Exploring the effects of deep brain stimulation and vision on tremor in Parkinson's disease - benefits from objective methods.
Per-Anders Fransson, Maria H Nilsson, Diederick C Niehorster and 6 others
PMID 32334622WHAT IT FOUND
Objective force-platform and motion-capture tests detected Parkinsonian tremor in 9 of 10 patients, including 3 missed by standard clinical scoring.
Turning deep brain stimulation on greatly reduced recorded tremor amplitude. Eyes open had smaller effects.
Key findings
01The two objective systems together found tremor in 9 of 10 patients, including 3 patients whose tremor was not seen on standard clinical scoring when DBS was on.
02Turning DBS on reduced the measured tremor peak power by 96% and 93% with eyes closed, and by 97% with eyes open, while the tremor peak frequency did not notably change.
03Opening the eyes reduced measured tremor peak power by 29% with the force platform and 1% with motion capture when DBS was off, and by 58% and 52% when DBS was on.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Only 10 patients were studied, and not all had visible tremor, so this is a small methodology case study rather than evidence that the tests work for all patients. Three patients, including two with the most severe tremor, could not complete the eyes-closed DBS-off test because of instability, so the most unstable patients may be underrepresented. The authors did not perform statistical analyses on peak tremor characteristics because of the case study design and uneven distribution of tremor peaks. The motion capture markers were placed at proximal body sites, not the same sites used for UPDRS or force-platform comparison, so differences between methods may reflect placement. With DBS on, tremor was usually so reduced that interactions between DBS and vision could not be explored. A washout period of at least 30 minutes between DBS states may not fully remove residual stimulation effects. Technical recording and offline analysis take time, which may limit routine clinical use.
Declared interests
The supplied text names Vetenskapsrådet as the funder. It does not report other conflicts of interest.
The easy way to misread this
Do not conclude that objective tremor recording is ready to replace clinical UPDRS scoring or that these findings prove a treatment benefit for Parkinson's disease. The study was a small methodology case study, and the authors did not statistically analyse peak tremor characteristics.