In conclusion, more research is needed on neuromotor interventions with respect to old and new treatment modalities and their place in an overall rehabilitation program, and on the methods for individualizing and modifying them for a patient-specific treatment plan. Until such
data become available, our job as clinicians will continue to be that of tailoring the best neuromotor interventional plan for our patient and, based on what we know, to guide parents in how to provide the best possible care for a child with CP.
REFERENCES 1. Novak I, McIntyre S, Morgan C, et al. A systematic
3. Rackauskaite G, Uldall PW, Bech BH, Østergaard JR.
5. Parkes J, Hill N, Dolk H, Donnelly M. What influences
review of interventions for children with cerebral palsy:
Impact of child and family characteristics on cerebral
physiotherapy use by children with cerebral palsy? Child
state of the evidence. Dev Med Child Neurol 2013; 55:
palsy treatment. Dev Med Child Neurol 2015; 57:
885–910.
948–54.
Care Health Dev 2004; 30: 151–60. 6. Elkamil AI, Andersen GL, Skranes J, Lamvik T, Vik T.
2. Majnemer A, Shikako-Thomas K, Lach L, et al.
4. Bailes AF, Succop P. Factors associated with physical
Botulinum neurotoxin treatment in children with cere-
Rehabilitation service utilization in children and youth
therapy services received for individuals with cerebral
bral palsy: a population-based study in Norway. Eur J
with cerebral palsy. Child Care Health Dev 2014; 40:
palsy in an outpatient pediatric medical setting. PhysTher
Paediatr Neurol 2012; 16: 522–7.
275–82.
2012; 92: 1411–8.
The Duncan-Ely test: time for standardization SUSAN STOTT University of Auckland – Department of Surgery, Faculty of Medical and Health Sciences, Auckland, New Zealand. doi: 10.1111/dmcn.12794 This commentary is on the original article by Lee et al. on pages 963–968 of this issue.
Stiff-knee gait is one of the most common gait patterns in children with cerebral palsy (CP) and is characterized by decreased dynamic range of knee flexion throughout the gait cycle, with reduced and delayed peak knee flexion in swing. Stiff-knee gait often leads to problems with foot clearance in swing, due to inadequate or poorly timed knee flexion, with consequent tripping and falling. One cause of stiff-knee gait is thought to be overactivity in the rectus femoris muscle. In normal gait, rectus femoris is active only from late pre-swing through to early initial swing and plays a primary role in restraining excessive passive knee flexion at the onset of swing.1 However, in children with CP, premature onset of rectus femoris activity during the first half of pre-swing is common and strongly associated with the features of stiffknee gait on three-dimensional gait analysis.2 The prone rectus test, or Duncan-Ely test, is widely used to determine overactivity in rectus femoris; with the patient positioned in prone, the knee is flexed and the effect on the ipsilateral hip observed. In its simplest form, the test is described as positive if there is a rise of the ipsilateral hip off the bed, or as negative if there is no hip rise. More recently, authors have sought to further quantify the measure, by using the Ashworth Scale to describe the degree of resistance to flexion or ‘estimating’ the knee flexion angle at which the hip rise occurs.3 The presence of a positive Duncan-Ely test is one of a number of indications for a distal rectus femoris
transfer to address stiff-knee gait. Different authors are divided on the importance of this test; some arguing that a positive test is a predictor of better surgical outcomes, while others not finding any relationship between the presence of a positive Duncan-Ely test and surgical success.3,4 Lee et al.5 present a carefully done study of the reliability and validity of the Duncan-Ely test, measuring the knee flexion angle at which hip rise occurs when performed at three different speeds, based on the Tardieu descriptions of V1 (slow as possible); V2 (at the naturally occurring speed with gravity); and V3 (as fast as possible). Their results highlight the importance of standardization in performing the test, achieving single-rater intraclass correlation coefficients above 0.8 when knee flexion is performed at the fastest possible speed (V3). Rapid knee flexion at V3 also had the best performance accuracy, with overall good sensitivity and specificity of the knee flexion angle for one of the descriptors of stiff-knee gait, decreased dynamic knee flexion in the gait cycle. Intriguingly, the knee flexion angle had poorer performance accuracy for other aspects of stiff-knee gait, such as reduced and delayed peak knee flexion in swing. As the authors acknowledge, both rectus femoris and iliopsoas muscles fire during the performance of the Duncan-Ely test and this may have had an impact on the performance accuracy of the test when compared to three-dimensional gait parameters in swing.6 Nevertheless, the authors are to be commended for their attention to detail. Now that the Duncan-Ely test can be reliably performed and quantified, the next step is to assess how the knee flexion angle relates to different gait patterns, whether it changes with age, and the extent to which clinicians can rely on it as a predictor of post-operative success after rectus femoris transfer. Commentaries
895
REFERENCES 4. Muthusamy K, Seidl AJ, Friesen RM, Carollo JJ, Pan
6. Perry J, Hoffer MM, Antonelli D, Plut J, Lewis G,
Z, Chang FM. Rectus femoris transfer in children
Greenberg R. Electromyography before and after surgery
2. Knuppe AE, Bishop NA, Clark AJ, Alderink GJ, Barr
with cerebral palsy: evaluation of transfer site and
for hip deformity in children with cerebral palsy. J Bone
KM, Miller AL. Prolonged swing phase rectus femoris
preoperative indicators. J Pediatr Orthop 2008; 28:
Joint Surg Am 1976; 58: 201–8.
activity is not associated with stiff-knee gait in children
674–8.
1. Perry J. Gait Analysis: Normal and Pathological Function. Thorofare, NJ: SLACK Inc, 1992: 95.
with cerebral palsy: a retrospective study of 407 limbs. Gait Posture 2013; 37: 345–8. 3. Kay RM, Rethlefsen SA, Kelly JP, Wren TA. Predictive value of the Duncan-Ely test in distal rectus femoris
5. Lee SY, Sung KH, Chung CY, et al. Reliability and validity of the Duncan-Ely test for assessing rectus femoris spasticity in patients with cerebral palsy. Dev Med Child Neurol 2015; 57: 963–8.
transfer. J Pediatr Orthop 2004; 24: 59–62.
GLUT1 deficiency syndrome and ketogenic diet therapies: missing rare but treatable diseases? JOERG KLEPPER Department of Pediatrics, Klinikum Aschaffenburg, Aschaffenburg, Germany. doi: 10.1111/dmcn.12807 This commentary is on the the original article by Schoeler et al. on pages 969–976 of this issue.
Every paediatrician recognizes that his/her knowledge of rare diseases is limited. We all share a substantial basic fear that we might miss a treatable disease in a complex patient. Glucose transporter type 1 deficiency syndrome (GLUT1-DS) is such a disease. It is caused by impaired glucose transport into brain. The resulting brain energy crisis causes seizures, developmental delay, and movement abnormalities in children. It is diagnosed by isolated low cerebrospinal glucose and/or mutations in the SLC2A1 gene and can be treated very effectively by ketogenic diet therapies (KDT). These diets provide ketones as an alternative fuel to the brain, effectively controlling seizures and improving development.1 Schoeler et al.2 have investigated whether a positive response to KDT indicates undiagnosed GLUT1-DS. The condition was identified in 1 out of 246 participants (0.4%) by SLC2A1 gene analysis. However, 2 out of 246 participants (0.8%) without SLC2A1 mutations were seizure-free at every follow-up point and single-variant and gene burden association tests gave no significant results. The authors concluded that a favourable response to KDT is not solely explained by mutations in SLC2A1. The paper raises several important questions.
Is a favourable response to KDT a useful tool to identify undiagnosed GLUT1-DS? The answer is ‘yes’: in general it seems justified to consider rare but treatable diseases even if a single patient may benefit from the diagnosis. Also, Schoeler et al. based the
896 Developmental Medicine & Child Neurology 2015, 57: 890–8
diagnosis on SLC2A1-mutations alone: lumbar punctures were not performed in all cases. SLC2A1-negative variants presenting with isolated hypoglycorrachia may have remained undiagnosed. These patients exist – a recent report from Japan classified 4 out of 32 patients (12.5%) as SLC2A1-negative.3
Who will benefit from KDT? KDTs are established non-pharmacological therapies for intractable childhood epilepsy. The modified Atkins diet or the low glycemic index treatment have further improved compliance and effectiveness and have expanded KDT beyond childhood epilepsy into adult neurological and metabolic disease.4 KDT are the treatment of choice for GLUT1-DS and pyruvate dehydrogenase deficiency. Younger children respond better and increasing data indicates that in Dravet syndrome, tuberous sclerosis complex, and myoclonic astatic epilepsy, KDT appear especially beneficial. However, as stated in the article we are still lacking predictive parameters. What are the implications of this article? Clinical implications are threefold: (1) KDT are effective beyond GLUT1-DS; (2) consider GLUT1-DS when KDT are beneficial; and (3) the diagnosis of GLUT1-DS is based on hypoglycorrhachia and SLC2A1 mutations. Future research should focus on parameters indicating a favourable response to KDT. In SLC2A1-negative variants the potential disease mechanisms downstream of DNA mutations such as impaired mRNA splicing, protein assembly, transportation, intracellular storaging, and activation need to be investigated.5 Finally, it is about time to establish an international clinical classification of GLUT1-DS. In this context a patient databank recently established by UT Southwestern Medical Center, University of Texas will contribute to achieve this goal (www.g1dregistry.org).
data become available, our job as clinicians will continue to be that of tailoring the best neuromotor interventional plan for our patient and, based on what we know, to guide parents in how to provide the best possible care for a child with CP.
REFERENCES 1. Novak I, McIntyre S, Morgan C, et al. A systematic
3. Rackauskaite G, Uldall PW, Bech BH, Østergaard JR.
5. Parkes J, Hill N, Dolk H, Donnelly M. What influences
review of interventions for children with cerebral palsy:
Impact of child and family characteristics on cerebral
physiotherapy use by children with cerebral palsy? Child
state of the evidence. Dev Med Child Neurol 2013; 55:
palsy treatment. Dev Med Child Neurol 2015; 57:
885–910.
948–54.
Care Health Dev 2004; 30: 151–60. 6. Elkamil AI, Andersen GL, Skranes J, Lamvik T, Vik T.
2. Majnemer A, Shikako-Thomas K, Lach L, et al.
4. Bailes AF, Succop P. Factors associated with physical
Botulinum neurotoxin treatment in children with cere-
Rehabilitation service utilization in children and youth
therapy services received for individuals with cerebral
bral palsy: a population-based study in Norway. Eur J
with cerebral palsy. Child Care Health Dev 2014; 40:
palsy in an outpatient pediatric medical setting. PhysTher
Paediatr Neurol 2012; 16: 522–7.
275–82.
2012; 92: 1411–8.
The Duncan-Ely test: time for standardization SUSAN STOTT University of Auckland – Department of Surgery, Faculty of Medical and Health Sciences, Auckland, New Zealand. doi: 10.1111/dmcn.12794 This commentary is on the original article by Lee et al. on pages 963–968 of this issue.
Stiff-knee gait is one of the most common gait patterns in children with cerebral palsy (CP) and is characterized by decreased dynamic range of knee flexion throughout the gait cycle, with reduced and delayed peak knee flexion in swing. Stiff-knee gait often leads to problems with foot clearance in swing, due to inadequate or poorly timed knee flexion, with consequent tripping and falling. One cause of stiff-knee gait is thought to be overactivity in the rectus femoris muscle. In normal gait, rectus femoris is active only from late pre-swing through to early initial swing and plays a primary role in restraining excessive passive knee flexion at the onset of swing.1 However, in children with CP, premature onset of rectus femoris activity during the first half of pre-swing is common and strongly associated with the features of stiffknee gait on three-dimensional gait analysis.2 The prone rectus test, or Duncan-Ely test, is widely used to determine overactivity in rectus femoris; with the patient positioned in prone, the knee is flexed and the effect on the ipsilateral hip observed. In its simplest form, the test is described as positive if there is a rise of the ipsilateral hip off the bed, or as negative if there is no hip rise. More recently, authors have sought to further quantify the measure, by using the Ashworth Scale to describe the degree of resistance to flexion or ‘estimating’ the knee flexion angle at which the hip rise occurs.3 The presence of a positive Duncan-Ely test is one of a number of indications for a distal rectus femoris
transfer to address stiff-knee gait. Different authors are divided on the importance of this test; some arguing that a positive test is a predictor of better surgical outcomes, while others not finding any relationship between the presence of a positive Duncan-Ely test and surgical success.3,4 Lee et al.5 present a carefully done study of the reliability and validity of the Duncan-Ely test, measuring the knee flexion angle at which hip rise occurs when performed at three different speeds, based on the Tardieu descriptions of V1 (slow as possible); V2 (at the naturally occurring speed with gravity); and V3 (as fast as possible). Their results highlight the importance of standardization in performing the test, achieving single-rater intraclass correlation coefficients above 0.8 when knee flexion is performed at the fastest possible speed (V3). Rapid knee flexion at V3 also had the best performance accuracy, with overall good sensitivity and specificity of the knee flexion angle for one of the descriptors of stiff-knee gait, decreased dynamic knee flexion in the gait cycle. Intriguingly, the knee flexion angle had poorer performance accuracy for other aspects of stiff-knee gait, such as reduced and delayed peak knee flexion in swing. As the authors acknowledge, both rectus femoris and iliopsoas muscles fire during the performance of the Duncan-Ely test and this may have had an impact on the performance accuracy of the test when compared to three-dimensional gait parameters in swing.6 Nevertheless, the authors are to be commended for their attention to detail. Now that the Duncan-Ely test can be reliably performed and quantified, the next step is to assess how the knee flexion angle relates to different gait patterns, whether it changes with age, and the extent to which clinicians can rely on it as a predictor of post-operative success after rectus femoris transfer. Commentaries
895
REFERENCES 4. Muthusamy K, Seidl AJ, Friesen RM, Carollo JJ, Pan
6. Perry J, Hoffer MM, Antonelli D, Plut J, Lewis G,
Z, Chang FM. Rectus femoris transfer in children
Greenberg R. Electromyography before and after surgery
2. Knuppe AE, Bishop NA, Clark AJ, Alderink GJ, Barr
with cerebral palsy: evaluation of transfer site and
for hip deformity in children with cerebral palsy. J Bone
KM, Miller AL. Prolonged swing phase rectus femoris
preoperative indicators. J Pediatr Orthop 2008; 28:
Joint Surg Am 1976; 58: 201–8.
activity is not associated with stiff-knee gait in children
674–8.
1. Perry J. Gait Analysis: Normal and Pathological Function. Thorofare, NJ: SLACK Inc, 1992: 95.
with cerebral palsy: a retrospective study of 407 limbs. Gait Posture 2013; 37: 345–8. 3. Kay RM, Rethlefsen SA, Kelly JP, Wren TA. Predictive value of the Duncan-Ely test in distal rectus femoris
5. Lee SY, Sung KH, Chung CY, et al. Reliability and validity of the Duncan-Ely test for assessing rectus femoris spasticity in patients with cerebral palsy. Dev Med Child Neurol 2015; 57: 963–8.
transfer. J Pediatr Orthop 2004; 24: 59–62.
GLUT1 deficiency syndrome and ketogenic diet therapies: missing rare but treatable diseases? JOERG KLEPPER Department of Pediatrics, Klinikum Aschaffenburg, Aschaffenburg, Germany. doi: 10.1111/dmcn.12807 This commentary is on the the original article by Schoeler et al. on pages 969–976 of this issue.
Every paediatrician recognizes that his/her knowledge of rare diseases is limited. We all share a substantial basic fear that we might miss a treatable disease in a complex patient. Glucose transporter type 1 deficiency syndrome (GLUT1-DS) is such a disease. It is caused by impaired glucose transport into brain. The resulting brain energy crisis causes seizures, developmental delay, and movement abnormalities in children. It is diagnosed by isolated low cerebrospinal glucose and/or mutations in the SLC2A1 gene and can be treated very effectively by ketogenic diet therapies (KDT). These diets provide ketones as an alternative fuel to the brain, effectively controlling seizures and improving development.1 Schoeler et al.2 have investigated whether a positive response to KDT indicates undiagnosed GLUT1-DS. The condition was identified in 1 out of 246 participants (0.4%) by SLC2A1 gene analysis. However, 2 out of 246 participants (0.8%) without SLC2A1 mutations were seizure-free at every follow-up point and single-variant and gene burden association tests gave no significant results. The authors concluded that a favourable response to KDT is not solely explained by mutations in SLC2A1. The paper raises several important questions.
Is a favourable response to KDT a useful tool to identify undiagnosed GLUT1-DS? The answer is ‘yes’: in general it seems justified to consider rare but treatable diseases even if a single patient may benefit from the diagnosis. Also, Schoeler et al. based the
896 Developmental Medicine & Child Neurology 2015, 57: 890–8
diagnosis on SLC2A1-mutations alone: lumbar punctures were not performed in all cases. SLC2A1-negative variants presenting with isolated hypoglycorrachia may have remained undiagnosed. These patients exist – a recent report from Japan classified 4 out of 32 patients (12.5%) as SLC2A1-negative.3
Who will benefit from KDT? KDTs are established non-pharmacological therapies for intractable childhood epilepsy. The modified Atkins diet or the low glycemic index treatment have further improved compliance and effectiveness and have expanded KDT beyond childhood epilepsy into adult neurological and metabolic disease.4 KDT are the treatment of choice for GLUT1-DS and pyruvate dehydrogenase deficiency. Younger children respond better and increasing data indicates that in Dravet syndrome, tuberous sclerosis complex, and myoclonic astatic epilepsy, KDT appear especially beneficial. However, as stated in the article we are still lacking predictive parameters. What are the implications of this article? Clinical implications are threefold: (1) KDT are effective beyond GLUT1-DS; (2) consider GLUT1-DS when KDT are beneficial; and (3) the diagnosis of GLUT1-DS is based on hypoglycorrhachia and SLC2A1 mutations. Future research should focus on parameters indicating a favourable response to KDT. In SLC2A1-negative variants the potential disease mechanisms downstream of DNA mutations such as impaired mRNA splicing, protein assembly, transportation, intracellular storaging, and activation need to be investigated.5 Finally, it is about time to establish an international clinical classification of GLUT1-DS. In this context a patient databank recently established by UT Southwestern Medical Center, University of Texas will contribute to achieve this goal (www.g1dregistry.org).
