Cerebral Palsy Classifications
Cerebral palsy is classified according to the main type of movement disorder involved. Depending on which areas of the brain are affected, one or more of the following movement disorders can occur:
- Stiff muscles (spasticity)
- Uncontrollable movements (dyskinesia)
- Poor balance and coordination (ataxia)
Cerebral Palsy is classified into four types:
Spastic CP is the most common type of CP. People with spastic CP have increased muscle tone. Spasticity is a category of movement disorders where the brain’s inability to control or fine tune muscle activation result in stiffness of an arm, hand or leg. Spastic CP is described by what parts of the body are affected:
- Spastic hemiplegia/hemiparesis typically affects the arm and hand on one side of the body, but it can also include the leg.
- Spastic diplegia/diparesis involves muscle stiffness that is predominantly in the legs and less severely affects the arms and face.
- Spastic quadriplegia/quadriparesis is the most severe form of cerebral palsy. It is caused by widespread damage to the brain or significant brain malformations.
(See examples further below on the page.)
What is Diplegia?
Diplegia is a term used when cerebral palsy compromises the movement control of the lower limbs (legs) more significantly than those of the upper limbs. ("di" means two)
What is Quadriplegia?
Quadriplegia is a term used when all four limbs, both arms and both legs have impaired control. ("quad" means four)
What is Hemiplegia?
Hemiplegia is a term used when one side including upper and lower limbs (arm and leg) is severely impaired (usually the upper limb more so than the lower limb).
Dyskinetic cerebral palsy (also includes athetoid, choreoathetoid, and dystonia) is a category of movement disorders represented by abnormal uncontrolled jerky movements that occur when an area of the brain called basal ganglia is damaged. Patients with dystonia are unable to “fine-tune voluntary movements,” like shaking hands with a friend. (See examples further below on the page.)
Ataxia cerebral palsy affects balance and depth perception. Individuals with ataxic CP may be unsteady when they walk and may have a difficult time controlling their hands or arms.
Mixed types of CP refer to symptoms that do not correspond to any single type of CP, but are a mix of types. The most common type of mixed cerebral palsy is spastic-dyskinetic CP.
What is the Gross Motor Function Classification System (GMFCS)?
The Gross Motor Function Classification System is an internationally accepted system to classify the impairments of persons with cerebral palsy. This classification ranges from levels I to V. Persons at GMFCS I, II and III tend to be able to walk independently or with assistive devices such as canes, crutches or walkers. Wheelchair users tend to be at levels IV and V.
Spasticity and or dystonia affects all GMFCS levels. Patients who are able to walk with or without devices are affected by muscle shortening and decreased joint flexibility. The difficulty to control the muscles results in difficulty to walk as well and what is called atypical or pathological gait, which is the technical term for walk. These atypical ways of walking are often ways that the patients “find” to overcome the difficult to control their muscles. On top of that, as the child grows and continues to walk with atypical patterns the bones and joints can become twisted, bent or deformed.
Patient Spasticity Examples
Spasticity results from the brain’s inability to control or fine tune muscle activation or tone in cerebral palsy patients. The stretch reflex is exacerbated, and this phenomenon becomes more prominent with faster muscle stretching.
In a patient with spasticity, the examiner attempts to quickly bend or flex the patient’s knee. When doing so the examiner can feel (and at times see) what is commonly referred to as “catch.” In other words, the examiner is initially able to start bending the knee, but the movement is suddenly curtailed. In other words, the movement is stopped or prevented for a short period then the muscle “let go” and the bending or movement continues as the examiner to pushes. The quicker and stronger the examiner tries to bend the knee the more intense is the “catch.” The muscle lying in front of our thighs is called quadriceps and it must stretch to allow the knees to bend. In this example, as soon as the knee is pushed into bending the quadriceps spasticity blocks the movement.
Spasticity is found in multiple muscles in patients with cerebral palsy. Therefore proper and fine-tuned movements of the limbs or any part of the body are compromised and often limited. Anytime a muscle is stretched the reflex is triggered and this stops or interrupts the movement momentarily or throughout the range of motion.
A child with spasticity trying to walk, while the foot is on the ground (in every step) the calf muscles are stretched primarily as the leg bone rolls forward over the foot. As soon as this rolling mechanism starts, the stretch reflex in the calves is triggered and makes the movement stop. Sometimes the spasticity is so significant that the muscle is never stretched, it becomes short and the result is the patient, usually young children walking on their toes. This is called equinus deformity.
Today, we know that, of the three muscles that constitutes the so-called calf muscles on each leg, only two, are spastic in many patients (they are called medial and lateral gastrocnemius). The third muscle, which is called soleus, is often not so compromised by spasticity.
It is believed that, muscles grow due to the bones’ growth. Muscles themselves are being activated, shortening, and stretching all day long. Just think of a child: they never stop—they are constantly running, jumping, falling. A muscle that is constantly “under the influence of spasticity” rarely has a chance to stretch fully during such activities. Bone growth can be affected by cerebral palsy, but the muscles tend “fall further behind.” This situation leads to what is commonly known as muscle shortening or later, muscle contracture. The joints that are controlled by those muscles become less mobile.
The strong two muscles that help us bend our hips are called ileo-psoas. The same way as with the calf muscles, psoas is often spastic in cerebral palsy. When psoas spasticity is severe, this muscle may shorten. In this situation the hip cannot stretch or extend all the way. This is called hip flexion deformity. The hip or hips are always bent a bit when the person tries to stand or walk, or even when they are lying down.
Patient Dystonia Examples
On the other hand, dystonia occurs when many muscles receive contradicting or poorly tuned information from certain parts of the brain called the basal ganglia regarding a desired or undesired movement. Dystonia can be global or involve the whole body, focal when it appears for instances in one hand or eye or finger, and segmental when it is found in one arm or leg. Dystonia is manifested through repetitive muscle contractions, twisting and posturing of the involved body part.
Our orthopedic mentors used to say that “we as medical examiners feel spasticity and observe dystonia.” Unlike spasticity, dystonia produces unintended movements in all directions.
Example 1 – Dystonia: A dystonic arm can often sway from a bent elbow position to an extended elbow position continuously. Posturing means that the same elbow may remain in an extended or stretched position for some minutes and then revert to a bent of flexed position for another extended and unpredictable amount of time. Dystonia therefore tends to take longer to induce a fixed muscle shortening or deformed or stiff joint. More often than not, the joints become more impaired because of the continued (difficult to control) movements throughout the patient’s life.
Muscle stiffness, joint stiffness, dystonic movements and posturing caused by either spasticity and or dystonia significantly impair patient’s abilities to move arms, hands, legs, feet, spine, neck, to swallow, to speak, to breath in a typical and functional. Muscle and joint pain, degenerative arthritis, scoliosis, mal-nutrition, speech and communication difficulties are unfortunately common in various severities in people with cerebral palsy.