Cerebral Palsy - General - Pediatrics

Introduction

Nonprogressive upper motor neuron disease (static encephalopathy) due to injury to immature brain
- orthopaedic manifestations
  - contractures (this topic)
  - fractures (this topic)
  - upper extremity deformities
  - hip subluxation and dislocation
  - spinal deformity
  - foot deformities
  - gait disorders
Epidemiology
- demographics
  - by definition onset must be before first two years of life, although diagnosis may be delayed in very mild cases
  - Most common cause of chronic childhood disability
  - Incidence: 2-3 per 1000
Pathophysiology
- pathoanatomy
  - leads to muscle imbalance with a mixture of weakness and spasticity
  - the encephalopathy is static while the affected portion of the musculoskeletal system changes with growth
- risk factors
  - prematurity (most common)
  - anoxic injuries
  - prenatal intrauterine factors
  - perinatal infections
    - toxoplasmosis
    - rubella
    - cytomegalovirus infection
    - herpes simplex
    - ToRCH
  - meningitis
  - brain malformations
  - brain trauma - NAT
Associated conditions
- orthopaedic manifestations characteristic of CP
  - primary
    - abnormal tone
    - loss of motor control
    - impaired balance
    - spasticity
    - (hypotonia)
    - (dyskenesias such as chorea and athetosis)
  - secondary (growth and spasticity related)
    - contractures
      - starts as dynamic contractures, become static with time (continuous muscle contraction results in shortening) and growth (growth of bones occurs at a faster longitudinal rate than muscles in spastic cerebral palsy)
    - upper extremity deformities
    - hip subluxation and dislocation
    - spinal deformity
    - foot deformities
    - gait disorders
    - fractures
      - often associated with non-ambulators secondary to low bone mineral density
      - bisphosphonates may be useful
        
        IV pamidronate considered with >3 fractures and a DEXA z-score <2 SD
Prognosis
- most reliable predictor for ability to walk is independent sitting by age 2

Classification

Physiologic Classification
Spastic (most common)	Velocity-dependent increased muscle tone and hyperreflexia with slow, restricted movement due to simultaneous contraction of agonist and antagonist muscles. Most amenable to operative treatments.
Athetoid	Characterized by constant succession of slow, writhing, involuntary movements
Ataxic	Characterized by inability to coordinate muscle movements. Results in unbalanced, wide based gait.
Mixed	Usually mixed spastic and athetoid features and involves the entire body
Hypotonic	Usually precedes spastic or ataxic for 2-3 years
Anatomic Classification
Quadriplegic	Total body involvement and nonambulatory
Diplegic	Legs more than arms but usually still ambulatory. IQmay be normal (injury in brain is midline)
Hemiplegic	Arms and legs on one side of the body, usually with spasticity; will eventually be able to walk, regardless of treatment
Gross Motor Function Classification Scale (GMFCS)
Level I	Near normal gross motor function, independent ambulator
Level II	Walks independently, but difficulty with uneven surfaces, minimal ability to jump
Level III	Walks with assistive devices
Level IV	Severely limited walking ability, primary mobility is wheelchair
Level V	Nonambulator with global involvment, dependent in all aspects of care

Evaluation

History
- clinical history
  - perinatal history
  - growth & development
  - prior medical treatments
- functional status
  - sitting/standing posture
  - upper and lower extremities function
  - communication skills
  - acuity of hearing and vision
Physical exam
- general musculoskeletal exam
  - motion, tone, and strength
  - Rotational limb profiles for torsional deformities
- gait
  - gait lab analysis
  - plantigrade feet
  - crouch
  - stiff knee gait
- spine exam
  - presence and flexibility of scoliosis
  - spinal balance and shoulder height
  - pelvic obliquity
  - resting head posture
  - hamstring contractures (lead to decreased lumbar lordosis)
- hips
  - hip contractures
    - flexion contracture (lead to excessive lumbar lordosis)
    - adduction contracture
  - hip instability and dislocations are common, may be looked over as a contracture alone
    - observe thigh length in sitting, leg length when supine, or galleazzi test
    - adductor contracture can make examination difficult
- foot and ankle
  - equinovarus and planovalgus deformities common
  - observe wear patterns, callouses
  - note hypertonicity
  - toe walking or absent heel strike during gait secondary to gastrosoleus spasticity and contracture
    - may hyperextend knee to obtain heel contact
  - provacative Silverskiold test to differentiate gastrocnemius contracture vs achilles contracture

Imaging

Radiographs
- standard radiographs should include
  - AP and lateral of hips
  - standing spine radiographs as baseline
MRI
- MRI of brain shows a spectrum of changes including
  - periventricular leukomalacia (PVL) white matter lesions most frequent (56%)
  - while grey matter lesions (18%)
  - brain malformations are less frequent (9%)

Treatment Spasticity & Deformity

Nonoperative
- physical therapy, bracing/orthotics, medications for spasticity
  - spasticity control
    - Botox (botulinum - A toxin)
      - competitive inhibitor of presynaptic cholinergic receptors with a finite lifetime (usually lasts 2-3 months)
      - used to maintain joint motion during rapid growth when a child is too young for surgery
      - often injected into gastrocnemius
      - helpful treatment in dynamic contractures; little benefit with static contractures
    - baclofen
      - reduces tone via unknown mechanism
        
        thought to act as GABA agonist
        
        intra-thecal administration is preferred route to avoid cognitive impairment seen with oral administration (poor bioavailability leads to difficulty with oral dosing)
        
        Intra-thecal baclofen tends to be used for non-ambulatory CP (GMFCS IV and V)
Operative
- soft tissue procedures/releases
  - indications
    - to improve function in child from 3-5 years of age with spasticity and voluntary muscle control
  - techniques
    - tenotomies for continuously active muscles (e.g. hip adductor)
    - tendon lengthening for continuously active muscles (e.g. achilles tendon or hamstring)
    - tendon transfers for muscles firing out of phase (e.g. rectus tendon or tibialis posterior)
      - tendon transfers in the upper extremity show the best improvement in function in patients with voluntary motor control
- selective dorsal rhizotomy
  - indications
    - ages 4 to 8, ambulatory spastic diplegia, and a stable gait pattern that is limited by lower extremity spasticity
  - neurosurgical resection of dorsal rootlets that do not show a myographic or clinical response to stimulation
  - contraindications
    - athetoid CP
    - nonambulatory patients with spastic quadriplegia (associated with significant spinal deformities)
  - falling out of favor due to limited functional gains and no reduced risk of subsequent musculoskeletal surgeries
- bony procedures/deformity correction
  - indications
    - usually performed in later childhood / adolescence
    - static contractures, progressive joint breakdown, and certain patterned gait-deterioration can be treated with combinations of myotendonous unit lengthening, tendon transfers, and osteotomies
  - SEMLS surgery (Single-Event, Multi-Level Surgery)
    - concept arose to limit multiple surgeries, anesthetics, and rehabilitation time for children
    - most successful when combined with a thorough gait lab assessment that predicts improvemenet in function with multiple level surgical interventions
    - simple lengthenings can cause deterioration in gait when other contractures are "uncovered"; SEMLS management seeks to avoid these iatrogenic complications
    - can be done on bilateral lower extremities in efforts to improve gait
  - specific procedures
    - see Cerebral Palsy Upper Extremity Conditions
    - see Cerebral Palsy Spine Conditions
    - see Cerebral Palsy Hip Conditions
    - see Cerebral Palsy Gait Disorders
    - see Cerebral Palsy Foot Disorders