Differences in the EMG pattern of leg muscle activation during locomotion in Parkinson’s disease Giovanni Albani Giorgio Sandrini a Gabriella Künig b Chantal Martin-Soelch c Alessandro Mauro Riccardo Pignatti Claudio Pacchetti a Volker Dietz d Klaus L. Leenders e Department of Neurology, IRCCS Italian Auxology Cen- tre, Piancavallo (Verbania) and Department of Neuro- science, University of Turin, Italy a IRCCS C. Mondino Institute of Neurology, University of Pavia, Italy b Institute of Neurology, University of Zürich, Switzer- land c Institute of Psychology, Basel, Switzerland d Swiss Paraplegic Centrum, Balgrist Hospital, Universi- ty of Zürich, Switzerland e Department of Neurology, University of Groningen, The Netherlands Reprint requests to: Dr Giovanni Albani Department of Neurology, Istituto Auxologico Italiano, Piancavallo (Verbania), Italy E-mail: giannialbani@libero.it Accepted for publication: May 25, 2003 Summary In this pilot study, EMG patterns of leg muscle activa- tion were studied in five parkinsonian patients with (B1) and five without (B2) freezing. Gastrocnemius me- dialis (GM) and tibialis anterior (TA) activity was analysed, by means of surface electromyography (EMG), during treadmill walking at two different belt speeds. Both groups showed reduced GM activity and an over- active TA at the lower speed compared with controls. Upon increasing the speed, the B2 patients showed a marked GM response (increment index 100%), while a moderate change was observed in the B1 group. Poor recruitment of the GM characterises parkinsonian gait in general; this pattern is much more marked in parkinsonian patients with freezing of gait, who show a loss of GM adaptation to variation of locomotion speed. KEY WORDS: adaptation, disability, electromyography, freezing, gait, Parkinson’s disease. Introduction Loss of interlimb coordination, freezing and dynamic postural instability are the main manifestations of parkinsonian gait (1,2). Prolonged stance or double support phase (3), reduced lateral shift of the body mass over the stance limb (4), and decreased propulsive forces (5) are some of the main biomechanical observations. Gait analysis reveals a characteristic pattern of leg muscle activation in Parkinson’s disease (PD) – in- creased tibialis anterior (TA) activity during the swing phase and reduced amplitude of the electromyographic (EMG) response and poor modulation in the leg exten- sor muscles during the stance phase (6,7). Gait disorders in PD may be either prominent or, even in the advanced stages of the disease, mild. Certain clinical features are more likely to be associated with disturbed gait: rapid course of motor symptoms (8), poor response to dopaminergic therapy (9) and an in- frequent presence of the tremor (10); disturbed gait al- so shows a positive association with speech problems and with motor symptoms that started on the left side of the body (11). The aim of this study was to evaluate whether the pres- ence of freezing is correlated with changes in the EMG patterns of leg muscle activation during walking on a treadmill. Materials and methods In order to evaluate the adaptive response of agonist/ antagonist muscles to an external stimulus (change in walking speed), this study focused, among the various parameters of gait (kinetic, kinematic, etc.), on EMG patterns of lower limb muscle activation. Ten idiopathic PD patients, five with freezing (B1) and five without freezing (B2), were studied in comparison with seven normal subjects (mean age: 63 years, four males/three females) (Table I, over). The inclusion criteria for B1 patients were: a) presence of freezing; b) Hoehn & Yahr stage ≥3; c) history of falls; d) no evidence of dysautonomic involvement; e) absence of dystonia and dyskinesia; f) absence of de- mentia. The inclusion criteria for B2 patients were: a) Hoehn & Yahr stage <3; b) no history of falls; c) good response to levodopa (L-dopa). All patients presenting fluctuating motor performances were investigated dur- ing the “on” state. Recordings were made while subjects were walking on a treadmill at belt speeds of 0.3 m/sec and 1.5 m/sec. One-minute recordings of walking in each speed condi- tion were made, the impact of the right leg triggered the biomechanical and electrophysiological signals. The Functional Neurology 2003; 18(3): 165-170 165