The movement and posture abnormalities that are characteristic of cerebral palsy are associated with underlying abnormalities of muscle tone, including dystonia, spasticity, and rigidity. The subtypes of cerebral palsy are defined according to the predominant muscle tone abnormality, its distribution and severity. There is widespread agreement that CP subtypes should be divided into the following groups. Spastic subtypes (hemiplegia: unilateral asymmetric spasticity; diplegia: bilateral symmetric spasticity, lower limbs more affected than upper limbs; quadriplegia: bilateral symmetric spasticity, upper and lower limbs affected equally), dystonic or athetotic type; and other miscellaneous types: hypotonic, mixed types, etc. These descriptive definitions are not useful when forming homogeneous cohorts of CP subtypes in rehabilitation research studies. Even when a preceding training session establishes precise criteria for each subtype based on these definitions and uses a "four limb" approach (defining the dominant muscle tone abnormality and its severity in each limb) the interobserver agreement in the classification of CP subtypes remains poor. This may be because there are no widely accepted definitions for the most common muscle tone abnormalities in cerebral palsy (spasticity, rigidity, dystonia) and examination methods vary widely. Recently, an interdisciplinary group of clinicians published a consensus document in which they set forth clear definitions for these disorders of muscle tone and recommendations on how to examine for them. Since the CP subtypes are defined according to the dominant muscle tone abnormality, we hypothesize that it may be possible to achieve acceptable interobserver agreement in the classification of the CP subtypes if these definitions and standard examination techniques are incorporated into the preceding training session with the other accepted elements. To test this hypothesis we will train clinicians from three different areas of expertise: child neurology, physiatry, physical therapy to classify subtypes of CP using accepted methods (establishing precise criteria for the subtypes and using a four limb approach) and will also train them to identify muscle tone abnormalities using the definitions and standard examination techniques in the consensus document. Following this training, we will ask the same clinicians to classify subtypes of cerebral palsy in a group of CP children. We will then measure interobserver agreement for the classification of CP using the kappa statistic. Achieving acceptable interobserver agreement in the classification of CP subtypes may facilitate the formation of homogeneous cohorts in research studies.

INCLUSION CRITERIA:

1. Children 6 to 18 years of age
2. Children must be previously diagnosed with cerebral palsy
3. Children born at any gestational age will be eligible.
4. Lesions must be pre-, peri- or post-natal and acquired before 2 years of age
5. Lesions must be non-progressive
6. Patients must be able to voluntarily move their upper and lower limbs

EXCLUSION CRITERIA:

1. Any subject who is pregnant
2. Children with an underlying known genetic or chromosomal disorder
3. Children with clearly identified familial or non-familial syndromes (without known chromosomal or genetic defect)
4. Cerebral lesions acquired after 2 years of age
5. Patients with progressive or neurodegenerative disorders
6. Patients with spinal disorders in the absence of cerebral lesions
7. Patients with sickle cell disease
8. Patients with cerebral lesions caused by emboli associated with congenital cardiac lesions
9. Patients with severe cognitive deficits who cannot follow simple verbal commands
10. Patients incapable of voluntary movement of either upper or lower limbs due to contractures.
11. Patients with prior rhizotomy
12. Patients with prior orthopedic (bone or soft tissue) surgery or serial casting
13. Patients with severe postural abnormalities who cannot maintain supported sitting.