potentials were investigated. A group of 36 with neurological evidence for the brain stem compression showed significantly prolonged latencies (Fig. 1), whereas the evoked potentials were nearly normal in the preceding state of CSF circulatory disturbances (21 cases). For one patient with a neurinoma of the right trigeminal root the post-operative reduction of the pathological latency shift is demonstrated (Fig. 2). Latency evaluation of evoked brain stem potentials are used in our clinical routine for differential diagnosis of retrocochlear hearing damages.

Acoustic Stimulation↗
PubMed1977

[The investigation of different types of vocal disorder by statistical frequency analysis (author's transl)].

Common disorders of the vocal cords were assessed by indirect and direct laryngoscopy and by stroboscopy, and they were compared over the frequency range of "a". Amplitude and frequency variations from the normal are illustrated in recurrent laryngeal nerve paralysis, intubation granuloma, chronic oedema, the hyperkeratosis of chronic laryngitis, hypokinesia and hypokinetic dysphonia. In several cases, the effects of exercise or previous surgery are demonstrated. The described technique gives a useful aid to the management of vocal cord disease.

Aged↗
PubMed1975

[Clinical diagnosis of the auditory pathway using different acoustical evoked responses (author's transl)].

Evoked responses originating from cochlea, brain stem, and cortex are clinically used for differential diagnosis of hearing losses. The diagnostic range and the reliability of the different ERA methods are discussed. In our clinic brain stem potentials recorded by a nonsurgical method have been used as a routine audiometric test in more than 900 cases. The procedure has proved to be easier than electrocochleography and gives nearly the same information about cochlear and middle ear function if there is no VIIIth nerve or lower brain stem damage. For topical diagnosis of the lower auditory pathway additional recording of ECoG is necessary. In the examination of a cortical deafness the recording of brain stem potentials yields the same result as the electrocochleography according to Aran (Fig. 2). In a case of an Apallic syndrome (Fig. 3) brain stem potentials are found only for high intensity clicks, and latencies are abnormally increased. The cochlear potentials simultaneously recorded from the promontory are quite normal. So damage of the brain stem is confirmed.

Adult↗