A Review of Cerebral Palsy for the Oral Health Professional

Individuals who have cerebral palsy (CP) face many physical challenges throughout their lifetimes in addition to societal barriers that can have an impact on quality of life. The ability to access appropriate dental care has long been an issue for people who have disabilities. Dentists should be integral members of teams of professionals involved in optimizing the health of individuals who have CP. As with all members of this interdisciplinary team, oral health care providers should have a thorough knowledge of the medical, cognitive, and rehabilitative issues associated with CP. With this knowledge the best possible health care can be provided.

Cerebral palsy (CP) is the most common form of neuromuscular disability affecting children. As more and more individuals who have CP continue to live in community settings, rather than institutions, and as their life spans increase, dentists and hygienists will be responsible for providing a continuum of oral health care to this population from childhood through later life.

The definition of CP has changed through the years, as researchers have increased their knowledge of the disorder in its various permutations. In 2004, an International Workshop on the Definition and Classification of Cerebral Palsy was held, with support from United Cerebral Palsy, the Castang Foundation, and the National Institute of Neurological Disorders and Stroke. Attendees at this meeting agreed on an updated definition of CP as follows:

Cerebral palsy (CP) describes a group of disorders of the development of movement and posture, causing activity limitation, that are attributed to non-progressive disturbances that occurred in the developing fetal or infant brain. The motor disorders of cerebral palsy are often accompanied by disturbances of sensation, cognition, communication, perception, and/or behavior, and/or by a seizure disorder.

This definition differs from earlier ones that focused solely on motor impairments and did not include mention of the additional developmental disorders that often are observed in individuals who have CP. This definition excludes discussions of what constitutes an immature brain and levels of functioning. These exclusions were intentional, with the belief that more precise definitions might result in limitations of services for many individuals who have CP.

Risk factors

“Cerebral paresis” first was described in 1861 in an article by William Little, an English surgeon. Little noted that most of the children who developed CP had histories of difficult births, and he theorized that the condition was the result of hypoxia during the birth process. Until recently, this belief remained widespread among the public and the medical profession. Biomedical research done in the past 20 years has shown that, in reality, birth complications are responsible for only a small fraction of cases of CP. It has been estimated that up to 70% to 80% of CP cases can be attributed to prenatal factors, with birth asphyxia responsible for a small number (approximately 10%) and the remainder due to identifiable postnatal conditions.

As stated in the definition of CP, the disorder develops subsequent to some type of insult to the immature brain. This insult can occur, however, anytime from during the prenatal period through the first few years of life. A wide range of risk factors have been implicated in the development of CP. Table 1 provides a list of conditions shown to place a child at risk for developing CP.

Table 1
Risk factors associated with cerebral palsy
Prenatal Perinatal Postnatal
Hypoxia Premature birth <32 wk or <2500 g Asphyxia
Genetic disorders Asphyxia Seizures in postnatal period
Metabolic disorders Blood incompatibility Cerebral infarction
Multiple gestation Infection Hyperbilirubinemia
Intrauterine infection Abnormal fetal presentation Sepsis
Thrombophilic disorders Placental abruption Respiratory distress syndrome
Teratogenic exposure Instrument delivery Chronic lung disease
Chorioamnionitis Meningitis
Maternal fever Postnatal steroids
Exposure to toxins Intraventricular hemorrhage
Malformation of brain structures Periventricular leukomalacia
Intrauterine growth restriction Shaken baby syndrome
Abdominal trauma Head injury
Vascular insults

From Jones MW, Morgan E, Shelton J.E. Cerebral palsy: introduction and diagnosis (Part 1). J Pediatr Health Care 2007;21(3):147; with permission.

It is not always possible to determine an exact cause in individual cases. Approximately 30% of cases have none of the known risk factors. Premature birth, especially associated with extreme low birth weight (<1000 g), places infants at significant risk for subsequent CP. The rate of CP in this population of infants is approximately 8% to 10%. Improved fetal monitoring during birth and higher rates of cesarean section have not had an impact on the rates of CP, however, and some investigators question whether or not many of these infants have pre-existing conditions that precipitate preterm birth and subsequent development of CP.

Prevalence

Birth prevalence rates for CP have not decreased in the United States or Europe over the past 30 years. One European study showed a slight increase in CP from the 1970s to the 1990s. The rate has remained approximately 2 to 3 per 1000 live births during that time. Rates in underdeveloped countries are similar or, in some cases, even lower than in developed countries. Some researchers have theorized that a greater incidence of multiple births and increased survival rates for extreme low birth weight infants in recent years may account for some of this inability to lower CP rates. United Cerebral Palsy has estimated that currently there are more than 500,000 individuals who have CP living in the United States. An estimated 87% to 93% of children who have CP are now living into adulthood, which increases prevalence in the adult population.

Prevalence

Birth prevalence rates for CP have not decreased in the United States or Europe over the past 30 years. One European study showed a slight increase in CP from the 1970s to the 1990s. The rate has remained approximately 2 to 3 per 1000 live births during that time. Rates in underdeveloped countries are similar or, in some cases, even lower than in developed countries. Some researchers have theorized that a greater incidence of multiple births and increased survival rates for extreme low birth weight infants in recent years may account for some of this inability to lower CP rates. United Cerebral Palsy has estimated that currently there are more than 500,000 individuals who have CP living in the United States. An estimated 87% to 93% of children who have CP are now living into adulthood, which increases prevalence in the adult population.

Subclassification of cerebral palsy

One method of classifying types of CP is according to the nature of the motor disorder observed. Three major types of motor disorders are encountered:

  • Spastic CP, which accounts for 70% to 80% of cases. Its predominant characteristic is increased muscle tone. This type of CP results from pyramidal (upper motor neuron) damage.

  • Dyskinetic CP, which is observed in 10% to 15% of cases. Motor characteristics include hypotonia, athetotic (slow, writhing) movements, abnormal postural control, and overall problems with coordination. Oromotor difficulties, including speech and swallowing difficulties, commonly are seen. Damage to basal ganglia or deep motor neurons is responsible for this type of CP.

  • Ataxic CP, which accounts for only approximately 5% of cases. These individuals have problems with voluntary movement, balance, and depth perception. It is caused by damage to cerebellar neurons.

Many individuals exhibit mixed motor involvement and cannot be categorized exclusively in any one of these groups.

Spastic CP can be subclassified further according to topography, that is, depending on which extremities are involved:

  • Quadriplegia: All four extremities, the trunk, and oromotor musculature are involved. This accounts for 10% to 15% of cases of spastic CP. Most of these individuals exhibit some degree of intellectual disability in addition to the motor disorder. These patients also are at high risk for seizures and sensory impairments. This type of CP has been associated with asphyxia in all infants and severe intraventricular hemorrhage in preterm infants.

  • Diplegia: 30% to 40% of cases of spastic CP, characterized by spasticity in the legs. Arms also can be affected but to a lesser extent. Approximately 30% of these individuals have intellectual disabilities or learning difficulties. Most are able to ambulate independently or with assistance. Approximately 50% of these cases are associated with preterm birth.

  • Hemiplegia: 20% to 30% of cases of spastic CP. One side of the body is involved. Usually, the arm is more involved than the leg. More than 60% of these individuals have normal intellectual development and are able to ambulate with or without assistance. They are at high risk for development of partial seizures. This type of CP is associated with vascular malformations in the brain and limited intraventricular hemorrhage in early childhood.

  • Monoplegia: This condition is extremely rare. Only one limb is involved, an arm or leg. Patients who have this subtype as an initial clinical diagnosis often are shown to have an underlying etiology other than CP.

Diagnosis

The diagnosis of CP not always is straightforward, but an early diagnosis is important in terms of optimizing therapeutic interventions. Clinical observation and parental report are the initial stages in formulating this diagnosis. Children who are severely affected, or who have a known risk factor, often are diagnosed at an earlier age than those who are affected more mildly.

Parents may report concerns in early infancy, such as difficulty with feeding, excessive crying, jitteriness, “stiff” posturing, or limpness (indicative of hypotonia). As children age, motor milestones, such as the ability to sit up unassisted or learning to walk, may be delayed. Physicians may note a persistence of primitive reflexes that normally are lost in the first few months of life. In a toddler who has learned to walk, abnormal gait patterns may be observed.

Part of the diagnostic process involves the exclusion of other etiologies, such as neurodegenerative, metabolic, or genetic disorders that have clinical presentations similar to CP. Neuroimaging studies, electroencephalography, chromosomal studies, and an array of blood tests all may be useful in making a definitive diagnosis.

Medical issues

Although the encephalopathy responsible for CP may be static, the physical and medical status seen in individuals who have CP is anything but static. CP is a lifelong disorder that requires a range of long-term therapies and acute interventions. Several physical complications are commonly associated with CP ( Box 1 ). Early predictions of future neuromuscular and intellectual deficits can be difficult or impossible to make, and the course of complications varies greatly from person to another.

Oct 29, 2016 | Posted by in General Dentistry | Comments Off on A Review of Cerebral Palsy for the Oral Health Professional
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