title: Gait and balance in Parkinson's disease subtypes: objective measures and classification considerations.
abstract: Parkinson's disease (PD) is often divided into tremor dominant (TD) and postural instability gait difficulty (PIGD) subtypes. However, objective measures of gait (e.g., stride length, variability) and balance have not been well studied in these subtypes. To better understand these motor subtypes, we objectively quantified gait and balance and their behavioral correlates. 110 patients with PD underwent a clinical evaluation and were stratified into PIGD and TD subtypes. Participants walked under single and dual task conditions while wearing a single body-fixed sensor, both "OFF" and "ON" medications and at home for 3 days. We also examined performance-based tests of mobility, balance, and fall risk. Stricter criteria were also applied, dividing the subjects into predominant representative subgroups: p-PIGD and p-TD. Both the PIGD (n = 62) and TD (n = 42) groups and the p-PIGD (n = 31) and p-TD (n = 32) subgroups were similar with respect to basic disease characteristics (e.g., disease duration, p > 0.69). Surprisingly gait speed, stride length, and variability did not differ between the PIGD and TD groups (p > 0.05). In contrast, the p-PIGD group had reduced gait speed (under single and dual task conditions), shorter strides, increased stride variability, and decreased stride regularity (regularity: p-PIGD 0.66 ± 0.10; p-TD 0.74 ± 0.08; p = 0.003). The p-PIGD group also scored worse on performance-based tests, compared to the p-TD. Clinical assessments of the disturbances seen in patients with the PIGD subtype are not consistent with objective measures; overlapping between the groups is seen in many objective features of gait and balance. These findings suggest that the proposed alternate classification scheme may be useful.
authors.affiliation: Center for the Study of Movement, Department of Neurology, Cognition and Mobility, Tel Aviv Sourasky Medical Center, 6 Weizman Street, 64239, Tel Aviv, Israel, talih@tlvmc.gov.il.
authors.forename: Talia
authors.initials: T
authors.lastname: Herman
authors.forename: Aner
authors.initials: A
authors.lastname: Weiss
authors.forename: Marina
authors.initials: M
authors.lastname: Brozgol
authors.forename: Nir
authors.initials: N
authors.lastname: Giladi
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Hausdorff
mesh_terms: D000368:Aged; D005260:Female; D005684:Gait; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D010300:Parkinson Disease / Q000145:classification* / Q000175:diagnosis / Q000503:physiopathology*; D004856:Postural Balance; D014202:Tremor / Q000503:physiopathology*; D016138:Walking