Clinical characteristics of impaired trunk control in children with spastic cerebral palsy

Research in Developmental Disabilities 34 (2013) 327–334

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Research in Developmental Disabilities

Clinical characteristics of impaired trunk control in children with spasticcerebral palsy

Lieve Heyrman a,*, Kaat Desloovere a,b, Guy Molenaers b,c, Geert Verheyden a, Katrijn Klingels a,Elegast Monbaliu a, Hilde Feys a

a Department of Rehabilitation Sciences, Faculty of Kinesiology and Rehabilitation Sciences, KU Leuven, Tervuursevest 101, 3001 Heverlee, Belgiumb Clinical Motion Analysis Laboratory, University Hospital of Pellenberg, Weligerveld 1, 3212 Pellenberg, Belgiumc Department of Development and Regeneration, Faculty of Medicine, KU Leuven, Herestraat 49, 3000 Leuven, Belgium

A R T I C L E I N F O

Article history:

Received 1 August 2012

Received in revised form 20 August 2012

Accepted 20 August 2012

Available online 19 September 2012

Keywords:

Cerebral palsy

Trunk control

Evaluation

Clinical characteristics

A B S T R A C T

This study aimed to identify clinical characteristics of impaired trunk control in hundred

children with spastic CP (mean age 11.4 � 2.1 years, range 8–15 years). Assessment of trunk

control was performed with the Trunk Control Measurement Scale (TCMS). Trunk control was

clearly impaired, indicated by a median total TCMS score of 38.5 out of 58 (66%). Median

subscale scores were 18 out of 20 (90%) for the subscale static sitting balance, 16 out of 28

(57%) for the subscale selective movement control and 6 out of 10 (60%) for the subscale

dynamic reaching. Total TCMS and subscale scores differed significantly between

topographies and severity of motor impairment according to the Gross Motor Function

Classification System (GMFCS). Children with hemiplegia obtained the highest scores,

followed by children with diplegia and children with quadriplegia obtained the lowest scores.

TCMS scores significantly decreased with increasing GMFCS level. In conclusion, trunk control

is impaired in children with CP to a various extent, depending on the topography and severity

of the motor impairment. The findings of this study also provide specific clues for treatment

interventions targeting trunk control to improve their functional abilities.

� 2012 Elsevier Ltd. All rights reserved.

1. Introduction

One of the key features of children with CP is deficient postural control (Brogren, Hadders-Algra, & Forssberg, 1998; Liu,Zaino, & McCoy, 2007; van der Heide et al., 2004). Development of postural control is a complex, long-term process andtherefore vulnerable for adverse conditions during early life (Hadders-Algra & Brogren, 2008). Given that postural control isan integral part of all motor skills, postural problems interfere significantly with activities of daily living (van der Heide &Hadders-Algra, 2005). The trunk, centre of our body, plays a crucial role in postural control and the organization of balancereactions (van der Heide et al., 2004) and consequently is of great importance for successful execution of functionalactivities. More specifically, trunk control is necessary to provide a stable base of support during execution of upper andlower limb movements, but it also includes active participation of the trunk during reaching and walking (Mayston, 2001;Prosser, Lee, VanSant, Barbe, & Lauer, 2010; Saavedra, Joshi, Woollacott, & van Donkelaar, 2009). Insights into these differentaspects of trunk control are indispensable to guide and delineate treatment interventions in children with CP.

* Corresponding author at: Department of Rehabilitation Sciences, Faculty of Kinesiology and Rehabilitation Sciences, KU Leuven, Tervuursevest 101,

3001 Leuven, Belgium. Tel.: +32 16 32 91 20; fax: +32 16 32 91 97.

E-mail address: [email protected] (L. Heyrman).

0891-4222/$ – see front matter � 2012 Elsevier Ltd. All rights reserved.

http://dx.doi.org/10.1016/j.ridd.2012.08.015

L. Heyrman et al. / Research in Developmental Disabilities 34 (2013) 327–334328

Despite its clinical importance, research into the specific characteristics of impaired trunk control in children with CPis currently lacking. Until now, trunk analysis has been embedded into more general postural control studies thatsimplified the entire trunk as a single unit (Brogren et al., 1998; Brogren, Hadders-Algra, & Forssberg, 1996; Hadders-Algra, van der Frits, Stremmelaar, & Touwen, 1999; van der Heide et al., 2004; Heide, Fock, Otten, Stremmelaar, &Hadders-Algra, 2005; Woollacott et al., 1998) and consequently provided little specific information on trunk control. Tothe best of our knowledge, no previous study has mapped the problems with trunk control that children with CPexperience. This might be partially explained by the limited number of available clinical measures to assess trunk control.Most clinical evaluation tools in children with CP are either too general assessments of functional activities (Russell,Rosenbaum, Gowland, & Hardy, 1993; Wang, Liao, & Hsieh, 2006), or addressing only limited aspects of trunk control(Bartlett & Birmingham, 2003; Bartlett & Purdie, 2005; Butler, Saavedra, Sofranac, Jarvis, & Woollacott, 2010; Fife et al.,1991; Franjoine, Gunther, & Taylor, 2003). To cover both static and dynamic aspects of trunk control, we thereforerecently developed a clinical scale measuring trunk control in sitting in children with CP, the Trunk Control MeasurementScale (TCMS). Reliability and validity (construct validity, discriminant ability) of the scale have been established andreported elsewhere (Heyrman et al., 2011).

In this study we want to unravel the clinical characteristics of trunk control in sitting in children with CP. Empiricalfindings indicate that the degree of trunk impairment varies from minor dysfunctions to clearly limited trunk control,depending on the topography and severity of the motor impairment (Hadders-Algra & Brogren, 2008). Children with CP aretraditionally classified according to the topographic distribution of the motor involvement into hemiplegia, diplegia andquadriplegia (Mutch, Alberman, Hagberg, Kodama, & Perat, 1992), or unilateral and bilateral CP (Cans, Guillem, & Arnaud,2000). The Gross Motor Function Classification System (GMFCS) (Palisano et al., 1997) grades the severity of the child’sfunctional limitations into five levels. So far, the comparison of clinical characteristics of impaired trunk control betweenthese topographies and severity levels has not yet been explored.

Therefore, the first aim of this study was to investigate characteristics of impaired trunk control in a large cohort ofchildren with CP. The second aim was to assess whether these characteristics would differ according to the differenttopographies and severity levels based on the GMFCS.

2. Methods

2.1. Participants

In total, 100 children with CP were recruited from seven private physiotherapy practices and six special education schoolsfor motor disabilities in Flanders, Belgium. Children were eligible for the study if they were diagnosed with spastic CP, agedbetween 8 and 15 years, able to sit without trunk or feet support for at least 30 min, and able to understand the testinstructions. Exclusion criteria were orthopaedic interventions and botulinum toxin injections performed in the last sixmonths, and implantation of an intrathecal baclofen pump or other spinal interventions.

Patient characteristics are presented in Table 1. The study group consisted of 52 males and 48 females with a mean age of11.4 years (SD 2.1 years). Forty-six children were diagnosed as diplegia, 38 as hemiplegia and 16 as quadriplegia. Accordingto the GMFCS, 47 children were classified as level I, 28 as level II, 16 as level III, and 9 as level IV. Ethical approval wasobtained from the Ethics Committee of the University Hospitals of Leuven. Written informed consent was obtained fromparents and children.

2.2. Assessment

Trunk control was evaluated by the Trunk Control Measurement Scale (TCMS) (Heyrman et al., 2011). This scale consistsof 15 items measuring two main components of trunk control: (a) a stable base of support (static sitting balance), and (b) an

Table 1

Patient characteristics and distribution of the GMFCS levels over the different typographies.

CP

Total Diplegia Hemiplegia Quadriplegia

n 100 46 38 16

Sex, n

Male 52 24 21 7

Female 48 22 17 9

Age

Mean (SD) 11.4 years (2.1 years) 11.4 years (2 years) 11.4 years (2.1 years) 11.2 years (2.3 years)

GMFCSa, n

1 47 16 31 –

2 28 19 7 2

3 16 11 – 5

4 9 – – 9a GMFCS: Gross Motor Function Classification System.

Table 2

Summary of the items of the Trunk Control Measurement Scale.

Item Task description

Static sitting balance1 Upright sitting – 10 s

2 Upright sitting – lifting arms

3 Upright sitting – crossing legs passively

4 Upright sitting – crossing legs actively

5 Upright sitting – abduction legs

Selective movement control6 Leaning forward 458 and return

7 Leaning backward 458 and return

8 Lateral flexion – upper trunk (elbow to table)

9 Lateral flexion – lower trunk (lift pelvis)

10 Rotation – upper trunk

11 Rotation – lower trunk

12 Shuffling pelvis (lateral flexion and rotation)

Dynamic reaching13 Forward reaching

14 Lateral reaching – bilateral

15 Crossed reaching – bilateral

L. Heyrman et al. / Research in Developmental Disabilities 34 (2013) 327–334 329

actively moving body segment (dynamic sitting balance). The subscale static sitting balance (items 1–5) evaluates the abilityof the child to maintain a stable trunk posture during movements of upper and lower limbs. The section dynamic sittingbalance is further divided into two subscales: selective movement control and dynamic reaching. The subscale selectivemovement control (items 6–12) measures selective trunk movements in the sagittal (flexion/extension), frontal (lateralflexion) and transverse (rotation) plane within the base of support. The subscale dynamic reaching (items 13–15) evaluatesthe performance of three reaching tasks, requiring active trunk movements beyond the base of support. An overview of theitems is given in Table 2. All items are scored on a two-, three- or four-point ordinal scale and administered bilaterally in caseof clinical relevance. Maximum scores on the three subscales are 20, 28 and 10, respectively, resulting in a total score from 0to 58. A higher score indicates a better performance.

2.3. Test procedure

Children were assessed in their therapist’s private practice, at school or at home. For test administration, the child wasseated on a table or bench without back, arm and feet support. No orthoses or shoes were worn during testing. The childstarted each item with the trunk in its most upright position. They were asked to maintain this position as much as possibleduring the performance of the items. The best of three performances was considered for scoring. Administration of the scalewas performed by three raters. Prior to testing, an interrater reliability study on 11 children with spastic CP was performed.Excellent reliability was found for the total TCMS and the three subscales with intraclass correlation coefficients rangingfrom 0.92 to 0.98.

2.4. Statistical analysis

Distribution analysis using the Kolmogorov–Smirnov test indicated that all variables were not normally distributed,except for ‘age’. Descriptive statistics (median, interquartile range (IQR)) were used to report total TCMS score, subscaletotals and item scores for the total group and the different subgroups, based on topography (hemiplegia, diplegia andquadriplegia) and GMFCS levels. Total TCMS scores, subscale totals and item scores were compared between eachtopography and GMFCS level using the Kruskal–Wallis test and post hoc Wilcoxon ranked sum tests. The level of significancefor post hoc analysis was set at p = .0167 for comparison according to topography and at p = .008 for comparison betweenGMFCS levels to correct for multiple testing. To further describe specific trunk problems for the different topographies andGMFCS levels, each item score was also converted into dichotomous score. A score of 0 was given in case a maximal score wasobtained, indicating no restraint in performance on that item. Other, submaximal, scores were converted into a score of 1,indicating a deficit. The frequencies of these submaximal scores for our total sample (N = 100) were expressed as apercentage and graphically presented in a bar chart (Figs. 1 and 2). Statistical analyses were conducted with SAS EnterpriseGuide 4.2 (SAS Institute, Inc., Cary, NC, USA).

3. Results

3.1. Total group

The median total TCMS score for the total group was 38.5 out of 58 (IQR 27.5–46), corresponding to 66% of the maximalscore. Median scores for the different subscales were 18 out of 20 (90%) for the subscale static sitting balance (IQR 16–19.5),

Fig. 1. Distribution of percentages of submaximal scores, indicating trunk deficits, per item for the different topographies.

Fig. 2. Distribution of percentages of submaximal scores, indicating trunk deficits, per item for the GMFCS levels I–IV.

L. Heyrman et al. / Research in Developmental Disabilities 34 (2013) 327–334330

16 out of 28 (57%) for the subscale selective movement control (IQR 10–20) and 6 out of 10 (60%) for the subscale dynamicreaching (IQR 2–8).

3.2. Subgroup analysis according to topography

3.2.1. Total TCMS and subscales

Descriptive statistics for the subscale and total TCMS scores for the different topographies are shown in Table 3. Themedian total TCMS score for children with hemiplegia was 44.5 (IQR 37–50), 40 (IQR 30–46) for diplegia, and 13.5 (IQR 8–21.5) for quadriplegia. Comparison of total TCMS and subscale scores between the topographies revealed highly significantdifferences between all topographies (p < .0001). Post hoc tests showed significantly higher scores for children with

Table 3

Median score and interquartile range of the total TCMS score, subscale totals and items scores for each topography. Comparison analysis between scores

was performed by use of the Kruskal–Wallis test (a = .05)* for the total group and post hoc Wilcoxon rank sum tests (a = .017)y between topographies.

TCMS (range) Hemiplegia

median (IQR)a

Diplegia

median (IQR)a

Quadriplegia

median (IQR)a

All types* Hemi–diy Hemi–quadriy Di–quadriy

Total TCMS (0–58) 44.5 (37–50) 40 (30–46) 13.5 (8–21.5) <.0001 .005 <.0001 <.0001

Static sitting balance (0–20) 18 (18–20) 18 (16–20) 8 (5–11.5) <.0001 NSc <.0001 <.0001

Selective movement control (0–28) 18.5 (14–22) 16.5 (10–19) 5 (2–8) <.0001 .016 <.0001 <.0001

Dynamic reaching (0–10) 8 (6–10) 5 (2–8) 1 (0–1.5) <.0001 .006 <.0001 <.0001

Item 1 (0–2) 2 (2–2) 2 (2–2) 2 (2–2) NAb – – –

Item 2 (0–2) 2 (2–2) 2 (2–2) 1 (1–2) <.0001 NSc <.0001 <.0001

Item 3 (0–4) 4 (4–4) 4 (4–4) 4 (1.5–4) <.0001 NSc <.0001 .0002

Item 4 (0–6) 4.5 (4–6) 4 (4–6) 0.5 (0–2) <.0001 NSc <.0001 <.0001

Item 5 (0–6) 6 (5–6) 5.5 (4–6) 0.5 (0–4) <.0001 .01 <.0001 <.0001

Item 6 (0–2) 2 (2–2) 2 (1–2) 1 (1–1) <.0001 NSc <.0001 .0002

Item 7 (0–2) 2 (1–2) 1 (1–2) 1 (1–1) <.0001 NSc .0002 .002

Item 8 (0–6) 4 (3–5) 4 (2–4) 0 (0–0.5) <.0001 NSc <.0001 <.0001

Item 9 (0–8) 6 (4–6) 5.5 (4–6) 0.5 (0–4) <.0001 NSc <.0001 .001

Item 10 (0–3) 2 (1–3) 2 (1–2) 0 (0–1) <.0001 NSc <.0001 <.0001

Item 11 (0–3) 2 (0–2) 1 (0–2) 0 (0–0) .0001 NSc .0001 .003

Item 12 (0–4) 2 (2–3) 1 (0–2) 0 (0–0) <.0001 .003 <.0001 .0004

Item 13 (0–2) 2 (2–2) 2 (1–2) 0 (0–1) <.0001 NSc <.0001 <.0001

Item 14 (0–4) 4 (2–4) 2 (0–4) 0 (0–0.5) <.0001 .003 <.0001 .0003

Item 15 (0–4) 2 (2–4) 1 (0–3) 0 (0–0) <.0001 NSc <.0001 .001a IQR: interquartile range.b NA: not applicablec NS: not significant.

L. Heyrman et al. / Research in Developmental Disabilities 34 (2013) 327–334 331

hemiplegia compared to children with diplegia, except for the subscale static sitting balance. Children with quadriplegiascored significantly lower than children with hemiplegia and diplegia for total TCMS and all three subscales.

3.2.2. Item analysis

Median item scores and IQR per topography are presented in Table 3. Kruskal–Wallis tests revealed significantly differentscores between all types (p � .0001) for all items, except for item 1. Post hoc tests between children with hemiplegia anddiplegia showed significantly higher scores for children with hemiplegia for trunk stability during abduction of the legs (item5), shuffling the pelvis (item 12) and lateral reaching (item 14). For children with quadriplegia, post hoc tests showed that allitem scores were significantly lower compared to children with hemiplegia and diplegia. Moreover, median scores of thechildren with quadriplegia were 0 on most items of the subscales selective movement control and dynamic reaching.

Visual inspection of the percentages of submaximal scores for each item (Fig. 1) further revealed that for the subscalestatic sitting balance most deficits were observed in items 4 and 5, measuring trunk stability during active crossing andabduction of the legs, respectively. Also, more than 60% of the children with quadriplegia showed deficits in trunk stabilityduring arm lifting (item 2). For the subscale selective movement control, children with hemiplegia and diplegia showed leastdeficits during forward trunk leaning (item 6), and to a lesser extent during backward trunk leaning (item 7). In contrast,almost all children with quadriplegia showed major difficulties in performing these items successfully. Performance ofthe other items of this subscale, evaluating selective lateral flexion and rotation of the trunk (items 8–12), showed deficits inthe vast majority of all children. For the subscale dynamic reaching, only 21% of the children with hemiplegia and 33% of thechildren with diplegia showed deficits in forward reaching (item 13), in contrast to 87% of the children with quadriplegia.Performance of lateral reaching (item 14) showed more deficits in children with hemiplegia (39%) and diplegia (67%), andmost deficits in these topographies were found during crossed reaching (item 15) (64% and 86%, respectively). None of thechildren with quadriplegia obtained a maximal score for lateral and crossed reaching.

3.3. Subgroup analysis according to GMFCS level

3.3.1. Total TCMS and subscales

Median subscale and total TCMS scores for the different GMFCS levels are presented in Table 4. The median total TCMSscore was 45 (IQR 43–51) for level I, 38 (IQR 31.5–43.5) for level II, 24 (IQR 17.5–26.5) for level III and 8 (IQR 8–12) for level IV.Total TCMS and subscale scores differed significantly between all levels (p < .0001) with decreasing median scores fromlevels I to IV. Post hoc tests revealed significant differences between all levels for total TCMS and all three subscales, exceptbetween level III and IV for the subscale dynamic reaching.

Table 4

Median score and interquartile range of the total TCMS score, subscale totals and items scores for each GMFCS level. Comparison analysis between scores

was performed by use of the Kruskal–Wallis test (a = .05)* for the total group and post hoc Wilcoxon rank sum tests (a = .008)$ between GMFCS levels.

TCMS (range) GMFCSa I

median

(IQR)b

GMFCSa II

median (IQR)b

GMFCSa III

median (IQR)b

GMFCSa IV

median

(IQR)b

All

levels*

I–II$ I–III$ I–IV$ II–III$ II–IV$ III–IV$

Total TCMS (0–58) 45 (43–51) 38 (31.5–43.5) 24 (17.5–26.5) 8 (8–12) <.0001 .0003 <.0001 <.0001 <.0001 <.0001 .005

Static sitting

balance (0–20)

19 (18–20) 17.5 (16–18.5) 14 (9–16) 6 (5–9) <.0001 .004 <.0001 <.0001 .0003 <.0001 .008

Selective movement

control (0–28)

20 (16–22) 16 (13–18.5) 8.5 (7.5–10) 2 (2–4) <.0001 .004 <.0001 <.0001 .0001 .0001 .007

Dynamic reaching

(0–10)

8 (6–10) 5.5 (2.5–8) 1 (0.5–2) 1 (0–1) <.0001 .004 <.0001 <.0001 .0002 .001 NSd

Item 1 (0–2) 2 (2–2) 2 (2–2) 2 (2–2) 2 (2–2) NAc – – – – – –

Item 2 (0–2) 2 (2–2) 2 (2–2) 2 (2–2) 1 (1–1) <.0001 NSd NSd <.0001 NSd <.0001 .004

Item 3 (0–4) 4 (4–4) 4 (4–4) 4 (4–4) 2 (1–4) <.0001 NSd .003 <.0001 NSd <.0001 NSd

Item 4 (0–6) 5 (4–6) 4 (4–5) 2 (2–4) 0 (0–0) <.0001 NSd <.0001 <.0001 .0004 <.0001 .002

Item 5 (0–6) 6 (5–6) 5.5 (4–6) 3 (1–4) 0 (0–0) <.0001 NSd <.0001 <.0001 .002 <.0001 NSd

Item 6 (0–2) 2 (2–2) 2 (1–2) 1 (1–2) 1 (1–1) <.0001 NSd .0001 .0001 NSd NSd NSd

Item 7 (0–2) 2 (1–2) 1 (1–1.5) 1 (1–1) 1 (1–1) <.0001 .001 <.0001 .0002 NSd NSd NSd

Item 8 (0–6) 4 (3–5) 3.5 (2–4) 2 (0–2) 0 (0–0) <.0001 NSd <.0001 <.0001 .0002 .0004 NSd

Item 9 (0–8) 6 (6–6) 5.5 (4–6) 4 (0–5) 0 (0–0) <.0001 NSd .0004 <.0001 NSd .0003 NSd

Item 10 (0–3) 2 (2–3) 2 (1.5–3) 1 (1–2) 0 (0–0) <.0001 NSd .002 <.0001 .004 <.0001 .0003

Item 11 (0–3) 2 (0–2) 1 (0–2) 0 (0–0) 0 (0–0) .0001 NSd .003 .0005 NSd .004 NS

Item 12 (0–4) 2 (2–3) 1 (1–2) 0 (0–0) 0 (0–0) <.0001 .0004 <.0001 <.0001 <.0001 .0001 NS

Item 13 (0–2) 2 (2–2) 2 (1–2) 1 (0–2) 0.5 (0–1) <.0001 NSd .0003 <.0001 NSd .003 NSd

Item 14 (0–4) 4 (3–4) 2 (1–4) 0 (0–0) 0 (0–1) <.0001 .004 <.0001 <.0001 .0003 .003 NSd

Item 15 (0–4) 3 (1–4) 2 (0–2) 0 (0–0) 0 (0–0) <.0001 NSd <.0001 .0001 .001 .002 NSd

a GMFCS: Gross Motor Function Classification System.b IQR: interquartile range.c NA: not applicable.d NS: not significant.

L. Heyrman et al. / Research in Developmental Disabilities 34 (2013) 327–334332

3.3.2. Item analysis

Median item scores and IQR per GMFCS level are given in Table 4. Kruskal–Wallis tests showed significantly differentscores between all levels (p � .0001) for all items, except for item 1. Post hoc comparison between level I and II revealedsignificantly higher scores for level I for backward leaning (item 7), shuffling the pelvis (item 12) and lateral reaching(item 14). Children with level II scored significantly higher compared to level III for trunk stability during active crossing(item 4) and abduction of the legs (item 5), for lateral flexion (item 8) and rotation of the upper trunk (item 10), and forshuffling the pelvis (item 12). Also, significant higher scores were obtained for lateral (item 14) and crossed reaching(item 15). Children with level III scored significantly higher than children with level IV for several items of the subscalestatic sitting balance (items 2 and 4) and selective movement control (item 10). Comparison between level I and level III,and level I and level IV revealed significantly higher scores for level I for almost all items, as well as between level II andIV, with significant higher scores for level II.

Visual inspection of the percentages of submaximal scores (Fig. 2) further showed that for the subscale static sittingbalance children with levels I, II and III showed deficits mainly on items evaluating trunk stability during active legmovements (items 4 and 5), while more than 75% of the children with level IV already showed difficulties in maintaining astable trunk during arm lifting (item 2). For the subscale selective movement control, best performances were found duringforward and backward trunk leaning (items 6 and 7), especially in children with levels I and II. Nearly all children showeddeficits during selective lateral flexion and rotation of the upper and lower trunk (items 8–12). For the subscale dynamicreaching, deficits in performance increased from forward reaching (item 13) to crossed reaching (item 15) in all levels, with75% of the children with levels III and IV showing deficits during all reaching tasks.

4. Discussion

This study investigated clinical characteristics of impaired trunk control in different topographies and severity levels ofchildren with spastic CP, by use of the Trunk Control Measurement Scale.

Our results showed that trunk control is clearly impaired in children with CP, as shown by a median total TCMS score of38.5 corresponding to 66% of the maximal score. Performance on the subscale static sitting balance was least impaired, witha median score of 18 out of 20 (90%). Children showed more difficulties with the items of the subscale selective movementcontrol and dynamic reaching, achieving only 60% of the maximum score on both subscales. These scores are clearly lowerthan scores obtained by typically developing (TD) children in a previous study (Heyrman et al., 2011). The median totalTCMS score was 53.5 corresponding to 92% of the maximal score and median scores on the subscales were 20 (100%), 24(86%) and 10 (100%), respectively. These findings confirm the problems of trunk control in children with CP and endorse theneed to further unravel the specific characteristics of impaired trunk control in this patient group.

Subgroup analysis of the total TCMS score and subtotals according to topography indicated that trunk control is leastimpaired in children with hemiplegia, followed by children with diplegia, and most impaired in children with quadriplegia.On the subscale static sitting balance, children with hemiplegia and diplegia showed only minor problems (median score 18out of 20) with no differences found between these two topographies, except for a significantly better trunk stability duringabduction of the legs in children with hemiplegia. In contrast, children with quadriplegia clearly showed difficulties (medianscore 8 out of 20) with static trunk control. The term ‘static’ refers to the test instruction to maintain a stable trunk positionduring performance of the items, still active trunk control such as anticipatory and compensatory postural adjustments arerequired to enhance this stable position during upper or lower limb movements (Bigongiari et al., 2011; Girolami, Shiratori,& Aruin, 2011). Hence, the results of our study suggest that children with quadriplegia have profound deficits in posturaladjustments. Item analysis further revealed that children with hemiplegia and diplegia showed most difficulties duringdisturbances caused by active lower limb movements, especially while crossing legs, whereas children with quadriplegiaalready showed difficulties during arm lifting which further indicates that their anticipatory and compensatory capacity ismore affected. These findings suggest that children with quadriplegia might benefit from therapeutic exercises demanding astable trunk while moving any other body part. For children with hemiplegia and diplegia, the focus should be more oncounterbalancing disturbances caused by lower limb movements.

For the subscale selective movement control the trunk itself needs to be actively moved in a controlled, selective manner inthree planes, requiring flexion/extension (sagittal plane), lateral flexion (frontal plane) and rotation (transverse plane) of thetrunk. In general, performance of selective trunk movements was difficult for all children. Diminished selective motorcontrol is one of the primary impairments in children with CP and therefore present in many of these children, as now clearlyconfirmed by the results of our study. In addition, these difficulties might be partially explained by a limited experience withcontrolled movements of the upper and lower part of the trunk and by reduced body awareness. Item analysis showed thatchildren with hemiplegia and diplegia succeeded best in executing selective trunk movements in the sagittal plane, with abetter performance in the forward than the backward direction. Previous research studying muscle activation patterns(Brogren et al., 1998; Hadders-Algra, Brogren, & Forssberg, 1998) also found differences between forward and backwardbody translations. These differences might be explained by the larger support surface of the legs, providing more stabilityduring forward leaning of the trunk. Also, differences in the degree of spinal modulation between dorsal and ventral muscleshave been put forward to contribute to the difference between forward and backward movement control (Brogren,Forssberg, & Hadders-Algra, 2001; Hadders-Algra et al., 1998). Besides these factors, familiarity with the movement as wellas the guidance of visual input during forward leaning might also partially explain the better performance in forward

L. Heyrman et al. / Research in Developmental Disabilities 34 (2013) 327–334 333

direction. In contrast to children with hemiplegia and diplegia, almost all children with quadriplegia already showeddifficulties in executing these sagittal movements properly. Performance of selective trunk movements in the frontal andtransverse plane was impaired in the vast majority of all children. In particular, children with quadriplegia showed majordifficulties in performing these selective movements, as none of the children obtained a maximal score for these items anditem scores were very low. These findings provide interesting clues for treatment aimed at improving performance ofselective movements of the upper and lower part of the trunk in different directions. Although previous research was mostlyaimed at postural analysis in the sagittal plane, one study also found decreased lateral stability in sitting in children with CPduring dynamic balance testing on a moveable platform (Liao, Yang, Hsu, Chan, & Wei, 2003). Interestingly, a recent study inTD infants aged 5–8 months indicated that infants’ sitting posture develops differently in the sagittal plane than in the frontalplane, with control of postural sway in the sagittal plane occurring earlier in development (Cignetti, Kyvelidou, Harbourne, &Stergiou, 2011). It seems that in most children with CP this developmental process becomes disrupted in this early phase.

The items of the third subscale dynamic reaching challenge another aspect of dynamic trunk control, i.e. to actively movethe trunk beyond the stability limits of the base of support during three reaching tasks, requiring forward, lateral and acombination of rotation and lateral displacement of the trunk. Item analysis revealed that children with quadriplegiashowed major deficits with trunk displacements in all directions. Children with hemiplegia and diplegia showed only minorproblems performing forward trunk displacements while reaching. Performing lateral trunk displacements was alreadydifficult for children with diplegia, and difficulties for both topographies were found when executing an additional rotationof the trunk during crossed reaching. Executing trunk rotations while reaching produces more challenges on postural controlin children with CP and consequently hampers the reaching performance, as shown in previous research (Ju, Hwang, &Cherng, 2012; Ju, You, & Cherng, 2010). These findings provide interesting clues for treatment interventions targeting activetrunk displacements for the different topographies.

We further investigated differences in trunk impairment according to the severity of the motor involvement, based on theGMFCS levels. Marked differences were found between total TCMS score and subscale totals for all GMFCS levels, exceptbetween level III and IV for the subscale dynamic reaching. Also, total TCMS score and subscale totals clearly decreased fromlevel I to level IV. These findings imply that trunk control is an important component of the functional abilities of childrenwith CP. Item analysis further revealed interesting differences between successive GMFCS levels. While children with GMFCSlevels I and II both have good functional abilities, still some differences in active trunk control, including backward trunkleaning, shuffling pelvis and lateral reaching were found, with children with level I performing better than level II. Also,comparison between levels II and III is of particular interest, because the discrimination between these two levels is basedupon the need of an assistive mobility device to walk. Children with level III showed more deficits than level II whilemaintaining a stable trunk during active leg movements, performing a selective lateral flexion and rotation of the upper partof the trunk, and shuffling the pelvis, demanding both lateral flexion and rotation of the lower part of the trunk. Children withlevel III also showed more deficits during lateral and crossed reaching. These findings indicate that both static and dynamiccontrol of the upper and lower part of the trunk, i.e. the pelvic region, are particularly more impaired in children who haveless walking abilities and provide indications for therapeutic exercises targeting trunk control to improve walking.

This study was the first to investigate characteristics of trunk control in children diagnosed with spastic CP. We foundmarked impairments, both in static and dynamic aspects of trunk control, in a large and heterogeneous group of children withCP. Also, major differences were found between the different topographies and GMFCS levels, demonstrating the discriminativevalue of the TCMS. The findings of the subscale and item analyses further enhanced the insights into trunk control and providedinteresting clues for treatment of trunk impairments in this patient group. Still, some critical reflections are warranted. Firstly,classification into subtypes was primarily based upon the distribution of the motor impairment using the traditionaltopographic classification into hemiplegia, diplegia and quadriplegia (Mutch et al., 1992). Other studies investigating posturalcontrol in children with CP have used the more recent classification of unilateral and bilateral spastic CP (Cans et al., 2000),with the latter comprising both children with diplegia and quadriplegia (van der Heide et al., 2004, 2005). However, the fact thatin our study marked differences in trunk control parameters were found between children with diplegia and quadriplegiasupports the use of the traditional classification when studying trunk control in children with CP. Secondly, we used the TCMS asoutcome measure to evaluate trunk control, which measures trunk performance in a sitting position and requires some sittingabilities for executing the items. Therefore, the scale is not suitable for more severely impaired children who are unable toremain sitting without support. The Segmental Assessment of Trunk Control (SATCo) (Butler et al., 2010) might be a moreappropriate measure to evaluate trunk control in these children. Still, our study group consisted of a heterogeneous group ofchildren with CP, also including children with GMFCS levels IV, which demonstrates the broad scope of the scale. Thirdly, onlychildren between 8 and 15 years were included in this study. The reliability of the TCMS for a younger age group still needs tobe established, and therefore younger children were not included. The analysis of trunk control in younger children with CPwill further broaden the insights into the characteristics of impaired development of trunk control in this patient group.

5. Conclusion

This study aimed at identifying clinical characteristics of impaired trunk control in a large group of children with spasticCP. In general, the results demonstrated that trunk control is clearly impaired in children with CP, however to a variousextent, depending on the topography and the severity of the motor impairment. Children with hemiplegia and diplegiashowed limited difficulties with static trunk control. Performance of active trunk movements, both within and beyond the

L. Heyrman et al. / Research in Developmental Disabilities 34 (2013) 327–334334

base of support was more impaired in these children, in particular in the frontal and transverse plane. Children withquadriplegia showed profound difficulties with both static and dynamic aspects of trunk control. Marked differences in trunkdeficits were also found between all GMFCS levels, with larger deficits found in more severely impaired children. Evaluationof trunk control by use of the TCMS can provide the clinician with valuable clues for treatment, specifically aiming at theimprovement of trunk performance.

Conflict of interest

The authors declare that the research is conducted in the absence of any commercial or financial relationships that couldbe construed as a potential conflict of interest.

Acknowledgements

Lieve Heyrman received a PhD fellowship of the Research Foundation Flanders (FWO). The authors would like to thankthe children and their parents for their cooperation, and the staff of the participating schools and private physiotherapypractices for their collaboration.

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