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Orthostatic tremor during modification of standing
Author(s) -
Spiegel Jörg,
Krick Christoph,
Fuss Gerhard,
Sood Dania,
Becker Georg,
Dillmann Ulrich
Publication year - 2006
Publication title -
movement disorders
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.352
H-Index - 198
eISSN - 1531-8257
pISSN - 0885-3185
DOI - 10.1002/mds.20684
Subject(s) - physical medicine and rehabilitation , electromyography , afferent , medicine , intensity (physics) , orthostatic vital signs , anatomy , physics , blood pressure , quantum mechanics
Primary orthostatic tremor (OT) occurs only during standing. We studied whether modification of the condition standing influences OT. In seven patients with OT, surface EMG was recorded from both tibialis anterior and gastrocnemius muscles during two maneuvers: relief, whereby the patient was gradually lifted by a crane, and tilting, whereby the patient was tilted by a tilting table to positions of 90° (upright standing), 45° (diagonal position), and 0° (lying position). We determined the parameters tremor frequency, tremor intensity, coherence, and phase shift between the different muscles. Relief did not influence OT. In contrast, tilting modified significantly tremor intensity and phase shifts; tremor frequencies and coherences were not influenced. We chose both these maneuvers because of their different impact on the standing condition: relief modifies the factors afferent input and muscle forcing but not the factor postural set, whereas tilting modifies all three factors. The fact that tilting modifies OT, whereas relief does not, suggests an important role of postural set in OT generation. Afferent input and muscle forcing seem to play less important role. © 2005 Movement Disorder Society