Medium and long latency EMG responses in leg muscles: Parkinson's disease.

Scholz, E; Diener, Hans-Christoph; Noth, Johannes; Friedemann, H.-H.; Dichgans, J.; Bacher, M.

doi:10.1136/jnnp.50.1.66

Cited by 99 publications

(49 citation statements)

References 13 publications

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“…Interestingly, similar observations were made in normal subjects after administration of dopamine antagonists (2), which further suggests that a central dopamine depletion is associated with decreased stabilizing ankle reflexes. On the other hand, some previous reports showed normal (30,42) or even elevated (31) LL reflexes in idiopathic PD patients. In view of the present findings, however, continuation of dopaminergic medication may have masked potential abnormalities of LL reflexes in these studies.…”

Section: Loss Of Predictable Scaling In Mftp-induced Parkinsonismmentioning

confidence: 65%

Long latency postural reflexes are under supraspinal dopaminergic control

et al. 1995

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Scaling of posturally stabilizing long latency (LL) reflexes in tibialis anterior muscles induced by "toe-up" rotational perturbations is abnormal in standing patients with Parkinson's disease. To investigate the contribution of dopaminergic pathways to abnormal scaling, we studied LL reflexes in 22 patients with selective hypodopaminergic syndromes: 10 psychiatric patients taking chronic neuroleptic medication (7 with mild parkinsonism), 8 patients with young-onset Parkinson's disease, and 4 patients with MPTP-induced parkinsonism. Results were compared with those of 10 healthy controls. Stimuli consisted of (a) 10 serial (predictable) perturbations of 4 degrees amplitude, (b) 10 serial (predictable) perturbations of 10 degrees amplitude, and (c) 20 randomly mixed (unpredictable) perturbations of either 4 or 10 degrees amplitude. In normal subjects, LL reflex amplitudes were adapted to match predictable variations in stimulus size, whereas under unpredictable conditions a "default" response emerged that anticipated the 10 degrees perturbation. LL reflex scaling under predictable conditions was intact in patients with neuroleptic-induced parkinsonism and young-onset Parkinson's disease, but the large default LL response under unpredictable conditions was absent. In patients with MPTP-induced parkinsonism, LL reflex scaling was absent during both predictable and unpredictable conditions. We conclude that abnormal scaling of posturally stabilizing LL reflexes is related to decreased supraspinal dopaminergic influence.

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Section: Loss Of Predictable Scaling In Mftp-induced Parkinsonismmentioning

confidence: 65%

Long latency postural reflexes are under supraspinal dopaminergic control

et al. 1995

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“…F1 and ML have been described to be enlarged in rigid patients with PD (Shahani and Young, 1971;Scholz et al, 1986). Although direct conclusions from drug-induced changes of spinal reflexes in normals to therapeutic effects in patients have to be drawn with caution, a possible effect of flupirtine in parkinsonian rigidity could be discussed with the ML response and F1 being decreased under the influence of the drug (Timmann et al, 1995).…”

Section: Discussionmentioning

confidence: 99%

Antiparkinsonian effect of flupirtine in monoamine-depleted rats

Schwarz¹,

Nolden-Koch²,

Purr³

et al. 1996

J. Neural Transmission

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Excitatory amino acid receptor antagonists lead to marked suppression of parkinsonian-like symptoms in rodent and primate models of Parkinson's disease and are able to potentiate the ability of L-DOPA to reverse akinesia and ameliorate muscular rigidity displayed in these animal models. Flupirtine, which is clinically used as a non-opioid analgesic agent, has some N-methyl-D-aspartate (NMDA) antagonistic properties in several in vivo and in vitro experiments. We now report that in monoamine depleted rats (pretreated with reserpine, 5 mg/kg, and alpha-methyl-para-tyrosine, 250 mg/ kg i.p.) flupirtine dose-dependently (1-20 mg/kg i.p.) suppressed rigidity, measured as tonic EMG activity in the gastrocnemius muscle, but had no effect on akinesia, measured as locomotor activity. In addition, it potentiated the antiparkinsonian effect of L-DOPA on akinesia and rigidity in this rodent model of Parkinson's disease. These effects of flupirtine are of particular clinical relevance, since flupirtine is devoid of the typical side effects of NMDA-receptor antagonists.

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“…Although latency of the MLR was generally in a normal range, amplitude increased with severity of the disease (Beckley et al, 1991;Scheppati and Nardone, 1991), which would further destabilize posture. This result suggests that there is a modulatory influence of supraspinal structures, such as the basal ganglia on the MLR (Scholz et al, 1987). The LLR also showed an increased Equilibrium in parkinsonism 563 amplitude (Scheppati and Nardone, 1991) and early onset, resulting in reversal of the normal distal-proximal activation sequence (Beckley et al, 1991).…”

Section: Latencies and Amplitudes Of Postural Responsementioning

confidence: 90%

“…A lack of relationship between medium loop reflex variables and variables for other EMG response components could have been due to abnormality in medium loop reflex patterns in persons with Parkinsonism (Beckley et al, 1991;Chan et al, 1979;Scholz et al, 1987). Because of this abnormality, the medium loop reflex would not scale with the normal short loop reflex (Beckley et al, 1991;Berardelli et al, 1983) or another abnormal long loop reflex pattern (Schieppati and Nardone, 1991;Tatton and Lee, 1975), resulting in low correlations between each other.…”

Section: Emgmentioning

confidence: 99%

The multicomponent nature of equilibrium in persons with parkinsonism: A regression approach

Toole

Park

Hirsch

et al. 1996

J. Neural Transmission

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Lower extremity strength and joint range of motion, body sway, and electromyography responses have all been determined to be factors in balance control of healthy older individuals. The purpose of this study was to identify variables which effect balance control (equilibrium scores) of persons with Parkinsonism, and examine their relationships and predictive abilities. The composite equilibrium score from the sensory organization protocol of the Equitest was used as the dependent variable for the regression analysis. The independent variables included: 1) strategy score; 2) path sway during voluntary body displacement; 3) percent peak torque of knee flexion relative to that of knee extension (%PTKFKE); 4) peak torque of inversion of the ankle at (PTINV); 5) dorsiflexion ROM; and 6) medium loop latency (EMG). The model produced a significant overall relationship accounting for 88% of the variability in equilibrium scores. Positive and significant coefficients indicated a predicted increase in the equilibrium composite score with increases in the strategy score, PTINV and %PTKFKE. These results suggest that postural control of persons with Parkinsonism can be strongly predicted by these three variables.

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Medium and long latency EMG responses in leg muscles: Parkinson's disease.

Cited by 99 publications

References 13 publications

Long latency postural reflexes are under supraspinal dopaminergic control

Long latency postural reflexes are under supraspinal dopaminergic control

Antiparkinsonian effect of flupirtine in monoamine-depleted rats

The multicomponent nature of equilibrium in persons with parkinsonism: A regression approach

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