Search PubMed⌕ Search

Biomedical subjects

U Reker

Publications and source records attributed to U Reker.

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

[Monosymptomatic onset of Menière's disease].

The occurrence of monosymptomatic courses of Menière's disease is not generally accepted, although cochlear forms are described in literature. Retrospectively, we evaluated the case histories of 108 patients with Menière disease, who developed the typical trias in the further course of the disease. Among these 108 patients, we found 39 with a true monosymptomatic course, i.e., in each case we could exclude the participation of either the cochlea, or the labyrinth by exact clinical investigations. Two-thirds of the patients first noticed the impairment of hearing, one-third the vertigo. Basing on a time interval of more than one year, there were still 18 patients with a monosymptomatic course. The average duration of the monosymptomatic courses is distinctly shorter than the duration of the typical trias and, consequently, we defined them as equivalents to early forms of the disease. At this early stage a diagnosis is possible by the fluctuating cochlear signs with their typical audiogram configurations, and the attack character of the vestibular symptoms.

Adult↗
PubMed1983

[Cervical nystagmus caused by proprioceptors of the neck].

A pathological nystagmus, occurring during turning of the trunk in relation to the head, which is held stationary in space, clearly points towards a cervical origin of vestibular vertigo. Such a cervical nystagmus may have a vascular origin by the compression of the arteriae vertebrales, or a proprioreceptive origin via the upper neck joints, or it may possibly be due to functional disturbances of the upper cervical spine. The dynamic characteristics of the so-called cervico-ocular reflex can be examined only in patients with non-functioning labyrinths, since in a healthy person the reflex is so strongly suppressed that it cannot be analyzed any more. In five patients with isolated bilateral complete vestibular deficiencies, we found a strong cervico-ocular reflex. Detailed examinations showed that nystagmus occurred during turning of the body in relation to the head ("phasic neck reflex"). On the other hand, when remaining in the extreme positions, the proprioreceptive nystagmus does not persist. Contrary to this, a cervical nystagmus due to vascular causes shows a latency period after torsion of the neck and increases if the head remains in the extreme position. Before assuming a cervical origin of a vestibular vertigo, an examination for cervical nystagmus should be carried out. Such a cervical nystagmus is the only definite pointer towards a relation between an upper cervical spine syndrome and vertigo, which is sometimes assumed rather uncritically.

Adult↗
PubMed1982

[Enhanced variability of the thermal test with patients with vestibular disease (author's transl)].

The reproducibility of nystagmus-intensity was measured with patients with peripheral vestibular disease, and with healthy persons, by a fivefold repetition of the same thermal stimulus. Variability of the data of the patients was considerably higher than of the healthy persons. Thus, the "normal" data have only a restricted value. Therefore, interpretation of thermal tests is more difficult for patients with an eventual vestibular disease. The origin of the enhanced variability seems to be the weakness of the reaction per se, because strong stimuli and hence strong reactions with healthy persons, have a lower relative standard deviation. Furthermore, tonic fluctuation in the diseased vestibular system is probable, as healthy ears of patients with unilateral vestibular disease show increased variability. An improvement of the method of the test is necessary. This can, for instance be achieved by an examination with eyes open under Frenzel's glasses and by repeated, by short and by strong stimuli.

Ear Diseases↗
PubMed1981

[The effect of non-coplanarity of the horizontal semicircular canals on experimental vestibular testing (author's transl)].

It is generally accepted that the horizontal semicircular canals are coplanar. One hundred three elliptic tomograms of human temporal bones have been evaluated for their planar relationship. The median was 180 degrees. However, the values varied between 160 degrees and 223 degrees. Differences of more than +/- 10 degrees were found in 31% of all cases. These anatomic variations are important for experimental vestibular testing, if, e.g., vestibulo-spin al effects result in a deviation or a torsion. With rotatory testing, stimulus intensity is a function of head inclination in relation to the stimulus plane. Non-coplanarity associated with head inclination results in asymmetric stimulus strength. With thermic testing, the effective stimulus is a function of the angle between temperature gradient across the canal and gravitation. Besides deviations from the perpendicular plane, rotations within this plane, according to Brünings "Schiefoptimumstellung", additionally cause asymmetrical errors.

Ear, Inner↗
PubMed1981

[Impedance measurement for the diagnosis of middle ear effusions (author's transl)].

Impedance measurement is especially important for the diagnosis of middle ear effusions with pre-school-children. Instead of simply classifying into different tympanogram types, a descriptive analysis of each parameter is preferable. The presence of the stapedius reflex, middle ear pressure, form of peak, compliance and gradient of the tympanogram are discussed separately as to their sensitivity and specificity regarding diagnosis of effusion. The diagnostic certainty of the tympanogram is thereby considerably increased.

Acoustic Impedance Tests↗
PubMed1981

[Vestibular neuronitis and its differential diagnosis (author's transl)].

The study gives a survey of the different terminologies, opinions regarding etiology, and differential diagnoses. In accordance with animal experiments, and our own experience with 71 patients, an activating therapy, including exercises, is recommended instead of bed-rest. Under special circumstances diagnosis may be difficult. For instance, a centrally reduced thermal reactivity of the healthy labyrinth may mimic a bilateral canal paresis. The vestibular type of Menière's disease, disseminated encephalomyelitis, herpes zoster oticus, or the complication of a chronic otitis media cannot always be differentiated from a unilateral vestibular paralysis.

Diagnosis, Differential↗
PubMed1980

Caloric testing by continuous automatic alternating irrigation.

Quantitative caloric test results show a high variability. They were described as questionable by Frenzel (1955) and a review of the test was recommended by Hood (1973). Thus, we developed a new method: continuous automatic alternating irrigation. An irrigator is connected to two water-baths of 30 degrees C and 44 degrees C. A time-relays switches over from one bath to the other every 60 s. The continuous, but alternating, irrigations produce subsequently alternating exponential temperature waves in the temporal bone. The mathematical model shows a quasi-periodicity and sufficient symmetry of the alternating thermal gradient across the canal, except for the first stimulus. After 11 irrigations of 60 s, a short (20 s) "washout" irrigation terminates the sequence. By the five repetitions of each stimulus and the additional possibility of correlating the response to the paper-marked stimulus periodicity the judgement is far more reliable and therefore, in doubtful cases, despite the five-fold data, quicker. The technical device is simple enough for routine use and inexpensive. The results of the caloric test are now much more clear-cut and the correlation to a known clinical pathology is remarkably high.

Body Temperature↗
PubMed1980

Peripheral-vastibular spontaneous nystagmus. Analysis of reproducibility and methoidolgies.

UNLABELLED: With peripheral spontaneous nystagmus the intensity and its reproducibility was electronystagmorgraphically analyzed with eyes open under Frenzel's glasses and with eyes closed. RESULTS: 1. The maximum intensity of a spontaneous nystagmus with eyes closed is several times higher than under Frenzel's glasses. 2. A weak nystagmus can, under Frenzel's glasses, only be recognized under favorable conditions. A rather long and careful search in a totally dark room is necessary. 3. With purely peripheral lesions, the spontaneous nystagmus with closed eyes shows large intensity fluctuations, and it may disappear temporarily despite mental arithmetics. Contrary to this, with eyes open under Frenzel's glasses, the intensity fluctuation of the nystagmus is remarkably lower. Therefore, even experimental examinations with patients should be carried out electronystagmorgraphically under Frenzel's glasses. The absolute reaction is lower, but the content of information is higher because of the significantly better reproducibility.

Adult↗
PubMed1980

Extent of reaction capacity of the vestibulo-ocular reflex.

On theoretical grounds, a high capacity of the vestibulo-ocular reflex, compensating for head velocities above 300 degrees/s, is assumed. However, in man the maximum eye speed, induced by solely vestibular stimuli, is only 100 degrees/s. With the usual clinical tests is seems impossible to get a sufficient strength of stimulus that would correspond to a strong physiological stimulus. With a systematic investigation with fistula symptoms finally a patient was found with an ideal mechanism of release of the fistula symptom. The maximum eye speed of the compensatory phase was 315 degrees/s. In this case, the vestibular phase was quicker than the so-called rapid phase. This now proven high reaction capacity constitutes the "missing link" between the hypothetical high capacity of the systems concept and the until now measured, only limited reactions after solely vestibular stimulation. For most physiological stimuli, i.e., quick head movements, the system can act as a simple reflex organ, being a velocity transducer with linear function thus successfully maintaining ocular fixation.

Aged↗
PubMed1980

[Binaural summation of the ipsilateral and contralateral acoustic stapedius reflex (author's transl)].

The binaural summation of the simultaneous contra- and ipsilateral acoustic stapedius reflexes was examined in 20 normal-hearing patients. In these patients, the effect of summation was most pronounced with subthreshold intensities. A contralateral reflex was increased by ipsilateral intensities 8 db below threshold. A reflex could also be elicited by binaural intensities which were contra- and ipsilaterally 4 db below threshold. As a result of our studies, we recommend a revision of the definition of a positive Metz-recruitment. Because of possible binaural summation effects, the absolute value of the contralateral stapedius reflex threshold should not exceed 105 db HL in spite of possible sensorineural hearing loss.

Acoustic Impedance Tests↗
PubMed1980

[Stapedius-reflex-audiometry by measuring the threshold for the re-inforcement of a pre-existing reflex (author's transl)].

The possibilities for predicting the pure tone threshold on the basis of the acoustic stapedius reflex threshold are improved by using two stimuli, e.g., white noise and pure tone, or two pure tones according to Sesterhenn and Breuninger. The principle of the monaural loudness summation with regard to the stapedius reflex was systematically examined with the aim to obtain the best suited range for clinical use with a double tone stimulus. The following procedure proved to be the most reliable one for an objective audiometry: A distinct reflex is produced by a basic pure tone of 4 kHz, 10 dB above its reflex threshold. The tone to be examined (1 kHz) was added with a delay of 0.5 s. A 1 kHz tone 28 dB below the reflex threshold (median) produced a clear re-inforcement of the basic reflex. Objective extrapolation possibilities from stapedius reflex threshold to pure tone threshold are thereby improved.

Acoustic Impedance Tests↗
PubMed1977

Normal values of the ipsilateral acoustic stapedius reflex threshold.

It is frequently taken for granted that the acoustically evoked stapedius reflex is bilaterally symmetrical. Contrary to this, Møller described an asymmetry of the acoustic stapedius reflex with an ipsilaterally 2--14 dB lower threshold. The determination of normal values of the ipsilateral acoustic stapedius reflex threshold with a large number of patients is difficult as the intensity of the stimulus depends considerably on the position of the probe in the acoustic meatus and is therefore not defined with sufficient accuracy. For this reason we determined the values of the ipsilateral threshold by applying a stimulus sound of high intensity to the deaf ear of unilaterally completely deaf patients with a normal headphone, which can be calibrated much more accurately. After subtraction of the individual cross hearing loss, the exact ipsilateral intensity was obtained. By this method a stapedius reflex could be evoked with 49 of the 62 patients. By mathematical consideration of the data of the positive cases, as well as the maximum available intensities with the negative cases, determination of the median value of the ipsilateral threshold was possible: at 0.5 kHz 59 dB; at 1kHz 62.5 dB; at 2 kHz 67 dB; at 4 kHz approx. 67 dB. The difference between ipsilateral and contralateral stapedius reflex threshold was in the range of 15 dB. A new definition of the normal value for the ipsilateral measured Metz recruitment appears necessary.

Auditory Threshold↗
PubMed1977

Caloric diagnosis maximum stimulus and suppression of habituation effects.

The relation between randomized caloric stimuli of 30 degrees - 5 degrees C to the parameters: duration, maximum frequency and maximum intensity was electronystagmographically examined on 25 persons. The duration and the maximum frequency showed only a slight correlation to the stimulus. There was a linear correlation to the maximum intensity and the stimulus between 30 degrees and 15 degrees C. But with temperatures below 15 degrees C the reaction did not increase. So the maximum intensity corresponds best to the characteristics of the temperature wave in the petrous bone and thus to the cupula deviation. By mathematical correction of the randomized stimulus sequence it was possible to show that habituation effects can be suppressed by certain test conditions, e.g. a constant degree of alertness of the subject and free head movements in the intervals. It is recommended to replace the 30 degrees C stimulus by a 17 degrees C stimulus: by this strong stimulus extra-vestibular interference and the influence of a latent spontaneous nustagmus are relatively suppressed and hypoexcitability is more accurately determined. Temperatures below 15 degrees C are not recommendable: the vestibular stimulus is not stronger but more painful and pseudocaloric effects are accentuated. When ascertaining correctly a spontaneous nystagmus we propose to refrain from the determination of directional preponderance, the value of which seems questionable.

Adaptation, Physiological↗
PubMed1977

[Acute isolated vestibular paralysis. A clinical and electronystagmographic follow-up study in 28 patients].

Twenty-eight patients with unilateral acute vestibular paralysis (vestibular neuronitis) were examined after a period of 4-140 months. Seventeen of these patients were examined by electronystagmography with caloric stimuli at 44 degrees, 30 degrees, 17 degrees and 0 degrees C. Most were free of subjective symptoms only one-third had slight unsteadiness after sudden head movement. Subjective symptoms were independent of the presence of permanent canal paralysis or partial recovery of caloric excitability. Spontaneous nystagmus of 3-6,6% intensities was found in 11 of 17 patients. The normal limit for physiological spontaneous nystagmus should therefore be below 3 degrees/s. The most reliable parameter was the maximum velocity of the slow phase, as a mean value of the 4 caloric responses (values corrected for spontaneous nystagmus). The results were: 6 patients with persistent canal paralysis; 4 patients with considerable hypoexcitability; and 7 patients with moderate hypoexcitability. In no patient complete restoration of normal caloric response was found. This is attributed to the described method of caloric testing, which permits exact measurement of small side differences in excitability.

Acute Disease↗
PubMed1977

[The diagnostic value of the Stepping Test of Unterberger (author's transl)].

Of the vestibulo-spinal reactions, the "stepping test" is considered to be the most important, especially for unilateral peripheral vestibular disturbances. Electronystagmography was performed on seven patients after transtemporal neurectomy of the vestibular nerve, 17 patients with a nearly compensated vesitbular defect after vestibular neuronitis, and seven patients after suboccipital removal of acoustic neuromas. These results were then compared to the spontaneous stepping test. The test could not be performed on six of the seven patients with the operated acoustic neuroma, and on three other patients. The test was positive in only ten of the other 22 patients. It was incorrect in five patients and equivocal in seven. A reliable spontaneous vestibulo-spinal reaction with nearly compensated peripheral vestibular defects could not be determined during the present study.

Adult↗
PubMed1976

Nystagmographic Analysis of the Fistula Symptom.

An electronystagmographic examination of the fistula symptom was carried out to ascertain the relation to pressure, the temporal pattern and the reversability of the nystagmus. The relation of nystagmus-intensity to pressure is not constant, often this relation is expressed by an s-curve. The nystagmus does not increase significantly above intensities of 70 degrees/s. The nystagmus-intensity has a typical temporal pattern: it starts immediately after application of pressure and for several seconds to minutes it practically remains on this level. Subsequently it slowly decreases. When, with a constant pressure, the nystagmus had faded out entirely, then, under relief of pressure, a nystagmus with reverse direction but equal intensity appears. After obtaining a fistula symptom there is a relative refractory time, which sometimes lasts for minutes. Only the change of pressure (which may have an effect of up to several minutes) and not the pressure by itself is decisive for the release of fistula symptom.

Electronystagmography↗