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Diagnosis

The diagnosis of cerebral palsy has historically rested on the person's history and physical examination and is generally assessed at a young age. A general movements assessment, which involves measuring movements that occur spontaneously among those less than four months of age, appears most accurate. Children who are more severely affected are more likely to be noticed and diagnosed earlier. Abnormal muscle tone, delayed motor development and persistence of primitive reflexes are the main early symptoms of CP. Symptoms and diagnosis typically occur by the age of two, although depending on factors like malformations and congenital issues, persons with milder forms of cerebral palsy may be over the age of five, if not in adulthood, when finally diagnosed.

Cognitive assessments and medical observations are also useful to help confirm a diagnosis. Additionally, evaluations of the child's mobility, speech and language, hearing, vision, gait, feeding and digestion are also useful to determine the extent of the disorder. Early diagnosis and intervention are seen as being a key part of managing cerebral palsy. Machine learning algorithms facilitate automatic early diagnosis, with methods such as deep neural network and geometric feature fusion producing high accuracy in predicting cerebral palsy from short videos. It is a developmental disability.

Once a person is diagnosed with cerebral palsy, further diagnostic tests are optional. Neuroimaging with CT or MRI is warranted when the cause of a person's cerebral palsy has not been established. An MRI is preferred over CT, due to diagnostic yield and safety. When abnormal, evidence from neuroimaging may suggest the timing of the initial damage. The CT or MRI is also capable of revealing treatable conditions, such as hydrocephalus, porencephaly, arteriovenous malformation, subdural hematomas and hygromas, and a vermian tumour (which a few studies suggest are present 5–22% of the time). Furthermore, abnormalities detected by neuroimaging may indicate a high likelihood of associated conditions, such as epilepsy and intellectual disability. There is a small risk associated with sedating children to facilitate a clear MRI.

The age when CP is diagnosed is important, but medical professionals disagree over the best age to make the diagnosis. The earlier CP is diagnosed correctly, the better the opportunities are to provide the child with physical and educational help, but there might be a greater chance of confusing CP with another problem, especially if the child is 18 months of age or younger. Infants may have temporary problems with muscle tone or control that can be confused with CP, which is permanent. A metabolism disorder or tumors in the nervous system may appear to be CP; metabolic disorders, in particular, can produce brain problems that look like CP on an MRI. Disorders that deteriorate the white matter in the brain and problems that cause spasms and weakness in the legs, may be mistaken for CP if they first appear early in life. However, these disorders get worse over time, and CP does not (although it may change in character). In infancy it may not be possible to tell the difference between them. In the UK, not being able to sit independently by the age of 8 months is regarded as a clinical sign for further monitoring. Fragile X syndrome (a cause of autism and intellectual disability) and general intellectual disability must also be ruled out. Cerebral palsy specialist John McLaughlin recommends waiting until the child is 36 months of age before making a diagnosis because, by that age, motor capacity is easier to assess.