Cerebral palsy (CP) is used to describe several different neurological disorders involving body movement and motor skills. The condition may manifest in different types of movement or muscle abnormalities (palsies), depending on the area of the brain affected by the disorder.

The four major types of CP are:

• Spastic (or pyramidal). Muscles are stiff, permanently contracted and unable to relax. Infants with spastic CP may also have periods of poor muscle tone (hypotonia). Spastic CP is the most common form, affecting 70 to 80 percent of patients with the disorder, according to the United Cerebral Palsy Foundation (UCPF). The spasticity (stiffness) and/or weakness (paresis or plegia) can affect both legs (spastic diplegia or paraplegia), the arms and legs (spastic quadriplegia), the left side of the body (left hemi-paresis), the right side (right hemi-paresis), one extremity (monoplegia) or both arms and one leg (triplegia).
  
  
• Athetoid (or dyskinetic). According to the UCPF, this form of CP affects an estimated 10 to 20 percent of patients. It is characterized by uncontrolled, slow, writhing movements typically affecting the hands, feet, arms, legs or face and tongue muscles. Patients with athetoid CP may drool or grimace. They may also have difficulty coordinating the facial muscles needed for speech (dysarthria).
  
  
• Ataxic. A rare form of CP that affects 5 to 10 percent of patients, according to the UCPF. Poor coordination, tremor, an unsteady walk with a wide gait and difficulty executing precise movements such as writing or buttoning a shirt are common characteristics.
  
  
• Mixed. Some people have a combination of the three major types of CP in varying degrees. The most common mix is spastic and athetoid disorders, but other combinations are possible.