Classification and types

Current official classification of cerebral palsy

The previous way of describing Cerebral Palsy (CP) was felt to be insufficiently accurate and is to be replaced by a new way of classifying CP (from the consensus conference). This is comprised of a description of four main dimensions -:

• Motor abnormalities
• Accompanying impairments
• Anatomical and neuro-imaging findings
• Causation and timing

This is relatively new and not all professionals have switched to this new way of thinking as yet. Therefore, most reports to date will still define and classify cerebral palsy as described below.

Classification according to limbs affected

• Monoplegia - only one limb is affected

• Hemiplegia – 20 - 30%; one side of the body is affected and usually affects the upper and lower limbs.

• Diplegia – 30 - 40%; impairment primarily of the legs (often with some involvement of arms to lesser extents).

• Quadriplegia (tetraplegia) – 10 -15%; all four limbs are affected and the trunk is often involved.

Classification according to movement disorder

Spastic Cerebral Palsy:

• Most common type ( 70- 80% of cases), as a result of impairment to the nervous pathway known as the pyramidal tract, which include the surface of the brain (‘motor cortex’) where voluntary movements are initiated, and the nerve fibres that carry the signals to the spinal cord.
• Spastic muscles are tight and stiff, and have increased resistance to being stretched. The stiffness affects certain patterns of muscles, causing an imbalance so the child’s limbs can be pulled into certain positions which then can be difficult to move out of.
• Spasticity may be mild and affect only a few movements, or severe and affect the whole body. The amount of spasticity usually increases over time.

Dyskinetic Cerebral Palsy: (Dystonic and Athetoid)

• Accounts for 10-15% of CP cases. As a result of impairment to the basal ganglia in the brain, this fine-tunes signals to the muscles.
• Affected children have variable muscle tone i.e. the tension in the muscles can change between low and high and can occur suddenly and be from one extreme to the other.
• It can cause children to become stuck in a position or can make it difficult for them to be still. The fluctuations often occur as a result of stimulation e.g. excitement, fear or effort. This often appears as posturing patterns e.g. neck arching back, arms stretching and turning inwards.
• Children with athetoid cerebral palsy have many involuntary movements and some are constantly in motion.
• They often have speech difficulties.
  

Ataxic Cerebral Palsy:

• Occurs in <5% of cases, due to impairment to the cerebellum, the brain’s major centre for balance and coordination.
• Affected children have jerky, uncoordinated movements caused by a disturbed sense of balance and depth perception. They usually have poor muscle tone, a staggering walk and unsteady hands.
  

Mixed Cerebral Palsy:

• Most children with cerebral palsy have a mixture of spasticity and dystonia
• Some will have a predominant spastic picture and others will have a predominant dystonic pattern.
• In some children, there is predominant underlying weakness as the main cause of functional impairment. Treatment that modifies spasticity (‘stiffness’) or dystonia (‘posturing’) has limited effects in improving function.
  

The classifications of movement disorder and number of limbs involved are usually combined. For example spastic diplegia refers to spastic type CP that affects primarily the legs.