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Biomedical subjects

J Dichgans

Publications and source records attributed to J Dichgans.

At least 253 records · Page 14Linked to original sources
PubMed1989

On the role of feedback in maintaining constant grip force in patients with cerebellar disease.

The effect of visual feedback on maintaining low finger forces was investigated in patients with chronic cerebellar disease. Precise information about deviation from target force was compared with discrete feedback signaling only 3 states of performance and a condition of withdrawal of feedback. Forces were produced under isometric conditions and against a spring load (anisometric condition). Large performance differences were observed dependent on feedback condition. Maintenance of anisometric force was found to be nearly normal in patients with severe deficits in controlling isometric force.

Biofeedback, Psychology↗
PubMed1989

[Asymptomatic carotid stenosis: is surgical prevention of infarct still justified?].

The present retrospective study compared the incidence of TIA, stroke, and death in patients with asymptomatic carotid stenosis (greater than 50%) during a follow-up period of 24 to 30 months. 65 patients were operated and 193 treated medically. The incidence of death was comparable in both groups. Death in most patients was due to cardiac disease or cancer. The annual incidence of TIA and stroke was not different between the two populations. Despite the low incidence of perioperative complications (%) surgery of asymptomatic carotid stenosis cannot be recommended at the present time.

Aged↗
PubMed1989

Central effects of drugs used in migraine prophylaxis evaluated by visual evoked potentials.

The present study used recordings of visual potentials evoked by pattern reversal (VEPs) to investigate the central effects of three drugs used in migraine prophylaxis: the calcium channel blocker nifedipine, the beta-1-selective blocker metoprolol, and the nonselective beta adrenoreceptor blocker propranolol. The study involved 58 patients with common or classical migraine who were treated in a double-blind randomized study over a period of 7 months, while the effectiveness of prophylactic treatment was recorded in headache diaries that were subjected to time series analysis. VEPs were recorded at the beginning of a 2-month baseline period without treatment, after 4 months of treatment, and at the end of a 3-month washout period. At baseline, migraine patients had significantly higher VEP amplitudes and longer latencies than did a group of 87 healthy control subjects. Patients were separated by statistical analysis into responders and nonresponders to each prophylactic treatment. Nifedipine had no effects on the frequency, intensity, and duration of migraine attacks, nor on amplitude and latency of the VEPs. In contrast, the use of beta blockers resulted in a significant decrease in VEP amplitude, both in responders and nonresponders, whereas VEP latency remained unchanged. VEP amplitudes returned to the initial values at follow-up in the nonresponders, but stayed at lower levels in responders. Beta blockers thus appear to have a significant effect on the increased excitability of the visual system in patients with migraine, although their action is not directly related to their reduction of migraine frequency.

Adult↗
PubMed1989

Analgesic-induced chronic headache: long-term results of withdrawal therapy.

Headache characteristics are described in 139 patients with chronic daily or almost daily headaches due to regular intake of analgesics and the short- and long-term results of drug withdrawal. Drug-induced headache was described as dull, diffuse, and band-like, and usually started in the early morning. The mean duration of the original headache (migraine or tension headache) was 25 years; regular intake of drugs and chronic daily headache had started 10 and 6 years prior to withdrawal therapy, respectively. Patients took an average of 34.6 tablets or analgesic suppositories or antimigraine drugs per week containing 5.8 different substances. The drugs most often used were caffeine (95%), ergotalkaloids (89%), barbiturates (64%), and spasmolytics, paracetamol, and pyrazolone derivates (45%-46%). A total of 103 patients (68 migraine, 35 tension or combination headache) were available for interviews at a mean time interval of 2.9 years after an inpatient drug withdrawal programme. Chronic headache had disappeared or was reduced by more than 50% in two-thirds of the patients. Positive predictors for successful treatment were migraine as primary headache, chronic headache lasting less than 10 years, and regular intake of ergotamine. Drug intake was significantly reduced and patients used single substances more often. Patients who originally suffered from migraine, superimposed on the daily headache, also experienced a significant improvement in the frequency of the migraines and their intensity. Migraine prophylaxis through beta-blocking agents and calcium channel antagonists was more efficient after drug-withdrawal therapy.

Adult↗
PubMed1989

Spinal arteriovenous malformations and fistulae: clinical, neuroradiological and neurophysiological findings.

Twenty-six patients with myelographic signs suggestive of a spinal arteriovenous malformation (AVM) were examined neurologically and neurophysiologically. By selective spinal angiography it was possible to differentiate between dural arteriovenous fistulae (dAVF 20 patients) and intradural AVMs (iAVM, 6 patients). Initial complaints were nonspecific and variable, mainly consisting of sensory disorders and muscle weakness. Later, patients suffered involvement of both the upper and lower motor neurons. There was a high percentage of lower motor neuron lesions (95%), especially in dAVF patients, which were mostly of widespread distribution and included several myotomes. Electrophysiological examination regularly revealed lower neuron involvement, frequently with pathological spontaneous activity in several myotomes, pathological sensory-evoked potentials after tibial nerve stimulation, but normal sensory conduction velocities of the sural nerve, indicating sparing of the sensory ganglion. Frequently there was a discrepancy between the localization of the dural fistula or angioma and the spinal level responsible for clinical symptoms. This suggests that it may be the inadequacy of the venous drainage system to cope with the blood volume rather than the AV-shunt that is responsible for the symptoms. An early diagnosis is essential, as removal of the shunt before there has been progression to severe neurological deficits (paraplegia) is the only way to ensure a satisfactory outcome.

Adult↗
PubMed1989

Significance of MRI-confirmed atrophy of the cranial spinal cord in Friedreich's ataxia.

The severity of Friedreich's ataxia was graded in ten patients by clinical examination and in five by use of posturography. These data were compared with neuroradiology findings. CT-confirmed infratentorial atrophy occured only in advanced cases of Friedreich's ataxia; the correlation with the clinical score was poor. On mid-sagittal MRI planes the diameters of fourth ventricle, brain stem at the level of the inferior olive and spinal cord at the levels of the foramen magnum and C3 were measured. Patients with Friedreich's ataxia had significant MRI-confirmed atrophy of the cranial spinal cord as compared with a normal, age-matched control group. This was also observed in patients with Friedreich's ataxia in the early stages. A reliable correlation between atrophy of the cranial spinal cord and the clinical score, however, could again not be found. MRI exploration of the cranial spinal cord may be recommended as an additional diagnostic marker in Friedreich's ataxia.

Adult↗
PubMed1989

Disturbances of motor preparation in basal ganglia and cerebellar disorders.

Movements of the arms (execution) in standing human subjects are preceded (preparation), accompanied, and followed (compensation) by muscular activity in postural trunk and leg muscles. Postural muscular activity compensates inertial forces acting on the body at the beginning and during arm movements and keeps the centre of gravity within the limits of stable upright standing. Standing normal subjects and patients performed bilateral arm elevations in response to an acoustic trigger. The beginning of EMG activity in the anterior deltoid muscle reflects the reaction time. Postural activity prior to the arm movement was observed in anterior tibialis, paraspinalis, and hamstring muscles. Compensatory muscular action occurred in the triceps surae. Motor preparation and compensation thus are an integral part of a motor programme. Muscles involved, latencies, and amount of EMG activity change with variations in the motor task (e.g. range of arm movement, changes in inertia of the arm, changes in initial body position). Reaction times and the pattern of preparatory and compensatory postural EMG activity were normal in most of the patients with Parkinson's disease. Reaction times were significantly increased in patients with cerebellar atrophy. The most prominent pathological feature in cerebellar patients was the inadequate temporal sequence of motor preparation and execution. Our results indicate that the basal ganglia play a minor role in motor preparation, whereas the cerebellum seems to coordinate the relative timing between motor preparation and execution.

Adult↗
PubMed1989

Development of feedback and feedforward control of upright stance.

Feedback and feedforward (anticipatory) adjustments of stance were investigated in 58 children with normal development aged between seven months and 14 years, and in 14 children with motor and mental retardation aged between 21 months and seven years. Feedback responses after tilting the body were elicited in all but the two youngest children, aged seven and nine months. The observed rapid decrease in feedback response latency with age suggests considerable acceleration of central transmission. Effective anticipatory postural adjustments (feedforward) were elicited only in the normal children over four years of age. The development of both feedback and feedforward continued until adolescence.

Adolescent↗
PubMed1989

Neuroleptically induced dystonia in Huntington's disease: a case report.

A patient with Huntington's disease developed acute dystonia whilst treated with tiapride. Sulpiride and tetrabenazine also induced dystonia. The anticholinergic biperiden depressed the syndrome but worsened psychopathology. Finally a combination of tetrabenazine and clozapine was successful in treatment of both chorea and dystonia. According to this observation, acute dystonia may occur in Huntington's disease as a consequence of neuroleptic treatment.

Benzamides↗
PubMed1989

Neurophysiological characteristics of spinal arteriovenous malformations.

The aim of the study was to identify the clinical and neurophysiological pattern of deficits in spinal arteriovenous malformations (AVM) to allow an early diagnosis which is the prerequisite for effective treatment by early surgery or embolization. Among 26 patients with myelographic signs of a spinal AVM, selective spinal angiography disclosed 20 cases with a dural AV-fistula (dAVF) and 6 patients with an intradural AV-malformation (iAVM). Although the main pathogenetic factor in both disorders may be different, clinical and neurophysiological findings proved to be of limited value in differential diagnosis. Clinical symptoms presented by the patients were a variable combination of lower motor neuron lesion, sphincter disturbance, sensory transverse lesion and partly additional signs of upper motor neuron involvement. Electromyography invariably showed an increased rate of polyphasia and frequently pathological spontaneous activity usually in several myotomes. Normal sensory conduction velocity of the sural nerve contrasted with almost regularly pathological SEP's after tibial nerve stimulation. The distribution if clinical and neurophysiological findings suggests rather widespread lesions of the lower cord and/or cauda equina, frequently at a lower level than the angiographically localized shunt. This suggests a vascular myelopathy on the basis of insufficient venous drainage at least for the frequent dural AV-anomaly.

Adult↗
PubMed1988

Cerebellar dysfunction in patients with bronchogenic carcinoma: clinical and posturographic findings.

Neurological examination and posturography showed cerebellar signs in 13 of 50 unselected patients with bronchogenic carcinoma not complicated by other diseases. The occurrence of cerebellar signs did not depend on the histological type of tumour or the extent of tumour spread. Most of the clinically affected patients had mild to pronounced cerebellar atrophy, revealed by CT. The correlation between the amount of CT-confirmed atrophy and the severity of clinical symptoms, however, was poor. Since other reasons for cerebellar dysfunction (e.g. chemotherapy, chronic alcoholism, metastases) were excluded, cerebellar signs were attributed to paraneoplastic cerebellar degeneration or to a consequence of severe neoplastic illness. The high incidence of cerebellar dysfunction in patients with bronchogenic carcinoma confirms the frequent histopathological finding of cortical cerebellar degeneration in malignant disease.

Aged↗
PubMed1988

Cerebellar dysfunction in patients with bronchogenic carcinoma: immunological investigations.

Sera from seven patients with bronchogenic carcinoma and cerebellar dysfunction were tested for anti-Purkinje cell antibodies (APCA) by indirect immunofluorescence and indirect immunoperoxidase reaction. Specific APCA as described in paraneoplastic cerebellar degeneration (PCD) were not detected in any of these patients or in control patients. The lack of APCA in patients with bronchogenic carcinoma and their presence in association with ovarian or breast cancer indicate that different pathogenetic mechanisms may play a role in PCD.

Aged↗
PubMed1988

Twenty-four-hour tremor recordings in the evaluation of the treatment of Parkinson's disease.

A new method of prolonged recording of EMG provides a good estimate of spontaneous and induced diurnal variations in resting tremor in Parkinson's disease. It provides a record and a measure of the effects of treatment. Tremor intensity shows considerable variations even over short periods of time. Therefore short-term measurements of tremor are unhelpful. Long-term recordings agree better with the patient's assessment than with the clinical rating score. Repeated recordings over a similar 10-h period on 3 consecutive days in one patients showed fairly constant measures of occurrence and intensity of tremor. In contrast to accelerometer measurements of tremor, artefacts caused by movements and general activity of the patient do not materially interfere with tremor evaluation using surface EMG.

Adult↗
PubMed1988

[Applications and uses of static and dynamic measurement of posture (posturography)].

Posturography is a very useful clinical instrument to quantify, analyze, and document postural sway and to differentiate patterns of instability that are typical for the different types of lesions encountered within the cerebellum and to differentiate cerebellar ataxia from spinal ataxia. An objective method of measurement like this is most valuable for follow-up studies and the surveillance of therapeutic efficacy. The method of recording short, medium, and long latency reflexes in leg muscles after a sudden tilt of a movable platform toe-up is not only totally atraumatic and fast, but more importantly it gives significant hints towards the possible site of a central lesion in the sensory-motor system.

Cerebellar Ataxia↗
PubMed1988

Control of isometric finger force in patients with cerebellar disease.

Control of isometric forces during grasping or handling of objects is an essential feature of all skilled manual performances. Previous studies of hand function in cerebellar patients were restricted to movements; force control was only investigated under isotonic conditions in combination with movements. Control of isometric forces during voluntary contraction of finger muscles was investigated in 31 patients with chronic cerebellar disease and in 20 normal controls. Eight patients with Friedreich's ataxia were considered to be typical for a disease affecting the afferents to the cerebellum; 4 patients with anterior lobe atrophy, which affects leg movements to a greater extent than finger movements, were compared with 3 patients with hemisphere lesions; 16 patients suffered from diffuse cerebellar atrophy. Using a recently developed microcomputer system for the continuous measurement of finger force, control of isometric force was studied in several tasks within the same subjects. The tasks included the maintenance of constant force output at different force levels with and without visual feedback, fast repetitive force changes, tracking of a sinusoidal target presented visually, and measurement of maximum grip force. The amount of voluntary contraction in terms of muscular power was normal in all patients; in all other tasks clear deficits were observed. The extent of the disturbances was highly variable between patients even within the same clinical subgroup. The detailed analysis of force traces revealed a great variety in types of disturbance. The frequently observed slowing of the speed in repetitive force changes can be attributed to different components in different patients and not only to difficulties at turning points as might be predicted from comparable movement studies. In addition, performance deficits across different tasks were not uniform, indicating dissociation of impairment. Deficits in maintaining force, which may be interpreted as dysmetria or due to tremor, do not necessarily imply an abnormality in diadochokinesis, as measured in fast repetitive force changes, nor does the converse apply.

Adolescent↗
PubMed1988

T and B cell specific immune responses to purified protein derivative in the cerebrospinal cavity may be maintained and regulated independently of systemic immune control.

In vivo activated T cells could be isolated from cerebrospinal fluid (CSF) of a patient suffering from chronic meningitis of unclear origin. Although the patient's skin reactivity to purified protein derivative (PPD) was negative, and peripheral T cells did not proliferate to this antigen in vitro, the majority of T cell clones from CSF specifically recognized PPD on either autologous or allogeneic HLA class II compatible macrophages. Remarkably, peripheral blood mononuclear cells potently suppressed the PPD-specific proliferative responses of healthy donors. The selective enrichment of oligoclonal IgG in the CSF but not in the patient's serum further indicated T and B cell responses lacking systemic feedback control. Analyses of a persisting immune stimulation in the CSF provide a potent diagnostic tool and may explain neurological complications as observed in a number of autoimmune diseases and chronic infections.

Adult↗