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Biomedical subjects

J Dichgans

Publications and source records attributed to J Dichgans.

At least 289 records · Page 16Linked to original sources
PubMed1985

Thymectomy in myasthenia with pure ocular symptoms.

Eighteen patients with exclusively ocular symptoms of myasthenia were thymectomised. Suspected thymoma, resistance to pyridostigmine therapy or relapse following immunosuppressive therapy were taken as indications for surgery. The mean preoperative observation period before operation was 40 months, and after operation was 26 months. There was no operative or postoperative morbidity or mortality. Histological thymic abnormalities were found in all patients (in one case, thymoma; in four, persistent thymus; in 13, thymic hyperplasia). The histological abnormalities were identical to those found in generalised myasthenia. This included the distribution of T-cell subtypes as identified by use of monoclonal antibodies. The severity of ocular symptoms was rated using a score developed for this purpose. The score progressively declined after surgery to an average of 70% of its initial amount in 80% of patients. Full remission occurred in three cases. No patient developed generalized myasthenia. Antibody titres against acetylcholine receptors if elevated preoperatively also dropped following surgery, with one exception. Clear criteria for the expected therapeutic success of thymectomy could not be identified. Based on our results, and on the assumed significance of the thymus gland for pathogenesis, thymectomy should be considered in patients with pure ocular symptoms.

Adult↗
PubMed1985

[Clinical evaluation system (score) of ocular symptoms in myasthenia gravis].

A new rating scheme (score) is presented for ocular symptomatology in myasthenia gravis. The score (0-10) combines separate ratings upper eyelid weakness (ptosis) and paralysis of the outer ocular muscles (double vision). It is relatively insensitive to subjective influences and to the rater's experience. It yields replicable values which are especially important for longitudinal studies, for testing new therapeutic strategies and for their statistical validation.

Blepharoptosis↗
PubMed1984

Effects of rectilinear acceleration and optokinetic and caloric stimulations in space.

During the flight of Spacelab 1 the crew performed a number of experiments to explore changes in vestibular function and visual-vestibular interactions on exposure to microgravity. Measurements were made on the threshold for detection of linear oscillation, vestibulo-ocular reflexes elicited by angular and linear movements, oculomotor and posture responses to optokinetic stimulations, and responses to caloric stimulation. Tests were also conducted on the ground, during the 4 months before and on days 1 to 6 after flight. The most significant result was that caloric mystagmus of the same direction as on the earth could also be evoked in the weightless environment.

Acceleration↗
PubMed1984

The significance of proprioception on postural stabilization as assessed by ischemia.

In order to further investigate the role of proprioceptive input from the legs for the maintenance of upright human posture ischemia was bilaterally applied at the level of the ankle or the thigh. Preservation of efferent innervation was ascertained by measurements of the maximal force of voluntary dorsi- and plantarflexion. Visual stabilization was excluded by eye closure. To test different frequency domains of postural stabilization, subjects were exposed to sudden ramp tilts or to sinusoidal low frequency (0.3 Hz) anteriorposterior displacements of the supporting platform. The results indicate that proprioceptive input from skin, pressure and joint receptors of the foot (ischemia at the ankle) is of minor importance for the compensation of rapid displacements, but plays a significant role when the platform moves at low frequencies. M1 and M2 responses in the stretched triceps surae and the late antagonistic response of the anterior tibial muscle (M3) are preserved with ischemia of the foot. Reversible ischemic paralysis or other (yet unidentified) mechanisms of destabilization must be responsible for the severe decrease of postural stability observed with ischemia at the level of the thigh and sinusoidal platform movements. Complete loss of the proprioceptive input from the legs leads to a pathognomonic 1Hz body tremor both under static and dynamic conditions.

Electromyography↗
PubMed1984

[Chronic analgesic-induced headache].

Fifty-two patients, most of whom had had daily headaches for years, were examined and treated. Among them there were 40 who originally had migraine, the others had vasomotor or post-contusional headaches. Average duration of the migraine was 21 years, of chronic headache 7.6 years. All patients had been taking analgesics of a mixed type regularly and for a long time, on average 35.6 tablets or suppositories weekly. All patients had taken more than three different drugs. After an observation period of 3-6 months for grading the headaches and registering the amount of drug intake, all patients were admitted to hospital when all analgesics were at once discontinued. Changing degrees of withdrawal symptoms were the rule: increased headaches, nausea, vomiting, tachycardia, sweating, sleep disorders, and in some also hallucinations and cerebral episodes. At the end of the hospital stay chronic headache had completely disappeared or markedly improved in 77% of patients. Even after an average of 16 months of subsequent observation, chronic headache continued to be significantly improved in 70% of patients. There was a significant reduction in frequency and intensity of attacks in the patients with originally typical migraine. Regular intake of analgesics of the mixed type induces chronic headaches. These are most commonly caused by ergotamine tartrate and aminophenol derivatives, while psychological and physical dependence on anti-migraine drugs is initiated and maintained by additional barbiturates, caffeine and codeine.

Adrenergic beta-Antagonists↗
PubMed1984

Early stabilization of human posture after a sudden disturbance: influence of rate and amplitude of displacement.

The functional role of short-, medium- and long-latency responses for the maintenance of upright posture was investigated in twenty healthy subjects standing on a platform which could be rotated in pitch around the subject's ankle joints. Tilting the platform toe-up evokes a stretch reflex in the triceps surae muscle (TS, latency 55-65 ms) and at higher speeds and amplitudes of platform displacement a medium-latency response (latency 108-123 ms). Both responses functionally destabilize posture, since they enforce the induced backward displacement of the body. Compensation of body displacement in this situation is achieved by a long-latency EMG response in the anterior tibial muscle (TA 130-145 ms). Platform movement toe-down elicits a rather small medium-latency response in TA (103-118 ms), but no short-latency response. A late compensatory response occurs in the triceps surae muscle (latency 139-170 ms). The mean latency of the late antagonistic EMG response was significantly shorter than that of a voluntary movement triggered by a somatosensory stimulus. Integrals of rectified EMG responses from the two muscles were linearly related to the amplitude and to a smaller degree to the velocity of platform displacement. The slope of this function (gain) varied depending on the direction of ankle displacement and the functional importance of the subsequent EMG responses. Destabilizing short- and medium-latency responses of the stretched muscle had a lower gain relative to amplitude than the late stabilizing response of the antagonist. This functionally adaptive modulation of gain was not seen in relation to the rate of platform displacement.

Adult↗
PubMed1984

Improvement of ataxia in alcoholic cerebellar atrophy through alcohol abstinence.

Postural instability was measured and short, medium and long latency EMG responses to angular displacement of the ankle were recorded from leg muscles in a group of 17 alcoholics who presented with clinical signs of cerebellar atrophy of the anterior lobe. Recordings were performed twice (average interval 18.5 months) to determine the effects of continued drinking versus abstinence on the signs of the cerebellar damage. Patients who were abstinent (n = 11) exhibited a significant, sometimes dramatic decrease of body sway whereas patients who continued drinking (n = 6) showed increased body sway when the eyes were closed. Short and medium latency EMG responses were unaltered in both groups of patients. The integral of the long latency response of the antagonist tended to increase with continued abuse and to decrease in abstinent patients.

Adult↗
PubMed1984

[Correlation of acetylcholine receptor antibodies and clinical severity of myasthenia gravis in combined immunosuppressive therapy].

The correlation between the severity of symptoms in myasthenia gravis (score) and the level of acetylcholine receptor-antibodies (ACHR-Ab) was studied in 24 patients treated with immunosuppressive therapy. This correlation was significant in every case regardless of whether or not thymectomy was performed in addition. It was demonstrated by means of a long-term follow up study, that a change in ACHR-Ab preceeds the corresponding change in score by 2-4 months in 80% of our patients. Measurements of ACHR-Ab ease the management of the therapy with immunosuppressants and make it safer. This is particularly true prior to and after termination of the treatment. A change in ACHR-Ab level by more than 20% indicates a change in score.

Adult↗
PubMed1984

The significance of delayed long-loop responses to ankle displacement for the diagnosis of multiple sclerosis.

The present study compares the results of sensory evoked potentials after stimulation of the tibial nerve with measurements of short (M1), medium (M2) and long-loop latency (M3) responses of leg muscles in 42 patients suffering from multiple sclerosis. EMG responses were elicited by a movable platform which was tilted in pitch toe-up around the subject's ankle joint. The short latency response of the triceps surae muscle was nearly always normal in latency. The M2 response was lacking in about 30% of the patients and 10% of normals. The long latency response (M3) in the antagonistic anterior tibial muscle was significantly delayed (beyond 162 msec = AM + 2.5 S) in 69% of the patients. The delayed M3 response was found to indicate demyelination as reliably as the delayed somatosensory evoked potential (66% of the patients). The frequency of coincident results in the entire group was 86%. Additional information is gained in cases where SEPs are normal, but M3 is delayed (7%). Furthermore, patients lacking P40 of the SEP still exhibit M3 responses, the latency of which may be measured (24%). The results favour the assumption that M3 is mediated by a supraspinal pathway.

Ankle↗
PubMed1984

Quantification of postural sway in normals and patients with cerebellar diseases.

Posturography was performed in 41 patients with cerebellar diseases by means of a force measuring platform using an on-line computer program which calculated sway path, sway area, antero-posterior and lateral sway components and the amount of visual stabilization. Postural ataxia was quantitatively studied in 8 patients with spinal ataxia (Friedreich's), 6 patients with vestibulocerebellar lesions, 11 patients with anterior lobe atrophy, 7 patients with hemispheral cerebellar lesions, and 9 patients with a disease affecting all parts of the cerebellum. Patients with lesions of the cerebellar hemispheres could not be separated from normals by means of posturography. Lesions of the spino-cerebellar afferents (Friedreich' ataxia) caused an omnidirectional low frequency sway with preserved visual stabilization. Patients with anterior lobe atrophy showed a predominant antero-posterior sway, often with a spontaneous high frequency body tremor around 3 Hz. Vestibulo-cerebellar lesions exhibited omnidirectional low frequency sway poorly stabilized by vision. Quantitative posturography helps to localize cerebellar lesions and allows for quantitative follow-up studies of cerebellar diseases.

Adult↗
PubMed1984

The European vestibular experiments in Spacelab-1.

A series of experiments were performed in the Spacelab-1 mission on November/December, 1983, pre-, in-, and postflight. These experiments covered various aspects of the functions of the vestibular system, the inflight tests comprising threshold measurements for linear movements in three orthogonal axes, optokinetic stimulation, vestibulo-ocular reflexes under linear and angular accelerations, caloric stimulation with and without linear accelerations; pre- and postflight tests repeated the inflight protocol with the addition of subjective vertical and eye counter-rotation measurements using a tilt table. One of the most surprising and significant results was the caloric test: strong caloric nystagmus on the two subjects tested was recorded inflight; this was contrary to what was expected from Barany's convection hypothesis for caloric nystagmus.

Adaptation, Physiological↗
PubMed1984

Characteristic alterations of long-loop "reflexes" in patients with Friedreich's disease and late atrophy of the cerebellar anterior lobe.

Sudden tilting of a platform around the axis of the human ankle joint causes a regular pattern of short and medium latency EMG responses in the stretched triceps surae muscle and a long latency response in its antagonist, the anterior tibial muscle. This paper reports alterations of these EMG responses in 41 patients with cerebellar lesions. Patients with anterior lobe atrophy exhibited normal latencies of all EMG responses, but an increase in duration and amplitude of the long latency response. This may at least partially explain the 3 Hz postural tremor, which can be evoked in these patients through a toe-up tilt of the platform. Patients with lesions restricted to the vestibulocerebellum and to the cerebellar hemispheres exhibited normal latencies of all EMG responses. The most specific finding in all of the patients suffering from Friedreich's ataxia (affecting spinal afferents) was the massive delay of the stabilising response of the anterior tibial muscle. The fact that the patients with lesions restricted to the cerebellum invariably exhibited normal latencies of postural "reflexes" indicates that the exact "timing" of these responses is independent of the cerebellum. The duration and amplitude of the long latency response of the antagonist, however, seems to be controlled by the cerebellum.

Afferent Pathways↗
PubMed1984

Clinical symptoms of cerebellar dysfunction and their topodiagnostical significance.

The clinical symptoms of cerebellar dysfunction are reviewed in relation to modern concepts of cerebellar physiology. Special attention is given to their topodiagnostical significance. Hypotonia, hyporeflexia, asthenia, delayed onset and offset as well as slowing of voluntary movement, ataxia, dysmetria, tremor and myoclonus result from damage of the lateral cerebellar hemispheres and the dentate nucleus. Three different key patterns of postural ataxia result from lesions of the anterior lobe, the vermal part of the vestibular cerebellum and dysfunction of cerebellar afferences respectively. The long latency response (M3) is significantly prolonged in patients with anterior lobe atrophy. Oculomotor symptoms mainly result from either lesions of the cerebellar flocculus, causing dysfunction of retinal-image stabilization or from damage to the dorsal vermis (VI and VII) and the fastigial nuclei, resulting in saccadic dysmetria.

Animals↗
PubMed1983

[Stenoses and occlusions of the extracranial arteries. A field study of unselected subjects and patients with intermittent claudication].

Doppler sonography of the extracranial arteries was done in 556 unselected patients (greater than 40 years) in a prophylactic study. 226 high risk patients with arterial occlusive leg disease (AOD) served as control group. Doppler sonography revealed stenoses or occlusions of the carotid, vertebral and (or) subclavian arteries in 9.17% of normal persons and in 38.05% of AOD patients. Medical treatment is available only for stenoses (not occlusions) of the carotid arteries. Thus the frequency of asymptomatic internal carotid stenoses--only stenoses of more than 50% lumen diminution can be detected--of 2.33% in the group of normal probands and of 17.2% in the patient group is the reference value and justification for use of Doppler sonography for prophylactic assessment. The atraumatic and safe method with a success rate of 2.33% is suitable particularly in increased risk factors (age, males, smoking, hypertension, diabetes). As a prophylactic investigation in patients with arterial occlusive disease Doppler sonography is mandatory before prospective operations.

Adult↗
PubMed1983

Variability of postural "reflexes" in humans.

The functional role of spinal and supraspinal EMG-responses for the maintenance of upright human posture was investigated in ten healthy subjects standing on a force measuring platform, which could be rotated in pitch around an axis aligned with the subject's ankle joint. Voluntary changes of body posture prior to the platform movement by leaning forward or backward led to a change in the amplitude and temporal organization of EMG-responses as compared to platform movements starting from a neutral position. Tilting the platform toe-up while leaning backward led to an increase of the latency of the short- and medium-latency responses in the triceps surae muscle and to a decrease of the latency of the stabilizing response in the anterior tibial muscle. Functionally, a cocontraction of both antagonistic muscles could be observed which partly compensated for the destabilizing action of the "reflex" response in the stretched triceps surae muscle. In analogy, leaning forward and tilting the platform toe-down led to a cocontraction of the two antagonistic muscles. The observed changes of latencies of short-, medium-, and long-latency response show the functional variability of segmental and suprasegmental "reflex" mechanisms. EMG-activities, which are functionally destabilizing posture, can be suppressed or compensated by reflexive cocontractions of antagonists.

Adult↗
PubMed1983

Mechanisms of postural ataxia after intake of alcohol.

The effect of an acute intoxication with alcohol on the stability of stance was examined in 12 healthy subjects. They drank 11 of wine within 1 h. The resulting blood alcohol concentrations ranged between 0.9 and 1.67 mg/ml. Static posturography at the end of drinking and 1 h later revealed a significant increase in body sway which was mainly due to an increase in anteroposterior sway only present with closed eyes. A comparison of the results of posturography after acute intoxication with the data of patients with permanent lesions confined to the different functional subunits of the cerebellum shows that the acute effect of alcohol largely resembles that of a chronic lesion of the cerebellar anterior lobe (the spinocerebellum).

Adult↗