title: An accelerometry-based study of lower and upper limb tremor in Parkinson's disease.
abstract: Over the past two decades, several studies have aimed to quantify the kinetic properties of tremor with primary focus on the upper limbs. However, there is a lack of investigation into the properties of tremor in the lower limbs. The objective of this preliminary study was to investigate the properties of oscillatory movement, at rest and in posture, in both the upper and lower limbs of Parkinson's disease (PD) patients with clinically undetectable to modest rest/postural tremor and healthy controls. PD patients (N = 16) and controls (N = 8) were examined clinically by a movement disorders specialist and oscillatory movements in all four extremities were evaluated using a portable biaxial accelerometer. While tremor intensity and frequency did not differ between groups, the intraindividual variability of rest and postural tremor frequency in the dexterity-dominant lower limb was lower in people living with PD than in healthy adults. Additionally, rest tremor frequency was discrepant between upper and lower limbs in PD. Our work introduces the possibility that minute variations in lower limb movements, which are imperceptible upon expert clinical exam, can be used to differentiate a diseased sample from a healthy one. These preliminary findings suggest that additional work using objective tremor measurement may improve our understanding of lower limb motor dysfunction in PD and lead to the refinement of current, and the development of new, metrics to enhance early diagnosis, differential diagnosis, and symptom quantification.
authors: Sierra-Pacific Mental Illness Research, Education, and Clinical Center, VA Palo Alto Health Care System, Palo Alto, CA 94304, USA. bscanlon@stanford.edu
authors: Blake K
authors: BK
authors: Scanlon
authors: Bonnie E
authors: BE
authors: Levin
authors: Daniel A
authors: DA
authors: Nation
authors: Heather L
authors: HL
authors: Katzen
authors: Alexandra
authors: A
authors: Guevara-Salcedo
authors: Carlos
authors: C
authors: Singer
authors: Spiridon
authors: S
authors: Papapetropoulos
mesh_terms: D061725:Accelerometry; D000368:Aged; D005260:Female; D006801:Humans; D035002:Lower Extremity / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications*; D011187:Posture / Q000502:physiology; D012720:Severity of Illness Index; D014202:Tremor / Q000209:etiology* / Q000473:pathology*; D034941:Upper Extremity / Q000503:physiopathology*