Motor Development and Disorders


Motor Development and Disorders

Catherine Morgan, PhD Michael E. Msall, MD, FAAP


Typical Versus Atypical Development

Motor milestones are rapidly achieved in the first year of life with very few differences noted cross-culturally. This is helpful for primary pediatric health care professionals, as the typical sequential attainment of milestones in early childhood provides a window into neurodevelopment. Variations in both timing and sequence of milestone acquisition are often the first red flags alerting clinicians that all is not well developmentally. Differentiating between typical development that is simply slower than average and early signs of a more global delay or a defined neurodevelopmental disorder is not always straightforward. Developmental assessments are based on a neuromaturational model of development; however, current indications are that development is not linear but is a result of interaction between multiple subsystems.1 It has been shown in typically developing children that progression on formal testing is not stable, and infants can move between percentile ranks.2 Moreover, most children with disabilities continue to make some progress, and it is often not until a series of assessments are carried out that the rate of development is regarded as significantly slow enough to warrant further investigations or intervention. Unfortunately, this approach often delays access to intervention in the period of most rapid neural change.

The WHO Multicentre Growth Reference Study3 provides helpful windows of achievement of gross motor skills. This longitudinal study, which followed 816 children from 5 different cultural groups (Ghana, India, Norway, Oman, and the United States) from 4 to 24 months of age, demonstrated the normal variation in gross motor milestone achievement in healthy children (see Table 14.1). This study found that the sequence of development chiefly varied with respect to the timing of crawling on the hands and knees. Most infants achieved this skill prior to walking with assistance; however, 8.5% did not crawl until later, and a further 4.3% never achieved crawling on the hands and knees. In this study, the narrowest window of achievement was for independent sitting. Ninety-nine percent of infants were sitting by 9 months, and the average age for sitting was 5.9 months. The age for independent walking ranged from 8 to 17 months with a mean age of 12 months; however, the mean age for walking with assistance was significantly earlier at 9 months.


Adapted with permission from WHO Multicentre Growth Reference Study Group. WHO Motor Development Study: windows of achievement for six gross motor development milestones. Acta Paediatr. 2006;95(S450):86–95.

Hand function emerges early in life with simple holding of toys beginning at 2 months and quickly developing into intentional grasping and mouthing of toys at around 3 to 4 months. By 6 months, infants can reach unilaterally and grasp a toy, transfer toys between hands, and can use both hands in coordinated action by 7 months. Coor-dinated sequential actions and more refined grasps are present by 9 to 10 months.

Primary pediatric health care professionals have at their disposal a number of screening instruments that can be utilized to identify early signs of developmental delay. The Ages & Stages Questionnaires (ASQ) with the following 3 extra questions are a good place to start when parents present concern about their infants’ motor development4:

1.Is there anything your baby (or child) is doing with his or her arms, legs or body movements that concerns you?

2.Is there anything your baby (or child) is not doing with his or her arms, legs and body movements that concerns you?

3.Is there anything that you have tried to teach your infant (or child) to do involving his or her hands or whole body movement that has taken longer to learn than you think it should?

The American Academy of Pediatrics (AAP) provides a useful algorithm for evaluation of motor delay beginning at 9 months of age.5 Signs of motor delay, however, are often evident prior to 4 months of age, including poor head control in prone and supported sitting, as well as incomplete visual tracking. Early asymmetries in hand function are not regarded as normal, and handedness is not apparent until between 2 and 4 years of age. Any asymmetry ought to be closely monitored or investigated more thoroughly, including brain magnetic resonance imaging (MRI) and evaluation by a physician, occupational therapist, or physical therapist. The primary pediatric health care professional might not be able to determine if these early delays are purely motor or more global at this time; however, referral for more thorough assessment and early intervention ought not to be delayed.

Motor delays that should prompt referral for early intervention include:

1.Poor head control at 4 months in prone or supported sitting

2.Asymmetry in upper limb function at any age

3.Not using hands purposefully by 4 months

4.Not sitting independently or taking weight through the feet by 9 months

5.Parental concern based on rate of development or unusual postures or movements

Spectrum of Motor Disorders

The spectrum of motor disorders in childhood is wide ranging from high prevalence, lower morbidity disorders such as developmental coordination disorder [DCD], to low prevalence, higher morbidity conditions such as cerebral palsy [CP]. Some authors have postulated that a continuum exists between these disorders because both are nonprogressive and occur in the developing brain.6

Developmental Coordination Disorder

The terms developmental dyspraxia, minimal/minor neurological dysfunction, and clumsy child syndrome have all been used to describe the same clinical presentation; however, the most generally accepted terminology is now developmental coordination disorder or DCD. Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition7 criteria required other general medical conditions (eg, intellectual disability, epilepsy, or autism spectrum disorder [ASD] to be excluded and required the motor impairment to be disproportionately impaired compared to verbal and nonverbal cognitive abilities. However, as motor coordination difficulties are a common marker for higher risk for a spectrum of comorbid communicative, cognitive, attention, and autism spectrum disorders, a broader perspective is in order. The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5)8 and the European Academy of Childhood Disability9 have emphasized the critical importance of a qualitative and quantitative approach to this disorder linked to evidence-based support.

Developmental coordination disorder affects approximately 5% to 6% of school-aged children, and children born preterm are 6 to 8 times more likely to be diagnosed with the condition.10 Developmental coordination disorder is often not diagnosed until at least 5 years of age, although screening and the start of treatment can occur earlier. Children with this condition experience significant difficulties with activities of daily living and academic achievement due to poor performance of gross and fine motor skills.10

Although DCD is regarded as a mild motor disorder when compared to CP, the effects on the child’s and family’s quality of life can be significant.11 In 2011, the European Academy of Childhood Disability produced comprehensive clinical guidelines for the diagnosis, assessment, and management of DCD.12,13 Among these recommendations was evidence that task-oriented training approaches were more effective in improving motor function than sensory motor integration therapies. A subsequent systematic review and meta-analysis confirmed that interventions such as neuromotor task training and cognitive orientation to occupational performance have a larger effect on outcome than traditional approaches.14

Cerebral Palsy

Cerebral palsy is a heterogeneous condition and the most common physical disability of childhood. Current prevalence is estimated at 1 in 500 live births in developed countries.

Cerebral palsy is defined as “a group of disorders of the development of movement and posture, which are attributed to non-progressive lesions of the developing fetal or infant brain. The motor disorders of cerebral palsy are often accompanied by disturbances of sensation, perception, cognition, communication, and behaviour, by epilepsy, and by secondary musculoskeletal problems.”15

The diagnostic label “cerebral palsy” does not imply anything about etiology or severity and is regarded as a clinical descriptive diagnosis.16 To achieve a level of consistency in the use of the term CP, worldwide CP register groups have adopted a set of inclusion and exclusion criteria.17 However, some discrepancies remain. For example, the Surveillance for Cerebral Palsy in Europe excludes central hypotonia as a subgroup of CP, while other registers include these children as hypotonic CP.18 Both groups, however, emphasize that this hypotonia is of central nervous system origin and does not involve hypotonia with flaccid weakness. The latter is characteristic of processes involving spinal cord, muscle, or peripheral nerves. There is very rarely one specific cause of CP, and hence the phrase “causal pathways to cerebral palsy” is best used to describe etiology.19 Much research has been done to identify individual risk factors for CP; however, little is understood about how risk factors diverse in timing act together to produce an eventual diagnosis of CP.20

– Type and Topography

There are 3 major classifications used to describe cases of CP: physiological motor type, topography, and function. The motor type and topography classifications are more traditional but notoriously unreliable.20 Major advances have occurred in describing gross motor, manual ability, communicative, eating and drinking, and self-care functioning.

When classifying based on physiological motor type, the movement disorder is described based on

1.spasticity (velocity-dependent resistance to stretch),

2.dyskinesia (choreoathetosis [hyperkinesia with hypotonia] or dystonia [hypokinesia with hypertonic movements characterized by involuntary twisting postures or repetitive movements]; includes nearly 4% to 7% of children with CP),

3.ataxia (loss of coordination with abnormal movement force, rhythm, and accuracy; includes 4% to 6% of children with CP), and

4.hypotonia (pure, generalized decreased muscle tone without flaccid weakness; includes only 2% of children with CP).20

When classifying based on topography, the following categories are used: hemiplegia/ unilateral (involvement of 1 side of the body; includes about 38% of children with CP), diplegia (both lower limbs affected more so than upper limbs; includes about 36% of children with CP), and quadriplegia (all 4 limbs affected with upper limbs at least as affected as lower limbs; includes about 26% of children with CP). There are also rare cases in which only 1 limb is affected (monoplegia) or 1 upper limb is spared (triplegia). In Europe, diplegia and quadriplegia are collapsed into one category, known as bilateral CP, in order to increase reliability of classification.20

Functional classifications are very helpful for clinicians both for describing severity of impairment and for prognosticating about future needs. Two motor classifications for both gross motor function (Gross Motor Function Classification Scale [GMFCS]) and manual ability (Manual Ability Classification Scale [MACS]) are now widely used, and recently, a communicative functioning classification scale (CFCS) and an eating and drinking ability classification scale (EADACS) have been added.

The Gross Motor Function Classification Scale (GMFCS), considered to be the “contemporary gold standard” of CP classification, is a 5-level ordered scale describing an individual’s functional mobility.20,21 GMFCS classification is based on the child’s ability to sit, transfer, and mobilize (see Figure 14.1).20

The GMFCS was initially developed for children from 6 to 12 years of age, but an expanded and revised version was later developed for ages 2 to 18 years.22 It is also important to be cautious in using the current GMFCS among children under 2 years of age, as 40% will change their level.23

Motor development curves for CP incorporating GMFCS levels are widely used to discuss prognosis with families and plan achievable rehabilitation goals.24 Longitudinal assessment of these curves demonstrates that children with CP achieve 90% of their gross motor development potential by age 5 years across all GMFCS levels.24 In addition, children at GMFCS level V reach this point before 3 years of age.24 When counseling families, it is important to note that, based on GMFCS prevalence rates, mild CP is more common than severe CP.20


Figure 14.1. Gross motor function classification scale (GMFCS).

Reproduced with permission. Copyright © Bill Reid, Kate Willoughby, Adrienne Harvey, and Kerr Graham, The Royal Children’s Hospital; CanChild.

The Manual Ability Classification Scale (MACS) and mini-MACS (used prior to age 4 years) classify how children with CP use their hands in everyday activities.25,26 These 5-level scales range from “handles objects easily and successfully” to “does not handle objects and has severely limited ability to perform even simple actions.”25,26 Studies have shown there is not always a high correlation between MACS and GMFCS levels; however, the relationship is variable across subgroups of children with hemiplegia, diplegia, and quadriplegia.27 It is recommended that both measures are used in clinical practice.

– Prevalence

Over 750,000 children and adults in the United States are affected by CP. The lifetime cost of CP was estimated to be $1 billion per individual and $1.2 billion in direct medical costs for all children born with CP in the year 2000.28 However, because accurate population tracking similar to the Centers for Disease Control and Prevention (CDC) Autism Surveillance Network is not currently taking place in the United States, these aggregated costs should be viewed as a preliminary estimate.

– Diagnosing Cerebral Palsy

Risk Factors

Risk factors for CP are various, reflecting the heterogeneity of the condition. Approximately 40% of all children with CP were born preterm, yet less than 10% of all preterm infants go on to have CP.29 Cerebral palsy has frequently been linked with both prematurity and low birth weight in the United States, Australia, Scandinavia, and Western Europe. In one European study, it was found that approximately 54% of children with CP were born at term gestation while 18% were born at 32 to 36 weeks’ gestation, 16% were born at 28 to 31 weeks’ gestation, and 11% were born at <28 weeks’ gestation.30

There are 5 particularly important risk factors for CP in preterm cohorts. The first is the presence of parenchymal brain injury (intraventricular hemorrhage grade 3 or 4, ventriculomegaly, or cystic periventricular leukomalacia [PVL]). One study found that while cystic PVL was highly predictive of future CP, it was not predictive of outcome severity.22 Furthermore, in this study, cystic PVL and a related lesion of periventricular hemorrhagic infarction (PVHI) could account for only 32% of CP cases and 13% of cognitive disability cases.28 Therefore, it has been concluded that brain abnormalities other than PVHI and cystic PVL are likely responsible for a significant percentage of preterm CP cases.28

The second key risk factor for CP is multiple gestation. There is evidence that twin pregnancies have a higher rate of CP than singleton pregnancies (20 in 1,000 compared to 2 in 1,000) and that the rate continues to increase for pregnancies of triplets (100 in 1,000) and quadruplets (500 in 1,000).28

The other 3 key risk factors for CP are chronic lung disease (determined by the need for supplemental oxygen at 36 weeks’ gestation), retinopathy of prematurity stage 4 or 5, and the presence of severe infection (eg, postnatal sepsis, necrotizing enterocolitis, meningitis).28 A key risk factor for CP in term infants is neonatal encephalopathy. These infants account for 25% of term children with CP. However, the majority of term CP infants have no identifiable risk factors around the time of birth.31 A recent systematic review identified placental abnormalities, malformations, low birth weight, meconium aspiration, instrumental or emergency Caesarean delivery, birth asphyxia (unspecified timing/duration), neonatal seizures, respiratory distress syndrome, hypoglycemia, and neonatal infections as consistent risk factors for CP in term infants.32 Other research has identified abnormal posturing, limited ability to lift head from floor in prone position, head lag, poor visual tracking, and poorly coordinated eye movements as developmental risk factors that may be useful in the early identification of CP.20

However, ultimately there are no biomarkers that can accurately predict which infants will have CP. Further, clinical risk factors can only partially identify subpopulations of infants who are at increased risk of CP.20

Diagnosis Timeline

Formal diagnosis of CP has traditionally occurred in the second year of life based on clinical examination and often after the exclusion of other conditions. About half of all children who are diagnosed with CP spend time in a neonatal intensive care unit or special care nursery as newborns. Theoretically, the risk for CP in these children ought to be established early, as they undergo multiple assessments and are monitored regularly in the first years of life. Register data indicates that infants with neonatal risk factors associated with more severe forms of CP, such as neonatal encephalopathy, are often diagnosed earlier. A recent population register study showed, however, that preterm infants were not more likely to be diagnosed earlier unless they had an abnormal cranial ultrasound (CUS).33 Yet, some studies of preterms have shown that one-third of cases of CP are not detected when CUS alone is used as a neuroimaging modality.34 In fact, earlier detection of CP does not routinely occur in these infants, often delaying access to intervention.35

For children with no apparent traditional risk factor, investigations typically begin when it becomes apparent that motor milestones are not being reached. However, as many standardized motor tests are not specifically predictive of CP, and as motor signs such as spasticity often do not appear until the second year, it can still be some time before an official CP diagnosis is given. Register data indicates that ambulant children with CP are not diagnosed until 17 months of age on average and that ambulant children with bilateral spastic CP have an even later median diagnostic age of 23.9 months.31

In recent years, a large body of evidence has accumulated that suggests CP can and should be diagnosed earlier. Many things should be taken into consideration when seeking to make an early diagnosis, including any history of CP risk factors, the presence of any brain structural abnormalities, abnormal general movement between 12 and 20 weeks’ postterm equivalent age, abnormal neurological signs, poor feeding skills, eye tracking difficulty, the presence of opisthotonic postures in the supine position, and a lack of integration of strong primitive reflexes into voluntary motor patterns.20 It is also important to determine a comprehensive quantitative and qualitative assessment framework for examining fine, gross, visual, and oral motor skills through the first 6 months of life. A systemic review has demonstrated that the absence of fidgety movements at 12 weeks post conception has a 98% sensitivity and 91% specificity for CP. This tool is superior to MRI (86%, 89-97%), neurological exam (88%, 87%), and cranial ultrasound (74%, 92%).36

Physical Examination

During the physical examination, the child should be in a relaxed state and nonintrusive observations should be the starting point. These observations include the infant’s general state and his or her spontaneous demonstration of neurological skills, such as 360-degree visual tracking, strong sucking, symmetric facies, lifting the head and chest, and supporting weight on forearms or wrists in prone position. Other key observations occur with gentle handling and include head lag on pull to sit; flipping or early rolling in a nongraded fashion (which reflects abnormally persistent primitive reflexes); becoming unfisted and demonstrating midline and manipulative hand play; and batting at, obtaining, and transferring objects.20

An early diagnosis of CP can be established by considering motor delay in combination with indicators of abnormalities of tone, reflexes, and postural motor control.20 Historically, Capute and Shapiro have emphasized the importance of the motor quotient involving observed postural skills.37

A recent consensus statement has emphasized the value of General Movement Assessment (98% sensitivity), term age brain MRI (86-89% sensitivity), and the Hammersmith Infant Neurological Evaluation (HINE) (90% sensitivity) before 5 months corrected age.38

After 5 months corrected age, the most predictive tools for detecting CP were a brain MRI (86-89% sensitivity), the HINE (90% sensitivity), and a standardized motor assessment with the Developmental Assessment of Young Children (89% predictive) or the Alberta Infant Motor Scale (86% predictive).38

Recently, Maitre and colleagues described standardization of the neurological exam using the HINE in high-risk infant follow-up programs.3941 Additionally, webinars and training workshops for general movements have been offered through the CP Research Foundation and the CP Alliance.

By definition, a CP diagnosis requires the presence of a movement and posture disorder that limits the child’s ability to perform activities. These neurological impairments might include spastic weakness, unusual postures, and challenges during feeding. Of course, the younger the child is, the more difficult it is to observe these.20

Feeding Difficulty

Difficulty with oral feeding is one of the most frequently occurring and recognizable CP risk factors. Difficulty with oral feeding can also be recognized early, as it is an infant’s first voluntary motor skill. Difficulty sucking and swallowing, extended feeding time for small volumes, and respiratory distress during feeding are all manifestations of poor oral feeding skills.20 By 4 to 6 months of age, many children with CP exhibit feeding difficulty in addition to difficulty with head control and an abnormal neurological examination.20


Brain imaging is widely used to document the presence and extent of brain structural integrity in CP, and increasingly sophisticated tools are under development. A number of systematic reviews have demonstrated that certain defined patterns of injury in the grey and/or white matter nearly always lead to CP, indicating the importance of appropriately timed neuroimaging in the diagnostic process.42,43 For example, MRI exams at 36 weeks postmenstrual age in former very low and extremely low birth weight preterm infants are incredibly valuable for the highest-risk cohort of preterm infants.28 There is also considerable evidence that CP can be predicted with neuroimaging in the newborn period, provided the optimal sequences and timing are used.44,45 Evidence-based recommendations for timing and use of preferred imaging modalities are available for preterm infants and those with neonatal encephalopathy;46 however, recommendations for infants not considered high-risk are more complicated. The AAP suggests that the MRI be carried out in the case of increased tone,5 and the American Academy of Neurology and the Child Neurology Society have produced an evaluation parameter, also recommending imaging be conducted during the diagnostic process.47 However, clinical research also documents outcomes that do not seem to “match” imaging findings, and it is estimated that up to 15% of children with CP have normal neuroimaging. It should also be noted that although understanding of the etiology of CP is growing, methods of CP detection in high-risk populations still need much improvement, as there is currently no imaging strategy with 95% sensitivity and specificity and none that accurately predicts the severity of disability.28 The combined use of neuroimaging, standard motor developmental assessment (General Movement Assessment, Test of Infant Motor Performance), and neurological examination provides the best information for early and accurate diagnosis of CP.29 When a diagnosis of CP cannot be made with confidence due to nonspecific or conflicting clinical results, the designation “high risk of CP” should be given, and the infant should be referred for early intervention services.

Further Assessments

While all children diagnosed with CP will have a motor impairment, the motor impairment rarely exists in isolation. There are several impairments, diseases, and functional limitations that frequently co-occur with CP, all of which further impact a child’s prognosis and independence and should be screened for during the diagnostic process.48 In particular, epilepsy and intellectual disability combined with severe physical disability tend to impact prognosis and life expectancy the most.20 There are many other comorbidities of CP. Chronic pain is one of the most common, affecting approximately 3 in 4 children with CP.48 Others include cognitive impairment, which affects almost 50% of children with CP, and sleep disorders, which affect 20%.49 Behavior disorders affect 25%, epilepsy 28%, scoliosis 7%, and hearing impairment 7%.20,30 Some studies have shown that visual impairment affects 42% of children with CP, and that 10% are functionally blind.30 Difficulties with feeding are also common, and 41% of children with CP experience functional walking limitations, 69% experience fine motor limitations, and 58% experience communication challenges.30 In school-aged children, specific learning disorders often appear, including challenges with reading, mathematics, handwriting, attention deficit and executive function, anxiety, and ASD.

The natural history of CP usually involves secondary musculoskeletal impairment, and early hip surveillance is now considered the standard of care50 due to the high prevalence of hip pathology, even in children as young as 2 to 3 years of age. Current recommendations are for the initial AP pelvic radiograph to be taken at 12 to 24 months of age or at the time of diagnosis if later.51

– Informing Families of Diagnosis

The primary goal when informing families of developmental diagnoses is to be supportive and link families to informed management resources that set achievable goals and allow them to feel empowered. The critical aim is to be proactive and give all children with evolving neurodevelopmental disability quality support while not being too pessimistic or overwhelming caregivers with either fear or a myriad of details.20 Informing a parent of his or her child’s diagnosis will be a difficult conversation, but it is important that it be done well. Many parents report being dissatisfied with the amount of information they receive at diagnosis and a lack of discussion about the likely impact of CP on their families. The parents’ chief criticisms are unclear information and the clinician conveying a pessimistic future outlook in delivering the news.20 When communicating news to families, primary pediatric health care professionals must recognize that parental acceptance of the CP diagnosis will be a shifting and ongoing process, and that continuous dialog will be needed.20

At the initial diagnosis, in their efforts to understand the news, parents of children with cerebral palsy will almost always ask whether the child will walk, talk, and be able to learn. Individual answers will depend on the severity of physical disability, the type of motor impairment, and the presence of comorbid conditions, most of which may be very difficult to determine during the neonatal period and in the first year of life.20

It is important for parents to understand that though CP currently has no cure, it does not mean that developmental progress does not occur. Primary pediatric health care professionals can comfort parents in the difficult task of coming to terms with an individual child’s activity limitations by helping them to maintain hope. For example, knowing that mild CP is more common than severe CP can offer parents hope. In addition, there is currently substantial neuroprotection and neuroregenerative research under way that is investigating enhanced plasticity and potential cures.52 Parents should be coached to be mindful of their child’s function in the longer term rather than pursuing overly ambitious physical feats. Parents can also be reassured that severity of physical disability does not predetermine quality of life.20

The most important messages to convey to parents are highlighted in Box 14.1.

Box 14.1. Key Messages for Parents

Cerebral palsy (CP) is not a disease but a neurodevelopmental disability in functioning. The motor disability, though initially obvious, may not be the major ongoing challenge. A comprehensive, functional approach with cooperation between medical, dental, educational, and community professionals is essential.

There are more than 50,000 preschool children, 200,000 school-aged children, and 400,000 adults with CP.

It is important that parents incorporate key therapeutic techniques into children’s activities of daily living, build to the child’s strengths, and have fun with their children.

All children with CP learn. Health and educational professionals can help families promote their children’s exploration, communication, literacy, and academic skills.

Teens with CP rate their quality of life in more optimistic terms than parents and professionals do.

Adults with CP prioritize communication, self-care, independence, education, friendships, and community participation.

Advances are occurring in scientific research involving neuroprotection and neuroplasticity.

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Oct 22, 2019 | Posted by in PEDIATRICS | Comments Off on Motor Development and Disorders
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