title: Side onset influences motor impairments in Parkinson disease.
abstract: In right-handers, the left hemisphere has greater ipsilateral control of the upper extremities than the right hemisphere. This asymmetry is not as profound among left-handers. We sought to determine whether Parkinson disease (PD) maintains this pattern of ipsilateral control and affects motor impairment. Using right- and left-hand sub-scores from the Unified Parkinson Disease Rating Scale (UPDRS), we calculated a lateralized impairment score to compare ipsilateral influence among four groups: right-handed-right-sided onset (RH-RSO), right-handed-left-sided onset (RH-LSO), left-handed-right-sided onset (LH-RSO), and left-handed-left-sided onset (LH-LSO). We hypothesized that right-handed patients with RSO (left hemisphere dysfunction) would have lower scores, hence more deficits in both hands, than the other groups. Among right-handers, the RSO patients (left dominant hemisphere dysfunction) had a significantly lower mean lateralized impairment score than LSO patients (micro = 2.09 versus micro = 4.06; p < 0.001). Further, RHRSO also had lower scores than both the LHLSO (micro = 4.52, p < 0.05) and LHRSO (micro = 4.27, p < 0.05) groups. The symmetry of impairments indicates deficits in both hands and supports more ipsilateral involvement of the affected left hemisphere in RH-RSO patients. Therefore, we suggest that PD does retain an asymmetric ipsilateral influence. The low numbers of left-handed subjects and the significant percentage of left-handers with a dominant left hemisphere prevented a clear interpretation of our findings in left-handed subjects.
authors.affiliation: Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Kim C
authors.initials: KC
authors.lastname: Stewart
authors.forename: Hubert H
authors.initials: HH
authors.lastname: Fernandez
authors.forename: Michael S
authors.initials: MS
authors.lastname: Okun
authors.forename: Ramon L
authors.initials: RL
authors.lastname: Rodriguez
authors.forename: Charles E
authors.initials: CE
authors.lastname: Jacobson
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Hass
mesh_terms: D000368:Aged; D004185:Disability Evaluation; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019957:Motor Skills Disorders / Q000209:etiology*; D010300:Parkinson Disease / Q000503:physiopathology*; D012189:Retrospective Studies; D012720:Severity of Illness Index