Treatment of patients with essential tremor.
ABSTRACT Essential tremor is a common movement disorder. Tremor severity and handicap vary widely, but most patients with essential tremor do not receive a diagnosis and hence are never treated. Furthermore, many patients abandon treatment because of side-effects or poor efficacy. A newly developed algorithm, based on the logarithmic relation between tremor amplitude and clinical tremor ratings, can be used to compare the magnitude of effect of available treatments. Drugs with established efficacy (propranolol and primidone) produce a mean tremor reduction of about 50%. Deep brain stimulation (DBS) in the thalamic nucleus ventrointermedius or neighbouring subthalamic structures reduces tremor by about 90%. However, no controlled trials of DBS have been done, and the best target is still uncertain. Better drugs are needed, and controlled trials are required to determine the safety and efficacy of DBS in the nucleus ventrointermedius and neighbouring subthalamic structures.
Article: Tremor erkennen und therapieren[Show abstract] [Hide abstract]
ABSTRACT: Der Tremor ist eine rhythmische unwillkürliche Bewegung einer oder mehrerer Extremitäten, der als eigenständige neurologische Erkrankung, auch im Rahmen anderer neurologischer oder internistischer Erkrankungen sowie als Nebenwirkung von Medikamenten auftreten kann. Besonders die primär neurologischen Tremorformen können differenzialdiagnostische Probleme bereiten — mit erheblichen Konsequenzen für therapeutische Entscheidungen.InFo Neurologie & Psychiatrie. 11/2012; 14(11):46-54.
- [Show abstract] [Hide abstract]
ABSTRACT: In Parkinson disease, tremor is a challenging symptom to manage, partly due to inadequate characterization. The current (classic) model of tremor is characterized by a resting tremor with a single strong peak in 3.5-6.5Hz range. The presence of action tremor, including postural, isometric, and kinetic tremors, has been disputed in the literature but not comprehensively evaluated. Analysis of hand tremor in action compared to rest, and possible subgrouping of tremor trends, may improve characterization. Twenty Parkinson patients and 14 controls were recruited. Tremor amplitude was measured across 9 sequentially loaded tasks, in off and on medication states. Tremor energy was separated into 2 frequency bands (B1, 3.5-6.5Hz; B2=physiological tremor, 7.5-16.5Hz) across all activity levels. Automatic classification was used for subgroup analysis. Automatic classification yielded 3 predominant tremor trends (G1, G2, and G3). These were significantly different from each other and from controls. G1 demonstrated closest resemblance to classical Parkinsonian tremor, with highest tremor energy at rest and with overall dominance in B1 for lower loads. G2-G3 did not show tremor energy dominance in either band. Medication reduced tremor energy only for G1 in both B1 and B2. Subgrouping the loading effect on tremor is a novel and viable method of rationalizing (non-classic) action tremor in Parkinson disease. Rest and action tremors appear not to be limited to 3.5-6.5Hz and may have considerable share of physiological tremor. Finding the contribution of each frequency band to total tremor energy and their trends with load may optimize therapy options. Copyright © 2014 Elsevier Ltd. All rights reserved.Clinical biomechanics (Bristol, Avon) 12/2014; 30(2). · 1.76 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: 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 ± 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 "closed-loop" DBS systems to prevent tremor emergence.Journal of Neuroscience 10/2014; 34(43):14475-83. · 6.75 Impact Factor