|
Abnormal muscle tone, reflexes, sensory and motor disabilities
are very commonin spastic cerebral palsy(C.P.). Without
appropriate rehabilitation management, those often lead to
delayed growth, body deformities and severe functional
disabilities, which complicate their communication and
functional independenceabilities. The incidence rate of C.P. has
been estimated at 0.6~5.9 per 1000 children in Taiwan, and the
severe at 0.2 per 1000 children inTainan City.In addition to
this large population, lack of proper rehabilitation and
treatment programs has generated severe complications for most
C.P. children in Taiwan.In 1985, Hundertmark suggested that an
adjustable seatingand positioning (S.P.)system was an effective
device for the C.P.. Other research studies also reported that
the proper S.P. could reduce tone, decrease deformities
andimprove functional activities. S.P. devices are important in
rehabilitative technology for the C.P., but the related research
and clinical practice are lacking in Taiwan.This study was aimed
to investigate the effect of S.P. on muscle tonefor the spastic
C.P. by using EMG and an adjustable S.P. system developed in our
laboratory . The optimal position of each individual subject had
been quantified. Using this experimental protocol, customized
and adjustableS.P. systemcouldbe prescribed, designed, and
fabricated to provide effective seating for moderate and severe
C.P..Because of lack of systematic studies on S.P. in the
literature, EMG investigation on normal subjects was conducted
to provide baselinedata, and the experimental results showed
that the more increasing in muscle force and tone is, the higher
IEMG and the lower PSD(power spectrum density) Mean and Median
frequencies are. Based on muscle biomechanics, this may be
contributed to hypertrophied slow and atrophic fast muscle
fibers. This experimentalso indicates that a 90/0(back-angle/
seat-angle) position is the optimal seating for healthy human
beings.The results of C.P. subjects showed that IEMG values for
extensors of lower extremities and trunk in seating were lower
than those in supine. This indicated that S.P. was more
effective than supine management in muscle tone reduction and
abnormal reflexes. Although the anterior tilted seat-angle and
back-angle had increased IEMG valuesand muscle tone compared to
other positioning, the result of statistic analysis was lack of
significant difference. When the analysis had focused on total
body muscles together, the anterior tilted back showed
significant increased in muscle tone. TheTwo-Way ANOVA test
showed that the seat-angle and back-angle had no significant
differences on main treatment of muscle tone, which was
primarily due to sample size of subjects as well as the nature
of large variations. However, the generaltrend of experimental
data showed that hip flexed angle maintained at 90 degree and
seat-angle posterior reclined to 10 degree position could
decrease IEMGvalues and muscle tone and increase PSD Mean
frequency.In this study, it is found that the optimal seating
position of C.P. is also dependent on theduration of S.P.
training. For the subject without enough S.P. training,
posterior reclined back is suggested. Therefore, it is
importantto provide early rehabilitation management with
appropriate S.P. to match individual needs.It isbelievedthat
each C.P. person has his/her individual position needed, and the
hip flexed angle at 90 degree and seat-angle posterior reclined
to 10 degreeprovides an important and useful clinical guidance
to evaluate and prescribe S.P. for the C.P.. These results are
valuable to study, design and develop customized S.P. of
individual C.P.. The PSD Mean of normal subjects is higher than
that of C.P. subjects. The C.P. subject with shorter duration of
S.P. training has lower PSD Mean frequency. In addition to
hypertrophied slow and atrophic fast muscle fibers, decreased
conduction velocity of muscle for action potential through
accumulation of metabolic by-products may contribute to more
lower frequency components generated for the PSD Mean shifted to
lower frequency. This result of 90/0 for most comfortable
position in normal subjects is not only agreed with but also
proved for the suggestion of optimal seating in most
literatures.
|