The diagnosis of cerebral palsy has historically rested on the patient's history and physical examination. Once diagnosed with cerebral palsy, further diagnostic tests are optional.

The American Academy of Neurology published an article in 2004 reviewing the literature and evidence available on CT and MRI imaging. They suggested that neuroimaging with CT or MRI is warranted when the etiology of a patient's cerebral palsy has not been established - an MRI is preferred over CT due to diagnostic yield and safety. When abnormal, the neuroimaging study can 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 tumor[20] (which a few studies suggest are present 5 to 22%). Furthermore, an abnormal neuroimaging study indicates a high likelihood of associated conditions, such as epilepsy and mental retardation.