Adam Shortland

Architecture of the medial gastrocnemius in children with spastic diplegia

Ultrasound images were obtained of the medial gastrocnemius at different ankle joint positions with the knee extended. Fascicle length and deep fascicle angle were measured in five normally developing adults (mean age 33 years, age range 24 to 36 years) and in five normally developing children (mean age 7.8 years, age range 7 to 11 years), and in seven children with spastic diplegia (mean age 10 years, age range 6 to 13 years). These architectural variables were similar in the groups of normally developing adults and children. Importantly, no statistical difference could be found between the normally developing children and those with diplegia for fascicle length. Deep fascicle angles were reduced significantly in the clinical group at a particular ankle joint angle but not at the resting angles. The difference in deep fascicle angles is explained as a function of resting muscle length and is not attributed any clinical importance. Our results do not explain the structural origin of muscle contracture explicitly. However, they do indicate that most of the fixed shortness in the medial gastrocnemii of ambulant children with spastic diplegia is not due to reduced muscle fascicle length. We suggest that muscle contracture may be better explained in terms of shortness of the aponeuroses of pennate muscles, such as the medial gastrocnemius, through reduced muscle fascicle diameter.

Sodium channel protein expression enhances the invasiveness of rat and human prostate cancer cells

Expression of Na+ channel protein was analysed in established cell lines of rat and human prostatic carcinoma origin by flow cytometry using a fluorescein‐labelled polyclonal antibody. In many cell lines examined, the obtained frequency distribution profiles were bimodal and identified a subpopulation of cells which expressed high levels of Na+ channel protein. A significant positive correlation was demonstrated between the proportion of channel‐expressing cells and the functional ability of individual cell lines to invade a basement membrane matrix in vitro. In addition, two transfectant cell lines containing rat prostate cancer genomic DNA were found to express significantly elevated levels of Na+ channel protein when compared with the original benign recipient cell line. Enhanced Na+ channel expression by two metastatic derivatives of these transfectant cells directly correlated with increased invasiveness in vitro. These studies strongly support the hypothesis that expression of Na+ channel protein and the metastatic behaviour of prostatic carcinoma cells are functionally related, either by endowing the membranes of these cells with specialised electrophysiological properties (e.g. enhancing their motility and/or secretory activities) and/or by perturbing endogenous mechanisms regulating ionic homeostasis within the cells.

Short-term outcome of multilevel surgical intervention in spastic diplegic cerebral palsy compared with the natural history.

Outcome in 24 ambulant children with spastic diplegic cerebral palsy, in whom multilevel surgical intervention was recommended following gait analysis, is reviewed. Twelve children had surgical intervention (treatment group; eight males, four females; mean age 9 years 10 months, SD 3 years 4 months) while the other 12 did not (control group; five males, seven females; mean age 10 years 1 month, SD 2 years 11 months). All children had interval three-dimensional gait analyses (mean time between analyses: control group, 14.1 months; treatment group, 17.9 months). At follow-up the control group (mean age 11 years 9 months) showed a significant increase in minimum hip and knee flexion in stance which was not related to age, the interval between analyses, changes in the passive joint range of motion, nor changes in anthropometric measurements. The treatment group (mean age at follow-up 11 years 3 months) showed a significant improvement in minimum knee flexion and in ankle dorsiflexion in stance. Parents of nine children said their childs walking distance had increased following intervention. Of five children using posterior walkers preoperatively, two continued to use them postoperatively; two were using crutches or sticks and the remaining child walked independently. Two children who walked independently preoperatively used sticks postoperatively for community ambulation. The deterioration seen in the kinematics of the control group suggests that previous outcome studies comparing postoperative gait with preoperative gait have underestimated the immediate effects of surgery. It also raises concerns about the long-term effects of surgical intervention.

Increases in muscle volume after plantarflexor strength training in children with spastic cerebral palsy

Children with spastic cerebral palsy (CP) have small, weak muscles. However, change in muscle size due to resistance training in this group is unknown. We investigated the effect of plantarflexor strengthening on muscle volume, gait, and function in 13 ambulant children with spastic CP (seven males, six females; mean age 10y 11mo, SD 3y 0mo, range 6y 11mo–16y 11mo; eight with diplegia, five with hemiplegia; Gross Motor Function Classification System level I, six; level II, five; level III, two). Assessments were performed before training, 5 and 10 weeks into training, and at a 3‐month follow‐up. Medial and lateral gastrocnemius volumes were computed from three‐dimensional ultrasound images. The number of unilateral heel raises able to be achieved on each side was assessed. Function was measured using three‐dimensional gait analysis, the ‘timed up and go’ test, the Gillette Functional Assessment Questionnaire, and the Functional Mobility Scale. Training involved heel raises or Thera‐Band resistance, 4 times a week for 10 weeks. Medial and lateral gastrocnemius volumes increased by 17 and 14% at week 5 (p=0.03, p=0.028). This increase was maintained at week 10 and follow‐up (medial gastrocnemius p=0.001, p<0.001; lateral gastrocnemius p=0.006, p=0.007). Heel raises (mean number) increased by week 5 (p=0.002). This was maintained at week 10 and follow‐up (p<0.001; p<0.001). No significant change in measured function was observed. Muscle volume increased in response to training in children with spastic CP. The role of progressive strength training in maintaining long‐term function is discussed.

Changes in the Volume and Length of the Medial Gastrocnemius After Surgical Recession in Children With Spastic Diplegic Cerebral Palsy

Background: Morphology is an important determinant of muscle force and power generation. Children with spastic diplegic cerebral palsy (SDCP) have reduced muscular strength, which in part is caused by inadequate muscle growth. There is a widespread concern that surgery to correct soft tissue deformities may exacerbate the underlying muscle weakness and further retard muscle growth. In this study, we compared measurements of medial gastrocnemius (MG) muscle morphology in typically developing (TD) children to those in children with SDCP with calf muscle deformities before and after corrective surgery. Methods: We measured the length and volume of the MG muscle belly using 3-dimensional ultrasound immediately before and at 7 weeks and 1 year after vulpius procedure (VP) surgery in children with SDCP. We made similar measurements in a group of TD children. The SDCP group consisted of 7 children (6 boys, 1 girls; total of 8 limbs; age range, 6-10 years; mean 8 years 1 month, SD ± 1 year 11 months) and the TD group consisted of 10 children (4 boys, 6 girls; age range, 6-12 years; mean, 9 years 5 months; SD ± 2 years 6 months). Results: The children with SDCP presented with MG muscle bellies both smaller and shorter than the TD children even when normalized to body mass and limb length, respectively. Muscle belly length was reduced by surgery and remained unaltered 1 year later, despite skeletal growth. Muscle volume was not significantly changed 7 weeks after surgery, but increased significantly between 7 weeks and 1 year after surgery. Conclusions: Children with SDCP presented with short and small MG when compared with TD children. Our results indicate that gastrocnemius muscle volume recovers within a year of VP surgery. Clinical Relevance: This study is the first to investigate the effects of surgery on muscle belly volume and length in the human subject. The study indicates that VP surgery is not an agent of long-term muscle atrophy in individuals with SDCP with plantarflexion deformities.

Muscle deficits in cerebral palsy and early loss of mobility: can we learn something from our elders?

Ambulant young people with cerebral palsy (CP) have reduced muscle volumes in their lower limbs (as low as 50% of their weight‐matched typically‐developing peers). Yet, they may complete a ‘timed up‐and‐go’ test at similar speeds to unaffected persons. Perhaps, these individuals are able to maintain high levels of function because their muscle deficits have not fallen below the threshold values required to perform certain motor tasks. This is consistent with data from studies of progressive strengthening in children with mild CP. These programmes improve muscular output but have limited immediate effect on functional capacity. Sarcopenia is responsible for much of the loss of muscle mass in the typically developing adult. The decline in muscle mass begins in the mid‐twenties and occurs rapidly after the 7th decade. It is possible that the muscle deficits characteristic of young people with CP, coupled with the decline of muscle properties in adulthood, contribute to an early loss of mobility in this group. In the typically developing elderly, progressive strengthening is thought to extend mobility. Perhaps, the real value of strengthening programmes in CP is to improve muscular reserve in the short‐term and to maintain muscle mass above critical thresholds in the long‐term.

Could muscle deformity in children with spastic cerebral palsy be related to an impairment of muscle growth and altered adaptation

Skeletal muscle deformity is common in children with spastic cerebral palsy (CP), but the underlying mechanisms are unclear. This review explores some possible factors which may influence the development of muscle deformity in CP. Normal muscle function and growth appear to depend on the interaction of neuronal, endocrinal, nutritional, and mechanical factors, and also on the development of an appropriate balance between muscle protein synthesis and degradation, and between the development of contractile and non‐contractile components. In this context, the changes seen in muscle in children with CP are reviewed and discussed. It is suggested that the development of muscle deformity in children with CP may be related to a multifactorial impairment of muscle growth, on which adaptation of the extracellular matrix due to altered loading may be imposed.

Botulinum toxin and cerebral palsy: time for reflection?

Botulinum toxin A (BTX-A) is increasingly being used in early management of spasticity in ambulant children with cerebral palsy (CP), with the aim of improving function, promoting muscle growth, and delaying the need for surgical intervention. However, there is a lack of evidence about the long-term outcome of BTX-A injections. The focus on spasticity as the predominant problem in younger children with spastic CP may not fully consider the associated muscle weakness. It also raises concern that although BTX-A may improve function in the short term, it has the potential to affect muscle growth and function adversely in the long term. A cautious approach to the early use of BTX-A, with the use of objective outcome measures within a specialized multidisciplinary setting, is recommended, particularly in ambulant children with spastic diplegic CP, until further evidence is available on the long-term outcome of early BTX-A injections in children with CP.

Lower limb muscle volumes in bilateral spastic cerebral palsy.

AIM Muscle weakness is a feature of individuals with spastic cerebral palsy (SCP) but there are few reports in the literature of muscle volume in this group. This study compares muscle volumes in adolescents and young adults with SCP with those of their typically developing (TD) peers. DESIGN Measurements of the volumes of nine major lower limb muscles in 19 independently ambulant subjects with SCP (mean age 14.2 years (sd 2.7), 11 male, GMFCS I (n=5); GMFCS II (n=14)), 19 TD subjects (mean age 16.5 years (sd 3.0), 11 male) were made using magnetic resonance imaging. RESULTS Lower limb muscles were smaller in the SCP group (p≤0.023 in all muscles) than the TD group with the exception of the vastii (lateralis+intermedius; p=0.868) and gluteus maximus (p=0.056). Average muscle volume deficit was 27.9%. Muscle volume deficits were significantly greater for distal muscles than proximal muscles (p<0.001). CONCLUSIONS Reduced muscle size in adolescence and the natural history of sarcopenia in adulthood may contribute to the early loss of mobility of adults with SCP.

Accurate measurement of muscle belly length in the motion analysis laboratory: potential for the assessment of contracture

Two-dimensional ultrasound imaging was combined with motion analysis technology to measure distances between remote anatomical landmarks. The length of the belly of the medial gastrocnemius muscle in five normal adults (nine limbs) was estimated using this technique. Our results in vivo were similar to the reported data for the lengths of muscles in cadavers, and were consistent with the expected relationship between muscle belly length and ankle joint angle. Experiments in vitro demonstrated that the accuracy of the device was better than 2 mm over 20 cm. Measurements on the same subject on different occasions showed that the results were repeatable in vivo. Rendering of the reconstructed volume of a foam phantom gave results comparable to photographic images. This validated technique could be used to measure muscle lengths in children with spastic cerebral palsy and indicate which muscles had fixed shortening, and to what extent.