Cerebral palsy (CP) is a disorder of movement and posture that results from permanent and non-progressive damage to the developing brain in the peri-natal period. Recognised causes for CP:

• Prematurity (intra-cerebral haemorrhage, anoxia)
• Trauma (difficult delivery, NAI)
• Infection (TORCH: Toxoplasmosis, Other (syphilis, varicella-zoster, parvovirus B19), Rubella, Cytomegalovirus and Herpes)
• Toxic injury (prenatal and postnatal period)
• Unknown in 30%

Several systems are in use to describe different aspects of the condition:

Physiological

• Spastic:  increased muscle tone due to motor cortex and pyramidal tracts damage – by far the most common and the only one with which the orthopaedic surgeon may be involved.

• Dyskinetic: Abnormal movements caused by damage to the extra-pyramidal system and basal ganglia. A few types have been described:

1. Athetoid: slow writhing movements of the fingers, hands, and the rest of upper limb. The mouth and lower limbs may also involved
2. Ballismus and hemiballismus: Infrequent jerky, purposeless movement involving a single limb
3. Chorea: Random movements of the limbs that increase during rest and may improve with movement
4. Dystonia: Involuntary sustained muscle contraction that result in abnormal posture. The muscle tone fluctuates and often increases with effort and emotion

• Ataxic: problems with balance and coordination caused by damage to the cerebellum
• Mixed

Anatomical

• Monoplegia (single limb)
• Hemiplegia (one side of body)
• Diplegia (both lower limbs involved, mild upper limb involvement)
• Quadriplegia or ‘Total body involvement’

Functional

The ‘Gross Motor Function Classification System’ (GMFCS) was developed to describe the child’s abilities based on self-initiated movement, with emphasis on mobility(1). It is not valid before the age of 4 years old.

I – Walks without limitations

II – Walks with limitations

III – Walks with a hand-held mobility device (eg crutch)

IV – Self mobility limited, may use powered mobility

V – Transported in a manual wheelchair

Another functional classification which is becoming less popular nevertheless it is useful:

1 – Community ambulator

2 – Household ambulator

3 – Therapeutic ambulator

4 – Non-ambulator

GMFCS levels. They are usually established when the child is 4 years old and remain relatively stationary until adulthood

Diagnosis is rarely made at birth. Recognised symptoms include difficulty sucking, swallowing and dribbling at the mouth. The child may feel stiff or wriggle awkwardly. Milestones are delayed. CP is commonly associated with mental retardation, convulsions, speech impediments, defects of hearing and visual impairment. Muscle spasm can cause several musculoskeletal problems that need surgical interventions (see part II for the details). These include:

Upper limb (see section 5.2 for details)

Spine

Scoliosis (15 - 25%). Highest risk in spastic quadriplegia. Correction is usually indicated in severe scoliosis (Cobb angle > 60°)

Neuromuscular hip dysplasia

This is quite common, particularly in non ambulator CP. It includes adduction contractures, excessive femoral anteversion (causes in-toeing), coxa valga, acetabular dysplasia and subsequent dislocated hip.

A child with severe CP. He has severe scoliosis and a dislocated left hip

The knee

There is usually flexion deformity of the knee and patella alta. Hyperextension deformity may develop secondary to equinus deformity of the foot

Foot and ankle

Muscle imbalance around the foot and ankle can cause various well recognised patterns such as cavo-varus, calcaneovalgus, equinus and hallux valgus deformities.

Severe feet deformity in a child with severe CP. Note the loss of medial arch, Midfoot break, forefoot abduction and valgus heel.

Mild cavo-varus foot in a child with severe spastic CP. Note the varus heel, flexed first ray and high medial arch.

For best result, the management of CP should be ideally undertaken by dedicated multidisciplinary team.  As problems develop in response to growth in a child with CP, the more severely involved children tend to be kept under regular (e.g. annual review) until they reach skeletal maturity. The lack of provision of services to these children beyond maturity is a source of almost universal concern to their parents/guardians.

The principle of treatments include:

a) Range and strength of movement - Physiotherapy led, patient and parent delivered stretching and strengthening program

b) Maintain position & accommodate weakness - Appropriate orthoses and assistive devices

c) Decrease spasticity:

• Systemic (baclofen)
• Regional (selective dorsal rhizotomy (SDR)) Local (botulinum toxin)

d) Address deformity – tenotomies, tendon transfer, osteotomies and joints reduction.

Baclofen

It is GABA receptors inhibitor. It is usually used children who are too small or too young for a more effective treatment. Unfortunately the effective dose is associated with unpleasant side effects which often lead to discontinuation. Side effects include sedation, confusion, memory loss, dizziness, ataxia, weakness which are the cause of cessation.  Intra-thecal Baclofen has less systemic side effects (although significant local risk) and the therapeutic dose is 1% than the oral dose.

Botulinum 

It is a potent neurotoxin which prevents acetylcholine release reducing muscle spasm. This usually lasts for 3-4 months. The usual dose is 12 units per kg (400 units maximum).

Selective Dorsal Rhizotomy (SDR)  

This is a surgical intervention performed by neurosurgeon. It has shown promising results in selected cases.  Current criteria include children between four and eleven years of age with a diagnosis of spastic diplegia, usually following premature birth with adequate muscle strength in the legs and trunk and moderate to severe spasticity.

Orthoses

They are used;

• Maintain position
• Temporising measures
• Redirect forces
• Improve function

Assistive devices

These include:

• Canes and crutches
• Walkers to help with balance: A rear walker is most often used as it promotes extension of the lower limbs and the back.
• Wheelchair  (manual or motorized)
• Standers to maintain the child in an upright position which facilitates social interaction and some mechanical loading.