AGE-DEPENDENT
CLINICAL RESULTS OF EMG-TRIGGERED ELECTROSTIMULATION IN THE TREATMENT OF STROKE
PATIENTS
Mokrusch T
University of Erlangen-Nürnberg
GESET German Headquarters
c/o Hedon-Klinik
D-49811
EMG-triggered electrotherapy is able to reduce spasticity and to increase voluntary muscle force, thus showing a significant improvement of life quality and well-being. The present study was performed in stroke patients to evaluate possible age-dependencies in the clinical outcome of this therapy. A series of 61 indoor stroke patients (31-79 years) were treated with an observation time of 6-10 weeks. EMG-triggered electrotherapy was performed 7-10 times a week. Patients were devided into three groups (I: <50ys; II: 51-70ys; III: >71ys). Spasticity was reduced in each group (pendulum test and modified Ashworth-scale), showing a significantly better improvement I vs. II (p<0.01) and II vs. III (p<0.005). There was a higher increase of muscle contraction force (hand-held myometer) in the younger groups (I+II vs. III, p<0.002). There was also a better improvement in the abilities of daily living and life quality (I vs. II p<0.005, and II vs. III p<0.005). EMG-triggered electrostimulation in stroke patientes is more effective in younger patients then in elderly people.
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Low
frequency electrostimulation, triggered by electromyographically measurable
voluntary muscular activity (EMG-triggered electrotherapy) is able to reduce
spasticity and to increase voluntary muscle contraction force, and this kind of
therapy is superior to conventional electrotherapy as well as to physiotherapy
alone. Additionally, it shows a significant improvement of life quality and
well-being. One of the first publications on this topic was Hansen’s paper from
1979 (1), a review paper has been published by the GESET working group in 1999
(2), including studies of our own group (3,4). Previous investigations have
found that even patients with a stroke history of more than one year may profit
of EMG-triggered electrotherapy (5). Usually, this kind of therapy has some
positive effect even in elderly people, with the clinical impression that
elderly people may react somehow less or in a slower time course. Thus, the
present study was performed in stroke patients to evaluate possible
age-dependencies of the clinical outcome.
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Methods
A series of 61 indoor (ischemic) stroke patients with
incomplete spastic hemiparesis (31-79 years, left hemisphere: N=29, right
hemisphere: N=32) were treated for 8.2+1.5 (6-10) weeks. Additionally to
physiotherapy, EMG-triggered electrotherapy was performed 7-10 times a week
using conventional devices, industrially provided by several German companies
(see acknoledgment). The stimulation was performed in therapeutical sessions
with a duration of 30 minutes each. Stimulation intensity varied, always
resulting in a good contraction without causing any pain. During one session,
the forearm extensor muscles, which are antagonistic to the spasticity pattern,
were trained by the patient using his own voluntary muscular activity to
trigger the stimulation device by voluntarily lifting his hand and his fingers.
Including the breaks which were necessary for the patient’s relaxation,
recreation and concentration, during one session 50 stimulations were performed
on average. Patients were devided into three groups (Group I: <50ys,
N=13; group II: 51-70ys, N=29; group III: >71ys, N=19). Spasticity
was evaluated using the pendulum test of the arm (3) and the modified
Ashworth-scale. Muscle contraction force was measured with a hand-held myometer
(Penny & Giles,
Results
Spasticity:
Spasticity was reduced in each of the three groups. This was an overall and general effect and was not restricted to the muscle groups as stimulated. The pendulum test of the arm, resulting from the behaviour als well of flexor as of extensor muscles (normal range 1.6+0.4) showed an increase of 0.70 to 0.99 in group I, of 0.72 to 0.91 in group II and of 0.72 to 0.82 in group III, showing a significantly better improvement in group I vs. group II (p<0.01) and II vs. III (p<0.005). The modified According to these results, the modified Ashworth-scale showed a decrease of 7.1 to 3.8 in group I, 7.2 to 4.2 in II and 6.9 to 4.9 in III, showing a significantly better improvement in group I vs. group II (p<0.01) and II vs. III (p<0.01).
Muscular contraction force:
The contraction force of the stimulated muscle groups (hand- and finger extensors) increased as well as the force of the antagonistic flexors. There was a higher increase of contraction force in the younger groups with no significant differences between group I and II, but I+II vs. III, p<0.002 when evaluating the tetanic extension force of the hand (increase of 5.4+1.0 kp vs. 2.6+1.9 kp) and p<0.01 when evaluating the tetanic extension force of the forearm (increase of 4.3+1.1 kp vs. 2.8+1.1 kp).
Abilities of daily living:
There was also a better improvement in the abilities of daily living using the Barthel index with an increase of the overall score of 30+11 in group I, 25+8 in group II and 15+12 in group III (I vs. II p<0.005, and II vs. III p<0.005) and the FIM (I vs. II p<0.01, and II vs. III p<0.005).
Life quality:
According to their ADL-improvement, younger patients stated a better improvement of their life quality (Bf-S-well-being-Scale: -20+8 in group I, -15+4 in group II and -5+4 in group III (I vs. II p<0.01, and II vs. III p<0.01).
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According to extensive own clinical experiences in more then 500 patients and to a large number of studies that have been published during the last 20 years, including studies of our own group (3), EMG-triggered electrostimulation can be rercommended as a valuable tool in the rehabilitation of stroke patients. The results of the present study are able to confirm these previous studies. Additionally they indicate a time dependency of the clinical outcome to the patient’s age. Patients younger then 50 years show a greater improvement on each level of investigation than elderly people do. The decrease of spasticity, the increase of voluntary muscle contraction force, the improvement of their abilities of daily living and their well-being is significantly better than in elderly patients. Younger stroke patients seem to have a greater cerebral capacity of regulation and regeneration, indicating a greater plasticity of the brain tissue and the neuronal network (6), additionally, we know a particular lesion-induced plasticity from the animal experiment (7). However, it is possible that the better results of the younger patients only mean that they react earlier then elderly patients, and not necessarily better. Thus, the clinical meaning and therapeutical consequence of these findings are that an indication for this kind of therapy has to be given independently of the patients age, as elderly patients had a similar profit. To decide whether elderly stroke patients have the same chances for clinical improvement and only need a longer time of therapy, a follow-up study now is planned to investigate the velocity of the time course of the clinical improvement with EMG-triggered electrostimulation in elderly stroke patients during an observation period of 6 months.
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(1) Hansen GvO: EMG-countrolled functional electrical stimulation of the paretic hand.
Scand J Rehabil Med 1979: 11; 189-93
(2) Mokrusch T, Bossert FP, David E, Lange A, Blum B: The
value of EMG-controlled electrostimulation in therapy und rehabilitation of
central nervous system lesions - comment of the GESET. ZEE 1999: 1; 30-6
(3) Mokrusch T: Behandlung der hirninfarktbedingten
spastischen Hemiparese mit EMG-getriggerter Elektrostimulation. Neurol Rehabil
1997: 3; 82-6
(4) Mokrusch T: Electromyographically measurable voluntary
muscular activity. The Lancet Conference 1998: 71-2
(5) Cauraugh J, Light K, Kim S, Thigpen M, Behrmann A:
Chronic motor dysfunction after stroke - Recovering wrist and finger extension
by electromyography-triggered neuromuscular stimulation. Stroke 2000: 31;
1360-4
(6) Aizawa H, Inase M, Mushiake H, Shima K, Tanji J:
Reorganization of activity in the supplementary motor area associated with
motor learning and functional recovery. Exp Brain Res 1991: 84; 668-1
(7) Witte OW: Lesion-induced plasticity as a potential
mechanism for recovery and rehabilitative training. Curr Opinion Neurol 1998:
11; 655-62
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