Definition of Cerebral Palsy from the Washington Workshop 2004
Cerebral palsy (CP) is a well-recognized neurodevelopmental condition beginning in early childhood and persisting through the lifespan. Originally reported by Little in 1861 (but not then called ‘cerebral palsy’), CP has been the subject of books and papers by some of the most eminent medical minds of the past hundred years. Beginning at the end of the 19th century Sigmund Freud and Sir William Osler both contributed important perspectives on the condition. From the mid-1940s the founding fathers of the American Academy for Cerebral Palsy and Developmental Medicine (Carlson, Crothers, Deaver, Fay, Perlstein, and Phelps) in the United States, and Mac Keith, Polani, Bax and Ingram of the Little Club in the United Kingdom, were among the leaders who moved the concepts and descriptions of CP forward.
It has always been a challenge to define ‘cerebral palsy’, as documented by the number of attempts that have been made over the years. For example, Mac Keith and Polani (1959) defined CP as ‘a persisting but not unchanging disorder of movement and posture, appearing in the early years of life and due to a non-progressive disorder of the brain, the result of interference during its development.’ In 1964, Bax reported and annotated a definition of CP suggested by an international work group, which has become a classic and is still used. It stated that CP is ‘a disorder of movement and posture due to a defect or lesion of the immature brain.’ Though this brief sentence is usually all that is cited by authors, additional comments were added by Bax: ‘For practical purposes it is usual to exclude from cerebral palsy those disorders of posture and movement which are (1) of short duration, (2) due to progressive disease, or (3) due solely to mental deficiency’. The group for which Bax was the reporter felt that this simple sentence could be readily translated into other languages and hoped that it might be universally accepted. They felt that it was wiser at that time not to define precisely what they meant by ‘immature brain’, as any such definition might limit services to those in need. Like its predecessors, this formulation of the CP concept placed an exclusive focus on motor aspects, and also stressed the specific consequences of early as opposed to late-acquired brain damage. Sensory, cognitive, behavioral and other associated impairments, though very prevalent in people with disordered ‘movement and posture due to a defect or lesion of the immature brain’, and often significantly disabling, were not formally included in the concept.
The heterogeneity of disorders covered by the term CP, as well as advances in understanding of development in infants with early brain damage, led Mutch and colleagues to modify the definition of CP in 1992 as follows: ‘an umbrella term covering a group of non-progressive, but often changing, motor impairment syndromes secondary to lesions or anomalies of the brain arising in the early stages of development.’ This definition emphasized the motor impairment and acknowledged its variability, previously underscored in Mac Keith’s and Polani’s definition, and excluded progressive disease, a point introduced in Bax’s annotation.
An International Workshop on Definition and Classification of Cerebral Palsy was held in Bethesda, Maryland, July 11-13 2004, co-sponsored by United Cerebral Palsy Research and Educational Foundation in Washington and the Castang Foundation in the United Kingdom, with special support provided by the National Institute of Health/National Institute of Neurological Disorders and Stroke. The task of the attendees was to revisit and, if possible, update the definition and classification of cerebral palsy in light of emerging understanding of developmental neurobiology and changing concepts about impairments, functional status and ‘participation’. Reassessment of the definition of CP was prompted by a host of factors: changes in delivery of care to children with disabilities; recognition that children with slowly progressive inborn errors of metabolism can present with motor difficulties indistinguishable from those of children with nonprogressive disease; increased availability of high-quality brain imaging to identify impairments in brain structure; acknowledgment that developmental motor impairment is almost invariably associated with a range of other disabilities; and increased understanding about associated antecedents and correlates of CP.
The group agreed that CP as conceptualized previously had proved to be a useful nosologic construct, but that previous definitions had become unsatisfactory. They underlined that CP is not an etiologic diagnosis, but a clinical descriptive term. Reservations were expressed about the focus on motor deficit, given that persons with neurodevelopmental disabilities may present impairments of a wide range of functions that may or may not include severe motor manifestations, therefore calling for the need of an individual, multidimensional approach of each affected person. However, it was proposed that the concept should be retained to serve diagnostic, management, epidemiological, public heath services, and research purposes. It was felt that an updated definition of CP, taking into account the advances in the understanding of physiological and pathological brain development as well as changes in terminology, should be proposed for international use to meet the needs associated with these purposes, as well as to ease communication between the concerned fields. As in the original concept, the motor disorder is emphasized, while it is recognized that other developmental disorders can accompany it. This emphasis is justified by phenotypic differences in motor disorder according to whether pathological processes occur early or at late with respect to development, with different management and outcome implications. More generally, it is also justified in the context of brain developmental conditions, given the importance of motor aspects in child development. Children with CP most often present to medical attention for motor abnormalities even if they have other developmental problems.
In order to underline the idea that a comprehensive approach to CP needs to be multidimensional and that management of patients with CP almost always requires a multidisciplinary setting, common accompanying disorders were identified. This addition reflects the idea that CP is one group of neurodevelopmental disorders which involve numerous developing functions. As in other neurodevelopmental disorders, various manifestations of the disordered brain may appear more significant in different persons or at different periods, e.g. some aspects of the motor impairment, intellectual disability, epilepsy, attentional difficulties and many other.
Progressive disorders that were previously excluded from the concept may be consistent with the proposed definition. This may be justified by the presentation (or even course) of some slowly progressive disorders that may be similar to that of CP, therefore calling for similar diagnostic questioning, as well as by the common needs in terms of clinical follow-up, management and societal issues.
The document that follows presents an updated definition of cerebral palsy, an annotated explanation of the terms used, and the thinking behind the choice of those words. It is hoped that this document will spur discussion, and lead eventually to the goal, first envisioned by Bax 40 years ago, of international consensus and adoption of a common set of ideas about this condition.
“Cerebral palsy describes a group of developmental disorders of movement and posture, causing activity restriction or disability, that are attributed to disturbances occurring in the fetal or infant brain. The motor impairment may be accompanied by a seizure disorder and by impairment of sensation, cognition, communication and/or behavior.”
Annotation
The following notes explain and discuss each of the terms in the definition in order:
“Cerebral palsy 1 describes a group2 of developmental3 disorders4 of movement5 and posture6, causing7 activity restriction8 or disability9, that are attributed10 to disturbances11 occurring in the fetal12 or infant13 brain14. The motor impairment may be accompanied15 by a seizure disorder16 and by impairment of sensation17, cognition18, communication19 and/or behavior20.”
1. ‘Cerebral palsy’ – It was generally agreed that the CP concept, essentially a clinical formulation based on phenomenology, remains useful in the current state of nosology. Although the word ‘palsy’ has become largely obsolete in medical nosography and it has no univocal connotation, the term ‘cerebral palsy’ is entrenched in the literature and it is used universally by clinicians, therapists, epidemiologists, researchers, policy makers, health care funding organizations and lay persons. It has, however, been variably used, with poor comparability across different places and times, indicating the need for a consensual definition. It was proposed to keep the term to relate future research in CP to existing published work.
2. ‘a group’ – There is general agreement that CP is a widely heterogeneous condition in terms of etiology as well as types and severity of disabilities. Several groupings are possible and warranted to serve different purposes. These groupings may show overlap. Therefore, the singular form ‘CP’ is used (as opposed to ‘cerebral palsies’) as an umbrella term.
3. ‘developmental’ – This notion of alteration in development is essential to the CP concept. It distinguishes it from phenotypically similar disorders due to late-acquired lesions in children or adults. It is also important with regard to management strategies that may include interventions that address the developmental consequences of the functional limitations associated with CP, and interventions that are directed at the underlying neurobiological processes. The developmental nature of CP almost always implies impacts on the developmental trajectories of the people who have CP. CP manifests very early in child development, usually before 18 months of age, with delayed or aberrant motor progress. The clinical picture of CP evolves with time, development, learning, training, therapies and other factors.
4. ‘disorders’ – This refers to conditions in which there is disruption of the usual orderly processes of child biopsychosocial development. The disorders are persistent.
5. ‘movement and
6. posture’ – Abnormal motor behavior (reflecting abnormal motor control) is the core feature of CP. It is characterized by various abnormal patterns of movement and posture related to defective coordination of movements and/or regulation of muscle tone. Patients with CP may also have other neurodevelopmental disabilities that affect adaptive functioning, sensory function, learning, communication and behavior, as well as seizures. Abnormal motor control may be further impaired by features that are associated with CP. However, patients with neurodevelopmental disabilities that do not affect movement and posture are not considered to have CP.
7. ‘causing’ – Activity restriction or disability are presumed to be a consequence of the motor disorder. Thus disorders of movement and posture that are not associated with activity restriction or disability are not CP.
8. ‘activity restriction’ – The World Health Organization’s International Classification of Functioning, Disability and Health (ICF) (WHO 2001) speaks of ‘activity’ as “…the execution of a task or action by an individual”, and identifies ‘activity restriction’ as “…difficulties an individual may have in executing activities”. This term amplifies the previous concept of ‘disability’ to recognize changing international concepts and terminology.
9. ‘disability’ – The word ‘disability’ has been defined and used according to the traditional WHO framework outlined in the 1980 International Classification of Impairment, Disability and Handicap, wherein ‘disability’ was defined as “…any restriction or lack… of ability to perform an activity in the manner or within the range considered normal for a human being.” The terms ‘activity restriction’ and ‘disability’ are included in the new definition of cerebral palsy to recognize both traditional and contemporary language that refers to the functional impact of cerebral palsy on the person.
10. ‘attributed to’ – Understanding of developmental neurobiology (including the effects of genetic, chemical, and other influences on brain development) is increasing rapidly, such that it is becoming possible to identify structural and other evidence of brain maldevelopment in people with cerebral palsy. As a consequence structural-functional connections and correlations are becoming more clearly delineated than has previously been possible. It must, however, be acknowledged that at the present time a full understanding of causal pathways and mechanisms leading to cerebral palsy remains elusive in many cases.
11. ‘disturbances’ – This term refers to events or processes that in some way interrupt, damage or otherwise influence the expected patterns of brain maturation, although in a proportion of cases it is not possible to identify a specific ‘disturbance’ or a specific timing of the events that appear to impact on maturation. These disturbances may include cerebral dysplasia.
12. ‘fetal or
13. infant’ – The specification ‘fetal or infant’ reflects that disturbances that occur very early in human biological development impact differently on motor function than disturbances that occur later. There is no explicit upper age limit as, depending on aspects of motor functioning, the first two or three years of life may be concerned. Therefore, this notion of early lesion would appear more useful clinically than arbitrary time limits. In practical term, disturbance resulting in CP is presumed to occur before function has developed for each considered function (e.g. walking, manipulation, etc.)
14. ‘brain’ - The term ‘brain’ includes the cerebrum, the cerebellum and the brain stem. It excludes motor disorders of spinal, peripheral nerve, muscular or mechanical origin, although alterations in the neuromuscular and musculoskeletal systems may occur in CP as a consequence of the chronic motor impairment and may further restrict motor function of patients with CP.
15. ‘accompanied’ – In addition to the disorder of movement and posture, people with CP may show other disorders or impairments. These may be caused by the same disturbances as those that caused CP and/or represent indirect consequences of the motor impairment and/or be caused by independent factors (hence the term ‘accompanied by’ as opposed to ‘associated with’).
16. ‘seizure disorder’ – Virtually every seizure type and many epileptic syndromes may be seen in patients with CP. Rarely, the seizure disorder may be the cause of CP (e.g., as a consequence of prolonged infantile status epilepticus), or it may result in further motor impairment.
17. ‘sensation’ – All sensory modalities may be affected.
18. ‘cognition’ – Both global and specific cognitive processes may be affected, including attention.
19. ‘communication’ – Expressive and/or receptive communication and/or social interaction skills may be affected.
20. ‘behavior’ – This also includes behavioral problems in the context of psychiatric disorders, such as ADHD, mood disorders and anxiety disorders.
It is hoped that this definition will clarify the CP concept and allow unified use of the term both within and across the concerned fields. As it relies essentially on clinical aspects and does not require sophisticated technology, it should be possible to apply it very widely.
Bax MCO. (1964). Terminology and classification of cerebral palsy. Developmental Medicine and Child Neurology 6: 295-307.
Mac Keith and Polani (1959)
Mutch LW, Alberman E, Hagberg B, Kodama K, Velickovic MV. (1992). Cerebral palsy epidemiology: where are we now and where are we going? Developmental Medicine and Child Neurology 34: 547-555.
World Health Organization. (2001) International Classification of Functioning, Disability and Health (ICF). Geneva: World Health Organization.
World Health Organization. (1980) International Classification of Impairment, Activity and Participation – ICIDH. Geneva: World Health Organization.
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