Developmental Coordination Disorder (Dyspraxia)

Etiology

DCD's etiology is not fully understood, but research has provided insights into potential factors contributing to the condition. Children with this disorder comprise a heterogeneous population, justifying the premise that multiple mechanisms may contribute to DCD. For example, studies suggest that DCD may be related to abnormal neurological maturation processes, including the under-activation of motor learning-associated brain regions and altered development of motor and sensory pathways. Psychological factors may also play a role.[4]

Accurate motor execution requires the harmonic integration of strength, balance, and proprioceptive, vestibular, visuospatial, and procedural learning. Studies show that children with DCD tend to present with abnormal brain activation patterns and white matter connections on functional MRI. Parietal, frontal, and cerebellar cortex areas are those mainly implicated in DCD.[5][6] 

DCD is hypothesized to have a genetic predisposition. However, the specific genes that may be linked to this condition have not been identified as shared genetic susceptibility with various neuropsychiatric disorders may lead to erroneous DNA analysis results.[7] 

Epidemiology

DCD's prevalence ranges between 1.8% and 6%.[8] The condition is 7 times more common in boys than girls. Edwards et al found that prematurity and low birth weight are the strongest risk factors (odds ratio 6.3, 95% CI 4.4-9.0) for developing DCD.[9] The disorder has increased prevalence among lefthanded or ambidextrous children, suggesting possible incomplete lateralization.[10]

Langevin et al also reported that DCD co-occurred with attention-deficit hyperactivity disorder (ADHD) in 30% to 50% of cases, indicating a common neural substrate underlying attention and motor disorders. This co-occurrence may have both etiologic and diagnostic implications.

Pathophysiology

Children's developmental milestones are built on the correct and timely achievement of previous ones. Achieving motor milestones is typically predictable. Infants learn to roll over, sit, crawl, walk, and manipulate objects to complete tasks. The right superior parietal lobule is responsible for accurate motor task performance. Developmental dyspraxia initially presents with poor motor coordination and clumsiness in completing age-appropriate motor tasks. The condition's effect on a child's development is critical.

Neurodevelopmental tasks aim to tune the nervous system to the environment. Motor development is key to early environmental exploration and development of the child's concept of the outer world. Simple tasks, such as turning the doorknob and using a fork to eat, require a mental map of one's body parts and the environment. Such a map forms after multiple repetitive, exploratory motor acts that let the child learn about their body and peripersonal space. Motor development disturbances may bias an individual's perception of the environment and their body's boundaries.

Early signs of DCD may include delayed motor milestone achievement and difficulty completing age-appropriate everyday tasks such as brushing the teeth, catching a ball, cutting paper, and writing. The motor difficulties may persist in adolescence and be associated with attentional problems, anxiety, low self-esteem, and obesity.[11]

History and Physical

The clinician should suspect DCD in school-age kids presenting with milestone delays or academic difficulties. History should include birth, developmental, educational, and past medical history. Musculoskeletal conditions and past trauma, especially if resulting in a brain injury, should be elicited. Medications, vaccinations, allergies, and diet must be noted.[12]

The physical examination should investigate alternative motor impairment causes, such as musculoskeletal damage. A comprehensive medical examination often uncovers significant neurodevelopmental delays, including limb choreiform movements, mirror movements, and other signs indicating poor fine and gross motor coordination. The physical findings should demonstrate that motor disturbances are not due to psychosocial or neurological disorders, including corticospinal, cerebellar, extrapyramidal, neuromuscular, neurometabolic, and peripheral nerve conditions. Available standardized questionnaires and observation forms for evaluating activities of daily living (ADLs) and childhood academic activities are not specific for diagnosing DCD. However, the Developmental Coordination Disorder Parent Questionnaire-Revised Version (DCDQ-R) has evidence level 2 and may be used in DCD diagnosis.

Dysfunction in various brain areas is often the cause of motor difficulties in DCD. The neurologic examination should assess behavior, cognition, comprehension, vision, eye movements, coordination, motor activity, focal and lateralized deficits, tone, strength, and stretch reflexes. Children with DCD tend to have significantly longer movement times and less accuracy than controls. These patients also rely considerably on visual feedback and require more time to execute motor tasks, such as handwriting, to optimize accuracy.

Handwriting difficulties are particularly important to note. Handwriting is a highly complex motor skill that requires several cognitive and linguistic processes before, during, and after execution. Despite being able to construct sentences, children with DCD have impaired thought expression, which can prolong the completion of handwriting tasks. Prunty et al estimated that children with DCD took an average pause duration of over 10 seconds at a time without improving composition quality. When memory resources are focused on transcription skills, longer writing times may reduce attention to organizing ideas, constructing sentences, syntax, vocabulary choice, and spelling.  

Comparing the quantity and quality of verbal production during writing is crucial when evaluating a child diagnosed with DCD. Spelling errors and vocabulary choices may affect production speed and content quality. Letter formation is the most important legibility predictor. Difficulties in these areas may significantly impact academic performance, and academic struggles may produce emotional problems.

The Detailed Assessment of the Speed of Handwriting (DASH) is an objective tool used for evaluating 4 handwriting speed aspects: copying in the child's best handwriting, copying quickly, alphabet writing, and free writing for 10 minutes. Handwriting evaluation in children with DCD should also include spelling and composition skills. Combining multiple methods and objective tools helps identify various aspects of the patient's neurologic problem and guide treatment.[13]

Collaboration with physical and occupational therapists allows physicians to determine the patients' motor competence using standardized tests. Assessment tools such as the Movement Assessment Battery for Children, 2nd edition (MABC-2) and Bruininks-Oseretsky Test of Motor Proficiency, 2nd edition (BOT-2) are useful.[14][15] However, the application of these tests to the adolescent and adult populations is limited.[16]

Children with suspected DCD must be assessed for the functional and emotional impact of the disorder on daily activities. The condition may indirectly affect family, teachers, and peers with whom the child interacts. Longitudinal studies show that children with DCD experience greater academic and sociobehavioral problems.[17] Clinicians should likewise be aware that the degree of cooperation and motivation during the examination may impact motor performance. Children with early motor developmental problems are at much greater risk for later neuropsychiatric disorders, such as attention-deficit/hyperactivity disorder (ADHD), behavioral inhibition, childhood anxiety disorder, obsessive-compulsive disorder (OCD), autism spectrum disorder (ASD), and schizophrenia.[18][19][20]

Evaluation

The ICD-10 defines DCD as a disorder characterized by seriously impaired motor coordination development not solely accounted for by general intellectual retardation or any specific congenital or acquired neurological disorder. Meanwhile, the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition, Text Revision (DSM-5-TR) defines the criteria for diagnosing DCD, which are as follows:

• The achievement and performance of coordinated motor skills are substantially below what is expected, given the child's chronological age and opportunity for skill learning and use.
• The poor performance persistently and significantly interferes with ADLs appropriate to chronologic age and impacts academic and school productivity, prevocational and vocational activities, leisure, and play.
• The symptoms began in the early developmental period.
• The motor and expressive difficulties are not better explained by intellectual disability or visual impairment and cannot be attributed to another neurologic or neuromuscular condition affecting movement (eg, cerebral palsy, muscular dystrophy, degenerative disorder).

Evaluating children with suspected DCD requires an interprofessional approach involving pediatricians, pediatric psychiatrists and neurologists, and physical and occupational therapists. DCD must be diagnosed before formal school entry. Developmental history, ADLs, and academic performance must be thoroughly assessed. However, differentiating and identifying associated comorbidities, if present, may be particularly challenging.[21]

Psychosocial and mental health issues may also arise with DCD and severely impact participation in leisure and social activities. A systematic review highlights the quality of life domains affected in children with DCD, shedding light on the condition's broader impact on their well-being.[22]

Peters et al demonstrated in 2013 that neuroimaging studies are crucial for understanding DCD's correlates and unraveling its underlying pathophysiology. Additionally, assessing executive functions over 2 years provides insights into the condition's long-term cognitive impact.[23] Near-infrared spectroscopy offers valuable information about DCD's neurodevelopmental aspects, as it allows the investigation of cortical activity when executing fine motor tasks.[24]

Treatment / Management

Recent meta-analyses reveal that the most effective DCD therapies are task-oriented approaches, motor-training programs, and physical therapy.[25] Task-oriented approaches are therapeutic interventions that help improve independence in performing ADLs, such as personal care, leisure activities, arts, and academic activities. These task-oriented approaches are designed—(A1)

• Specifically for the patient.
• To be goal-oriented.
• To be task- and context-specific.
• To actively involve the patient.
• To reach functionality, not normality.
• To involve the caregiver to enable transfer of care.

The goal of care is to enhance the learning of motor skills while focusing on global functions like sensory integration, visual-motor perception, and muscle strength.

The Cognitive Orientation to daily Occupational Performance (CO-OP) intervention has proven effective in improving motor skills and satisfaction with child-chosen motor goals for children with DCD.[26] Neuromotor task training has also produced promising results as a child-centered and task-oriented treatment program for children with DCD.[27] The delivery approach of these therapies is essential, as recent studies suggest greater effectiveness when the techniques are administered to smaller groups of patients.(A1)

The patient should also be given time to practice and integrate newly acquired basic skills into their daily routine. Caregiver participation is crucial in ensuring consistency and learning reinforcement. Pharmacologic therapies reduce attentional challenges and may be beneficial to patients with coexisting neuropsychiatric disorders such as ADHD.

A summer camp intervention has proven effective in improving motor skills in children with DCD, highlighting the potential benefits of such approaches.[28] Notably, no evidence exists that fatty acids and any particular vitamin supplements may affect motor functions.

Differential Diagnosis

DCD's differential diagnosis is vast and includes conditions presenting with both motor, coordination, and academic difficulties such as cerebral palsy, ADHD, ASD, intellectual disability, muscular dystrophy, sensory processing disorder, specific learning disorder, anxiety, fetal alcohol spectrum disorders, inborn errors of metabolism, neuromuscular diseases, epilepsy, brain tumors, and intellectual disability. A thorough clinical assessment and appropriate use of neurologic assessment tools can distinguish DCD from these common conditions.

Other disorders that may cause incoordination and clumsiness in children must be ruled out. Abnormal physical findings such as neurocutaneous marks, visual deficits, musculoskeletal abnormalities, hypotonia or hypertonia, weakness, ataxia, and adventitious movements should raise concerns for other disorders such as tumors.[29] No specific laboratory or imaging tests are recommended for diagnosing DCD. However, standard modalities such as thyroid function tests and magnetic resonance imaging may help evaluate alternative or coexisting conditions.

Several studies have addressed DCD's relationship with other disorders. International clinical practice recommendations for DCD offer valuable insights into its diagnosis, assessment, intervention, and psychosocial aspects, aiding in its differential diagnosis and addressing key clinical questions. Additionally, the European Academy for Childhood Disability (EACD) has offered recommendations on DCD's definition, diagnosis, and treatment, emphasizing the need for accurate differential diagnosis and intervention strategies.[30]

The influence of comorbidities like obesity on DCD's development must be examined.[31] DCD's potential overlap with language impairment and learning disabilities underscores the complexity of the DCD diagnostic process.[32]

Prognosis

Children with mild DCD symptoms who are promptly diagnosed and treated may learn to overcome their motor performance difficulties and achieve their goals over time. However, most children with DCD require long-term medical assistance and a tailored academic plan during critical developmental periods. Associated comorbidities and mental health diseases may severely impact the quality of life of patients with DCD.

Complications

Delayed diagnosis and treatment of DCD may lead to short- and long-term health and psychosocial complications. Motor milestone delays may affect the child's physical fitness. Children with DCD participate less in team sports and may develop decreased flexibility, strength, and endurance. DCD's negative effect on a child's participation in group activities may cause sociobehavioral problems that may persist in adolescence.

Adolescents with DCD report unique physical, social, and emotional challenges that severely impact their performance in sports and manual labor. Such difficulties may cause social marginalization.[33]

DCD in adults usually presents more heterogeneously and often results from failure to recognize subtle symptoms during childhood. Adults with DCD tend to experience motor challenges with estimating distances. Such impairments may manifest, for example, when driving or crossing the road. Adults also report difficulty with executive functioning, attention, and learning new skills.[34] DCD may lead to medical problems such as anxiety, low self-esteem, OCD, ASD, schizophrenia, and metabolic syndrome in adults.