Overview

Cerebral palsy (CP) is a group of neurological conditions that develop in infancy or early childhood and involve impediments to the motor functions of the body. Types of cerebral palsy are distinguished based on the parts of the body it affects or the location of the brain injury that caused the disorder and the specific impact on motor functions.¹

According to the movement disorder observed in the affected individual, there are four main types of cerebral palsy:^1,2

1. Spastic CP characterised by the  stiffness of the muscles which results in difficulties performing movements 
2. Dyskinetic CP characterised  by involuntary uncontrolled movements
3. Ataxic CP characterised by  shaky movements, lack of balance and coordination 
4. Mixed CP, which is a combination of symptoms observed in other types of CP

What is cerebral palsy?

The umbrella term cerebral palsy refers to a group of neurological health disorders that appear in infancy or early childhood. Cerebral palsy is caused by brain development abnormalities or brain damage which most often occurs during foetal development. Due to improperly developed or damaged brain areas that are responsible for muscle movement, the ability to control movements, as well as maintain balance and posture, is disrupted.

The symptoms appear in early childhood and differ from person to person in terms of type and severity. Most individuals experience motor function disabilities which vary from mild to severe and depend on the area of the brain that has been damaged. However, the disorder is not progressive, which means that the symptoms do not worsen over time.

The damage to the brain is irreversible and the disabilities that are consequently developed are permanent. However, current  available treatments and medications might help to improve the motor functions of the body and the ability to communicate with the surrounding world.^2,3,4

Types of cerebral palsy

Learning about types of cerebral palsy and characteristic motor dysfunctions might help the caregivers to understand the patient’s  condition better, manage the symptoms, and provide the best possible care.

Classification based on the scope and severity

In mild cases, cerebral palsy might give symptoms in only one limb but in the most severe cases, almost all the body is affected.

• Monoplegia – the symptoms affect only one limb
• Hemiplegia – one side of the body is affected, either left or right. Approximately 40% of people diagnosed with CP have this type of disorder
• Diplegia – this type of CP affects mainly both legs, the symptoms experienced in the arms are milder
• Triplegia – three limbs of the patient are affected by CP. Their torso, facial, and oral muscles might also be affected
• Quadriplegia – all four limbs are affected. Most often, in the case of this type of CP, the patient’s torso, facial, and oral muscles are also affected^1,5

Classification based on the type of movement disorder

Depending on the location of the brain injury and the damaged area of the brain, patients experience different types of symptoms.

Spastic cerebral palsy

Spastic cerebral palsy is diagnosed in approximately 80% of the patients which makes it the most common type of CP. As a result of damage to the motor cortex, which is considered a command centre for controlling muscle movements, the muscles stiffen and tighten and the movements look stiff and jerky.^1,5

In healthy individuals, performing a movement involves turning on specific types of muscles and subsequently turning off other groups of muscles. This coordination and control over the muscles makes the movement smooth and seamless. In the case of patients diagnosed with spastic cerebral palsy, both groups of muscles might remain active at the same time or the wrong group of muscles may be turned on, which makes the movement difficult to perform or in some cases even impossible.^1,5 

Dyskinetic cerebral palsy

People suffering from dyskinetic cerebral palsy (also known as athetoid CP), experience involuntary movements which are developed as a consequence of damage to the basal ganglia. The basal ganglia is a brain region responsible for communication between the motor cortex and the spinal cord. When this communication is disrupted, the movements might become involuntary and uncontrollable.¹

There are three types of dyskinetic cerebral palsy characterised by different types of involuntary movements. They are developed due to damage to different structures within the basal ganglia.

• Dystonia – twisting and repetitive movements

These involuntary muscle contractions and awkward postures are most often triggered by attempts to perform movements. Dystonia might affect only one part of the body being triggered by an attempt to perform a particular movement such as dystonia in the foot muscles (focal dystonia) or be widespread throughout the whole body (generalised dystonia). Generalised dystonia affects the motor functions of the body but usually also causes speech and swallowing difficulties.¹

• Athetosis – slow, ‘stormy’ movements

The individuals affected by athetosis experience slow continuous writhing movements present at rest which worsen upon an attempt to move. The fluctuations in muscle tone cause an inability to maintain a posture, or even difficulties standing and sitting.¹

• Chorea – unpredictable, irregular movements, sometimes referred to as ‘dance-like’ movements

This type of dyskinetic cerebral palsy can affect different body parts. The involuntary movements experienced in the case of chorea are brief and abrupt. Individuals might also experience difficulties with speech and swallowing.¹

Ataxic cerebral palsy

As a result of the damage to the cerebellum (balance centre of the brain), individuals experience shaky movements and trouble keeping balance and coordination. Approximately 6% of the people diagnosed with cerebral palsy have this type of disorder, which makes it the least common. Ataxic movements are imprecise and clumsy, which is most observed when attempting to perform a movement such as walking or picking up objects. Individuals suffering from this type of cerebral palsy experience unsteady, shaky movements and tremors, and difficulties maintaining balance coordination due to their sense of balance being impaired by the disorder.¹

Mixed cerebral palsy

As a consequence of an injury and damage to multiple areas of the brain, the patients experience symptoms characteristic of different types of cerebral palsy.⁵ 

Diagnosis of cerebral palsy types

Doctors usually use brain imaging such as CT or MRI. Scans, but also electroencephalogram (EEG), which tests the brain activity of a child, measured by a series of electrodes attached to the child’s scalp. Specialists most often also use the Gross Motor Function Classification System (GMFCS) to determine the type of cerebral palsy. GMFCS is a five-level ranking system created to examine the overall motor functions of the child. It is based on the evaluation of gross motor functions such as sitting and walking. Children ranked in level 1 are able to walk without limitations and sit independently, whereas level 5 means that the child experiences severe motor dysfunctions and movement limitations (the level of severity increases from 1 to 5).⁵

Summary

Different types of cerebral palsy are categorised following one of two methods of classification. The first is based on the scope of the disorder and how widespread throughout the body it is. Thus, it distinguishes the following categories: monoplegia (only one limb is affected), hemiplegia (one side of the body), diplegia (mainly both legs), triplegia (mainly three limbs), quadriplegia (all four limbs are affected by CP).

The other method of classification involves information about characteristic motor dysfunction observed in the individuals diagnosed with cerebral palsy but also the damaged area of the brain attributed to the development of the specific type of CP. Spastic CP is caused by damage to the motor cortex which leads to stiffness of muscles that impedes the ability to perform smooth coordinated movements. Dyskinetic CP is developed as a consequence of damage to the basal ganglia and its symptoms include involuntary movements which might differ depending on the specific part of the basal ganglia being damaged.

The last common type of CP is ataxic cerebral palsy which is a result of a damaged cerebellum causing shaky movements, lack of balance, and coordination. If the individual experiences a combination of symptoms characteristic of more than one type of cerebral palsy, they are diagnosed with mixed CP, which means that the disorder is caused by multiple brain regions being damaged.