The effects of visual rhythms and optic flow on stride patterns of patients with Parkinson’s disease E. van Wegen a, * , I. Lim a , C. de Goede a , A. Nieuwboer b , A. Willems b , D. Jones c , L. Rochester c , V. Hetherington c , H. Berendse d , J. Zijlmans d , E. Wolters d , G. Kwakkel a a Department of Physical Therapy, VU University Medical Center (VUmc), Amsterdam, The Netherlands b Department of Rehabilitation Sciences, Faculty of Physical Education and Physiotherapy, Katholieke Universiteit Leuven, Belgium c School of Health, Community and Education Studies, Northumbria University, Newcastle upon Tyne, UK d Department of Neurology, VU University Medical Center (VUmc), Amsterdam, The Netherlands Received 18 February 2005; revised 19 April 2005; accepted 24 June 2005 Abstract This study was aimed at determining the effects of rhythmic visual cueing under changing visual conditions on stride frequency in patients with Parkinson’s disease (PD; nZ21) and healthy age matched controls (nZ7) while walking at different speeds on a treadmill. Stride frequency and stride length in patients with PD as well as controls were not rigidly coupled to walking speed and could be manipulated with walking speed as well as by using spatial and temporal rhythmic visual cues. q 2005 Elsevier Ltd. All rights reserved. Keywords: Parkinson disease; Gait; Cueing; Visual 1. Introduction It has been well established that patients with Parkinson’s disease (PD) exhibit specific changes in gait patterns during walking. Patients with PD walk at a reduced overall speed and a shorter stride length in comparison with healthy age-matched control subjects [1]. Cadence (i.e. number of steps made in 1 min) may be normal, but is often elevated when speed of walking is taken into account. This increased cadence appears to be a compensation for the reduced stride length [2]. Several studies suggest that cadence control is still intact and can be modulated for a variety of conditions [1,3,4]. On the other hand patients with PD seem to have particular difficulty with the internal regulation of stride length [2,3,5–7]. In addition to changes in stride parameters, changes in foot fall patterns, trunk position as well as reduced trunk rotation and absence of arm swing have been observed [8– 11]. Even with an ‘optimal’ medication regimen gait-related movement problems persist and could be related to the occurrence of falling [12–14]. Taken together, the mobility problems can have a large impact on activities of daily living in PD patients [15–17]. In many observational studies, gait changes are investigated during tests at the preferred walking speed during over ground walking. However, since variables such as stride length and stride frequency tend to change as a function of walking speed, same-speed comparisons need to be undertaken in order to eliminate the effects of speed on stride parameters [11,18]. At a fixed speed, the shorter stride length in PD may be compensated for by an elevated cadence [2]. Thus, when controlling for speed, adaptation of cadence by an external rhythm might offer a possible strategy to indirectly influence stride length regulation. Several studies have shown that auditory rhythms can positively influence stride characteristics of gait in PD, presumably by compensating for basal ganglia disease causing an inability to internally generate rhythmic move- ments [9,19–22]. Such external cues can be defined as Parkinsonism and Related Disorders 12 (2006) 21–27 www.elsevier.com/locate/parkreldis 1353-8020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.parkreldis.2005.06.009 * Corresponding author address. Department of Physiotherapy, VU Univer- sity Medical Center, de Boelelaan 1117, P.O. Box 7075, 1081 HV Amsterdam, The Netherlands. Tel.: C31 20 4440463; fax: C31 20 4440469. E-mail address: e.vanwegen@vumc.nl (E. Wegen).