Resetting of tremor by mechanical perturbations: A comparison of essential tremor and parkinsonian tremor

Lee, Robert G.; Stein, Richard B.

doi:10.1002/ana.410100606

Cited by 196 publications

(52 citation statements)

References 25 publications

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“…to modify the basic parameters of tremor, i.e., amplitude f 10], phase [11], and frequency [12]. This work demonstrated that most observed phenomena could by generally explained in terms of interactive models, but which specific mecha nisms were consistent with the present data?…”

Section: Discussionsupporting

confidence: 79%

“…This work demonstrated that most observed phenomena could by generally explained in terms of interactive models, but which specific mecha nisms were consistent with the present data? Some re searchers have previously suggested various physiological mechanisms that may be implicated here [5,11 ], but since our data do not appertain to such mechanisms, we, like Rack and Ross [12], shall discuss this in systemic, rather than physiological, terms.…”

Section: Discussionmentioning

confidence: 83%

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Is Parkinsonian Arm Tremor a Resting Tremor?

Hadar

Fc²

1993

Eur Neurol

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Arm tremor in Parkinson’s disease occurs during rest which has been explained by a specific tremulous mechanism activated during rest. During action or posture maintenance, the tremor may persist or recur, but with reduced amplitude. We present 2 patients with idiopathic Parkinson’s disease who showed persisting arm tremor which was most marked during action rather than during rest. The patterns of upper limb tremor were investigated during rest, maintenance of fixed posture, and slow movement, using an advanced computerized movement-monitoring system (Coda 3). Four parkinsonian patients showing tremor under all conditions were studied, comparing 2 patients whose tremor was most marked during rest with 2 whose tremor was most marked during action. All showed intermediate amplitudes during posture maintenance. Patterns of tremor frequency were very similar between patients, irrespective of amplitude characteristics. These features suggest that tremors in all patients originate in a single, complex mechanism which may involve both central and peripheral mechanisms.

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Section: Discussionsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 83%

Is Parkinsonian Arm Tremor a Resting Tremor?

Hadar

Fc²

1993

Eur Neurol

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“…It is generally believed that Parkinsonian and cerebellar tremors often depend upon rhythmic activity generated within the CNS (for review see Marsden, 1984), though an interaction with spinally mediated stretch reflexes is frequently mooted (e.g. Lee & Stein, 1981;Marsden, 1984;Rack & Ross, 1986). Our data show that in principle a very active stretch reflex loop could oscillate autonomously in the frequency range 3-8 Hz.…”

Section: Relationship To Pathological Tremorsmentioning

confidence: 60%

Instability in human forearm movements studied with feed‐back‐controlled muscle vibration.

Procházka

Trend

1988

The Journal of Physiology

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SUMMARY1. Frequency-modulated vibration was applied to the elbow flexor and extensor tendons to produce reflex movements of the forearm in normal subjects. The modulating (command) signal caused equal and opposite deviations from the 40 Hz carrier frequency so that when flexor vibratory frequency increased, extensor frequency decreased, and vice versa.2. It is argued that the movements resulted largely from the reflex action of muscle spindle primary afferents whose firing frequency had been 'taken over' and modulated by the vibration.3. Bode plots relating forearm movements to command signal (modulating) frequency showed the transfer function of the I a afferent-CNS-muscle-load system to have a low-pass filter characteristic. The phase lag of movement on command increased progressively with command signal frequency, exceeding 180 deg at 3-4 Hz.4. The transduced forearm movements were fed back to provide the command signal to the vibrators (and thus indirectly to the spindle afferents) via a filter mimicking the dynamic responsiveness of muscle spindle primary endings. Our aim was to 'break into' the reflex arc, and re-route it so that we could artificially vary the gain without significantly altering the dynamics of the pathway.5. Nearly all subjects developed forearm oscillations (tremor) when the gain exceeded a threshold value. Subjects varied widely in their threshold, though for a given subject the threshold remained fairly constant from day to day. The results suggest that reflexly active individuals may not have a large safety margin with respect to forearm instability. 6. The frequency range of the oscillations observed in seven subjects was 3-8 Hz.The frequencies depended upon the level of flexor-extensor co-contraction, and increased from 3 to 5 Hz at 10 % co-contraction to 5-8 Hz at 100 % co-contraction. An analysis of the mechanical impedance of the arm provided estimates of tremor frequencies consistent with these results. 7. These unexpectedly low tremor frequencies led us to propose that it may be erroneous to expect stretch reflexes to contribute to forearm tremor in the range * Present address:

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“…Tremor amplitude and phase are susceptible to limb perturbations (Lee and Stein, 1981;Elble et al, 1992). Moreover, tremor may worsen after peripheral nerve damage, e.g., in paraproteinaemic/inflammatory neuropathies (Saifee et al, 2013).…”

Section: Tremor Onset Before Thalamomuscular Coherencementioning

confidence: 99%

Thalamomuscular Coherence in Essential Tremor: Hen or Egg in the Emergence of Tremor?

Pedrosa¹,

Quatuor²,

Reck³

et al. 2014

J. Neurosci.

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Thalamomuscular coherence in essential tremor (ET) has consistently been detected in numerous neurophysiological studies. Thereby, spatial properties of coherence indicate a differentiated, somatotopic organization; so far, however, little attention has been paid to temporal aspects of this interdependency. Further insight into the relationship between tremor onset and the onset of coherence could pave the way to more efficient deep brain stimulation (DBS) algorithms for tremor. We studied 10 severely affected ET patients (six females, four males) during surgery for DBS-electrode implantation and simultaneously recorded local field potentials (LFPs) and surface electromyographic signals (EMGs) from the extensor and flexor muscles of the contralateral forearm during its elevation. The temporal relationship between the onset of significant wavelet cross spectrum (WCS) and tremor onset was determined. Moreover, we examined the influence of electrode location within one recording depth on this latency and the coincidence of coherence and tremor for depths with strong overall coherence ("tremor clusters") and those without. Data analysis revealed tremor onset occurring 220 Ϯ 460 ms before the start of significant LFP-EMG coherence. Furthermore, we could detect an anterolateral gradient of WCS onset within one recording depth. Finally, the coincidence of tremor and coherence was significantly higher in tremor clusters. We conclude that tremor onset precedes the beginning of coherence. Besides, within one recording depth there is a spread of the tremor signal. This reflects the importance of somatosensory feedback for ET and questions the suitability of thalamomuscular coherence as a biomarker for "closedloop" DBS systems to prevent tremor emergence.

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Resetting of tremor by mechanical perturbations: A comparison of essential tremor and parkinsonian tremor

Cited by 196 publications

References 25 publications

Is Parkinsonian Arm Tremor a Resting Tremor?

Is Parkinsonian Arm Tremor a Resting Tremor?

Instability in human forearm movements studied with feed‐back‐controlled muscle vibration.

Thalamomuscular Coherence in Essential Tremor: Hen or Egg in the Emergence of Tremor?

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