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G Deuschl

Publications and source records attributed to G Deuschl.

At least 19 recordsLinked to original sources
PubMed2001

Effects of bilateral subthalamic nucleus stimulation on parkinsonian gait.

Gait analysis was carried out to assess the effects of L-dopa and bilateral subthalamic nucleus stimulation on gait velocity, cadence, stride length, and gait kinematics in nine patients with PD. Substantial effects of bilateral subthalamic nucleus stimulation on gait, with an increase in gait velocity and stride length comparable to that of a suprathreshold L-dopa dose, were found. Interestingly, stride length was more improved by L-dopa and cadence more by subthalamic nucleus stimulation. In two patients with freezing during the "on" period, subthalamic nucleus stimulation failed to reduce this symptom effectively.

Antiparkinson Agents↗
PubMed2001

From theory to therapy: implications from an in vitro model of ramified microglia.

Microglia are the principal immune cells in the central nervous system (CNS), characterized by a highly specific morphology and unusual antigenic phenotype. An increasing number of studies have focused on the role of microglia in the pathogenesis of neurodegenerative diseases. To elucidate the function of microglial cells under several neuropathological conditions, we have studied and established a cell culture model that allows us to cultivate microglial cells in their inactive, resting (ramified) phenotype. In the first part of this work, we describe the interaction of microglia cells with their epithelial (astrocytic) microenvironment. The second part reviews experiments with microglia cell cultures to elucidate underlying signalling pathways and summarizes recent advances of our knowledge in microglial molecular pathways that may ultimately lead to neurodegeneration.

Animals↗
PubMed2001

The pathophysiology of tremor.

Tremor is defined as rhythmic oscillatory activity of body parts. Four physiological basic mechanisms for such oscillatory activity have been described: mechanical oscillations; oscillations based on reflexes; oscillations due to central neuronal pacemakers; and oscillations because of disturbed feedforward or feedback loops. New methodological approaches with animal models, positron emission tomography, and mathematical analysis of electromyographic and electroencephalographic signals have provided new insights into the mechanisms underlying specific forms of tremor. Physiological tremor is due to mechanical and central components. Psychogenic tremor is considered to depend on a clonus mechanism and is thus believed to be mediated by reflex mechanisms. Symptomatic palatal tremor is most likely due to rhythmic activity of the inferior olive, and there is much evidence that essential tremor is also generated within the olivocerebellar circuits. Orthostatic tremor is likely to originate in hitherto unidentified brainstem nuclei. Rest tremor of Parkinson's disease is probably generated in the basal ganglia loop, and dystonic tremor may also originate within the basal ganglia. Cerebellar tremor is at least in part caused by a disturbance of the cerebellar feedforward control of voluntary movements, and Holmes' tremor is due to the combination of the mechanisms producing parkinsonian and cerebellar tremor. Neuropathic tremor is believed to be caused by abnormally functioning reflex pathways and a wide variety of causes underlies toxic and drug-induced tremors. The understanding of the pathophysiology of tremor has made significant progress but many hypotheses are not yet based on sufficient data. Modern neurology needs to develop and test such hypotheses, because this is the only way to develop rational medical and surgical therapies.

Animals↗
PubMed2001

Cervico-thoracic disc protrusions in controlled compressed-air diving: clinical and MRI findings.

Prevalence of cervical and thoracic disc protrusions was investigated by MRI in 24 military long-term compressed-air divers and 24 controls. A total of 26 disc protrusions (17 cervical disc protrusions) were detected in 58% of the divers whereas 18 protrusions were detected in 38 % of the controls (13 disc cervical protrusions). There was no significant difference between groups and no correlation with the diving experience. Neurological examination revealed no clinical abnormalities. In contrast to a recent study, our results suggest that long-term divers are at no increased risk for accumulating spinal disc protrusions or intramedullary abnormalities.

Adult↗
PubMed2001

Amitriptyline enhances the central component of physiological tremor.

OBJECTIVES: Postural tremor is a regularly encountered side effect of amitriptyline which can be strong enough to cause discontinuation of therapy. The aim was to characterise amitriptyline induced tremor and to assess if the central or reflex component of physiological tremor was modulated by this drug. METHODS: The postural hand tremor was measured in 15 patients on a clinical rating scale, by power spectral analysis of accelerometer, forearm flexor, and extensor EMG before and after the beginning of amitriptyline treatment for major depression or chronic pain syndrome. A coherence analysis between flexor and extensor muscles on the same side was performed. RESULTS: There was a clinically visible increase in postural tremor in a third of these patients. The tremor amplitude measured by accelerometer total power increased in every patient under amitriptyline. The EMG synchronisation as reflected by significant peaks in the flexor or extensor spectrum generally occurring at higher frequencies (8-18 Hz) than the accelerometric tremor frequencies (6-11 Hz) did not change. The number of patients with a significant flexor-extensor coherence in the 7-15 Hz range increased significantly under amitriptyline, the frequency bands of significant coherence corresponded with the EMG frequencies, and both were independent of changes to the hand's resonant frequency by added inertia. CONCLUSIONS: An enhancement of postural tremor under amitriptyline is a common phenomenon although not always clinically apparent. The increase in EMG-EMG coherence indicates an increased common central drive to the motor units as its frequency is not influenced by peripheral resonance or reflex mechanisms. This is the first account of a drug induced enhancement of the central component of physiological tremor.

Amitriptyline↗
PubMed2001

Comparative analysis of the gait disorder of normal pressure hydrocephalus and Parkinson's disease.

OBJECTIVES: Comparative gait analyses in neurological diseases interfering with locomotion are of particular interest, as many hypokinetic gait disorders have the same main features. The aim of the present study was (1) to compare the gait disturbance in normal pressure hydrocephalus and Parkinson's disease; (2) to evaluate which variables of the disturbed gait pattern respond to specific treatment in both diseases; and (3) to assess the responsiveness to visual and acoustic cues for gait improvement. METHODS: In study 1 gait analysis was carried out on 11 patients with normal pressure hydrocephalus, 10 patients with Parkinson's disease, and 12 age matched healthy control subjects, on a walkway and on a treadmill. In study 2, patients with normal pressure hydrocephalus were reinvestigated after removal of 30 ml CSF, and patients with Parkinson's disease after administration of 150 mg levodopa. In part 3 visual cues were provided as stripes fixed on the walkway and acoustic cues as beats of a metronome. RESULTS: The gait disorder in both diseases shared the feature of a reduced gait velocity, due to a diminished and highly variable stride length. Specific features of the gait disturbance in normal pressure hydrocephalus were a broad based gait pattern with outward rotated feet and a diminished height of the steps. After treatment in both diseases, the speed increased, due to an enlarged stride length, now presenting a lower variability. All other gait variables remained unaffected. External cues only mildly improved gait in normal pressure hydrocephalus, whereas they were highly effective in raising the stride length and cadence in Parkinson's disease. CONCLUSION: The gait pattern in normal pressure hydrocephalus is clearly distinguishable from the gait of Parkinson's disease. As well as the basal ganglia output connections, other pathways and structures most likely in the frontal lobes are responsible for the gait pattern and especially the disturbed dynamic equilibrium in normal pressure hydrocephalus. Hypokinesia and its responsiveness to external cues in both diseases are assumed to be an expression of a disturbed motor planning.

Aged↗
PubMed2000

Neurologic outcome of controlled compressed-air diving.

The authors compared the neurologic, neuropsychological, and neuroradiologic status of military compressed-air divers without a history of neurologic decompression illness and controls. No gross differences in the neuropsychometric test results or abnormal neurologic findings were found. There was no correlation between test results, diving experience, and number and size of cerebral MRI lesions. Prevalence of cerebral lesions was not increased in divers. These results suggest that there are no long-term CNS sequelae in military divers if diving is performed under controlled conditions.

Adult↗
PubMed2000

Multiple oscillators are causing parkinsonian and essential tremor.

The tremors of Parkinson's disease (PD) and essential tremor (ET) are traditionally considered to depend on a central oscillator producing rhythmic activation of the motoneurones of all extremities. To test this hypothesis, we have compared electromyographic tremor activity in different muscles of the affected limbs using cross spectral analysis, including coherence and phase. Surface electromyographic recordings from both arms, legs, and the neck were analyzed in 22 patients with PD and 28 patients with ET. Volume conduction between neighboring muscles producing artificial "coherence" has been found to be an important methodologic problem. We have developed a mathematical test to exclude data that could distort the results. According to this test, 10% or 25% of muscle combinations from the same limb had to be excluded from further analysis in PD or ET, respectively. In both, patients with PD and ET, we found a considerable number of muscle combinations oscillating at virtually the same frequency (delta frequency <0.4 Hz) without showing a significant coherence. Thus, the frequency difference between different muscles is not sufficient to measure the correlation between two muscles. Significant coherencies between muscles within the same arm or leg were found in 70% or 90% of patients with PD or ET, respectively, whereas only one patient with PD and not a single patient with ET showed significant coherencies between muscles from different limbs. The phase between coherent muscles of the same arm of patients with PD showed a preference of either a reciprocal alternating pattern for antagonistic muscles in forearm flexor and upper arm extensor as opposed to a co-contraction pattern between the hand flexors and the triceps brachii. In patients with ET such clear differences were lacking. We conclude that multiple oscillators are responsible for the tremor in different extremities of patients with PD and ET. Differences between PD and ET concerning the phase relation within the arm may either be related to the topography within the basal ganglia or to differently involved-spinal pathways.

Arm↗
PubMed2000

Kinetic tremor in a reach-to-grasp movement in Parkinson's disease.

The aim of this study was to quantify the tremor of the hand during a natural movement (kinetic tremor) in tremor-dominant parkinsonian patients (n = 13). We used a three-dimensional camera system to kinematically analyze rest and kinetic tremors in an unrestrained reach-to-grasp movement, and additional tremor recordings were performed under standard postural and rest conditions using electromyography and accelerometry. The standard analysis showed a highly synchronized tremor with similar frequencies at rest and in sustained postural tasks, with and without loading. A kinematic recording was used to compare rest and action conditions. A strong inhibition of the resting tremor was present at the onset of the movement and reached its peak during deceleration. A kinetic tremor of low amplitude was present in most of the parkinsonian patients, but its occurrence was confined mainly to the terminal periods of the movement. The frequency of kinetic tremor was significantly higher than that at rest, before the onset of the movement in Parkinson's disease, as determined by the kinematic analysis (mean, 5.5 Hz vs 6.5 Hz; p <0.01). Our results confirm similarities between the tremor at rest and the oscillations during a sustained postural task in classic parkinsonian tremor. In contrast to this stable tremor, which seems to be generated by basal ganglia oscillators, a different pathophysiology of oscillations during motion must be considered. The kinetic tremor is most likely related to an enhancement of the physiologic tremor in the terminal phase of the reach-to-grasp movement.

Adult↗
PubMed2000

The pathophysiology of parkinsonian tremor: a review.

Parkinsonian tremor is most likely due to oscillating neuronal activity within the CNS. Summarizing all the available evidence, peripheral factors only play a minor role in the generation, maintenance and modulation of PD tremor. Recent studies have shown that not a single but multiple oscillators are responsible. The most likely candidate producing these oscillations is the basal ganglia loop and its topographic organization might be responsible for the separation into different oscillators which, nevertheless, usually produce the same frequency. The neuronal mechanisms underlying these oscillations are not yet clear, but three hypotheses would be compatible with the presently available data from animal models and data recorded in patients. The first is a cortico-subthalamo-pallido-thalamic loop, the second is a pacemaker consisting of the external pallidum and the subthalamic nucleus, and the third is abnormal synchronization due to unknown mechanisms within the whole striato-pallido-thalamic pathway leading to a loss of segregation. Assuming the oscillator within the basal ganglia pathway, the mechanism of stereotactic surgery might be a desynchronization of the activity of the basal ganglia-thalamo-cortical or the cerebello-thalamo-cortical pathway.

Animals↗
PubMed2000

Thalamic, pallidal, or subthalamic surgery for Parkinson's disease?

Levodopa is a highly effective treatment of all motor symptoms of Parkinson's disease. However, long-term treatment with levodopa can lead to motor fluctuations and levodopa-induced dyskinesias. Motor side effects can become so disabling as to warrant surgical treatment. Both ablative surgery and deep brain stimulation (DBS) for Parkinson's disease (PD) can be performed in different target areas. Thalamic surgery mainly improves tremor, and to a lesser extent also rigidity and dyskinesias, whereas pallidal and subthalamic nucleus surgery improves all motor symptoms and levodopa-induced dyskinesias. The efficacy and safety of unilateral pallidotomy is well established. DBS has a lower morbidity and is safe enough to be performed bilaterally. The subthalamic nucleus (STN) presently seems to be the most promising target for DBS in advanced stage PD.

Globus Pallidus↗
PubMed2000

Gait analysis in idiopathic normal pressure hydrocephalus--which parameters respond to the CSF tap test?

OBJECTIVES: Normal pressure hydrocephalus (NPH) is an often underestimated cause of hypokinetic gait disorders in the elderly. Diagnosing NPH is a complex problem, since many symptoms overlap with other neurological diseases. The purpose of the present study was to characterize the gait pattern in NPH quantitatively. Additionally, we analyzed the improvement of gait parameters following tapping of cerebrospinal fluid (CSF). METHODS: Gait analysis was performed in 10 patients and 12 age-matched healthy controls during overground and treadmill locomotion. RESULTS: Compared to healthy controls, patients with NPH walked significantly slower, with shorter and more variable strides and a somewhat lower cadence. The feet were not lifted to a normal height and the dorsal extension of the forefoot prior to heel-strike was insufficient. Balance-related gait parameters such as step width and the foot rotation angles were significantly increased in NPH, while their variability was lower. Only some gait parameters improved after tapping 30 ml CSF. Gait velocity increased by about 23% due to an increased stride length, while the cadence remained unchanged. Balance-related gait parameters and the foot-to-floor clearance during swing were not affected by the treatment. CONCLUSIONS: In conclusion, we found a triad of decreased stride length, decreased foot-to-floor clearance and a broad-based gait to be the typical features of the gait abnormality in NPH. Only the stride length improved following a diagnostic spinal tap. These results may help to more reliably diagnose the condition of NPH in a routine clinical setting.

Aged↗
PubMed2000

Determinants of physiologic tremor in a large normal population.

OBJECTIVES: It has been well established that peripheral mechanical resonant factors as well as central mechanisms may play a role in the generation of physiological tremor (PT). Furthermore it has been postulated that subject's attributes like age and sex might influence PT. The present study was designed to quantify these influences on PT in a large normal population. METHODS: Physiological hand and finger tremors were measured in a group of 117 normal subjects between 20 and 94 years of age using accelerometry and surface EMG recordings from the forearm flexor and extensor muscles. The hand tremor was measured in a postural position with and without weight, and the finger tremor was recorded with the arm outstretched, forearm supported and hand supported. Hand volume and grip force were measured in each subject. RESULTS: Hand tremor frequency (mean 7.7 Hz) was reduced significantly by added inertia (mean 5.2 Hz) and it was negatively correlated with hand volume while there was no correlation with grip force. Finger tremor showed, subject to the arm position, maximally 3 and at least two distinct frequency bands (1-4, 6-11 and 15-30 Hz) reflecting the resonance frequencies of the whole arm, the hand and the finger, respectively. A significant EMG peak was found in 50-80% of the recordings. This EMG synchronization gave rise to a corresponding accelerometer peak or a significant EMG-EMG coherence in about one-third of the population indicating a central component of PT because its frequency was unaffected by mechanical changes in the periphery. We did not find a significant influence of age on the tremor frequency, while the sex of the subjects slightly but significantly changed the frequency range of hand tremor. Multiple partial correlations revealed, however, that the only direct influence on hand tremor frequency is the hand volume indicating that the influence of sex on hand tremor frequency is an indirect effect produced by the significantly larger hands of male subjects. CONCLUSIONS: In conclusion, the main determinants of PT are the mechanical properties of the oscillating limb. Apart from the dominating peripheral resonance mechanism we found indications of an additional central component of PT in about one-third of the normal population. There was no age dependence of tremor frequency and it was shown that the influence of the subjects' sex on tremor frequency only represents an indirect mechanical effect.

Adult↗
PubMed2000

The clinical use of brainstem reflexes and hand-muscle reflexes.

Brainstem reflexes and hand-muscle reflexes can be elicited and recorded with routine EMG equipment. Not all these reflexes are useful in clinical neurology. But those that are - the subject of this review - exhibit distinct patterns of abnormality that have clinical diagnostic and localizing value in various diseases, including cranial neuropathies, focal lesions within the cervical cord, brainstem, and brain, movement disorders, and pain.

Adolescent↗