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Biomedical subjects

H J Gerhardt

Publications and source records attributed to H J Gerhardt.

At least 37 records · Page 2Linked to original sources
PubMed1983

[Surgical optic nerve decompression in marble bone disease (Albers-Schönberg disease)].

This contribution describes the performance of a transethmoidal decompression of the optic nerve in a 5 1/2-year-old boy with marble bones (osteopetrosis, Albers-Schönberg disease). As a result of the operation the function of the eye still with vision was maintained in an unvarying good state over a follow-up period of some 5 years. In the literature only one other case of this diagnosis has been reported in which such an operation was successfully performed, though in that case with craniotomy. The procedure reported here was the first in which the transethmoidal approach was used, which puts less strain on the patient. In addition to the description of the case the problems involved are discussed.

Child↗
PubMed1983

[Respiration rhythm-controlled electric stimulation of paralyzed laryngeal muscles--animal experiment findings].

Patients with bilateral paresis of the recurrent laryngeal nerves have primarily breathing difficulties. But on the other hand the common operations for widening the glottis produce voice problems. To overcome these difficulties a muscle stimulation device was developed, which is triggered by the inspiratory motion of the thorax. With this device impulses are transmitted by radiofrequency from a transmitter located outside the body to a receiver implanted into subcutaneous tissue of the neck and thence by electrode wires to the posterior cricoarytenoid muscle (PCA). In the dogs with one cut recurrent laryngeal nerve the paralyzed vocal cord (VC) moved regularly with abductions at inspiration by stimulating the PCA. The efficiency of that stimulating device was proved by taking photographs of the VC-motion and by recording the subglottal air pressure changes.

Animals↗
PubMed1981

Some new aspects on damages in the organ of Corti after pure tone exposure.

(1) The loss of hair cells after pure tone exposure at the critical level of intensity shows an exact correlation to the frequency, the time of sound exposure, and time of recovery as regards the quality and quantity. (2) The total extent of the damage of sensory cells has to be estimated higher than the hair-cell loss as observed under the light microscope. Although an improvement of the function of the organ of Corti was determined electrophysiologically from the 5th to the 10th day of recovery, the hair-cell degeneration was progredient during this period. (3) The hair-cell damage is apically more strongly marked from the area of damage than basically. (4) Depending on the experimental conditions there are considerable degenerative alterations in the nerve fibres and in the connective apparatus of the organ of Corti besides hair-cell losses and damages.

Acoustic Stimulation↗
PubMed1979

[Therapy problems in sphenoethmoidal meningoceles].

After a brief survey of the forms of cranial meningoencephaloceles, the current opinions on their development, symptoms and surgical therapy, a report is given on the case of a five-year-old boy suffering from a sphenoethmoidal meningocele of the size 3 x 3 x 4 cm. There was at the same time a wide median palate cleft, obviously a consequence of the meningoencephalocele. A further finding presented by the boy was a neuroradiologically diagnosed agenesis of the Corpus callosum and a median cheiloschisis. This suggests a central development disturbance as a primary cause. The attempt to perform an intracranial occlusion of the defect of the base, which was repeated twice, was not successful. It was only by a transpalatinal-transnasal extradural intervention (reposition of the meningocele after removing the epipharyngeal mucosa, blocking of the bony defect with a perforated tantalum plate) that the removal of the meningocele was successful. The closure of the palate cleft was then made by the oral surgeon. This surgical intervention may also be considered for the treatment of the transsphenoidal meningoencephalocele, which also presents many problems.

Child, Preschool↗
PubMed1978

[Multivariate variability investigations of acoustically evoked slow potentials (AEP) (author's transl)].

By means of the multivariate variance analysis the ratio of intra- and interindividual variability of the AEP--time function was investigated. 90 AEP from 9 normal hearing persons (10 AEP from every person, averaging sessions spread over 10 weeks) were analyzed. The 10 AEP of every person were treated as a random sample. A multivariate pair comparison (single comparison between samples) on the basis of 12 variables (time points) showed only for 1 out of 36 sample pairs no significant differences between the sample averages. By applying the discriminant analysis false classifications resulted only for 7 out of the 90 AEP (approximately 8%). These facts mean, that even throughout the time of 10 weeks the intraindividual differences of the AEP--time behavior are significantly smaller than the interindividual ones.

Acoustic Stimulation↗
PubMed1978

[Hair cell noise damage after improved hypoxia tolerance (author's transl)].

UNLABELLED: Guinea pigs were gradually adapted to a simulated altitude of 10,000 m. The round window microphone potential (RMP) frequency response was measured 24 hours after pure tone exposition (2.7 kHz, 130 dB, 1 hr). The electrophysiologically demonstrable sound induced damage of the organ of Corti of the adapted guinea pigs was significantly smaller than those of the nonadapted (normal) group. Altitude adapted animals: m = 18, Hb: 18.5 +/- 1.8 g%, Hc: 57.3 +/- 4.4+ RMP mean loss: 1.7 +/- 0.8 dB. CONTROLS: n = 18, Hb: 12.7 +/- 1.8 g%, Hc: 40.5 +/- 1.6%. RMP mean loss: 5.8 +/- 2.4 dB. All differences significant p less than 0.001. The evident possibility to reduce noise induced hair cell damage by means of previous adaptation to high altitude might be explained by the greater hypoxia tolerance and perhaps additional better oxygen supply to the receptor cells.

Adaptation, Physiological↗
PubMed1977

[The proof of age differences of slow acoustically evoked potentials of adults by a multivariate statistical analysis (author's transl)].

Many authors consider the nature of the slow acoustically evoked potentials to be partly a specific one. Therefore the AEP-time behavior probably contains more information about the functional state of the acoustical channel than it is got by the usual measurement of only 3 values (N1P2-amplitude, 2 latencies). A test of this hypothesis is possible with a multivariate mathematical procedure, which involves the whole AEP-time behavior. We are using the multivariate variance- and discriminant analysis. For the application of this statistical method random samples of patients with certain otologic diseases are needed. To avoid mistakes in grouping these samples some preliminary investigations had been necessary: This paper reports the results of multivariate investigations concerning age differences of the AEP in normal hearing adults. By means of the multivariate variance analysis the AEP of 3 age groups were examined (group 1: 15--34 years, group 2: 35--44 years, group 3: 45--60 years). At 1000 Hz as well as at 400 Hz significant differences between the group averages were found, which were not detectable by the usual N1P2-amplitude measurement. Furthermore with the discriminant analysis it is possible to perform a relatively reliable differentiation between the individual AEP of the age groups 1 and 3.

Acoustic Stimulation↗
PubMed1977

[Problems of localization of noise damage in the cochlea - 70 years after Wittmaacks first animal experiments (author's transl)].

Wittmaack was the first, who investigated noise damage of the inner ear by animal experiments 70 years ago. This paper deals with the problem of estimating the extend of the damaged area on the basilar membrane following noise exposure by evaluating the microphonic potentials (MP) detected from the round window. With the aid of a mathematic model it is possible to predict both the decrease of the MP after noise exposure and the localization of the damaged area on Corti's organ. These predictions are examined by morphological investigations using the method of Spoendlin and Brun.

Evoked Potentials↗
PubMed1976

[Otitis media and cochlea. Morphological and biochemical studies in guinea pigs (author's transl)].

The paper deals with: 1. the protein concentration in the perilymph (PL), the serum and the cerebrospinal fluid (CSF), 2. the protein pattern in the PL and 3. histological findings in the middle and inner ear in unilaterally ear-infected guinea pigs. The studies were performed 6 h to 21 days post infectionem (Fig. 1). The pathological changes in the middle ear, which, in most cases, were limited to the infected ear, were initially evaluated under the operating microscope and divided into 4 stages. The analytical and histological results were presented as functions of these stages. As the inflammation intensity increased, the protein concentration in the PL of the infected ears increased to a level exceeding that of the normal value more than ten times (Fig. 2). However, in the serum and in the CSF this concentration remained unchanged. Likewise, no significant protein increase in the PL of the contralateral ears was detectable in most cases. As the inflammation intensity increased, the number of the precipitation lines detectable immunoelectrophoretically increased in the PL of the infected ears (Fig. 3). An increase in the alpha1- and gamma-globulins and a decrease in Albumin was found by electrophoresis on cellulose acetate strips (Tab. 3). The histological findings correlated with initially established inflammatory stages of the middle ear mucous membrane (Tab. 4). As the inflammation intensity increased, the round window, too, was changed pathologically, so that in some cases of purulent otitis media middle ear secretion could enter the cochlea. The protein increase in the PL immediately after the infection is probably due to an increase in the blood vessel permeability in the inner ear.

Animals↗