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H Hefter

Publications and source records attributed to H Hefter.

At least 37 records · Page 2Linked to original sources

Workshop IV: drug treatment guidelines for the long-term management of Parkinson's disease.

An attempt was made to establish a decision algorithm for the treatment of idiopathic Parkinson's disease at various stages and in different subgroups such as akinetic-rigid or tremor dominance type. We suggest treating young patients with selegiline and a dopamine agonist. In the tremor dominance type we use either budipine or a dopamine agonist. Due to levodopa-induced dyskinesia, we try to avoid levodopa in the early stages of the disease and use it only later in more advanced situations in a combination therapy with dopamine agonists. Since IPS is not only based upon dopamine deficiency but also on resulting glutamatergic overstimulation, we advocate the use of a glutamate antagonist such as amantadine or budipine. Catechol-O-methyl inhibitors are very helpful when wearing-off occurs. Anticholinergics are only used in the early stages of tremor-dominant IPS because we fear enhancing the risk of dementia.

Adult↗

Coordination between breathing and forearm movements during sinusoidal tracking.

Time relationships (coordination) between breathing and rhythmical limb movements were analyzed during sinusoidal tracking movements of the forearm in 11 healthy subjects. The tracking rate was varied systematically between 0.1 and 1.0 Hz in 0.1-Hz steps. The aim of the study was to elucidate whether rhythmical tracking movements can entrain breathing, and whether this entrainment depends upon the movement rate. Subjects exhibited coordination between tracking movements and breathing at various rate ratios (1:1, 1:2, 1:3). At tracking rates of between 0.2 and 0.6 Hz, 1:1 coordination occurred with a maximum at 0.3 Hz; this rate range was called the 1:1 entrainment band. Coordination of 1:2 occurred at between 0.5 and 1. 0 Hz (the 1:2 coordination band) with a maximum at 0.7 Hz. Coordination of 1:3 could be detected at between 0.5 and 1.0 Hz. Different subjects showed 1:n entrainment bands at similar locations but different widths of the rate range studied. The breathing rate during tracking was significantly higher than at rest, and it was correlated positively with tracking rate. This correlation, however, depended upon the width of the entrainment bands. Breathing rates varied between 0.2 and 0.6 Hz for all coordination patterns. We conclude that the occurrence of fixed time relationships is an expression of the strength of central nervous system coupling between the two processes. The frequency of coordination between breathing and rhythmical tracking movements depends critically upon the movement rate.

Adult↗

Stavudine and the peripheral nerve in HIV-1 infected patients.

Stavudine (2',3'-didehydro-3'deoxythymidine) is a pyrimidine analogue that may be of great value in combination antiretroviral therapy (ART) for treating patients infected with human immunodeficiency virus type 1 (HIV-1). We assessed potential neurotoxic side effects by comparing peripheral nerve function in patients receiving ART including stavudine (n = 107) with that of patients receiving ART with zidovudine (n = 103). A cross-sectional analysis of electroneurographic data revealed no significant differences. In a follow-up examination of 31 patients newly started on ART with stavudine we observed no significant effects of the drug on electrophysiological measures. At a daily dose of 1.0 mg/kg the incidence of peripheral nervous system disease in our patients was about 10%. Repeated follow-up analysis of 13 patients on stavudine showed a significant reduction in sural nerve amplitude. Quantitative sensory testing in 13 patients revealed no systematic effect of stavudine on small nerve fibers. Peripheral nerve function in HIV-1 seropositive patients on ART with stavudine did not differ significantly from that in patients on ART with zidovudine. Therefore stavudine at a daily dose of 1.0 mg/kg is an alternative for patients who do not tolerate, or who have become resistant to zidovudine and can be recommended as a first-line drug in combination ART.

Acquired Immunodeficiency Syndrome↗

Long-term course and outcome in AIDS patients with cerebral toxoplasmosis.

OBJECTIVES: We compared clinical long-term course and outcome in all AIDS patients admitted to our outpatient department from January, 1989 to June, 1998 with toxoplasma encephalitis (TE) as first AIDS-defining infection (n= 106) and in 106 patients with Pneumocystis carinii pneumonia (PCP) as first AIDS-defining disease. MATERIAL AND METHODS: The 2 groups were matched with respect to age, sex, risk group, degree of immunodeficiency as measured by CD4 cell counts and duration of HIV-1-positivity. TE was diagnosed radiologically and by response to treatment. RESULTS: Forty-three TE patients surviving the first TE symptoms > 14 months developed dementive symptoms, leucoencephalopathy in imaging procedures and died from dementia. In contrast only 5 patients surviving PCP for an equally long period showed dementive symptoms. CONCLUSION: Cerebral infections like toxoplasma encephalitis (TE) may negatively influence HIV-1-activity so far latent in the brain.

AIDS Dementia Complex↗

Bilateral high-frequency stimulation of the internal globus pallidus in advanced Parkinson's disease.

We report here the results of an open prospective study in 9 patients suffering from severe Parkinson's disease with on/off fluctuations and restricted off-period mobility, who underwent bilateral implantation of stimulating electrodes in the internal pallidum. At 3-month follow-up, the total Unified Parkinson's Disease Rating Scale (UPDRS) motor score in the medication-off state was reduced from 54.1+/-14.8 to 23.9+/-11.7 (44.2%) when stimulation was turned on. Comparison of UPDRS subscores revealed significant improvements for tremor, rigidity, bradykinesia, gait and posture, and dyskinesias. The results of the clinical scoring could be confirmed by significant changes in the quantitative assessment of hand function and walking. Bilateral pallidal stimulation reduced the amount and severity of on/off fluctuations. Additional follow-up at 6 months (n=6), 9 months (n=6), and 12 months (n=4) did not show a decline in effectiveness of stimulation. There was no permanent morbidity associated with the procedure. A subtle reduction of verbal fluency, which was not evident to the patients, was the only cognitive side effect of the procedure in neuropsychological testing. Chronic bilateral high-frequency stimulation of the internal pallidum seems to be a neurologically safe and highly effective treatment for "off" symptoms, dyskinesias, and motor fluctuations in advanced stages of Parkinson's disease.

Adult↗

Neurophysiological abnormalities in the Westphal variant of Huntington's disease.

The Westphal variant of Huntington's disease (HD) is a distinct clinical entity of HD characterized by a rigid-hypokinetic syndrome and is often associated with a juvenile onset of disease. Definite genetic differences between the subtypes of HD have not been delineated so far. Here we present the results of a battery of neurophysiological tests including somatosensory-evoked potentials, blink reflexes, long-latency reflexes, and measurement of saccadic velocities in a Westphal HD patient. Although quantitative assessment of his motor performance showed a severe hypokinetic syndrome resembling Parkinson's disease, the results of somatosensory-evoked potentials and blink reflexes were indistinguishable from results obtained in hyperkinetic HD patients. Long-latency reflexes, however, which are typically absent in hyper-kinetic HD patients, were retained in this patient. It is concluded that neurophysiology in HD patients is not a mere reflection of the patient's symptomatology but can give insight into the underlying pathophysiological process.

Adult↗

Sinusoidal forearm tracking with delayed visual feedback. I. Dependence of the tracking error on the relative delay.

During forearm tracking of a sinusoidally moving target matching of proprioceptive and visual feedback was altered by introducing different visual delays. In five normal subjects seven target frequencies were tested ranging from 0.3 to 1.5 Hz. For each target frequency nine different delays were used ranging from 0 to 120% of the cycle duration with target frequency and delay being varied randomly. Tracking error revealed a cyclic behaviour with an increase up to delays of about 50% of the target cycle duration and an improvement for delays larger than 50%. Modulation of response frequency was less pronounced compared with tracking error variation but also was dependent on relative phase. The response frequency matched the target frequency at delays of 0 and 100% of cycle duration and was slightly lower than the target frequency with relative delays of about 50%. The introduction of a visual delay during sinusoidal forearm tracking leads to a spatial in addition to the temporal mismatch between proprioception and vision. The temporal and the spatial incompatibility influence the tracking performance differentially.

Adult↗

Sinusoidal forearm tracking with delayed visual feedback. II. Dependence of the relative phase on the relative delay.

The influence of delayed visual feedback on the phase relationships between target and response signal during a sinusoidal tracking task was analysed in five normal subjects. Target frequency was varied systematically between 0.3 and 1.5 Hz, and the delay between 0 and 120% of the target cycle duration. For each subject, 63 trials were recorded. Phase parameters (relative phase, absolute relative phase and percentage of positive relative phases) revealed a clear dependence on relative delay but not on target frequency. With relative delays close to 0 and 100% of the target cycle duration, subjects successfully tracked the target signal with a small phase lag. With delays in the 30-90% range, larger phase differences were observed. Furthermore, the (delayed) response signal usually preceded the target signal in this delay range. These findings provide further evidence for a dependence of tracking error on external delays in the visual feedback loop, and indicate that delays of about 50% of the movement cycle are more difficult to handle than are smaller or larger delays. The results are discussed with regard to the influence of different control strategies (feedback, feedforward) and different types of feedback (such as vision and proprioception) on motor control.

Adult↗

Force regulation is deficient in patients with parietal lesions: a system-analytic approach.

By means of a quantitative system-analytic investigation strategy, the postural motor control of the fingers was evaluated, to characterise the possible deficit of force regulation in patients with parietal lesions. In spite of a normal response to short torque pulses, the parietal-lesion patients had difficulties in returning to the preload level after the application of an additional step torque load to fingers II-IV of their left or right hands. The control offset (measured 500 ms after step torque application) was significantly larger in the patient group. This deficit in the investigated patients with parietal lesions to compensate for step torque loads was not due to a paresis, but rather resulted from a disturbance in the generation of a sufficient counterforce against the applied step torque within an adequate time window and motor pattern. This distinct force-regulation deficit was found in patients with left- and right-sided parietal lesions.

Adult↗

Human anterior intraparietal area subserves prehension: a combined lesion and functional MRI activation study.

It has been shown in nonhuman primates that the posterior parietal cortex is involved in coordination of arm and eye movements in space, whereas the anterior intraparietal area in the anterior lateral bank of the intraparietal sulcus plays a crucial role in fine finger movements, such as grasping. In this study we show by optoelectronic movement recordings that patients with cortical lesions involving the anterior lateral bank of the intraparietal sulcus have selective deficits in the coordination of finger movements required for object grasping, whereas reaching is much less disturbed. Patients with parietal lesions sparing the cortex lining the anterior intraparietal sulcus showed intact grasping behavior. Complementary evidence was obtained from functional MRI in normal control subjects showing a specific activation of the anterior lateral bank of the intraparietal sulcus during grasping. In conclusion, this combined lesion and activation study suggests that the anterior lateral bank of the intraparietal sulcus, possibly including the human homologue of the anterior intraparietal area, mediates the processing of sensorimotor integration of precisely tuned finger movements in humans.

Adult↗

Cerebral manifestation of Wilson's disease successfully treated with liver transplantation.

The main indication for orthotopic liver transplantation (OLTx) in Wilson's disease (WD) is severe hepatic decompensation. Our 15-year-old patient is the second case to date in whom OLTx was performed because of neurologic manifestations resulting from WD. His initial condition involving recurrent headaches, tremor, and athetoid hand movements progressively deteriorated during therapy with D-penicillamine, zinc sulfate, and trientine until he was severely dysarthric, unable to walk, and bedridden. After OLTx, his neurologic condition became almost normal.

Adolescent↗

Programming of a movement sequence in Parkinson's disease.

The execution of multiple-component movements has been shown to be impaired in Parkinson's disease patients. To determine whether this deficit is attributed to faulty motor programming, a two-segment movement was examined by studying the kinematics of the first segment when the second segment contained variable accuracy requirements. The performance of 15 Parkinson's disease patients was compared with an age-matched control group. Movement precision not only affected the kinematics of the final segment but also the kinematics of the first segment. This 'context effect' was observed in both groups. Since Parkinson's disease patients revealed similar movement patterns to those of controls, their motor programming appears to be intact. Furthermore, correlation analysis for the segment movement-times revealed subjects with high as well as low correlation indices in both groups. The correlation indices were related to the context effect only in the Parkinson's disease patients. Independent of these phenomenon. Parkinson's disease patients showed marked hesitations between the movement segments compared with controls, suggesting that they have difficulty in implementing and/or in switching between motor program steps. Impaired force control and a reduced capacity to terminate movements in Parkinson's disease are discussed as possible explanations of the deficit in motor program implementation.

Adult↗

Neurological impairment and recovery in Wilson's disease: evidence from PET and MRI.

We studied the relationship of regional cerebral glucose consumption (rCMRGlc) and striatal dopamine D2 receptor binding as assessed with positron emission tomography (PET) with the structural abnormalities of the brain in magnetic resonance images (MR), and the degree of neurological impairment in 18 patients with Wilson's disease (WD). The rCMRGlc was determined in the basal ganglia, the thalamus, the cerebral cortex, and the cerebellar hemispheres. The severity of neurological signs, defined by semiquantitative motor impairment scores, correlated highly (r = -0.80) with the reduction of striatal rCMRGlc. Clinical scores, striatal rCMRGlc, and the degree of MRI abnormalities showed no correlation with different indices of dopamine D2 receptor binding. Sequential PET measurements in three patients during treatment with chelating agents revealed a moderate increase of striatal rCMRGlc (in two patients) and a moderate to marked increase of striatal D2 receptor binding (in three patients) in association with clinical improvement. Our data suggest that the rCMRGlc represents a sensitive and objective measure for assessing and monitoring striatal and extrastriatal involvement in WD. The lack of correlation between the dopamine D2 receptor binding and striatal rCMRGlc and structural abnormalities may be explained by the wide spectrum of clinical manifestations and different responses to treatment in WD patients.

Adult↗

Virtual holography in diagnosis and therapy of sensorimotor disturbances.

It has been shown that VR techniques can be usefully applied in the field of sensorimotor disturbances. Virtual scenarios can be created in which patients perform specific motor tasks. Using an optoelectronic position tracking system for motion recording as well as for interaction with virtual objects, and using Virtual Holography as an adequate visualization technique, we are now developing and testing suitable scenarios. Furthermore, an advanced visualization and animation tool using VR technology for diagnosis purpose and therapy planning has been developed, which the physician can profit from during motion analysis.

Computer Graphics↗

Basal ganglia and cerebellar impairment differentially affect the amplitude and time scaling during the performance of forearm step tracking movements.

Forearm step tracking movements of different amplitudes were analysed in nine patients with cerebellar and five patients with parkinsonian symptoms in comparison to six normal subjects. Movements were made under two instructions: 1) track "as fast as possible" and 2) "as precisely as possible". Movement duration, acceleration duration and peak velocity increased with increasing amplitude. The ratio between acceleration and deceleration duration was independent of movement amplitude in the parkinsonian patients and the normal subjects. In the cerebellar patients, however, this ratio decreased with increasing amplitude. This impairment of the relative timing between acceleration and deceleration duration implies that, in contrast to parkinsonian patients, cerebellar patients cannot anymore utilize physiological scaling mechanisms when performing movements of different amplitudes.

Adult↗

Ataxic breathing during alternating forearm movements of various frequencies in cerebellar patients.

Breathing was analyzed at rest and during sinusoidal tracking movements of the forearm of the dominant side at various frequencies in 11 patients with a cerebellar impairment and in 9 healthy subjects. In the patients, breathing movements were always rhythmical as in normal subjects during rest, but sometimes were interrupted by intermittent breathing-arrests during tracking (breathing ataxia). In 9 of the 11 cerebellar patients, the normal phase relationships between breathing and forearm movements at target frequencies in the spontaneous breathing rate range were absent. Thus patients with cerebellar lesions not only show disturbed skeletomotor movements, but also show an impaired coordination between breathing and limb movements.

Adult↗