Cerebral Palsy

By admin On Jun 17, 2024

Ovid: Pediatrics

Editors: Tornetta, Paul; Einhorn, Thomas A.; Cramer, Kathryn E.; Scherl, Susan A.

Title: Pediatrics, 1st Edition

> Table of Contents > Section III: – Specialty Clinics > 18 – Cerebral Palsy

Cerebral Palsy

Arabella I. Leet

Cerebral palsy results in a wide spectrum of disease
ranging from severely affected children who rely on wheelchairs for
ambulation and who have low cognitive function to mildly involved
children who are difficult to distinguish from idiopathic toe walkers.
Cerebral palsy is a disorder of the central nervous system that causes
neuromuscular derangements in a cascade from abnormality in muscle tone
and strength that can, in turn, have secondary deleterious effects on
bones and joints. Orthopaedic management cannot address the true
location of pathology, which is in the brain, but instead focuses on
making the child more independent with increased functional capacity.

Since cerebral palsy may encompass such a large spectrum
of involvement, both physical and cognitive, treatment must be geared
to the needs of the individual child. The first step is to try to
estimate what might be the highest level of function achievable for a
child, and next devise ways to reach this highest level of function
whether through nonsurgical means (such as braces, medications, or
therapy) or by surgical interventions that can lengthen muscles or
correct bone deformity.

If the orthopaedist understands that what is most
essential to adults with cerebral palsy is the ability to communicate,
the neuromuscular issues become only a part of the management of
cerebral palsy. Thus, a team approach involving therapists,
physiatrists, orthotists, neurologists, developmental pediatricians,
and social workers is often necessary in order to more completely
address the complex needs of an individual patient.

PATHOGENESIS

Etiology

Cerebral palsy is caused by an injury to the developing
brain. By definition the injury is nonprogressive and occurs before age
2, when glialization of the brain is still occurring. The brain
injuries that cause cerebral palsy are diverse. Children with
hemiplegia tend to have a fixed focal lesion in the brain caused by
brain malformation, infection, or embolic event. The pattern of
diplegia results from injury around the third ventricle where the
corticospinal tracks descend from the motor cortex as the corona
radiata en route to the internal capsule. Since the tracks for the legs
are closest to the third ventricle, hemorrhage around the third
ventricle leads to the pattern of injury seen in diplegia where both
legs are involved. Bleeds around the third ventricle, diagnosed by
ultrasound in the nursery can be a predictive sign of diplegia, as can
periventricular leukomalacia (PVL).

Many causes can contribute to cerebral palsy, but almost
50% of children with cerebral palsy are born full term and 35% of the
time the exact etiology remains unknown (Box 18-1).

Epidemiology

Cerebral palsy is thought to have an incidence of 1 to 3
per 1,000 live births. It affects over 700,000 children and adults in
the United States. The incidence has remained unchanged over time, but
there has been a shift in the last half century from children with
ataxia (secondary to Rh incompatibility, which is now easily diagnosed
and treated) to children with diplegia (occurring as lower birthweight
children survive with better neonatal intensive care unit management).
Cerebral palsy is associated with prematurity (less than 32 weeks
gestation) and low birthweight (less than 1,500 g).

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Pathophysiology

The mechanism of brain injury is not yet completely
understood. Prematurity or endotoxins from maternal infection may
increase the brain tissue sensitivity to injury from other sources such
as hypoxia. After initial injury, there appears to be a cascade of
cellular events that generate the release of cytokines causing further
cellular damage by increasing apoptosis (programmed cell death).
Research on the causes of brain injury is ongoing.

Classification

Children with cerebral palsy are classified both by the type of muscle tone exhibited and the location of the disease (Table 18-1).
For example, a child whose leg involvement is greater than arm
involvement and who is spastic would be classified as cerebral palsy
subtype spastic diplegia.

DIAGNOSIS

Usually the diagnosis of cerebral palsy also is
multidisciplinary involving the pediatrician, neurologist,
orthopaedist, and physical therapist. Depending on the history, workup
often includes:

Computed tomography or magnetic resonance imaging or ultrasound of the brain
Serology to rule out intrauterine infection
Physical therapy evaluation for developmental assessment.
Orthopaedic evaluation of the musculoskeletal system
Other tests depending on the age and
needs of the child and the presence of visual or hearing impairments,
mental retardation, or medical problems (seizures or pneumonia)

Prognosis

Life expectancy is variable and generally
depends on the overall medical condition of the child, including
history of recurrent pneumonias, seizures, and nutritional status.
Parents often want to know whether their child will walk. Predictors of the ability to walk include:
- □ Loss of primitive reflexes before 24 months:
  - □ Moro
  - □ Parachute
  - □ Asymmetric tonic neck reflex
  - □ Extensor thrust
  - □ Neck-righting reflex
- □ Sitting by 2 years
- □ Development of reciprocal activities (e.g., crawling)
- □ In general, if walking is not achieved
  by 7 years, then it is unlikely that a child will develop the ability
  to walk in the future.

TABLE 18-1 CLASSIFICATION OF CEREBRAL PALSY

Type		Description
Tone
	Spastic	Increased stretch reflex, increased clonus
	Dyskinetic	Abnormal motor involvement
	Ataxic	Cerebellar involvement
	Mixed	Combinations of above
Location
	Quadriparesis	All limbs involved
	Diplegia	Legs involved to a greater extent than arms
	Hemiplegia	One-sided involvement

Physical Examination and History

Physical Examination

Observation of extraneous movements (i.e., athetoid motion)
Muscle tone
- □ Subjectively graded as high to low
Selective control (ability to place limbs in a desired location in space)
Sensibility
Contracture
- □ Fixed loss of motion to be distinguished from resistance secondary to high tone.
- □ There can be a high degree of
  variability between exams based on the child’s ability to relax. Tone
  will increase if the patient is upset, cold, or frightened.
Torsional deformity (results in lever arm dysfunction)
- □ Femoral anteversion
- □ External tibial torsion
Balance and equilibrium
Gait evaluation
- □ Observational gait analysis (Box 18-2)
- □ Three-dimensional gait analysis
  - □ Computer-based evaluation including kinetics, kinematics, and electromyelograph (EMG) analysis
Special physical exam tests used for
cerebral palsy to test muscles that cross two joints that are often
more specifically involved
- □ Phelps test: tests if gracilis muscle is involved compared with hip adductors
  
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  - □ The patient is positioned prone with the knee flexed.
  - □ As the knee is extended, the hip is observed for adduction.
- □ Silverskiöld test: used to distinguish involvement of gastrocnemius from the soleus.
  - □ With the patient supine, the ankle is dorsiflexed with the knee extended and then again with the knee flexed.
  - □ Since the gastrocnemius attaches at the
    distal femur it is relaxed with knee flexion, allowing the foot to
    dorsiflex if the soleus is not spastic or contracted.
- □ Duncan-Ely test: distinguishes whether
  the rectus femoris or iliopsoas is contracted by observing the pelvis
  rising with knee flexion when the patient is prone.
- □ Popliteal angle: determines the extent of hamstring involvement across the hip and knee joints (Fig. 18-1).

History

Prematurity
Low birthweight
Maternal toxemia
Placental complications: abruption or previa
Medical history to identify seizure
disorders, gastrointestinal reflux, pneumonias, and
strabismus—disorders often seen in children with cerebral palsy
Developmental milestones
Handedness
- □ Unusual to show hand dominance before 18 months
- □ Suspect hemiplegia if child is not using both hands

Figure 18-1 The popliteal angle is measured with the child supine and the hip flexed at 90 degrees.

Clinical Features

Children with severe involvement often have microcephaly
apparent to observation, as are extraneous movements. Assessment of
motor tone, by range of motion of joints, reveals increased tone,
clonus, or contractures. Specific secondary orthopaedic developments
from the brain injury include:

Hip subluxation/dislocation
- □ Children with cerebral palsy have
  structurally normal hips at birth, but muscle imbalance over time
  (especially increased adduction and flexion) can cause the hips to
  sublux and finally to dislocate completely causing hip pain and
  difficulty with seating and perineal care.
Scoliosis
- □ Curves tend to be long C-shaped or S-shaped curves that often include the pelvis.
Foot deformity
- □ Pes planovalgus in children with diplegia
- □ Equinovarus feet develop more commonly in children with hemiplegia.
Gait deviations
- □ Caused by deformities to joints from contractures or spasticity
- □ Proximal compensations are necessary to accommodate distal pathology.
- □ Problems with balance
- □ Gait analysis can be a useful tool to
  sort deformities (which can respond to surgical correction) from
  compensations (which will resolve without the need for intervention
  once the true pathology is resolved).
Upper extremity involvement
- □ Typically involves elbow flexion,
  forearm supination (from pronator spasticity), wrist volar flexion, and
  finger fisting or thumb-in-palm deformity
- □ Sensibility may be lost, making
  eventual use of arm problematic because correcting the deformity may
  not make up for the fact that there is poor sensory information being
  relayed back to the brain.
- □ The size of the involved arm has been shown to correlate well with the amount of sensibility:
  - □ If the involved arm is considerably
    smaller then the uninvolved side, much of the sensibility in the
    involved arm can be assumed to be decreased.
  - □ Hygiene problems can result from fisted hand position or from thumb in palm deformity.
Pathologic fracture
- □ Most children with cerebral palsy have
  a significant decrease in bone density. The etiology of low bone
  density includes the following:
  - □ Non-weightbearing
  - □ Seizure medications (Dilantin, Carbamazepine) can impede vitamin D absorption.
  - □ Poor nutrition leads to insufficient intake of calcium and vitamin D.
  - □ Casting after surgery leads to disuse osteopenia.
  - □ Fractures can occur with transfers or
    spontaneously (no recognized event), and are managed by casting (which
    can be difficult secondary to shortening while in a cast caused by
    muscle spasticity) or alternatively operative strategies including
    external or internal fixation.

Differential Diagnosis

Genetic syndromes
- □ Familiar spastic paraplegia
- □ Hereditary microcephaly
Progressive neurologic disorders

Radiographic Features

Anteroposterior pelvis: Check for hip subluxation using the Reimer Migration Index (Fig. 18-2).
Spine films: Use the Cobb angle technique to measure the amount of scoliosis.

TREATMENT

Decreasing Spasticity

Medical
- □ Baclofen: GABA antagonist, given either orally or intrathecally through pump.
- □ Botulinum toxin: temporary muscle paralysis.
- □ Valium: given at 0.1 mg/kg, most
  effective of all agents as a muscle relaxant, but also leads to central
  nervous system effects
Surgical
- □ Selective dorsal rhizotomy usually
  performed by a neurosurgeon; dorsal nerve rootlets are identified, and
  30% to 60% are divided from L1-S2. Candidate selection for rhizotomy
  must be done carefully. The procedure is best for ambulatory spastic
  diplegics. The most common complication of rhizotomy is weakness after
  the procedure.

Figure 18.2 Reimer’s Migration Index is a measure of the percentage of femoral head outside the acetabulum.

Maintaining Positioning

Bracing upper and lower extremities to maintain functional positions
- □ Ankle foot orthosis (AFO) made out of semi-rigid material
- □ May be solid or articulated, depending on ambulatory status
Seating system in nonambulatory children
- □ Position the trunk upright, head forward, so children can interact with the world around them
- □ Accommodate trunk and pelvic deformity in design of wheelchair
- □ Use of tilt chairs prevents skin breakdown in children who cannot shift their weight while sitting
- □ Use electric wheelchairs, if child capable of steering safely.
- □ Traditional custom wheelchairs are
  often difficult to transport in a car, thus families also will need a
  stroller-type device that is more portable.

Managing Deformity

Soft-tissue release: lengthening a
muscle, whether at the musculotendinous junction or through the tendon,
treats fixed contractures but also results in muscle weakness.
- □ Adductor tenotomy
  - □ Indications: a Reimer Migration Index
    of more than 50 percent, or loss of more than 30 degrees of hip
    abduction in hip extension resulting in difficulty with diapering, or
    perineal hygiene
- □ Gastrocnemius recession
  - □ Indication: for ankle equinus and a positive Silverskiöld test (soleus not contracted)
- □ Tendo-Achilles lengthening
- □ Reserved for equinus involving both gastrocnemius and soleus muscles
- □ Must be careful not to over lengthen the tendo-Achilles, which will result in an iatrogenic crouch gait
- □ Hamstring lengthening
  - □ Indications: popliteal angles greater
    than 45 to 60 degrees or difficulty with sitting secondary to extension
    of the pelvis from the proximal attachment of the hamstrings
  - □ Medial or medial and lateral depending on the amount of the popliteal angle preoperatively
Tendon transfer: aimed to rebalance muscles around a joint
- □ SPLATT/SPLOTT (split anterior or posterior tibialis tendon transfer)
  - □ Indications: hindfoot varus, passively
    correctable, and identification of spasticity (may require EMG) in
    either the posterior or anterior tibialis muscle
Osteotomies: correction of bone for torsional correction or to address deficiency of structures (i.e., acetabulum)
- □ Varus derotation osteotomy (VDO) of the proximal femur
  - □ Correction of valgus and anteversion of the proximal femur
  - □ Indication: for Reimer Migration Index of more than 50 degrees that cannot be corrected with adductor tenotomy
- □ Pelvic osteotomy (Dega, Chiari)
  - □ Indications: acetabular deficiency
  - □ Acetabulum usually deficient in
    children with cerebral palsy posteriorly or laterally, as opposed to
    hip dysplasia where the deficiency tends to be anterior
- □ May be performed in combination with VDO
- □ Os calcis lengthening
  - □ Indications: for flexible pes planovalgus
  - □ Navicular is subluxed on the talar head
Fusion
- □ Spine
  - □ Indications: for scoliotic curves of
    greater than 50 degrees that are rigid. Traction films can help
    determine curve flexibility, as can clinical examination.
  - □ Add anterior release or fusion for excessively large curves (more than 70 to 80 degrees)
  - □ Fuse to include the pelvis if there is pelvic obliquity
  - □ Since fusions are long, allograft often used as bone graft
- □ Subtalar joint
  - □ Indications: for pes planovalgus that is not passively correctable
  - □ Great toe for hallux valgus deformity
  - □ Routine bunion corrections less reliable
  - □ Must fuse in 20 to 30 degrees of dorsiflexion