title: Factor structure of motor signs in essential tremor.
abstract: Motor signs in essential tremor (ET) are varied. Patients may have limb tremors, including postural, kinetic (e.g. writing, pouring), and rest tremors, head tremor, voice tremor, or chin tremor. Factor analysis allows one to determine whether these signs fall into a smaller number of discrete domains. Such an analysis has not been performed on a group of ET cases. ET cases (n = 168) were recruited from the Neurological Institute of New York and a videotaped examination was performed. A factor analysis was performed on 17 motor items. Four distinct factors emerged, explaining 68.7% of the total variance. These were factor I (action tremor in the dominant arm), factor II (action tremor in the nondominant arm), factor III (tremor at rest) and factor IV (chin tremor, head tremor, and voice tremor). The demonstration of these four factors will be of potential use for pathological and genetic studies as well as interventional studies, as will be discussed.
authors.affiliation: G.H. Sergievsky Center, Department of Neurology, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, College of Physicians and Surgeons, Columbia University, New York, NY, USA. EDL2@columbia.edu
authors.forename: Elan D
authors.initials: ED
authors.lastname: Louis
authors.forename: LaKeisha
authors.initials: L
authors.lastname: Applegate
authors.forename: Pam
authors.initials: P
authors.lastname: Factor-Litvak
authors.forename: Michael K
authors.initials: MK
authors.lastname: Parides
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001132:Arm / Q000503:physiopathology; D004326:Drinking / Q000502:physiology; D020329:Essential Tremor / Q000145:classification / Q000503:physiopathology*; D005163:Factor Analysis, Statistical; D005260:Female; D006257:Head / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D011187:Posture / Q000502:physiology; D012146:Rest / Q000502:physiology; D012720:Severity of Illness Index; D014831:Voice / Q000502:physiology