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Biomedical subjects

U Thoden

Publications and source records attributed to U Thoden.

At least 19 recordsLinked to original sources
PubMed1999

[Neurogenic pain after deafferentation through trauma. Little-known pain syndrome following amputation, brachial plexus injury and nerve root avulsion].

Amputations may be followed by such phenomena as phantom-limb pain, and pain and involuntary movements of the stump. The sequelae of brachial plexus injuries or cervical root avulsion--the second large group of deafferentiation lesions associated with neurogenic pain--are less varied, and most of these cases involve damage to the substantia gelatinosa of the spinal cord. The two groups of deafferentiation lesions are described on the basis of our own experience and reports in the literature. A generally applicable effective form of treatment is not known, and possible therapeutic approaches, which need to be adapted individually, are discussed.

Amputation, Surgical↗
PubMed1992

A modified method of electronystagmography for recording eye movement during the galvanic vestibular test.

This study demonstrates a new technique for recording galvanic nystagmus using conventional electrooculography: a first pair of electrodes is placed at the nasal and lateral orbital margin of the left eye. An additional pair of electrodes is placed near the left angle of the mouth. This latter pair of electrodes picks up voltage variations induced by heart beat but only a minimal part of voltage variations caused by eye movements during bipolar, binaural electric stimulation. Electronic subtraction of the voltage variations near the angle of the mouth from the voltage variations at the equilateral eye cancels the cardiac interference and allows a pure recording of horizontal eye movements. 35 of 40 subjects could be examined successfully.

Adult↗
PubMed1992

Evaluation of the galvanic vestibulo-ocular response recorded with a modified electronystagmographic technique.

Previously, a simple method for recording galvanic nystagmus (GN) using conventional electronystagmography (ENG) was demonstrated. The present study reports on investigations made to examine the applicability of that technique. During a standard stimulus over 20 s, amplitudes and rate of saccades show no tendency to diminish. In a series of 10 repeated standard stimuli over 16 min, a parabolic relationship is observed between time on one side and on the other, the mean amplitude, the mean rate of saccades and the sum of amplitudes per stimulus duration. The threshold of GN was 1.29 mA and that of induced tilting sensation 3.64 mA. In a series of 8 repeated threshold stimuli, thresholds of GN and tilting sensation linearly increase (p less than 0.001). During the slow increase of the current, the amplitudes and frequency of saccades and the slow-phase velocity linearly increase (p less than 0.01). The direction of per- and poststimulatory galvanic nystagmus and tilting sensation were investigated. Several autonomic reactions and psychophysical sensations during stimulation were noted. In conclusion, it is thought that the modified ENG technique is a valid method for further clinical use and basic research and its applicability has proven to be good.

Adaptation, Physiological↗
PubMed1992

The vestibulo-ocular response during transient arousal shifts in man.

Horizontal vestibulo-ocular response (VOR) evoked by continuous sinusoidal rotation (0.1 Hz, +/- 90 degrees) was recorded in 20 young and healthy volunteers by DC oculography (EOG). Arousal was assessed by EEG and by reaction time measurement. While alert subject showed the characteristic VOR with vestibular nystagmus, the quick repositioning flicks disappeared during light sleep and changed to largely compensatory smooth eye deviations. This state of reduced arousal was also characterized by EEG attenuation and slow reaction times. Furthermore, we observed brief states with complete extinction of the vestibular response but without significant EEG change. The results demonstrate the high variability of VOR with shifting arousal. The polysynaptic system in the reticular formation which generates the fast phase of the nystagmus beat is far more modifiable than the three-neuronal reflex arc of the slow nystagmus component.

Acceleration↗
PubMed1991

Tonic cervical stimulation: does it influence eye position and eye movements in man?

In healthy subjects eye movements were analysed during body rotation, during trunk torsion either with the head passively held stationary in space or with the head voluntarily stabilized in space, and during voluntary head movements. Trapezoidal movements around the vertical axis were performed (+/- 40 degrees, plateau 10 s, duration of ramp 1 or 4 s). Moreover the influence of a tonic head deviation up to 40 degrees on optokinetic nystagmus and on vestibulo-ocular reflex during sinusoidal turning was examined. Eye movements were recorded by DC-electrooculography. Saccadic and slow components of eye movements and the shift of eye position during the plateau of the trapezoidal stimulus were analysed. For all modes of stimulation during the plateau no nystagmus occurred. At the end of the dynamic phase of the stimulus relatively frequent eye deviations--mostly in the direction of the head deviation--were observed, not only after turning the trunk with the head stabilized in space (cervical stimulation) but also after turning head and trunk together. The fact that such eye deviations are thus observed even in the absence of any tonic, especially cervical stimulus, supports the assumption that they cannot be attributed to a tonic stimulus but merely to an effect of the preceding phasic stimulus which outlasts them. Also amplitude and direction of eye shifts during the plateau do not depend on a tonic stimulus, but merely on the eye deviation reached at the end of the dynamic phase of stimulation. Optokinetic nystagmus and vestibulo-ocular reflex are not influenced by an additional tonic cervical stimulus.

Adult↗
PubMed1990

Association of tardive dyskinesia with increased frequency of eye movement disturbances in chronic schizophrenic patients. A clinical note.

The study of eye movement dysfunction in chronic schizophrenics by electronystagmography revealed a significant increase of saccadic dysmetria as well as saccadic intrusions in smooth pursuit in schizophrenic patients with tardive dyskinesia (TD) compared with those without TD and with healthy controls. The pattern of eye movement dysfunction in schizophrenia allows clear discrimination from patients with similar movement disorders due to Huntington's disease. Of several possible explanation's of the schizophrenic eye movement dysfunction the authors favour the hypothesis of a common pathogenetic link between TD and eye movement disorders in schizophrenia, consisting in an underlying dysfunction of regions involved in the regulation of involuntary attention such as the parietal cortex and striatolimbic structures of the right hemisphere. Recent literature supports the assumption of right hemispheric dysfunction in schizophrenia.

Adult↗
PubMed1990

[CT follow-up studies of conservatively treated lumbar intervertebral disk herniation].

A CT study was carried out on 43 patients with low back pain and sciatica who were treated conservatively. They were followed up for over 20 months (mean) clinically and monitored by CT before and after treatment. Initially, 38 of them had herniation and 5 had protrusion of the disc. At the time of follow-up only 24 of the initial 40 patients still had neurological deficits. In 76.7% of the patients CT showed an improvement (clear regression in 15 patients, moderate decrease in 18 patients). A favourable tendency towards regression was observed in disc herniation at the L5-S1 level and in cases showing sequestration. The prognosis was unfavourable in herniations at higher levels than L5-S1 and in lateral herniation reaching the intervertebral foramen.

Female↗
PubMed1989

Eye movements during voluntary head motion with minimized cervical input.

Eye movements were recorded using DC-electro-oculography in 20 healthy subjects during sinusoidal voluntary head movements and during similar voluntary head movements with minimized cervical input. The eye movements during these conditions were compared to the vestibulo-ocular reflex (VOR), to the cervico-ocular reaction (COR) and to the active COR (i.e., voluntary stabilization of the head in space while the trunk was moved sinusoidally). Each subject sat with eyes covered on a rotating chair. Sinusoidal movements having an amplitude of +/- 20 degrees and either 0.1 or 0.2 Hz were performed. Voluntary head movements and head movements with minimized cervical input showed no difference in the gain of the slow-phase velocity of the nystagmus, the saccadic activity (cumulated amplitude/time) and the maximum eye deviation. The distribution of saccades around the reversal of head movement in space represents the only significant difference between these conditions. While the saccades appear promptly after reversal during sinusoidal voluntary head movement, they appear during voluntary head movement with minimized cervical input just before the reversal of head movement in space. The direction of saccades always depends on the displacement of the head related to the trunk and is due to cervical input and/or central influences.

Adult↗
PubMed1988

Chronic central nervous system involvement in Lyme borreliosis.

We describe four patients with marked chronic meningoencephalomyelitis caused by tick-transmitted Borrelia burgdorferi infection. Imaging techniques showed either MS-like lesions or evidence of vascular involvement, as in other spirochetal infections, especially in meningovascular syphilis.

Adult↗
PubMed1986

Downbeat nystagmus indicates cerebellar or brain-stem lesions in vitamin B12 deficiency.

Two cases of vitamin B12 deficiency caused by gastric atrophy are described. Together with the neuropsychiatric features usually associated with this condition, a downbeat nystagmus syndrome was observed. It is concluded that vitamin B12 deficiency may also result in lesions to those cerebellar or brain-stem structures that are generally assumed to cause downbeat nystagmus.

Aged↗
PubMed1986

Influence of standing on vestibular neuronal activity in awake cats.

Single-unit activity of vestibular nuclear neurons was recorded in chronically prepared, awake cats. To examine the influence of tonic activation of limb proprioception on vestibular function, the vestibular modulation by horizontal rotation (0.2 Hz, 17 deg) and head-tilt (0.1 Hz, 7 deg) was recorded in animals with freely hanging limbs and was compared with the modulation in standing cats. Of 29 examined cells responding to horizontal rotation, only about 30% were affected during standing, with most exhibiting a decrease of the mean discharge rate and gain. In contrast, about 70% of the 28 tilt-modulated cells showed pronounced effects during standing with a decrease of the gain and an increase of the mean discharge rate. The increase of the mean discharge rate in tilt cells may be caused by the excitatory spinovestibular afferent fibers or by the efferent vestibular system. For the observed inhibitory effects on the gain different mechanisms may be responsible: cerebellar inhibition and/or efferent vestibular receptor control. This control of labyrinthine information by somatosensory afferent fibers may serve for the stability of equilibrium in the moving animal.

Animals↗
PubMed1985

Piracetam improves visuomotor and cognitive deficits in early Parkinsonism--a pilot study.

The influence of Piracetam on Parkinsonism was studied in 18 patients and 18 matched controls. Clinical, visuomotor and psychometric variables were measured. Piracetam improved visuomotor reaction time (RT) and accuracy in 6 mildly affected and tracing time in 6 moderately affected patients, the clinical condition and the organic brain syndrome in all patients investigated. The improvement of the prolonged RT seems to be correlated with bradyphrenia. No drug influence could be observed in the prolonged interhemispheric transfer time. As the mildly affected patients displayed the clearest effect of Piracetam, its administration in early and mild stage of parkinsonism is recommended.

Aged↗
PubMed1985

Huntington's disease: visuomotor disturbance in patients and offspring.

In 15 patients with Huntington's disease, 17 offspring at risk and 63 healthy controls, visuomotor performances were assessed by quantitative (statistical) and qualitative analysis. The much enlarged error score of the nondominant left hand in patients with Huntington's disease was explained as callosal dyspraxia. Five of the 17 offspring revealed results similar to that of the patients.

Adolescent↗
PubMed1984

Responses to corneal stimulation in vestibulospinal units of nucleus Deiters.

In precollicular decerebrated cats, the response patterns of antidromically identified vestibulospinal Deiters's neurons to stimulation of corneal receptors were investigated. These patterns were compared with the responses of the somatosensory receptors of the neck and limbs as well as with the vestibular input of the horizontal semicircular canals. Of the 162 antidromically driven Deiters's units, 23 were influenced, mainly bilaterally, from corneal receptors. Response latencies evoked by electrical stimulation of the cornea ranged from 6 to 16 ms (mean 12 ms). In 99 Deiters's cells, the influence from the limbs was examined: 51 revealed primarily an ipsilateral modulation from proximal joint receptors. Convergence with joint receptor input was found in 16 of the 18 corneally driven cells tested. Of the 115 cells tested, 15 neurons responded to neck rotation in the horizontal plane. A contribution from the lateral semicircular canals was found in 7 of the 101 examined Deiters's neurons. The connection of corneal receptors with the spinal motor system, via a vestibulospinal pathway, may mediate a nociceptive reflex protecting the eyes and the face.

Afferent Pathways↗
PubMed1983

Cervico-ocular responses (COR) during slow sinusoidal head movements in subjects with bilateral labyrinthine lesions.

Eye movements in five patients with chronic bilateral labyrinthine loss were tested with sinusoidal movements during cervico-ocular stimulation and active head movements (0.05, 0.1 and 0.2s-1; 20, 40, and 60 degrees) and were compared with healthy subjects. Consideration was given to saccadic activity and slow phase velocity of nystagmus and overall gaze shift. The cervico-ocular response was not altered in the patients. During active pendular head movements the saccadic activity and slow phase velocity of nystagmus were more reduced than the eye shifts. The phase relation of eye shifts was not changed. In our patients neck to eye responses did not compensate for the abolished vestibulo-ocular reflex.

Adolescent↗
PubMed1982

The effect of cervical and vestibular reflexes on eye movements in Huntington's chorea.

In 8 patients with manifest Huntington's Chorea vestibulo-ocular (VOR) and cervico-ocular (COR) reflexes were compared with eye movements during active head turnings. Seated patients were stimulated with their eyes closed by sinusoidal swings around the vertical axis at frequencies of 0.05, 0.1 and 0.2s-1 with amplitudes of 20, 40 and 60 degrees. 1) With all stimuli and in all patients a weak nystagmus was elicited in the direction of head movements, superimposed on larger slow eye deviations. 2) The averaged total saccadic amplitudes were smaller than in normals, increased with stimulus amplitudes and were smallest for COR, followed by VOR and active head movements. 3) The gain (peak velocity of slow phase of nystagmus to peak stimulus velocity) was only slightly below norm values and decreased with increasing stimulus frequency and amplitude. 4) The peak amplitudes of average slow eye deviations increased with stimulus amplitudes. In VOR they were comparable to norm values but were below them during COR and active head movements. 5) In normal subjects these slow eye deviations were compensatory to head movements in VOR but anticompensatory in COR and during active head movements. In choreic patients during COR and more often during active head movements these slow eye movements were compensatory for the head turning.

Adult↗