Motor function after selective dorsal rhizotomy: a 10-year practice-based follow-up study

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1 DEVELOPMENTAL MEDICINE & CHILD NEUROLOGY ORIGINAL ARTICLE Motor function after selective dorsal rhizotomy: a 10-year practice-based follow-up study ANNIKA LUNDKVIST JOSENBY 1 PHILIPPE WAGNER 2 GUN-BRITT JARNLO 1 LENA WESTBOM 3 EVA NORDMARK 1 1 Division of Physiotherapy, Department of Health Sciences, Health Sciences Centre, Lund University, Lund. 2 RC Syd. National Centre for Quality Registers, Skåne University Hospital, Lund. 3 Division of Paediatrics, Department of Clinical Sciences (Lund), Lund University, Lund, Sweden. Correspondence to Dr Annika Lundkvist Josenby at Division of Physiotherapy, Department of Health Sciences, Health Sciences Centre, Lund University, SE Lund, Sweden. annika.lundkvist@med.lu.se This article is commented on by McLaughlin on pages of this issue. PUBLICATION DATA Accepted for publication 5th December Published online 21st March ABBREVIATIONS BSCP Bilateral spastic cerebral palsy GMFM Gross Motor Function Measure OMG Ontario Motor Growth PROM Passive range of motion SDR Selective dorsal rhizotomy AIM The aim of this study was to explore changes in motor function up to 10 years after selective dorsal rhizotomy (SDR). METHOD The participants comprised 29 children (20 males, nine females) with bilateral spastic diplegia who were consecutively operated on at a median age of 4 years and 3 months and followed until a median age of 15 years. SDR was combined with physiotherapy and regular follow-up visits. The distribution of preoperative Gross Motor Function Classification System (GMFCS) levels was as follows: I, n=1; II, n=7; III, n=8; IV, n=12; and V, n=1. Muscle tone in hip flexors, hip adductors, knee flexors, and plantar flexors was assessed with the modified Ashworth scale, passive range of motion in hip abduction, popliteal angle, maximum knee extension, dorsiflexion of the foot was measured with a goniometer, and gross motor function was assessed using the Gross Motor Function Measure (GMFM-66). The results were compared with preoperative values, taking into account age at the time of SDR. RESULTS After 10 years, muscle tone in hip flexors, hip adductors, knee flexors and plantar flexors was normalized in 19, 24, 13 and 23 participants respectively; mean change in passive range of motion ranged from )2.0 to 8.6, and the mean increase in GMFM-66 was Changes in GMFM-66 were associated with preoperative GMFCS level and GMFM-66 scores. INTERPRETATION Children who underwent SDR and physiotherapy and were regularly followed up by an experienced team showed improved gross motor function for up to 10 years postoperatively. Selective dorsal rhizotomy (SDR) is a neurosurgical spasticityreducing intervention for children with cerebral palsy (CP). In combination with physiotherapy, SDR has been reported to improve functional outcome in spastic diplegia. 1 The CP subtype spastic diplegia is synonymous with the later-introduced term bilateral spastic CP (BSCP) in individuals classified as Gross Motor Classification System (GMFCS) levels I to IV and accounts for about one-fifth of individuals with BSCP assessed as GMFCS level V. 2 It has been shown that passive range of motion (PROM) in the major joints of the lower limbs decreases between the ages of 2 and 14 years in individuals with BSCP. BSCP is associated with the lowest range of popliteal angle and knee extension of all the CP subtypes. 3 In combination with physiotherapy, SDR has been shown to benefit the components of body function and body structure, as defined by the International Classification of Functioning, Disability and Health (ICF). 4 It has also been reported that 5 years after SDR, muscle tone in the lower limbs is improved and PROM in hip abduction, popliteal angle, and dorsiflexion of the foot is increased. 5,6 In addition, according to a recent literature review, 7 a meta-analysis 8 of three randomized controlled trials provides level II evidence that capacity in gross motor function, as measured with the Gross Motor Function Measure (GMFM), is significantly increased after SDR, as determined by follow-up examinations performed 9, 12, and 24 months postoperatively. After 9 12 months, the functional improvements were greater in children receiving SDR and physiotherapy than in children receiving only physiotherapy. Furthermore, a significant increase in motor function capacity 5 years postoperatively, as assessed with the GMFM, has been reported. 5,9 In a 20-year follow-up of SDR, functional outcome in the dimensions body function, body structure and activity of the ICF was reported to be improved. 10 However, a recently published 10- year follow-up study concluded that, in spite of a reduction in muscle tone after SDR, contractures could not be prevented and long-term functioning was not improved. 11 The quality of ª The Authors. Developmental Medicine & Child Neurology ª 2012 Mac Keith Press DOI: /j x 429

2 the evidence reported in the 5-, 10-, and 20-year follow-up studies was assessed as level IV according to the above-mentioned articles. 5,7,9 11 Development of gross motor function has been measured with the 66-item GMFM (GMFM-66) in longitudinal studies The GMFCS classifies gross motor function in children with CP. 15,16 Children assessed as GMFCS level I have the least, and those assessed as level V the greatest, functional limitation. In the Canadian Ontario Motor Growth (OMG) study, which involved 657 children, the GMFM-66 score depended on age and the severity of functional limitation according to the GMFCS. 14 Children with all subtypes of CP were included, but children treated with orthopaedic surgery, SDR, botulinum toxin A, or intrathecal baclofen were excluded. In the OMG study, the GMFM-66 results were analysed according to the initial GMFCS level in order to establish maximum scores and the age at which 90% of the maximum score was achieved the age-90. In the case of children classified as GMFCS level II, the maximum GMFM-66 score was 68.5 and age-90 was 4 years and 11 months; for those classified as GMFCS level III, the maximum score was 53.5 and age-90 was 3 years and 2 months; and for those classified as GMFCS level IV, the maximum score was 39.5 and age-90 was 3 years and 2months. 13 Children assessed as GMFCS level I or II exhibited an increase in gross motor function, as measured by GMFM-66, during childhood and motor function continued to improve into adolescence. Among children in GMFCS levels III to V, GMFM-66 scores increased during childhood, but declined during early adolescence. 13,17 As SDR is an irreversible procedure and is performed in very young children, it is important to study its positive and negative effects on body function body structure, activity participation, and other health domains from a lifetime perspective. According to a recent review of long-term results after SDR, 7 there is a need for longitudinal follow-up studies of activity and participation. Safety and motor function in children 5 years after undergoing SDR in Lund, Sweden, have previously been reported. 5 The aim of this study was to describe changes in muscle tone, PROM, and gross motor function capacity 10 years after SDR, and to determine factors that could be associated with these changes. We hypothesized that at 10 years muscle tone would be reduced compared with preoperatively, PROM would show no clinically significant reduction, and gross motor function would be improved compared with the development expected if SDR had not been performed. Outcomes at 10 years were analysed in relation to preoperative GMFCS levels, preoperative values, and age at SDR. METHOD Participants The first 35 children to undergo SDR at the University Hospital in Lund, Sweden, were followed for up to 5 years. Of these, 29 participants, now adolescents (20 males, nine females), and their parents participated in this practice-based follow-up study 10 years after SDR. All of the children who underwent SDR had BSCP, or, more precisely, spastic What this paper adds Ten years after undergoing SDR combined with physiotherapy, muscle tone was normalised and mean passive range of motion was unchanged. Mean capacity of gross motor function was increased. Long-term changes in gross motor function were associated with preoperative GMFCS levels. diplegic CP, according to the Swedish classification. The subtype BSCP also includes spastic tetraplegia, which in the Swedish classification is defined as massive total motor disability involving all four limbs, with the upper limbs affected to at least the same degree as the lower ones. 2 In the Swedish classification, all cases (GMFCS I V) in which the lower limbs are more affected than the upper ones are assigned to the spastic diplegic CP subtype (Table I). The median age at the 10-year follow-up was 15 years. Five adolescents classified preoperatively as GMFCS level III (n=3) or IV (n=2) chose not to participate 10 years after SDR. Another adolescent, classified preoperatively as GMFCS level IV, wanted to participate but cancelled the appointment because of health problems unrelated to SDR. The characteristics of the participants are presented in Table I. Three of the six non-participants in the 10-year follow-up study lived outside the Skåne Blekinge region. Apart from this and a slightly higher mean birthweight in the children followed for only 5 years postoperatively, there was no major difference between the participating group and the original group. Preoperative GMFCS levels were determined according to the original version of the classification. 15 At the 10-year follow-up, the GMFCS Expanded and Revised version, 16 which includes an additional age band for adolescents (12 18y), was used. GMFCS level was found to have improved in seven of the 29 participants, in two cases by two levels (preoperative GMFCS levels III and IV respectively). One participant deteriorated from GMFCS level II to level III. The children were selected for SDR using the criteria proposed by Peacock and Staudt; 1 the presence of dystonia, ataxia, or severe contractures was considered a contraindication. The children, their parents, and often their local physiotherapist participated in the follow-up visits at the spasticity clinic, which consisted of regular assessments of function and recommendations regarding physiotherapy and orthoses based on the child s functioning and environment. The assessments were performed preoperatively and at 6, 12, and 18 months and 3 and 5 years postoperatively. The optional 10-year follow-up was added to the programme in The operation was combined with intensified goal-directed physiotherapy. The recommended frequency of individualized physiotherapy sessions for the first 6 months was 1 hour twice a week and thereafter once a week until 18 months postoperatively. In addition, physical leisure activities were encouraged. 5 For a more detailed description of selection criteria, pre- and postoperative treatment, surgical techniques, etc., for this cohort, see Nordmark et al. 5 The overall goals of the intervention were to improve activities and independence in motor and functional skills, for example the improvement of alignment, balance when sitting and standing, transfers, and walking and or wheeled mobility. 430 Developmental Medicine & Child Neurology 2012, 54:

3 Table I: Characteristics of the first 35 children with bilateral spastic cerebral palsy who underwent selective dorsal rhizotomy (SDR). Baseline data from participants followed for 10 years (n=29) and participants followed for 5 years only (n=6) were collected preoperatively Child characteristics Participants in 10y follow-up (n=29) Participants followed until 5y only (n=6) Males females (n) Year of birth (n) Median age at SDR, y:mo (range) (n) 4:3 (2:6 6:7) 3:11 (3 3 5:9) Median age at 10-year follow-up, y:mo (range) 15:0 (12:10 17:1) Gestational age (completed weeks): < > not specified (n) Birthweight (g): median (range) (n) 1477 ( ) a 1800 ( ) a Epilepsy preoperatively: yes no (n) Cognitive disability: severe moderate no or minor (n) Severe visual impairment (n) 4 0 Domicile: region of Skåne and Blekinge other parts of Sweden abroad (n) GMFCS level preoperatively I II III IV V(n) GMFCS-E&R level 10y postoperatively I II III IV V(n) Number who underwent additional postoperative orthopaedic surgery at 10y, according to preoperative GMFCS level I II III IV V Number who had received botulinum toxin A injections at 10y according to preoperative GMFCS levels I II III IV V Number of additional orthopaedic surgery interventions according to location hip knee foot at 10y Type of additional orthopaedic surgery: soft tissue skeletal (n) 9 11 a Data from one participant missing. GMFCS, Gross Motor Function Classification System; GMFCS-E&R, Gross Motor Function Classification System Expanded & Revised. Measures Muscle tone of the hip adductors, hip flexors, knee flexors, and ankle plantar flexors was rated with the six-grade modified Ashworth scale according to Peacock and Staudt. 1 In this study no increase in muscle tone was defined as normal (1) and hypotonic (0) muscle tone. PROM was measured for hip abduction with the hips and knees extended, for the popliteal angle with 90 flexion of the hip and a fully extended knee representing 180º, for maximum knee extension with extended hips, and for ankle dorsiflexion with the knee extended and the foot inverted. PROM was measured with a goniometer relative to standardized anatomical landmarks 18 and rounded to the nearest 5. Based on the preoperative data, a clinically significant reduction in PROM was defined as reduction in hip abduction and dorsiflexion of the foot of more than 10, reduction in knee extension of more than 5, and reduction in the popliteal angle of more than 15. The GMFM is a criterion-referenced measure based on normal gross motor developmental milestones; all items are achievable by a 5-year-old child with no motor disability. The GMFM-66 is one version, in which a child s gross motor function is observed and tested against 66 standardized items. It has been found to be valid and reliable for children with CP and has good longitudinal construct validity GMFM-66 scores were obtained using the Gross Motor Ability Estimator. 22 The GMFM-66 has not been used in any previous 10-year follow-up studies after SDR. All assessments of muscle tone and PROM during the 10-year study period were carried out by the same physiotherapists (ALJ and EN); they were examined in scoring the GMFM by the constructors of the measure. The children undergoing the intervention were videotaped during all sessions. All measurements were considered in relation to preoperative GMFCS level. Statistics Muscle tone Ninety-five per cent confidence intervals (95% CIs) were calculated, using the binomial distribution, for the proportion of children rated with muscle tone at 1 or 0 on the modified Ashworth scale after 10 years. Moreover, the change in this proportion between baseline and 10 years after the operation was analysed using the exact version of McNemar s test. PROM For each muscle group, the mean of the PROM values for the left and right sides was calculated before and 10 years after the operation for each study participant. The change in PROM from baseline to 10 years after the operation was then analysed using the mean individual change in the mean PROM together with 95% CIs based on bootstrap standard errors. In order to investigate what factors influence the change in PROM after 10 years, multiple linear regression was used, with the mean individual change in mean PROM as the dependent variable. Factors included in the analysis were GMFCS level, age at operation, and preoperative mean PROM. For confidence interval and p-value calculations, bootstrap standard errors were used. GMFM Factors influencing changes in the GMFM scores between baseline and 10 years after the operation were analysed using multiple linear regression. Factors included in the analysis were GMFCS level, age at operation, and preoperative GMFM score. Motor Function 10 Years After SDR Annika Lundkvist Josenby et al. 431

4 The development of the GMFM score with age for three GMFCS groups, I to II, III, and IV to V, was plotted in a graph. The mean development was described using a seconddegree polynomial of age. The corresponding parameters were estimated by including terms for age and age to the power of two in a linear regression analysis. All statistical tests were two-sided, and p values below 0.01 were considered statistically significant. This limit was lowered from the standard limit of 0.05 in order to account for multiple testing. All calculations were made using Stata 12 (StataCorp LP, College Station, TX, USA). Separate GMFM-66 mean development curves for each of the GMFCS groups II, III, and IV were additionally created using non-linear regression analysis in the statistical programming language R. 23 The method used to describe the mean development is the same as was used when analysing the OMG study by Hanna et al. 13 The method, referred to as the stable-limit model, assumes that the GMFM-66 score stabilizes after a certain age and estimates the maximum GMFM- 66 score together with the age at which 90% of the maximum is reached. 14 The curves were created to enable a simple comparison between the GMFM-66 score development of the OMG and the current study population. Approval for the study was obtained from the local ethics committee at the Medical Faculty at Lund University, Sweden (LU ). The parents caregivers gave their written informed consent for the children to participate in the study. RESULTS At 10-year follow-up, muscle tone in hip flexors hip adductors, knee flexors,and plantar flexors was reduced to normal in 19, 24, 13, and 23 participants respectively (Table II). Results from the regression analysis of muscle tone were inconclusive and thus not reported. The mean changes in PROM were small (Table III). The increase in PROM in dorsiflexion of the foot was associated with preoperative GMFCS level at a p-level of Age at SDR and preoperative PROM were not associated with changes in PROM (Table IV). A progressive increase in gross motor function as measured by the GMFM-66 was seen over the 10 years. Individual development of GMFM-66 is illustrated in Figure 1. The changes in GMFM-66 scores were associated with preoperative GMFCS level (p=0.008 and 0.045) and preoperative GMFM-66 score (p=0.017; Table IV). The mean development of GMFM-66 showed a maximal score of 79.4 and age-90 of 7 years and 8 months in participants in GMFCS level II, a GMFM-66 maximum score of 54.7 and age-90 of 2 years and 2 months in participants of GMFCS level III, and a GMFM-66 maximum score of 45.4 and age-90 of 3 years and 2 months in participants of GMFCS level IV (Fig.2). DISCUSSION This is the first study to describe changes in muscle tone, PROM, and GMFM-66 in a group of children followed up by the same clinical team for a period of 10 years after SDR. SDR reduced spasticity effectively, a finding that has also been reported in other studies. 5,6,10,11 At follow-up, muscle tone was found to have declined to normal levels in the knee flexors in only 13 of 28 children. In fact, in this group, muscle tone was clearly reduced from severely increased to slightly increased. In our study, children undergoing SDR combined with goal-directed physiotherapy and followed up structurally showed fewer muscles with contractures than is usual in the development of children with CP. The mean changes in PROM were small in the case of hip abduction, popliteal Table II: Proportion of participants with normal (1) or hypotonic (0) muscle tone according to the modified Ashworth scale by Peacock and Staudt, preoperatively and at 10 years postoperatively Muscle group Proportion of participants with normal or hypotonic muscle tone preoperatively (n) Proportion of participants with normal or hypotonic muscle tone at 10y (n) p value Hip flexors <0.001 Abductors <0.001 Knee flexors <0.001 Plantar flexors <0.001 p values were obtained using the exact McNemar s test. Table III: Mean passive range of motion (PROM) and Gross Motor Function Measure (GMFM-66) before selective dorsal rhizotomy and 10 years later Preoperative mean (SD) 10y mean (SD) Mean change (SD) SEM Joint angle (degrees) Hip abduction 28.9 (6.9) 28.7 (5.9) )0.9 (9.8) 2.13 Popliteal angle (8.8) (11.9) )0.8 (12.9) 2.40 Knee extension )1.5 (5.6) )5.8 (13.3) )2.0 (12.1) 2.58 Dorsiflexion 3.9 (10.2) 12.4 (11.8) 8.6 (13.2) 2.45 GMFM-66 score 48.6 (9.7) 59.2 (17.2) 10.6 (11.8) 0.57 SEM, standard error of the mean. 432 Developmental Medicine & Child Neurology 2012, 54:

5 Table IV: Influence of preoperative GMFCS level, value of variable, and age at SDR on mean changes in PROM and gross motor function as measured by the GMFM-66, 10 years after SDR GMFCS level III vs I II GMFCS levels IV V vs I II Preoperative value Age at SDR Variable Mean p-value 95% CI Mean p-value 95% CI Mean p-value 95% CI Mean p-value 95% CI PROM Hip abduction )11.3 to 12.7 ) )8.14 to 4.72 ) )0.87 to 0.49 ) )4.44 to 2.04 Popliteal angle ) )21.1 to 5.93 ) )19.4 to )0.52 to )3.74 to 5.65 Knee extension ) )18.5 to 6.96 ) )26.7 to )0.71 to 1.31 ) )8.08 to 0.31 Dorsiflexion ) )11.1 to a )0.10 to )3.53 to 3.58 GMFM-66 score ) ** )16.5 to ) a ) a )9.8 to )1.0 ) )3.7 to 0.08 a p 0.05, **p<0.01. CI, confidence interval. GMFCS, Gross Motor Function Classification System; SDR, selective dorsal rhizotomy; PROM, passive range of motion; GMFM-66, 66-item Gross Motor Function Measure. GMFM GMFCS I II III IV V GMFM SDR Sample OMG Sample SDR Sample OMG Sample SDR Sample OMG Sample GMFCS II GMFCS III GMFCS IV Age [y] Age [y] Figure 1: Changes in Gross Motor Function Measure (GMFM-66) scores over time in relation to age and preoperative Gross Motor Function Classification System (GMFCS) level in individual participants followed up for 5 years (n=35) or 10 years (n=29) postoperatively. The GMFM-66 scores of the six children followed for only 5 years are thus included. The black line represents mean development among participants classified as GMFCS level I or II, the red line represents the mean development for participants of GMFCS level III, and the green line represents the mean development of participants of GMFCS levels IV and V. angle, and knee extension but larger in the case of dorsiflexion of the foot. In contrast, a total population study in our area found that progressive restriction of lower extremity joint motion from the ages of 2 14 years was more severe in those with BSCP than in those with any other CP subtype, and that mean PROM restriction increased with increasing GMFCS level. 3 In the same study, 55 of 155 (39%) children with BSCP were classified as GMFCS level I, with the lowest risk of contracture development. As only one of the 29 children in the present study who underwent SDR had been classified preoperatively as GMFCS level I, whereas 20 children were classified as GMFCS level Figure 2: Comparison of predicted mean development of Gross Motor Function Measure (GMFM-66) as a function of age among individuals classified as Gross Motor Function Classification System (GMFCS) level II (n=7), III (n=8), or IV (n=12) who underwent selective dorsal rhizotomy (SDR) in our study and participants of GMFCS level II (n=80), III (n=122), and IV (n=137) in the Ontario Motor Growth study (OMG). III to V, it is likely that fewer contractures were recorded in the SDR-operated children in their adolescence than are usually seen in adolescents with BSCP. We hypothesized that contracture development would be reduced in children who underwent SDR compared with those who did not, and that PROM would show no clinically significant reduction. We found only small changes in PROM, in both directions, and these mainly lacked clinical significance. Among the participating group, the most common location for additional postoperative orthopaedic surgery was the foot (Table I). This may contribute to the improved PROM of the foot; however, stabilizing surgery was mainly performed in the hindfoot, which actually may not increase the PROM. The importance for function of contracture prevention became evident to us during the first years of follow-up after Motor Function 10 Years After SDR Annika Lundkvist Josenby et al. 433

6 the implementation of a secondary prevention programme that was introduced in the region in To prevent the development of contractures intensive physiotherapy and the use of orthoses should be combined, especially at times of rapid growth. The prevention of contractures has been shown to be associated with a lesser decline in the gross motor capacity of adolescents with CP. 17 In accordance with these results we found a low incidence of severe contractures and an improvement in gross motor function capacity in the present study. All children with CP typically receive less physiotherapy intervention as they get older, which may lead to more restriction in joint motion. However, factors other than those described by the domains body structure and body function may also lead to reduced range of motion. It has been shown that young people with CP like other young people are increasingly participating in passive activities such as watching TV or other sedentary pursuits. Also adolescents with CP have been shown to participate less than their typically developing peers in physical activities as a result of personal factors such as lifestyle, coping, and personal preferences as well as reduced social participation. 24,25 A risk of measurement error has been reported for PROM measurements using goniometry, and this risk must also be taken into account when considering the results of the present study. 26 Although the same physiotherapists performed the measurements in each child in order to attain as reliable a measurement as possible, the prerequisites changed along with the increasing body size of the participants, measured in the course of the 10 years of the study. We found that the development of gross motor function was associated with age and GMFCS level before the operation, as was expected in accordance with previously described motor development. 14 The preoperative GMFCS levels were III to V in 20 of the 29 children. The latest OMG motor growth study 13 shows that in children with such a high level of motor dysfunction GMFM scores typically deteriorate during adolesence. Clinical experience shows that children with dyskinetic and ataxic CP are less prone to motor function deterioration. On the contrary, motor function often continues to improve at school age. Along with BSCP, these subtypes were included in the OMG study, as was unilateral spastic CP, which is also a subtype associated with fewer functional limitations. Differences in subtypes may influence the results when compared with studies of children with BSCP only, as in this case. Figure 2 shows that improvement in participants classified as GMFCS III and IV was faster in our study than in the OMG study. However, motor development in GMFCS II group was slower than in the OMG study. Both the GMFCS level II and IV groups reached a higher maximum score in our study than in the OMG study, whereas the maximum score achieved by the GMFCS III group was similar to that achieved by the same group in the OMG study. The mean maximum development of GMFM-66 in children undergoing SDR seems to be better than, or at least as good as, that in the OMG study group. However, this result needs to be interpreted with great caution because of the very small size of the SDR group. Motor growth in children classified as GMFCS levels I and V was not compared with the OMG study, as our study included only one child of each level. Another long-term follow-up study after SDR reported a decline in gross motor function capacity between 3 and 10 years postoperatively. 11 However, most of the participants in that study were classified as GMFCS level IV, which greatly influenced the development of the group as a whole. We have shown that changes in gross motor function depend on preoperative GMFCS level, and we therefore believe that it is important to present results for each individual (Fig. 1), as well as by subgroup according to GMFCS level, to achieve a better understanding of the development of gross motor function in children undergoing SDR and physiotherapy. In the present study, the children s preoperative gross motor function was determined according to the original GMFCS classification. At follow-up, the participants were adolescents, and the GMFCS Expanded and Revised version was used. Changes between GMFCS levels may, therefore, reflect real changes in performance in gross motor function and or differences between the two versions. Furthermore, changes may be related to changes in the individual s physical or social environment or, for example, changes in individual preferences. We found that GMFCS levels were unchanged in 21 of the 29 participants, a finding similar to previous reports of stability of the original version of GMFCS. 27 Among the SDR operated children the GMFCS level mainly decreased, reflecting an improvement in gross motor function 10 years after SDR (Table I). The children who underwent SDR were followed at regular intervals by the same clinical team. 5 The six adolescents followed for 5 years differed from the participants followed in this 10-year follow-up study only in that half of them lived outside the region. The larger number of males may be explained by the general sex distribution in spastic diplegia. The prevalence of spastic diplegia in a population of children with CP has previously been reported to be 1.3 per 1000 males and 0.7 per 1000 females. 2 At the time SDR was introduced at our hospital, the preliminary results of randomized controlled studies were available. 7 We chose a prospective practice-based design for our outcome studies. At defined follow-up intervals, the chosen standardized assessments were used to evaluate the clinical effects of ongoing treatment activities and to identify new goals, together with the children, their parents, and physiotherapists. Neither the selection criteria nor treatment have changed over the years. By tracking the children in the clinical follow-up, the selection team have learned who is likely to be suitable for the intervention. We still perform SDR, but less frequently than in as other spasticity treatments, especially botulinum toxin, have become available. The decreasing number of children with severe spastic diplegic CP in younger birth cohorts is another gratifying cause. 28 This longitudinal study presents outcomes in the ICF domains body structure and body function as well as activity. According to the definitions given in a recently published review 7, our study achieves an evidence grade of level IV out 434 Developmental Medicine & Child Neurology 2012, 54:

7 of V: for the first time, a standardized and validated measure, the GMFM-66, has been used to monitor gross motor function capacity over a period of 10 years following SDR. 7 In 1993, when SDR was introduced in our hospital, we chose the Ashworth scale modified by Peacock and Staudt 1 to measure muscle tone, as at that time no more reliable method was available. We have chosen to continue with the same assessment methods conducted by the same physiotherapists over the 10-year period to facilitate follow-up of development in each child. The GMFM-66 measures gross motor function capacity, i.e. what the person can do in specific test situations. This study revealed that functional capacity improved over the follow-up period. An increase in capacity does not automatically lead to improved capability and performance, as it is up to the individual to choose to perform more activities and participate in more events in daily life. To monitor the development of capability and performance in our children adolescents over time, we used the Pediatric Evaluation Disability Inventory (PEDI). In children with more severe functional limitations in particular, the PEDI has been shown to be more sensitive to changes than the GMFM in short-term follow-ups after SDR. 29 The preoperative goals of the intervention in children at GMFCS levels IV to V are rather directed towards a performance of functional skills and independence in activities of daily life than activities of gross motor function as measured with the GMFM, which makes the PEDI a more valid measure for these children. Their long-term PEDI results after SDR will be presented and discussed in a future paper. CONCLUSIONS Children who underwent SDR in combination with physiotherapy and regular follow-ups by an experienced team showed improved motor function for up to 10 years postoperatively. ACKNOWLEDGEMENTS This study was supported by the Medical Faculty at Lund University, the Region Skåne, and the Linnéa and Josef Carlsson s Foundation. REFERENCES 1. Peacock W, Staudt L. Functional outcomes following selective dorsal rhizotomy in children with cerebral palsy. J Neurosurg 1991; 74: Westbom L, Hägglund G, Nordmark E. Cerebral palsy in a total population of 4 11 year olds in southern Sweden. Prevalence and distribution according to different CP classification systems. BMC Pediatr 2007; 7: Nordmark E, Hägglund G, Lauge-Pedersen H, Wagner P, Westbom L. Development of lower limb range of motion from early childhood to adolescence in cerebral palsy: a population-based study. BMC Med 2009; 7: World Health Organization. International Classification of Functioning, Disability and Health (ICF). Geneva: World Health Organization, Nordmark E, Josenby A, Lagergren J, Andersson G, Strömblad L-G, Westbom L. Long-term outcomes five years after selective dorsal rhizotomy. 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