Impaired discharge of the eye velocity storage mechanism in patients with lesions of the vestibulo-cerebellum.
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Adult↗
Biomedical subjects
J Dichgans
Publications and source records attributed to J Dichgans.
Increased shortening reaction in Parkinson's disease reflects a difficulty in modulating long loop reflexes.
Short and medium latency electromyographic (EMG) responses to stretch of the triceps surae muscle and long latency EMG responses (LL) in the anterior tibial muscle (TA) were evoked by toe-up tilt of a movable platform while standing or sitting, in normal subjects and patients with Parkinson's disease. With the stimulus parameters used (amplitude 4 degrees, velocity 50 degrees/s), LL in TA were absent in normals while sitting, but were present in 11 of the 12 patients with Parkinson's disease. In patients, LL latencies were identical in both positions. The results indicate that patients with Parkinson's disease have difficulty modulating long latency responses according to functional demands. Long latency responses in TA in the sitting position may correspond to the shortening reaction observed by others when much stronger stimuli were used.
Ankle Joint↗
Stenosis and occlusion of the subclavian artery: ultrasonographic and clinical findings.
Continuous-wave (CW) Doppler sonography has proved to be a reliable tool both to detect subclavian stenosis or occlusion and to detect reversal of blood flow in the vertebral artery. This method is entirely atraumatic and in contrast to angiography allows investigation of asymptomatic patients and provides more representative data for epidemiological studies. The incidence of subclavian stenosis or occlusion was 1.15% among the 23,500 patients examined in our department between 1978 and 1985. Of the 272 patients with unilateral or bilateral subclavian stenosis or occlusion, 54% were asymptomatic with no subjective complaints and were normal upon neurological examination; 29% reported vertebrobasilar transient ischaemic attacks (TIAs), with or without concomitant TIAs or infarction in the vascular territory of the carotid arteries; and 17% complained of symptoms exclusively referring to the region of carotid blood supply. Reversal of blood flow in the ipsilateral vertebral artery was detected in 152 patients (56%). The incidence of neurological symptoms within this group was double that found in patients without steal. None of the patients suffered from permanent vertebrobasilar damage. In most cases, subclavian artery disease was due to atherosclerosis. For 13 patients an inflammatory, iatrogenic, traumatic, or congenital aetiology could be assumed. The marked preponderance of left-sided subclavian stenosis or occlusion, reported by others, could be confirmed among our patients, but was less pronounced for tight stenoses than for occlusions. Mild-to-moderate subclavian stenoses were about equally distributed on each side.
Adolescent↗
Pseudotumor cerebri: clinical and neuroradiological findings.
Pseudotumor cerebri (PTC) is a diagnosis per exclusionem applied to a condition of increased intracranial pressure in the absence of an intracranial infection, a space-occupying lesion, or hydrocephalus. Diagnostic criteria should include the evaluation of possibly disturbed cerebral venous outflow, which may result in similar clinical findings. Disturbed venous drainage should be separated from the syndrome of PTC because it represents a condition of well-defined origin and therapeutic regimen. Course and prognosis of PTC are not related to the increased intracranial pressure, the degree of papilledema, or to the duration of the disease. Functional cerebral disorders and EEG abnormalities are rare, indicating that brain tissue is not primarily affected. Correspondingly, computerized tomography (CT) scans with respect to the cerebrum are normal in about 90% of the cases; but enlarged optic nerve sheaths (46.7%) and empty sella (45.7%) are frequent findings on CT-scans. They most likely represent a direct consequence of long-term increased pressure within CSF spaces. This observation favors the assumption of disturbed CSF-pressure regulation either by increased production of CSF or its decreased rate of absorption. Brain edema (slit ventricles) as assessed by CT is a rare finding (11.4% of our cases). It may be a hint towards a different pathogenetic entity.
Adult↗
Paraneoplastic cerebellar degeneration associated with Hodgkin's disease.
A case of paraneoplastic cerebellar degeneration (PCD) associated with Hodgkin's disease is presented. The features that make this case particularly interesting are the simultaneous occurrence of PCD with a relapse of Hodgkin's disease, which has been present for 17 years, and the arrested progression of cerebellar dysfunction after a subacute onset. Cerebellar atrophy was revealed by computed tomography and magnetic resonance imaging. In contrast to two previously reported cases, anti-Purkinje-cell antibodies were not detected.
Adult↗
Medium and long latency EMG responses in leg muscles: Parkinson's disease.
Short, medium, and long latency EMG responses to muscle stretch from triceps surae and anterior tibialis muscles were recorded in normals and in 33 patients with Parkinson's disease. The latencies of all EMG responses except short latency were normal in patients with Parkinson's disease. The integrals of the medium latency responses in the stretched triceps surae muscle were significantly increased in patients. This result indicates a modulatory influence of the basal ganglia on medium latency EMG responses.
Adult↗
Changes in sensorimotor functions after spinal lesions evaluated in terms of long-latency reflexes.
Lesions of the central afferent and efferent pathways cause onset-delays of long-latency EMG responses from anterior tibial muscle after passive dorsiflection of the ankle joint in standing subjects. In 23 patients with spinal tumour or cervical stenosis and clinical signs of a medullary lesion, short-, medium- and long-latency EMG responses from distal leg muscles after ankle dorsiflection were recorded prior to and after surgical intervention. Fifteen of the patients were re-examined between 1 and 2 years after surgery. The results of the follow-up study support the hypothesis of a supraspinal pathway for long-latency EMG responses in distal leg muscles and show their significance as a quantitative measure of sensorimotor functions.
Electromyography↗
Mechanically evoked cerebral potentials and long-latency muscle responses in the evaluation of afferent and efferent long-loop pathways in humans.
Standing humans were subjected to sudden tilts of a platform toe-up. This resulted in a long-latency response in the anterior tibial muscle with a mean latency of 132 ms. The same physiological stimulus was applied to evoke cerebral potentials. The mechanically evoked potential was characterized by a positive peak with a mean latency of 76.4 ms. Absolute peak latencies were variable between subjects but the side difference after separate stimulation of both legs was only around 2 ms. The recording of both, mechanically evoked long-latency muscle responses and cerebral potentials allows a separate evaluation to be made of afferent and efferent central pathways.
Adult↗
European vestibular experiments on the Spacelab-1 mission: 5. Contribution of the otoliths to the vertical vestibulo-ocular reflex.
The gain of the vestibulo-ocular reflex in the sagittal plane may be due to a cooperation between otoliths and the vertical semi-circular canals. The present space experiment was aimed at studying the influence of the absence of gravity stimulation on the otoliths, by comparing VOR gain and phase in space and on ground. Measurements were taken the 5th and the 7th day of flight, the subject being asked to perform, eyes closed, active head oscillations in pitch while fixating an imaginary target in front of him. No significant decrease of the VOR gain was found in space, but a change in phase was noted. A significant increase of the VOR gain was found 14 h after landing. Control experiments have been done on ground on several subjects. They indicate that pitch VOR gain during active head movements is about one, with eyes open in darkness at 1 Hz.
Adaptation, Physiological↗
Development of postural control in children: short-, medium-, and long latency EMG responses of leg muscles after perturbation of stance.
Short (SL), medium (ML), and long (LL) latency EMG responses of leg muscles were recorded after perturbation of stance by means of a sudden toe-up tilt of a movable platform. 56 healthy children varying in age between 14 months and 15 years were investigated. All three responses were present when children were able to stand on the recording platform. The SL-response in the triceps surae muscle, which corresponds to the mono- and oligo-synaptic spinal stretch reflex, showed a decreasing latency up to the age of 5 years. This reflects the increasing peripheral nerve conduction velocity. The ML-response in the triceps surae muscle, which as the SL-response has no stabilizing effect in this experiment, showed somewhat delayed maturational changes. The LL-response in the relaxed anterior tibial muscle helps to restore upright posture even in the youngest children. Its maturational changes in terms of latency by far exceed the range that can be explained by the increase of peripheral and spinal conduction velocities. Its mechanisms of maturation, besides the biophysical optimalization of a polysynaptic network, may include learning in terms of selecting the shortest pathways by way of synaptic potentiation within structures involved in the supposedly transcortical pathway of the LL-response. Qualitative observations made during the trials showed that the pattern of postural adaptation changed with age, suggesting the development of additional intersegmental mechanisms.
Adolescent↗
Correlation of clinical signs with CT findings in patients with cerebellar disease.
The severity of cerebellar signs and the degree of cerebellar atrophy depicted by computed tomography (CT) were independently graded in 108 patients with cerebellar disorders. The overall agreement between these independently scaled measures was only 28%. In patients with involvement of the cerebellar hemispheres and anterior lobe, clinical signs tended to be more pronounced than the cerebellar atrophy revealed by CT. The opposite was true for patients with lesions of the caudal vermis. Patients with Friedreich's ataxia had no or only minor CT abnormalities. Close correlation between the degree of infra- and supratentorial atrophy was found only in chronic alcoholics. The poor correlation between changes in cerebellar structure detected by CT and clinical disability suggests the need for caution in CT interpretation.
Adolescent↗
Incidence of peripheral neuropathy and cerebellar ataxia in chronic alcoholics.
A total of 78 chronic alcoholics were examined neurologically as well as by electroneurography, myography and posturography. Clinical signs of peripheral neuropathy were detected in 45% of these patients, with electromyographic and neurographic abnormality in 67% and 55% respectively. Clinical signs of cerebellar ataxia were found in 33% of our patients, whereas posturographic measurements of increased sway were recorded in 69%. The posturographic characteristics of cerebellar anterior lobe atrophy were observed in two-thirds of the latter patients. The severity of cerebellar-ataxia did not correlate with the degree of neuropathy. This lack of correlation is interpreted as an indication of different pathogenetic mechanisms acting on peripheral nerves and cerebellum.
Adult↗
Superior sagittal sinus thrombosis: neuroradiological evaluation and clinical findings.
The spectrum of clinical signs in cases of superior sagittal sinus thrombosis includes not only focal neurological deficits, seizures and mental disturbances, but also symptoms which may lead to a diagnosis of pseudotumour cerebri (PTC). In 14 cases of angiographically (or autopsy) proven thrombosis of the superior sagittal or both lateral sinuses, the "empty triangle" sign on contrast CT examination was the most reliable sign, suggesting the diagnosis in 70%. Indirect CT signs (venous infarcts) were observed in all 8 patients with focal neurological signs, but appeared rather delayed in 3 cases. In contrast, patients with "benign" intracranial hypertension or PTC (6 cases) had normal unenhanced scans (4 cases) or showed slight diffuse brain oedema (2 cases). Magnetic resonance imaging was performed in 4 patients with findings suggestive of intravascular coagulation; however, due to the complexity of flow phenomena, further studies employing this new imaging technique will first have to be performed. Thus, angiography remains the best diagnostic tool and should not be delayed if there is a clinical suspicion of thrombosis.
Adolescent↗
[Function-oriented neurophysiologic diagnosis: long loop reflexes in spinal and cerebral lesions].
Neurophysiological methods which allow to identify objectively lesions of the efferent cortico-spinal pathways in humans are with the exception of transcutaneous electrical stimulation of the motor cortex nor available. Long latency EMG responses from leg muscles are mediated by a "transcortical loop" and offer the possibility to detect in combination with sensory evoked potentials lesions both of the afferent proprioceptive and the efferent motor pathways. Subjects stood on a platform which was rotated toe-up (50 degrees/s, 4 degrees) around the axis of the ankle joint. This lead to two EMG responses of short- and medium latency in the stretched triceps surae muscle, and an EMG response of long latency (LL) from the antagonistic anterior tibial muscle. We investigated 135 patients with a spinal or cerebral lesion, detected by neuroradiological methods. We found a significant delay of LL in patients with spinal lesions and in patients with cerebral lesions on the affected side. A significant delay of LL could also be observed in patients with pure motor symptoms and normal latency of the cerebral potential (P 40) alone in the group of patients with spinal lesions revealed in about 45% a pathological result. The rate of pathological findings was about 65% when both methods (SEP and LL) were combined. The results indicate that the recording of LL is helpful to detect lesions of the efferent central pathways. In a follow-up study we investigated patients who underwent successful surgical treatment. We found a close correlation between the decrease in latencies of LL and the improvement of clinical signs.
Adult↗
Role of visual and static vestibular influences on dynamic posture control.
Postural stabilization in altered visual and vestibular conditions was investigated in humans subjected to fast transient disturbances and during sinusoidal movement of the standing support. Visual inputs were varied by applying stroboscopic illumination, stabilizing the visual surround in respect to head movements, inducing apparent body movement in pitch by continuously moving stripe patterns up or down and by eye closure. Static vestibular input was modified by bending the head forwards or backwards, or to the right or left shoulder (eyes closed). Neither biomechanical parameters of standing nor EMG responses of the anterior tibial and triceps surae muscles were modified by the different visual and vestibular conditions during fast transient (80 degrees/s) platform movements 4 degrees toe-up. Continuous regulation of upright stance during sinusoidal movements (1 Hz, 0.3 Hz), however, clearly depended on the different modifications of visual and vestibular inputs. Fast transient disturbances are easily compensated in a reflex-like manner independent of visual and vestibular feedback. Continuous regulation of upright posture during slow disturbances, however, clearly depends on the evaluation of afferent information from the visual, vestibular, and proprioceptive systems.
Adolescent↗
Treatment of drug-induced exogenous psychosis in parkinsonism with clozapine and fluperlapine.
A total of 13 patients with drug-induced psychosis in Parkinson's disease were treated with two non-classical neuroleptics-clozapine and fluperlapine. Patients mainly complained about severe hallucinatory symptoms and different degrees of paranoid delusions. Complete relief was observed in 8 patients, moderate improvement in 3 and no effects in 2. Parkinsonian disability did not increase under neuroleptic medication with clozapine and fluperlapine, but could be ameliorated by additional L-dopa or bromocriptine medication. The non-classical neuroleptics employed are dopamine D2 blocking agents with a preferential binding to mesolimbic, mesocortical and hippocampal D2 receptors and no substantial binding to striatal dopamine receptors. Restricted use of these two neuroleptics is necessitated because of the danger of agranulocytosis.
Aged↗
Medium- and long-latency responses to displacements of the ankle joint in patients with spinal and central lesions.
In order to elucidate further the possible pathways and the functional significance of long-loop reflexes we recorded short-, medium- and long-latency responses from leg muscles in 27 patients with spinal lesions, 20 patients with central lesions of the internal capsule or cerebral hemisphere, and in 18 control patients with frontal or occipital lesions without motor or sensory disturbances. Our normal population included 50 subjects, who were age and sex matched to the patients. The mean latency of the long-latency response (LL) in the anterior tibial muscle was significantly delayed in patients with spinal (164.5 msec) and central lesions (145.1 msec) compared to control patients (123.5 msec) and the normals (125.3 msec). This delay of LL could be observed in patients who exhibited only motor or sensory disturbances or a combination of both. The medium-latency response (ML) was absent in 47% of the records in patients with spinal lesions, mainly on the side which was clinically more affected. Its latency was normal if the response occurred. The integral of the LL response was enlarged in patients with spinal or central lesions, but was also enlarged in the control group. The results indicate that the ML response is segmental, but that its amplitude is modulated by supraspinal structures. The LL response probably corresponds to a transcortical 'reflex.'
Ankle Joint↗
[Serum levels of pyridostigmine in myasthenia gravis: methods and clinical significance].
Correlation studies on patients with myasthenia gravis are reported in which clinical assessment of fatigue and neurophysiological findings are compared to blood levels of pyridostigmine. Measurements using a high-pressure liquid chromatography method (HPLC), give reproducible results. The levels of pyridostigmine in the serum or plasma of healthy controls and of patients show no essential differences. Components of coffee, tea, chocolate and cigarettes can markedly disturb the chromatography by adding additional peaks, so that interpretation becomes difficult or impossible. Blood levels can be measured approximately one hour after oral intake of 60 mg pyridostigmine. Concentrations rise for two to four hours and then decline exponentially. The half-life of pyridostigmine was between 156 and 210 minutes. Despite identical oral dosages, the concentration differed intraindividually and interindividually among patients. While the blood level does not reach its maximum value for 1-1 1/2 to 3 hours, the maximum clinical and neurophysiological effect of pyridostigmine appears 30-60 minutes after ingestion. Variable distribution of cholinesterase inhibitors over the different compartments (blood, synaptic region) is assumed to cause this temporal lag. If the total amount of pyridostigmine is divided into 4-5 doses, the concentration profiles over the course of a day are relatively stable. There is no significant correlation between the variations in blood level throughout one day, and changes in myasthenic symptomatology. Effects of pyridostigmine can be measured at levels as low as 5 ng/ml; at levels above 40 ng/ml further improvement can be detected only rarely. Blood levels were lower if corticosteroids were administered simultaneously; azathioprine had no influence on blood levels. Blood levels assays allow better differentiation of cholinergic and myasthenic crises and the identification of disturbed absorption and interactions with other medications.
Adolescent↗