Cerebral palsy can be classified into different types by identifying which limbs are involved, the motor dysfunction experienced by the child, and the child’s capacity for independent mobility.

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Limb Involvement

Limb involvement can be broadly classified as bilateral cerebral palsy, meaning both sides of the body are involved or unilateral, meaning only 1 side of the body is involved. Some terms that are commonly used are:

• Quadriplegia. All 4 limbs are affected or have an impaired ability to move.
• Diplegia. The lower limbs (legs) are significantly more affected than the arms.
• Hemiplegia. Only 1 side of the body’s limbs are affected. This may also be referred to as unilateral cerebral palsy. Often, the arm is more affected than the leg.
• Triplegia. 3 limbs are affected. Usually both legs and one arm are affected.
• Monoplegia. 1 limb is affected. This is the least common type of cerebral palsy.
• Total body involvement. This term is used to describe a person who, in addition to the involvement of 4 limbs, has impairments in speech, vision or cognitive function.

Movement Disorder

This classification of cerebral palsy is described by the most prevalent movement disorder. In many cases, children with cerebral palsy will have more than 1 movement disorder present. 

Some of the common movement disorders include:

• Spasticity. The most common movement disorder in cerebral palsy, kids with spastic cerebral palsy have muscles that tighten or stiffen and prevents normal fluid movement. Spasticity is high muscle tone, which is worse when a patient is trying to move quickly as opposed to slowly. Moderate or severe spasticity may hinder movement and function and can make muscles and joints tight, leading to contractures. 
• Abnormal muscle tone. Muscle tone – or how “tight” muscles are – may be higher or lower than normal.
• Rigidity. Muscles that have rigidity feel heavy and like “a lead pipe” when they are moved passively regardless of how quick or slow the muscle is moving. Rigidity is found in cases of prematurity or near drowning.
• Hypotonia. Hypotonia is low muscle tone. These muscles are often described as loose or “floppy.” 
• Involuntary movements: Abnormal involuntary movement is caused by damage to the coordination centers of the developing brain and is referred to as dyskinesia.
• Dystonia. Involuntary, sustained, or intermittent muscle contractions that cause twisting and repetitive movements, abnormal postures or both.
• Athetosis. Slow, involuntary writhing movement of face and extremities.
• Chorea. Brief, irregular jerking movements that most commonly begin in the shoulders, neck, trunk and face.

Motor Function

One way to classify cerebral palsy is by examining a child’s capacity for independent mobility (e.g., walking and sitting). 

The most common classification for mobility is the Gross Motor Function Classification System (GMFCS), and it is divided into 5 levels, I-V, of independent ability based on normal motor milestones – walking, jumping, climbing stairs, etc. The higher the level of GMFCS, the more affected the child and the less independent mobility they have. 

GMFCS helps doctors and families understand a child’s current and future motor function, their relative risk for associated problems like scoliosis and hip dislocations, and what equipment, therapy, or surgery they might need in the future.