Short Communication Validation of GDI, GPS and GVS for use in Parkinson’s disease through evaluation of effects of subthalamic deep brain stimulation and levodopa Danielli Souza Speciali a , Joa ˜o Carlos Ferrari Corre ˆa a , Nata ´ lia Mariana Luna b , Rachael Brant c , Julia Maria D’Andrea Greve b , Wagner de Godoy d , Richard Baker e , Paulo Roberto Garcia Lucareli a, * a Department of Rehabilitation Science, Human Motion Analysis Laboratory, Universidade Nove de Julho, Sa ˜o Paulo, Brazil b Department of Orthopaedics and Traumatology, Universidade de Sa˜o Paulo, Sa˜o Paulo, Brazil c Department of Neurology, Universidade de Sa˜o Paulo, Sa ˜o Paulo, Brazil d Movement Analysis Laboratory, Albert Einstein Hospital, Sa ˜o Paulo, Brazil e School of Health, Sport and Rehabilitation Science, The University of Salford, UK 1. Introduction Movement disorders, particularly locomotor deficits, are frequent and incapacitating characteristics of Parkinson’s disease (PD) [1]. Three-dimensional gait analysis can characterize altera- tions in movement patterns, but results in a considerable amount of data that requires complex interpretation [2–5]. Gait indices such as the Gait Profile Score (GPS) [6] and Gait Deviation Index (GDI) [7] have recently been proposed and validated for different conditions. This study was designed to investigate their applica- tion to PD. Validation is based upon the known response of people with PD to levodopa and high frequency deep brain stimulation (DBS) of the subthalamic nucleus. Studies show improvements in kinematic variables of gait after DBS [4,8] or in patients who use only levodopa [9,10]. We establish whether the GDI, GPS, and the Gait Variable Scores (GVSs) which comprise the Movement Analysis Profile (MAP) reflect this. 2. Methods 2.1. Participants Participants were recruited from the Hospital das Clı ´nicas (HCFMUSP, Brazil). Inclusion criteria were: an adult diagnosed with PD, implanted bilateral DBS at least 12 months prior to assessment (frequency > 100 Hz, pulse amplitude 60–120 ms, voltage 2.5–5 V), clinically stable, classified between levels 1 and 3 on the Hoehn–Yahr modified scale under the effect of medication and stimulation [11] with a Mini Mental State Examination score greater than 24 points [12], and able to walk independently without the use of antiparkinsonian medication and with the DBS switched off. Exclusion criteria were: uncon- trolled infection or other pre-existing uncontrolled medical conditions, concomitant treatment with experimental drugs, a history of orthopedic surgery, and cognitive, visual, and auditory deficits. Sixteen individuals (11 male) were recruited (mean age Gait & Posture 39 (2014) 1142–1145 ARTICLE INFO Article history: Received 22 February 2013 Received in revised form 15 January 2014 Accepted 20 January 2014 Keywords: Parkinson’s disease Deep brain stimulation Gait Profile Score Gait Deviation Index Gait ABSTRACT The Gait Deviation Index (GDI), Gait Profile Score (GPS) and Gait Variable Scores (GVSs) have been proposed as measures of gait quality and validated for use with children with cerebral palsy. The aim of this study was to extend this validation to people with Parkinson’s disease by evaluating the effects of subthalamic deep brain stimulation and levodopa on gait. 16 participants had their gait evaluated with stimulation, medication or a combination of both. The Unified Parkinson’s Disease Rating Scale (UPDRS) showed statistically significant differences in agreement with previous studies. The GPS and GDI showed similar treatment effects as did GVS for hip and knee flexion/extension, as assessed with Cohen’s d where medium or large. Overall the results suggest that these gait indices are sensitive to treatment in this group of patients and that their use in groups other than children with cerebral palsy is valid. ß 2014 Elsevier B.V. All rights reserved. * Corresponding author at: Department of Rehabilitation Science, Human Motion Analysis Laboratory, Universidade Nove de Julho, Rua Vergueiro, 235 - Liberdade, Sa ˜o Paulo 01504-001, Brazil. E-mail addresses: danispeciali@ig.com.br (D.S. Speciali), jcorrea@uninove.br (J.C.F. Corre ˆa), nmsluna@gmail.com (N.M. Luna), greve@gmail.com (J.M.D. Greve), w.godoy@einstein.br (W. de Godoy), R.J.Baker@salford.ac.uk (R. Baker), paulolu- careli@uninove.br, plucareli@hotmail.com (P.R.G. Lucareli). Contents lists available at ScienceDirect Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost 0966-6362/$ – see front matter ß 2014 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.gaitpost.2014.01.011