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Biomedical subjects

K F Hamann

Publications and source records attributed to K F Hamann.

At least 37 records · Page 2Linked to original sources
PubMed1986

[Effect of stabilization of the visual field on rotatory testing].

The nystagmus of 20 normal subjects was compared by means of the rotatory test in the dark, in respect of visual fixation, and with stabilization of vision. Visual fixation was tested by means of a small lamp placed at a distance of 40 cm in front of the eyes of the subject. This point of fixation was attached to the rotating chair. Stabilization of vision was attained through a box placed above the head of the test person. This box - covering the whole visual field - moved synchronously with the rotating chair. Contrary to the test with fixation, the eye received no information about the real movement. The question was whether there would be any differences between the fixation test and the stabilization of vision. In both test conditions, fixation overrides the vestibular stimulus and results in suppressing both per- and postrotational nystagmus. This proves that the foveal vision and not peripheral vision is responsible for the suppression of fixation.

Adolescent↗
PubMed1985

[Critical remarks on so-called cervicogenic vertigo].

A critical review of neurophysiological literature is given about the part played by the neck proprioceptors in the regulation of vestibular functions. In comparison with vestibular and optokinetic influences the neck proprioceptors are of secondary importance. A critical review of the publications by the supporters of a cervical genesis of vertigo leads to the conclusion that "cervical nystagmus" must be proven before the concept of neck-triggered vertigo can be accepted. In relation to all forms of vertigo, vertigo induced by cervical disorder represents a very low percentage only.

Afferent Pathways↗
PubMed1984

[Inclinometry as a method of registering postural reactions].

Posturography is compared with inclinometry in four experimental conditions: Romberg's test, voluntary body sway, induced pendular body sway and galvanic stimulation. For all methods an agreement between the recorded curves can be seen. Inclinometry seems to be suitable for practice in spite of some possibilities of error. For scientific research, posturography should be preferred.

Humans↗
PubMed1984

[Posturographic study of alcohol-habituated subjects with different blood alcohol concentrations].

It was shown in a posturographic study that the body sway of 15 alcohol habituated persons did not change significantly up to amounts of 1% blood alcohol concentrations. A smaller group of 4 persons showed greater body sway amplitudes already in a moderate concentration. In otoneurologic diagnostic alcohol history, drinking customs and physical constitution play an important role in vestibular spinal examinations.

Adult↗
PubMed1983

[Treatment of vestibular function disorders by a training program].

This article reports on a training programme for vestibular diseases, involving exercises of the vestibulo-vestibular, the visuo-vestibular, the cervico-vestibular and the spino-vestibular reflexes. Twenty-five patients were examined; all patients but two showed good improvement of the vestibular complaints as demonstrated by vestibular diseases, electronystagmography and posturography.

Electronystagmography↗
PubMed1982

[Visuovestibular interaction in the regulation of body posture].

Visual stimulation can provoke egocentric illusory movements or changes of posture. Therefore, vestibulo-spinal tests were usually performed with eyes closed. A more sensible method seems to be the "visual stabilization", which is obtained by means of a box fixed on the head and with eyes open. In this manner, body instability due to vestibular disorders becomes more apparent.

Eye Movements↗
PubMed1981

[Vestibulo-spinal tests for medicolegal assessments (author's transl)].

For the medicolegal assessment of vestibular disorders, vestibulospinal tests are necessary. A minimum program includes the Romberg test, the Unterberger stepping test, and walking with eyes closed. When positive results are found, semi-quantitative evaluation is possible. However, this value is less important than is vestibulo-ocular examination.

Expert Testimony↗
PubMed1981

[Possible viral etiology of inner ear diseases (author's transl)].

After a short review of the possible viral etiology of inner ear diseases viral titers of 20 patients with inner ear problems are given. In the history of nearly all patients a viral infection was found. Inspite of some positive results in the titrations no significance was seen. Therefore we refute a relation between viral infection and inner ear troubles; for a practical point of view virological diagnostics is not indicated.

Antibodies, Viral↗
PubMed1980

Response of central vestibular neurons to horizontal linear acceleration in the rat.

Responses of central vestibular neurons to horizontal sinusoidal translation (F:0.25Hz) were recorded in albino rat. 57.5% of vestibular neurons were responding to this stimulation by a modulation of their firing rate, the mean phase angle of the response, averaged from the whole population being 22 +/- 79 deg. lag, relative to the peak of contralateral acceleration. Dynamic characteristics of phase and gain were studied and appeared to be different from previous reports on primary afferents: the gain decreased or was flat with increasing acceleration at one frequency, and the phase lag which was flat in the same conditions increased with increasing frequency. A phase lead of some units has been observed at low frequency (0.1 Hz). Regarding the convergence between otolith and canal inputs on nuclear vestibular neurons, it was shown that the major pattern of convergence is between canal and otolith inputs of same polarity.

Acceleration↗
PubMed1979

Electronystagmographic study in rabbits on the vestibular effect of vincamine.

Vincamine (Vincapront), the alcaloid isolated from Vinca minor L, was tested in rabbits at three dosages (1 mg/kg, 5 mg/kg, 10 mg/kg i.m.) in an electronystagmographic study. The parameters evaluated were: duration, rate and frequency of the post-rotatory nystagmus and the frequency of the per-rotatory nystagmus. While the post-rotatory nystagmus was found to show a reduction in duration and rate, the frequencies did not respond to vincamine. The 1 mg/kg dose had the strongest effect while that of the 10 mg/kg dose was weakest. As these findings may not be explained by sedative or habituation effects we consider the reduction of the post-rotatory nystagmus as an analogue in animal experiments of the vestibular effect seen in man. The electronystagmographic pattern of action corresponds to that of some other antivertiginous drugs.

Animals↗
PubMed1979

[Bilateral acoustic neuromas, a report of eight cases (author's transl)].

The treatment of bilateral acoustic neuromas is extremely difficult. An earlier diagnosis would give better opportunities to preserve facial and hearing function. We study on eight cases, the initial symptoms and the evolution to stimulate the interest of the E.N.T. specialist of this unrecognized disease.

Adolescent↗
PubMed1972

Modifications of dorsal horn cell activities in the spinal cord, after intra-arterial injection of bradykinin.

1. A method is described to study the modification in the activity of the lamina IV and V cells of the dorsal horn under the intra-arterial administration of bradykinin into the hind limb of the spinal cat.2. The modifications induced by intra-arterial injection of bradykinin preferentially affected the lamina V cells (77% of the units) and produced few changes in the lamina IV cells (16% of the units showed variations).3. 52% of the lamina V cells were activated; the mean increase in the firing rate was 700%. The mean latency of the effect was 20 sec and the mean duration was 47 sec. However, there was large variance in the excitatory effect across cells. On the other hand, for the same cell, the observed effects were perfectly reproducible and injections of physiological fluid induced no response.4. 25% of the lamina V cells were inhibited. Generally, the activity of the cell was reduced to 13% of its initial value; in some cases, a total suppression of activity was observed. The mean latency of the inhibitory effect was 12 sec and its duration 28 sec. All these units had a very wide inhibitory field (activated by stimulations of low intensity) which asymmetrically surrounds the excitatory field.5. This study confirms the role played by the lamina V cells in the transmission of nociceptive messages. The existence of inhibitory phenomena is in favour of the gate control theory described by Melzack & Wall (1965) without deciding the pre- or post-synaptic nature of these mechanisms.

Action Potentials↗