The influence of posture duration on hand tremor during tasks with attention-distraction in persons with Parkinson's disease.
Anne Sofie Bøgh Malling, Bo Mohr Morberg, Lene Wermuth and 3 others
PMID 31138267WHAT IT FOUND
Hand tremor intensity in Parkinson's disease increases significantly over a 30-second task, while it stays constant in healthy controls.
Clinicians should record tremor for at least 30 seconds to capture this time-dependent amplification.
Key findings
01Tremor intensity and maximal power increased significantly during the 30-second recording in the PD group, but remained unchanged in the healthy reference group.
02The increase in tremor intensity could not be explained solely by re-emergence, as tremor onset occurred early (mean 1.8 s rest, 1.4 s postural) and amplification continued after onset.
03The frequency of maximal power remained unchanged over time in the PD group, suggesting the same neural circuits were active despite the increased intensity.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTsWhat it means for SLPs
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What it does not show
The study used a subsample from a larger trial, so participants were not specifically recruited for this tremor analysis. No electromyography was performed, so the exact muscle activation patterns causing the amplification remain unknown. The healthy reference group had very low tremor intensity, making it difficult to detect subtle time-dependent changes that might exist in normal physiology.
Declared interests
The authors declared no competing interests. The study was supported by non-U.S. government funding.
The easy way to misread this
Do not assume that a brief tremor observation is representative of the patient's functional impairment. Tremor intensity in PD amplifies significantly over a 30-second period, so a short assessment may miss the severity seen during sustained tasks.