neck muscles show a denser distribution of muscle spindles as compared to other muscles , 
 and this can be interpreted to mean that high levels of proprioceptive function are required 
 of these muscles1 . in children with cerebral palsy ( cp ) , the proprioceptive senses can not provide the basis 
 for movement because of confusion among these senses due to abnormal levels of postural 
 tension . the increased tension causes functional disorders of the muscle spindles such that 
 they receive inadequate feedback regarding movements2 . that is , unstable trunk muscles lead to a weakening of the neck 
 flexor muscles and delays in the acquisition of localization functions , resulting in a lack 
 of head control and asymmetric postures that cause serious problems in their ability to 
 balance3 . on reviewing previous studies , 
 it can be seen that , although many studies have been conducted on trunk muscles and certain 
 muscles around the neck , therapeutic interventions , and gross motion analysis , there are 
 very few studies on balance ability and on the proprioceptive senses that form the basis for 
 efficiency of movement in daily living4 , 5 . the present study was therefore designed to 
 examine the differences in proprioceptive senses between children with diplegic cp and 
 children with hemiplegic cp by using a head position - reposition measuring instrument . this study involved 21 children who suffered from diplegic and hemiplegic cerebral palsy , 
 but did not have hearing and visual disabilities . the inclusion criteria were as follows : 
 ( 1 ) children with spastic diplegic cp ( n=12 ) and hemiplegic cp ( n=9 ) diagnosed by a 
 pediatric medical doctor from brain mri ( table 
 1table 1.general characteristics of the subjectsdiplegic grouphemiplegic groupgender ( m / f)7/54/5age ( years)7.92.27.02.2height ( cm)128.011.7125.610.8weight ( kg)23.27.422.66.6 ) . a score of 24 or higher on the 
 mini - mental state examination - korean version . ( 3 ) levels i , ii , and iii of the gross motor 
 function classification system ( gmfcs ) . all parents of the enrolled participants provided 
 written informed consent prior to this experiment in accordance with the ethical standards 
 established in the declaration of helsinki . the error value of the head position sense was evaluated using a head repositioning 
 accuracy ( hra ) test6 , 7 . it was 
 used to measure the difference between the start ( 0 position ) and return positions . all 
 subjects were instructed to close their eyes , and the target was moved so that the laser 
 pointer s beam projected onto the target . the subjects were told to memorize this position 
 because this was the reference position . they performed a neck flexion for 5 seconds and 
 then they were instructed to return to the reference position . the error value was measured 
 as the distance between the two marked points and repeated 3 times . the same procedure was 
 followed to assess extension , right rotation , and left rotation . the chi - square and 
 independent t - test were performed to compare the children s general characteristics , and the 
 differences in the error values of the head position sense ( flexion , extension , and 
 rotation ) between the diplegic cp and the hemiplegic cp group . statistical analysis was 
 performed using spss 20.0 for windows ( spss inc . , chicago , il , usa ) with a significance 
 level of =0.05 . there were significant differences between the error values of the joint position sense 
 ( neck flexion , extension , and rotations ) of the diplegic cp group and the hemiplegic cp 
 group ( p>.05 ) ( table 2table 2.comparison of the head position sense errors with values presented as mean  
 standard deviationdiplegic grouphemiplegic groupflexion ( cm)19.37.713.92.4extension ( cm)19.65.114.62.2right rotation ( cm)19.75.615.32.9left rotation ( cm)20.15.515.53.0*significant difference from pre - test at < 0.05 ) . * children with cerebral palsy have difficulty in maintaining proper posture or in keeping 
 their balance due to the low stability of their trunks and heads8 . the weakening of the deep neck flexor muscles and the 
 shortening of the sub - occipital muscles that appear in the forward head posture also appear 
 in similar forms in cerebral palsy patients with poor body alignment9 . cerebral palsy patients tilt their heads more excessively , 
 or show abnormal head directions due to muscle weakness and abnormal tension , which adds to 
 their muscle imbalance and reduces their ability to control fine movements2 . this phenomenon can be said to be typical 
 of children with diplegic cp who have poor trunk stability . premature birth , which accounts for 80% of children with diplegic cp , leads to the 
 destruction of neurologic structures due to complications , such as periventricular 
 leukomalacia ( pvl ) , resulting in distortions in vision and in the proprioceptive senses that 
 make up the self - centering sensory system10 . in addition , earlier studies have indicated that insufficient 
 development of trunk stability in the womb , due to the premature birth , creates problems in 
 postural stability , body alignment , and balance11 . it can be seen from the results that children with hemiplegia show 
 relatively better movements and postural alignment and have better proprioceptive senses 
 than children with diplegia . exercises to improve the proprioceptive senses have been used 
 in therapeutic programs and have been shown to relieve the joint instability that occurs due 
 to the impairment of the ability to control balance12 . these exercises work with the damaged muscle nervous systems and 
 improve the ability to achieve postural balance . therefore , evaluating and treating children 
 with cerebral palsy accurately involves considering the differences between children in 
 relation to their proprioceptive senses . based on the results of the present study , it is 
 possible to positively affect the sensorimotor system in order to bring about improvements 
 in joint stability and movement patterns .
[ purpose ] in the present study , in order to examine the differences in proprioceptive 
 senses between children with diplegic cp and children with hemiplegic cp , neck reposition 
 errors were measured . 
 [ subjects and methods ] head reposition senses were measured after 
 neck flexion , extension , and left - right rotation , using head repositioning accuracy tests . 
 these tests were done with 12 children with diplegic cp and nine children with hemiplegic 
 cp . [ results ] 
 the results indicated that children with diplegic cp had poorer head 
 repositioning senses after movements in all directions compared to children with 
 hemiplegic cp . 
 [ conclusion ] the results indicated that children with diplegic cp had 
 poorer head repositioning senses after movements in all directions as compared to children 
 with hemiplegic cp .