The effect of vibration therapy on spasticity and motor function in children with cerebral palsy: A randomized controlled trial

Abstract

As the motor system relies heavily on deep sensory stimulation, recent studies have investigated the effect of vibration stimuli. Although research suggests a positive influence of vibration on motor performance in individuals with neurological disorders, there are very limited numbers of studies in children with cerebral palsy (CP).
The objective of the present study was to evaluate the effects of sound wave vibration therapy on spasticity and motor function in children with CP.
In this 3-month trial, 89 children with spastic CP were randomized to either continue their physiotherapy treatment (PT) or to receive vibration therapy twice a week in addition to their PT program. The randomization was stratified according to the Gross Motor Function Classification System (GMFCS) level to ensure similar functional ability. Children were assessed at baseline and after the 12-week intervention period. The outcomes measured were spasticity level as assessed by Modified Modified Ashworth Scale (MMAS) and gross motor function as assessed by Gross Motor Function Measurement (GMFM-88). Subgroup analysis was performed for the GMFCS.
Significant differences between groups were detected for changes in spasticity level and gross motor function after the three months intervention.
In conclusion, vibration therapy may decrease spasticity and improve motor performance in children with CP. The results of the present trial serve as valuable input for evidence-based treatments in paediatric neurorehabilitation.

Full text

Uncorrected Author Proof
NeuroRehabilitation xx (20xx) x–xx
DOI:10.3233/NRE-130817
IOS Press
1
The effect of vibration therapy on spasticity
and motor function in children with cerebral
palsy: A randomized controlled trial
1
2
3
Ana Katusica,∗, Sonja Alimovicaand Vlatka Mejaski-Bosnjakb
4
aDay-care Centre for Rehabilitation “Mali dom-Zagreb”, Zagreb, Croatia5
bChildren’s Hospital Zagreb, Department of Neuropaediatry, Faculty of Medicine, University of Zagreb, Zagreb,
Croatia
6
7
Abstract. As the motor system relies heavily on deep sensory stimulation, recent studies have investigated the effect of vibration
stimuli. Although research suggests a positive influence of vibration on motor performance in individuals with neurological
disorders, there are very limited numbers of studies in children with cerebral palsy (CP).
The objective of the present study was to evaluate the effects of sound wave vibration therapy on spasticity and motor function in
children with CP.
In this 3-month trial, 89 children with spastic CP were randomized to either continue their physiotherapy treatment (PT) or to
receive vibration therapy twice a week in addition to their PT program. The randomization was stratified according to the Gross
Motor Function Classification System (GMFCS) level to ensure similar functional ability. Children were assessed at baseline and
after the 12-week intervention period. The outcomes measured were spasticity level as assessed by Modified Modified Ashworth
Scale (MMAS) and gross motor function as assessed by Gross Motor Function Measurement (GMFM-88). Subgroup analysis
was performed for the GMFCS.
Significant differences between groups were detected for changes in spasticity level and gross motor function after the three
months intervention.
In conclusion, vibration therapy may decrease spasticity and improve motor performance in children with CP. The results of the
present trial serve as valuable input for evidence-based treatments in paediatric neurorehabilitation.
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10
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14
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Keywords: Vibration therapy, cerebral palsy, spasticity, motor function
23
1. Introduction24
Cerebral palsy (CP) is the most common cause
25
of severe physical disability in childhood (Kuban &26
Leviton, 1994). It describes a group of permanent
27
disorders, effecting the development of movement28
and posture that are attributed to non-progressive
29
∗Address for correspondence: Ana Katusic, Day-care Centre for
Rehabilitation “Mali dom-Zagreb”, Bastijanova 1d, 10000 Zagreb,
Croatia. Tel.: +385 1 3746509; Fax: +385 1 6521009; E-mail:
ana@malidom.hr.
disturbances that occurred in the developing fetal or 30
infant brain (Rosenbaum, Paneth, Leviton, & Gold- 31
stein, 2007). The motor disorders of CP are often 32
accompanied by disturbances in sensation, percep- 33
tion, cognition, communication and behaviour, as well 34
as epilepsy and secondary musculoskeletal problems 35
(Morris, 2007). 36
The most common motor disorder in CP is spasticity. 37
According to a generally accepted definition, spastic- 38
ity is defined as ‘a motor disorder characterized by a 39
velocity dependent increase in tonic stretch reflexes 40
(muscle tone) with exaggerated tendon jerks, resulting 41
1053-8135/13/$27.50 © 2013 – IOS Press and the authors. All rights reserved

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2A. Katusic et al./Arandomized controlled trial
from hyper-excitability of the stretch reflex, as one com-
42
ponent of the upper motor neuron (UMN) syndrome’43
(Lance, 1980). The Support Programme for Assem-
44
bly of database for Spasticity Measurement (SPASM)45
consortium recently introduced an umbrella definition,46
which is increasingly being used. Spasticity was rede-47
fined as ‘disordered sensori-motor control, resulting
48
from UMN lesion, presenting as intermittent or sus-
49
tained involuntary activation of muscles’ (Pandyan et
50
al., 2005). In the clinical setting, spasticity is assessed51
as a velocity-dependent increased resistance to pas-
52
sive muscle stretch (Gorter, Verschuren, van Riel, &
53
Ketelaar, 2009).54
The goals of any spasticity treatment plan are to
55
improve passive (e.g. care giving) and active func-56
tion, and to prevent secondary problems such as pain,57
subluxation and contractures (Tilton, 2004). Although58
it is generally postulated that spasticity is related to
59
the severity of motor impairment, there is inconsis-60
tency on this topic in medical literature (Francis et61
al., 2004). There are findings supporting the hypothe-
62
sis that spasticity contributes to the motor impairment,
63
as expressed by Gross Motor Function Classification64
System (GMFCS) level, in CP (Himmelman, Beck-65
ung, Hagberg, & Uvebrant, 2007), but motor function66
may also be impaired by weakness, lack of selec-67
tive motor control, balance problems and perception68
difficulties. Hence the nature and strength of the rela-
69
tionship between spasticity and motor function remains70
unclear.
71
1.1. Vibration stimuli and motor performance
72
The importance of sensory stimuli in motor perfor-73
mance is well recognized. The motor system relies74
heavily on deep sensory system information to function75
properly. As proprioception is a crucial factor of motor76
control, the impact of vibrations was studied exten-77
sively. Research has increasingly demonstrated that
78
whole body vibration (WBV) supports the rehabilita-79
tion of patients with neurological diseases and disorders
80
(van Nes et al., 2004; Turbanski et al., 2005; Haas et al.,
81
2006; Ahlborg et al., 2006; Ebersbach et al., 2008; Ruck
82
et al., 2010). WBV has been utilized to deliver mechani-83
cal stimuli through repetitive sensorimotor stimulation.84
The number of studies on participants with CP is very85
limited. In 2006, Ahlborg’s study evaluated the effect of
86
WBV training compared with resistance training (RT)87
on spasticity, muscle strength and motor performance in88
adults with CP. Fourteen persons with spastic diplegia
89
were randomized to WBV training or RT. The results
90
showed significant reduction of spasticity in the knee 91
extensors and an increase of gross motor performance 92
in the WBV group only. Recently, Ruck and colleagues 93
(2010) conducted a randomized controlled pilot study 94
to evaluate the effects of WBV treatment in twenty 95
children with CP. In a six month trial period, children 96
were randomized to either continue their physiotherapy 97
(PT) program or to receive WBV treatment in addition 98
to PT. No significant group differences were detected 99
for changes in motor function, but the change in walk- 100
ing speed was significantly larger in the WBV group. 101
This data suggests that WBV can decrease spasticity, 102
increase muscle strength and improve motor perfor- 103
mance in persons with CP. 104
The present study employs the use of sound based 105
vibration treatment. This type of treatment, involves 106
pulsatile, sinusoidal low frequency sound within a range 107
of 30–80 Hz (Skille, 1991). A sine wave, or pure tone, 108
flows with a precisely matched increase and decrease 109
of amplitude. A frequency of 40 Hz has been found 110
to be effective in rehabilitation towards brain injuries 111
(Lehikonen, 1998). Llians and Ribary (1993) have 112
found that in some brain injuries, the 40 Hz wave disap- 113
pears or it is disturbed. The authors have suggested that 114
with auditory stimulation using 40 Hz sound, it is possi- 115
ble to reinforce this thalamus frequency. It has also been 116
established that 40 Hz stimulation through the body has 117
potential in the rehabilitation of brain injured clients. 118
Wigram (1997) conducted one of the first research 119
studies investigating the effect of sound vibration on 120
the range of motion in adult patients with CP. Find- 121
ings have shown that low frequency sound vibration 122
may improve range of motion. The observed effect 123
may be explained by the stimulation of skin receptors, 124
muscle spindles and vestibular system via vibration 125
transmission to the human body and by changes in 126
the thalamus and somatosensory cortex (Schuhfreid, 127
Mittermaiaer, Jovanovic, Pieber, & Paternostro-Sluga, 128
2005). 129
With the exception of a study conducted by King, 130
Almeida, & Ahonen (2009) regarding sound vibra- 131
tion as a treatment in Parkinson’s disease, there are 132
no high quality methodological studies investigating 133
this type of treatment in neurorehabilitation. This ran- 134
domized controlled trial was undertaken in order to 135
identify the influence of sound based vibration treat- 136
ment on spasticity and motor function in children with 137
CP. Our primary aim was to compare effects between 138
vibration treatment in addition to standard physiother- 139
apy and physiotherapy treatment alone. Our second 140
objective was to identify the characteristics of children 141

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A. Katusic et al./Arandomized controlled trial 3
who might have responded differently to the vibration
142
treatment.143
2. Materials and methods144
2.1. Participants145
One hundred and six children who had contact with146
the Day-care Centre for rehabilitation “Mali dom-147
Zagreb” were eligible for the study. Inclusion criteria148
were (1) classification of spastic CP (unilateral or149
bilateral) by neurological evaluation according to the
150
Surveillance of Cerebral Palsy in Europe (SCPE) pro-151
posal, (2) chronological age between 4 and 6 years152
old at the beginning of the study, (3) participation in153
ongoing physiotherapy treatment and (4) the absence
154
of planned surgery, significant medical problems or
155
other clinical factors that might bias the rehabilitation156
program. The present study was discussed with the157
child’s parents. One hundred and one were willing to158
participate.159
Children were randomly assigned to either continue160
their regular physiotherapy program unchanged (con-161
trol group) or to receive vibration treatment in addition162
to their physiotherapy program (intervention group).163
The randomization was stratified according to Gross
164
Motor Function Classification System (GMFCS) level165
for age band 4–6 years to ensure similar functional lev-
166
els in both groups (Wood & Rosenbaum, 2000). Twelve
167
children were not included in the final evaluation: four
168
children were lost to follow up, and eight children169
were unable to attend the treatment regularly due to170
organizational problems or illness. The remaining 89171
children were analyzed in the study. All participants172
were instructed not to alter their usual rehabilitation173
activities during participation.
174
The study was performed between March and175
December 2010 in Day-care Centre for rehabilita-
176
tion “Mali dom-Zagreb”. Approval for the study was
177
obtained from the Ethics Committee of the Faculty of178
Medicine, University of Zagreb. Full written informed179
consent was obtained from all parents.180
2.2. Treatment protocol181
During the 12-week intervention period all children182
attended physiotherapy treatment according to their183
rehabilitation program. The physiotherapy comprised184
of 3 sessions of 40 minutes per week. The thera-
185
pists providing physiotherapy treatment were blinded186
to the group allocation of children in order to avoid any 187
influence on the intervention. 188
Children in the intervention group in addition to 189
physiotherapy received sound based vibration treatment 190
twice a week. The vibration treatment was administered 191
in one-on-one sessions. The vibrations were deliv- 192
ered using vibroacoustic bedpad (VISIC bedpad-VSM 193
10, Acouve Laboratory Inc, Japan). Vibro transduc- 194
ers spaced throughout the bedpad are connected to an 195
amplifier and sound sources, permitting low frequency 196
sound waves. A sine wave of 40 Hz with sinusoidal 197
amplitude variations (6.8 seconds between peaks) was 198
used for each treatment session in duration of 20 min- 199
utes. Children were placed on the bedpad in supine 200
position with head in the midline. Some children needed 201
support with pillows in order to maintain appropriate 202
postural positioning. 203
Any additional visual or auditory stimuli were 204
removed from the room where the intervention took 205
place, in order to avoid influencing the procedure. 206
Before the sound stimuli was introduced, the therapist 207
explained to the child what will happen and that he 208
will stay in the room during treatment. Vibration was 209
introduced in a gradual fashion. During the procedure 210
children laid calmly and no other activities took place. 211
2.3. Measurements 212
The primary outcome measured was the change in 213
spasticity level. Spasticity was estimated according 214
to the Modified Modified Ashworth Scale (MMAS) 215
(Ansari, Naghdi, Moammeri, & Jalaie 2006). This scale 216
grades the level of resistance to passive stretching. In the 217
MMAS, spasticity is scored on an ordinal scale from 0 218
to 4 (Table 1). The reliability and validity of the MMAS 219
has been shown to be good (Ghotbi, Ansari, Naghdi, 220
& Hasson, 2011). The muscle groups estimated were 221
the elbow and wrist flexors in the upper limb, and hip 222
adductors, knee extensors and ankle plantar flexors in 223
Table 1
The Modified Modified Ashworth scale (MMAS)
Score Description of muscle tone
0 No increase in muscle tone
1 Slight increase in muscle tone – a catch and
release at the end of the range of motion
2 Marked increase in muscle tone – a catch in
the middle range and resistance throughout
the remainder of the range of motion
3 Considerable increase in muscle tone,
passive movement difficult
4 Affected part(s) rigid in flexion or extension

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4A. Katusic et al./Arandomized controlled trial
the lower limb. A total score was obtained by adding224
the scores for all muscle groups bilaterally. Hence, the225
MMAS total score ranged from 0 to 40. The standard-
226
ized test positions and movements were used, as have227
been described in previous studies (Ansari, Naghdi,228
Arab, & Jalaie, 2008). The joints were moved with a229
fast-stretching velocity.
230
Our secondary outcome measure was a change in
231
gross motor function assessed with the Gross Motor
232
Function Measure (GMFM-88). It consists of 88 items233
within 5 dimensions: (A) lying and rolling; (B) sitting,
234
(C) crawling and kneeling; (D) standing and (E) walk-
235
ing, running and jumping. The items are scored using a236
4-point scale (0, 1, 2, 3) and the scores for each dimen-
237
sions are expressed as a percentage of the maximum238
score for that dimension. A total score is obtained by239
adding the scores for all dimensions and dividing by240
5. The GMFM total scores can range from 0 to 100.
241
The reliability and validity of the GMFM has been242
shown to be good in children with CP (Russel, Avery,243
Rosenbaum, Raina, Walter, & Palisano, 2000).
244
The tests were performed before and after the 12-
245
week intervention period. All tests were performed by246
two physiotherapists who were experienced and trained247
in the use of measurements and blinded to treatment248
allocation.249
2.4. Statistical analysis250
As distribution did not satisfy the parametric assump-
251
tion, non-parametric Wilcoxon Matched Pairs test was252
used to analyze differences over time and Mann-
253
Whitney U test to analyze differences between the two254
groups. To gain insight in effect sizes and their con-255
fidence intervals, we calculated the lower and upper
256
quartiles. The level of significance was 0.05.257
We based the power analysis on the GMFM-88258
scores. In order to detect a mean change of 2.8 points259
between the groups with a 3.2-point of standard devi-260
ation (SD), the 70 participants were needed to gain261
a power of 95%. This mean change of 2.8 points on 262
GMFM-88 could be considered as a clinically mean- 263
ingful change of motor function (Wang & Jung, 2006). 264
The analyses were done with the program STATIS- 265
TICA version 6.1. 266
3. Results 267
All children tolerated the treatment well with no 268
report of discomfort. Table 2 shows the baseline 269
characteristics. 270
Based on neurological evaluation, 16% of children 271
in the control group and 18% of children in the inter- 272
vention group had classification of unilateral spastic CP 273
(USCP). In the control group 84% of children had clas- 274
sification of bilateral spastic CP (BSCP), and 82% in 275
the intervention group. At a baseline 77% of children 276
in the control group, and 80% of children in the inter- 277
vention group, were classified to a level V and IV. To 278
a level III and II were classified 23% of children in the 279
control group and 20% of children in the intervention 280
group (Table 2). 281
There were no significant differences in any of 282
presented variables between the control and the inter- 283
vention group at baseline (Table 2). 284
3.1. Spasticity 285
Medians and interquartile ranges for estimated spas- 286
ticity level at baseline, after 12-week intervention 287
period and change score are presented in Table 3. There 288
was a significant reduction of spasticity in the both 289
groups (Table 3, Fig. 1). The 12-week-change MMAS 290
total score showed that spasticity level decrease with 291
4.0 points (range −4.5 to −4.0) in the intervention 292
group and with 2.0 points (range −4.0 to 0.0) in the 293
control group. This change scores between both groups 294
significantly differ in favour of the intervention group 295
(p< 0.001). 296
Table 2
Baseline characteristic of the study populations
Control group Intervention group p
Sex (boys/girls) 20 (55)/24 (45) 32 (71)/13 (29)
Age 4.8 (4.4–5.7) 4.7 (4.0–5.4) 0.067
CP (USCP / BSCP) 7 (16)/37 (84) 8 (18)/37 (82)
GMFCS Level (II/III/IV/V) 4 (9)/6 (14)/4 (9)/30 (68) 4 (9)/5 (11)/3 (7)/33 (73) 0.638
GMFM-88 TS 17.8 (8.2–33.9) 18.4 (8.5–27.4) 0.799
MMAS TS 21.0 (12.5–33.5) 20.0 (13.0–30.0) 0.678
Results for sex, CP subtype and GMFCS Level are expressed as N (%). For the other variables results are given as
median (interquartile range). Pvalues were determined by using the Mann-Whitney U-test.

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A. Katusic et al./Arandomized controlled trial 5
Table 3
MMAS and GMFM total score at baseline, after 12-week intervention period and change scores.
Control group Intervention group p
Baseline 12-week Change Baseline 12-week Change
GMFM-88 TS 17.8 (8.2–33.9) 18.7 (10.8–34.3) 2.2 (0.0–3.0) 18.4 (8.5–27.4) 20.6 (12.5–30.9) 3.6 (3.0–4.2) <0.001
MMAS TS 21.0 (12.5–33.5) 21.0 (10.0–30.0) −2.0 (−4.0 to 0.0) 20.0 (13.0–30.0) 16.0 (9.5–25.0) −4.0 (−4.5 to −4.0) <0.001
The results are given as median (interquartile range). Pvalues were determined for difference between group change scores by Mann-Whitney U
Test.
Control groupIntervention group
40
30
20
10
0
MMAS at 3 months
MMAS at baseline
Fig. 1. Change in the MMAS total score before and after intervention
period per group. A lower MMAS score represents improvement in
spasticity level.
3.2. Gross motor function measure
297
Median values and interquartile ranges for the298
GMFM-88 total score at baseline, after 12-week inter-
299
vention period and change score are presented in300
Table 3. The total score significantly increased in the301
both groups (Table 3, Fig. 2). The GMFM-88 total score
302
improved with 3.6 points (range 3.0–4.2) in the inter-
303
vention group and with 2.2 points (range 0.0–3.0) in
304
the control group. This difference in change scores was
305
significant (p< 0.001).
306
3.3. Subgroup analysis
307
To identify characteristics of the children who might
308
have responded differently to the vibration treatment,309
subgroup analysis was performed in the intervention310
group for the level of functioning classified accord-311
ing to GMFCS. The ability of ambulation for children312
80
60
40
20
0
GMFM at 3 months
GMFM at baseline
Control
g
rou
p
Intervention
g
rou
p
Fig. 2. Change in the GMFM total score before and after intervention
period per group.
Table 4
Gross Motor Function Classification System (GMFCS) levels
I walks without limitations
II walks with limitations
III walks using a hand-held mobility device
IV self mobility with limitations
IV transported in a manual wheelchair
classified at levels V and IV is extremely low, and chil- 313
dren at levels III and II have walking ability in this age 314
band (Table 4). Thus, we compared group of children 315
classified at GMFCS levels V and IV (n= 36), and group 316
of children classified at levels III and II (n= 9). 317
Subgroup analysis showed that there were no signif- 318
icant differences in effects for both outcome measures 319
between group of children with GMFCS levels III and 320
II, and group of children with GMFCS levels V and IV 321
(Table 5). 322

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6A. Katusic et al./Arandomized controlled trial
Table 5
MMAS and GMFM change scores for subgroups according to
GMFCS levls
GMFCS levels V & IV III & II
Change score Change score p
GMFM-88 TS 3.5 (3.0–4.2) 3.9 (2.8–4.4) 0.504
MMAS TS −4.0 (−4.8 to −4.0) −4.0 (−4.5 to −3.0) 0.370
The results are given as median (interquartile range). Pvalues were
determined by Mann-Whitney U Test.
4. Discussion323
Vibration treatment as a method in the rehabilitation
324
of children with CP is a relatively untouched area of
325
research. To our knowledge, this present study is the326
first randomized controlled trial dealing with effects of327
sound based vibration stimuli on spasticity and motor328
performance in children with CP. The results of our329
study show that vibration treatment in addition to phys-330
iotherapy decreases spasticity level and enhances gross
331
motor performance in children with spastic CP. As332
proprioception is an important component of motor
333
control, we can assume that vibration stimuli recog-334
nized by the brain cortex and processed in the central335
nervous system will act on motor performance. This
336
assumption concurs with results of King and colleagues337
(2009) who reported that sound wave vibration ther-
338
apy has positive effects on motor symptoms and gait in339
persons with Parkinson’s disease.340
The improvement for both outcome measures was341
seen in both groups, but the type of treatment received342
had a significant effect. The significantly greater
343
decrease in spasticity level was seen in the intervention344
group. The intervention group also showed significantly
345
greater increase in motor performance as compared to
346
control group. The gross motor function, as assessed
347
by GMFM-88 change score, significantly increased for
348
3.6 points in the intervention group, and for 2.2 points
349
in the control group. According to a study of Wange &350
Jung (2006) a change score of 1.3 points on the GMFM-351
88 represent clinically meaningful improvement, and a352
change score of 3.7 points discriminates great improve-353
ment from a moderate improvement. Considering men-354
tioned levels of change scores, we conclude that chil-
355
dren in the intervention group showed great improve-
356
ment in motor progression, and children in the control
357
group had moderate extent of motor progression.358
As our sample consisted of 80% of children classified
359
at GMFCS level V and IV, it is important to consider the360
high presence of additional impairments in this popu-361
lation of children with CP. The GMFCS levels V and362
IV correlate strongly to at least three accompanying 363
impairments present in CP, namely learning disabil- 364
ities, seizures and visual impairments (Himmelmann 365
et al., 2006). The presence of those coimpairments 366
may affect a child’s motor development (Porro, van der 367
Linden, van Nieuwenhuizen, & Wittebol-Post, 2005) 368
and also outcomes of certain interventions. In order to 369
identify characteristic of the children who might have 370
responded differently to the vibration treatment, we 371
performed subgroup analysis according to GMFCS lev- 372
els. We compared two groups of children: (1) group of 373
children with more severe motor disability and higher 374
presence of additional impairments (GMFCS levels V 375
and IV) and (2) group of children with walking ability 376
(GMFCS levels III and II) and lower presence of addi- 377
tional impairments. Both subgroups showed significant 378
improvement in spasticity level and gross motor func- 379
tion (results not presented) after intervention period, 380
but the difference in change scores was not significant. 381
From presented results we could assume that there are 382
no differences in vibration effects for different GMFCS 383
levels, regardless to the severity of motor disability or 384
the presence of additional impairments. Anyhow, we 385
must take this consideration with great caution, while 386
there were four times more children classified at level 387
V and IV than children classified at level III and II. This 388
should be investigated in future studies. 389
Current evidence does not offer an explanation of 390
the specific neural adaptations that accompany a vibra- 391
tion treatment. One hypothesis is that sound based 392
vibration resonates throughout the body and facilitates 393
an ability to sense the position, location and orien- 394
tation (King et al., 2009). Vibration might also alter 395
the connectivity between corticospinal cells and spinal 396
motoneurons (Delecluse, Roelants, & Verschueren, 397
2003). The stimulation of proprioceptive pathways via 398
vibration treatment seems hereby crucial. It is assumed 399
that this repetitive stimulation rearranges motor con- 400
trol strategies, and may result in improved postural 401
stability (Schuhfried et al., 2005). One should also con- 402
sider the influence of vibration stimuli on central motor 403
structures, as it is shown that vibration activates the pri- 404
mary sensorimotor corticies, supplementary motor area 405
(SMA) and cingulate motor area (CMA). All these areas 406
are active when executing the limb movements (Naito 407
& Ehrsson, 2001). 408
The present study has a few limitations. Firstly, all 409
participants continued with their usual rehabilitation 410
activities, such as occupational, speech and/or vision 411
therapy. Therefore the impact of nonspecific factors on 412
interventions outcome cannot be determined. 413

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A. Katusic et al./Arandomized controlled trial 7
In addition, we wanted to capitalize on the ‘window
414
of opportunity’ for motor progress offered by possible415
spasticity decrease (Francis et al., 2004) as a result of
416
vibration treatment. As each child with CP need time417
to learn how to use any reduced muscle tone (Francis et418
al., 2004; Scholtes et al., 2006), we found it crucial419
to include active physiotherapy with vibration treat-
420
ment. Therefore we do not know how much of the effect
421
is specifically contributable to the vibration treatment
422
alone, or to the physiotherapy. From a statistical per-423
spective, this may be perceived as a weakness of this
424
study. Further research needs to be conducted on the
425
effectiveness of the single interventions on spasticity426
level and functional abilities, maybe by using a multiple
427
baseline design.428
Our outcome measures included two of the three429
domains of International Classification of Functioning,430
Disability and Helath – ICF (World Health Organiza-
431
tion, 2001). In the ICF domain of body functions and432
structures we used the MMAS, and in the ICF domain433
of activities we used the GMFM-88. As we should treat
434
and evaluate children on all ICF levels (Rosenbaum &
435
Stewart, 2004), the outcome measure in ICF domain436
of participation, as e.g. PEDI (Paediatric Evaluation of437
Disability Inventory) scale, should be included in future438
studies.439
Finally, the chosen frequency, amplitude and dura-440
tion of vibration stimuli were based on the minority of
441
studies. Therefore, there are many vibration parameters442
which should be considered for further investigations.
443
Also, there is a question of duration of treatment effects.
444
Future researches should take into account this issue by445
including several follow-up assessments after interven-
446
tion is completed.
447
5. Concluding remarks448
The results of the present study show that vibration
449
stimuli in addition to physiotherapy treatment signifi-
450
cantly improves the spasticity level and motor perfor-451
mance in children with CP. Considering the baseline452
characteristic of our sample, the gained results can be453
particularly relevant for young children with spastic CP454
who rely on wheeled mobility (GMFCS level V and IV).455
We assume that vibration treatment has a great poten-
456
tial in a therapeutic context for children with spastic457
CP. Anyhow, it should not be regarded as an exclusive458
treatment in rehabilitation of children with CP, but as459
a complementary intervention to active physiotherapy460
approach.
461
Acknowledgments 462
We wish to express our deepest gratitude to the chil- 463
dren and their parents who participated in this study. 464
The authors also thank J.S. and J.G. who obtained pre 465
and post measurements. 466
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