The clinical signs and symptoms are complex and varied, and the details can be found in the clinical manifestations of each type, which will not be described here. Some children may have hyperbilirubinemia, low birth weight, enamel green pigmentation, myocardial damage, and cardiac arrhythmias. It is often accompanied by hypo-intelligence and seizures. The newborn has cortical hypoplasia caused by different factors, resulting in “cortical blindness”. After early childhood, intraocular strabismus and refractive errors, such as myopia, amblyopia, and strabismus, are most common. Nystagmus, and occasionally total blindness, are rare. Difficulty in discerning the rhythm of sounds also occurs. Seizures Epilepsy is a very dangerous complication of cerebral palsy and can be severe and life threatening. Seizures are more common in spastic tetraplegia, hemiplegia, monoplegia, and with mental retardation, but rarely in tardive dyskinesia and ataxia. Sensory and cognitive abnormalities The child lacks proper visual-spatial and three-dimensional perception and has prominent cognitive deficits. Children have poor recognition of complex shapes and cannot distinguish between the shape of an object and its spatial context, and have poor color recognition. About two-thirds of the children are mentally retarded, and about one-fourth are severely retarded. The intelligence of spastic quadriplegia and ankylosing cerebral palsy is often worse, and severe retardation is rare in children with tardive dyskinesia.