Essential tremor: electrophysiological and pharmacological evidence for a subdivision.

Deuschl, Günther; Lücking, Carl Hermann; Schenck, E.

doi:10.1136/jnnp.50.11.1435

Cited by 65 publications

(31 citation statements)

References 8 publications

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“…A similar explanation can account for the observation that the PD group showed significantly lower values of the standard deviation of the phase, compared to patients with ET. The predominant opinion regarding activation pattern is that the alternating activity is characteristic for PD and the synchronous activity is characteristic for ET [13,20,28], although both forms of activation have been found in either condition [4,12,26]. To our surprise, the mean phase accounting for the predominant activation pattern was not significantly different between both groups, although a tendency towards clustering of the mean phase around 180 degrees was observed in PD, suggesting an alternating pattern of contraction.…”

Section: ■ Phase Distributioncontrasting

confidence: 58%

“…Initially, the activation pattern of the antagonistic muscles, as one can determine by visual inspection of the EMG, was shown to reveal an alternating behavior in PD in contrast to synchronous activity in ET [28]. Meanwhile, both forms of muscle activation have been found in either condition [12,23,26], and switches between these activation patterns were detected in one and the same patient [4,13]. Waveform analysis reflecting asymmetries of the tremor curves seemed to be a promising tool.…”

Section: Introductionmentioning

confidence: 99%

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Long-term EMG recordings differentiate between parkinsonian and essential tremor

et al. 2008

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The differential diagnosis of tremor is mainly based on clinical criteria.Nevertheless, these criteria are in some cases not sufficient to differentiate between different tremor forms. Long-term EMG has proven to be a valid and reliable method for the quantification of pathological tremors. The aim of the study was to develop a long-term EMG-based automated analysis procedure that separates parkinsonian tremor from essential tremor. Using longterm EMG tremor was recorded in 45 consecutive patients, 26 with Parkinson's disease (PD) and 19 with essential tremor (ET). Eight tremor parameters were generated automatically. By stepwise backward regression a subset of these criteria was extracted to achieve an automated classification of the tremor by a mathematical model. The obtained model was then tested on a new group of 13 patients in early stages of the disease. Significant differences between groups were found for tremor occurrence, tremor asymmetry, mean tremor frequency and standard deviation of phase of antagonistic muscles. Due to data overlap a classification of the two tremor forms was not possible based on a single tremor parameter. Using logistic regression, a linear formula based on the three parameters tremor occurrence, mean tremor frequency and standard deviation of phase was established and predicted the correct diagnosis in 93% of patients. The validation of the model on the new group of patients in early stages of the tremor disease yielded a correct diagnosis in 100% of cases. We conclude that long-term EMG recording allows a rater-independent classification of parkinsonian versus essential tremor.

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Section: ■ Phase Distributioncontrasting

confidence: 58%

Section: Introductionmentioning

confidence: 99%

Long-term EMG recordings differentiate between parkinsonian and essential tremor

et al. 2008

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“…Deuschl et al (15) reported 16 of 45 patients with essential tremor who had enhanced C-reflex. In their study, it was also demonstrated that tremors of those patients were responsive to primidone rather than propranolol.…”

Section: Discussionmentioning

confidence: 99%

Familial cortical myoclonic tremor as a unique form of cortical reflex myoclonus

Terada¹,

Ikeda²,

Mima³

et al. 1997

Movement Disorders

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Previously it was reported that some patients with tremor had the same electrophysiological findings as those seen in patients with cortical reflex myoclonus, and consequently the tremor was named "cortical tremor." In the present study, we examined six patients from three families with cortical tremor of relatively late onset. The inheritance pattern of cortical tremor was compatible with autosomal dominant trait. Those patients had relatively rhythmic involuntary movements (tremor) in the distal upper and lower limbs, especially during posture and/or fine movements. There was no cerebellar ataxia or dementia, and fits of loss of consciousness occurred only infrequently. Electrophysiologically, they had generalized spikes on electroencephalogram (EEG), giant cortical components of somatosensory evoked potential, an enhanced long-loop reflex (C-reflex), and cortical spikes preceding the rhythmic jerk demonstrable by the jerk-locked back averaging method, thus fulfilling the criteria of cortical reflex myoclonus. Furthermore, they had slow negative EEG shift starting 1-2 s prior to voluntary movements, suggesting that, as opposed to the conventional form of progressive myoclonus epilepsy (PME), the cerebellar efferent input to the motor cortices was normal. These clinical and electrophysiological pictures are distinct from those of familial essential tremor, familial essential myoclonus, or the conventional form of PME, and the term "familial cortical myoclonic tremor" will represent the clinical and electrophysiological features of this unique entity most appropriately.

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“…5,18 Moreover, monosynaptic spinal and long-latency stretch reflexes are invariably normal in ET. 9 Other evidence favors a central generator in ET. Several studies in patients with ET have shown abnormal activation of the central nervous system; for example, the cerebellum, the thalamus, and the medulla.…”

mentioning

confidence: 99%

Cortical excitability in patients with essential tremor

Romeo¹,

Berardelli²,

Pedace³

et al. 1998

Muscle Nerve

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Essential tremor: electrophysiological and pharmacological evidence for a subdivision.

Cited by 65 publications

References 8 publications

Long-term EMG recordings differentiate between parkinsonian and essential tremor

Long-term EMG recordings differentiate between parkinsonian and essential tremor

Familial cortical myoclonic tremor as a unique form of cortical reflex myoclonus

Cortical excitability in patients with essential tremor

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