1st Joint ESMAC-GCMAS Meeting - Análise de Marcha

O-46
ABNORMAL EMG-ACTIVITY IN PATHOLOGICAL GAIT IN PATIENTS
WITHOUT NEUROLOGICAL DISEASES
Brunner Reinald (Prof), Romkes Jacqueline (M.Sc.)
Laboratory for Gait Analysis, Children’s University Hospital, Basel, Switzerland
Summary/conclusion
The abnormal electromyographic (EMG) activity during gait seen in patients with cerebral
palsy (CP) was also found in orthopaedic patients without neurological involvement. The
abnormal EMG activity correlated best with muscle weakness. Weakness is a well recognised
problem in patients with CP, too. The results of this study suggest that muscle weakness may
be more important than spasticity to explain the pathological gait pattern, even in patients with
spasticity.
Introduction
Abnormal muscle activity in patients with CP during gait is commonly taken as of spastic
origin. Mimicking the individual gait pattern of a given patient with hemiplegic CP, however,
produced similar EMG abnormalities in normals [1]. This study investigates the incidence and
possible causes of abnormal EMG patterns in patients without neurological diseases.
Statement of clinical significance
In patients without neurological disease, abnormal muscle activity is either an indicator for a
compensation strategy or a physiological variety. If the pattern found in CP is found in
neurologically normals as well, the question of the origin of this pattern in CP rises. This study
contributes to the understanding of gait in CP.
Methods
All patients (n=39) without any neurological disease who were referred to the gait laboratory
between January 2003 and March 2005 were included in this study. The primary pathologies
varied widely (club feet, ACL-ruptures, Perthes disease, ECF, unclear pain syndromes and
more). Since January 2003 the routine of assessment in the gait laboratory was unchanged: the
clinical examination of the lower extremities comprised of a test of range of motion (RoM)
including all lengths of bi-articular muscles, a manual testing of muscle strength, and an
assessment of spasticity (modified Ashworth scale). Instrumented gait analysis was performed
(VICON 460, 2 Kistler force plates) including surface EMG of gastrocnemius medialis, tibialis
anterior, rectus femoris, and semitendinosus bilaterally. Two data sets were excluded for
artefacts. Raw EMG was analysed for abnormal activity. Any EMG activity duration
prolonged more than half of maximal activity out of the normal range [2] was considered
(figure 1: grey areas):
A) Plantar flexor hyperactivity (gastrocnemius medialis, figure 1a): Too early onset of
activation in terminal swing or at latest at initial contact in continuation till foot contact,
prolonged activity in stance, usually accompanied by a shut off of the tibialis anterior muscle.
B) Knee extensor hyperactivity (rectus femoris, figure 1b): Activity at mid-stance or later in
stance.
C) Hip extensor hyperactivity (semitendinosus, figure 1c): Hamstring activity reaching or
exceeding mid-stance.
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