Prevalence

CP is the most common physical disability in childhood. The prevalence of CP has been reported to range from 1 to 4 per 1000 live births. Yeargin-Allsopp and coworkers reported a higher incidence of CP in boys compared with girls, with a ratio of 1.5 to 1. The same study found a higher prevalence of CP in black compared with white children or those of Hispanic descent. Subsequent studies have confirmed these findings. Yeargin-Allsopp and colleagues also evaluated mobility. In that study, the majority (58.2%) of children walked independently, followed by those who were non-ambulatory or had limited mobility (30.6%), with the smallest number walking with an assistive device (11.3%).

Mobility difficulties have been associated with increased mortality of children with CP. In a study by Strauss and coworkers, those who were categorized as having poor mobility (defined by the inability to lift the head while in a prone position) had twice the mortality rate as those with high mobility (defined by the ability to roll or to sit). That same study found that the overall mortality rate of children with severe disabilities is declining by an estimated 3.4% per year.

Etiology

Due to the advances of modern medicine, risk factors such as rubella and kernicterus have decreased. In contrast, the survival of the very low birth weight infant has led to a population with an increased risk of CP. Risk factors for CP can be divided into pre-natal risk factors, maternal disease, and pregnancy related. Pre-natal risk factors, which have been associated with thrombosis and perinatal stroke, include advanced maternal age and primiparity, respectively. Maternal diseases such as diabetes, anemia, hypertension, epilepsy, thyroid dysfunction, and chronic renal disease have also been associated with CP. Associations have been found with multiple gestation (twins, triplets) and delivery factors such as assisted fertilization, plurality, placental disease, bleeding during pregnancy, preeclampsia or eclampsia, intrauterine exposure to infection (urinary tract infections, sexually transmitted diseases, and TORCH—Toxoplasmosis, Other [such as syphilis, varicella-zoster, parvovirus B19], Rubella, Cytomegalovirus, Herpes—infections among others), maternal fever in labor, restricted or excessive growth for gestational age, abnormal presentation at time of delivery, rupture of membranes longer than 24 hours before delivery, and induced labor. Apgar score of less than 7 at 5 minutes, low birth weight, and gestational age of less than 37 weeks are also risk factors for CP. Other causes in term infants and young children include infection, birth asphyxia, neonatal arterial infarction, and traumatic brain injury.

Although many risk factors for CP exist, the actual cause is a cerebral abnormality. CP may be caused by neonatal encephalopathy from infection, seizure, hypoxic-ischemic events, ischemic stroke, or congenital malformations.

Classification

CP has been classified into subtypes based on the dominant presentation of tone or movement into: (1) spastic; (2) non-spastic, hypotonic, dyskinetic (dystonic or choreoathetotic), and ataxic; (3) CP not otherwise specified. It has been further divided on the basis of limb involvement into unilateral (monoplegia, hemiplegia) or bilateral (diplegia, quadriplegia). Spastic CP is the most common, accounting for approximately 75% of all CP (63.6% bilateral, 36.4% unilateral).

Neuroimaging findings have been associated with specific CP subtypes. Bilateral spastic CP has most frequently been found to have periventricular white matter changes or hypoxic-ischemic findings on imaging. On the other hand, unilateral spastic CP has been associated with periventricular white matter lesions, periventricular gliosis, focal cortical dysplasia, and unilateral schizencephaly. Athetoid CP has been associated with cortical or deep gray matter lesions. In ataxic CP, lesion patterns are less common, but imaging may demonstrate cerebellar malformations.

Head, Eyes, Ears, Nose, and Throat

CP may be accompanied by visual deficits, sensorineural hearing loss, poor oral-motor control, and poor dentition. Vision may be hindered by strabismus (esotropia), nystagmus, cortical visual impairment, or retinopathy of prematurity. Difficulty with oral-motor control may lead to excessive drooling, dysphagia, or dysarthria.

Cardiovascular

Increased circulatory system disease, such as hypertension, atherosclerosis, heart and kidney damage, in adults with CP compared with age-matched peers has been reported. This may be correlated with the decrease in activity as patients age.

Pulmonary

Many CP-associated symptoms can lead to deterioration of the pulmonary system. Bronchopulmonary dysplasia (tachypnea, tachycardia, increased respiratory effort with nasal flaring, grunting, and accessory muscle usage with retractions and frequent oxygen desaturations) is seen in those who are delivered at a gestational age less than 30 weeks and who have a birth weight less than 1500 g. Dysphagia may lead to aspiration, which in turn can lead to pneumonia. Changes in tone and development of scoliosis can lead to decreased vital capacity and restricted airway disease. As patients with CP age, there may be an increase in respiratory illnesses, including pneumonia, influenza, and chronic obstructive pulmonary disease.

Gastrointestinal and Genitourinary

A high incidence of gastroesophageal reflux disease has been reported. This may be due to associated hiatal hernias, scoliosis, increased intra-abdominal pressure from spasticity, seizures, or neuromuscular incoordination. Regardless of cause, chronic gastroesophageal reflux may be manifested by dystonic posturing of the head and neck, increased spasticity, vomiting, and chronic irritability. Chronic peptic esophagitis may potentially cause esophageal mucosal ulceration and stricture formation. Constipation may arise because of low-fiber or liquid diet, use of medications (including opioids, antispasmodics, antihistamines, and anticonvulsants), immobility, decreased bowel motility, hypotonia, or skeletal abnormalities. Chronic constipation may in turn lead to megarectum, anal fissures, or soiling.

Musculoskeletal

Musculoskeletal disorder is the hallmark of CP. Its impact is lifelong and causes arthritic changes, deformity or contracture, and joint dislocation. This can lead to decreased mobility, osteoporosis, fracture, skin breakdown, and pain.

Pain is reported in both children and adults with CP and may be caused by muscle imbalance or spasticity. Back pain is commonly reported, followed by pain in weight-bearing joints. The presentation of CP can influence the location of pain. Foot and ankle pain is commonly reported in those with diplegic CP, whereas knee and hip pain is more frequent in quadriplegic CP. Neck pain, shoulder pain, and headaches are reported in those with dyskinesia. Pain can affect socialization and education as well as lead to fatigue and decreased mobility.

Decreased mobility can lead to osteoporosis. A study in 2008 reported that adults and children with spastic quadriplegia who are non-ambulatory have decreased bone density of the lower spine across their life span. Decreased mobility may also influence scoliosis progression over time. It was reported that curves of more than 40 degrees led to progressive worsening of spine curvature with age if not treated surgically. Curvature of the spine, whether scoliosis, kyphosis, or lordosis, can affect sitting balance, increase pain, affect pulmonary status, and cause difficulties with bowel and bladder management. The prevalence of scoliosis and the risk of being diagnosed with a moderate or severe scoliosis correlated with poor mobility and non-ambulatory status in patients.

Sitting may also be influenced by hip subluxation due to muscle imbalance, especially in spastic CP. Hip subluxation can lead to difficulties with wheelchair seating and fit, which may result in skin breakdown and pain, as persistent hip dislocations have been reported to increase pelvic obliquity.

Other joints commonly affected in CP include the knee, foot, and ankle. The most common disorders of the foot are equinus deformity, equinoplanovalgus deformity, and equinocavovarus deformity ( Fig. 125.1 ). Equinus deformity is a disorder of the hindfoot characterized by excessive plantar flexion of the hindfoot in reference to the ankle. It is seen with hypertonicity of the gastrocnemius or soleus muscles. Equinoplanovalgus deformity is seen with pronation of the forefoot and midfoot and is typically accompanied by hallux valgus and valgus deformity at the ankle. This is commonly seen with increased tone to the gastrocnemius and peroneals. Equinovarus deformity is seen with supination of the midfoot and involves the gastrocnemius and posterior tibialis muscles. Increased tone in the gastrocnemius muscle produces toe walking, which is common in CP.

Common disorders of the foot.

Excessive knee flexion due to increased tone in the hamstrings may be seen. However, increased tone alone does not lead to the crouched gait pattern commonly seen in CP. This pattern may be due to a combination of skeletal deformity, muscle weakness, spasticity, and poor motor control. It is characterized by flexion at the hips, due in part to increased tone of the iliopsoas, and flexion at the knees. Increased tone of the hip adductors may lead to further gait abnormality, producing a scissoring gait pattern.

Neurologic

Neurologic symptoms are manifested across a range of body systems. This may include impairments of oral-motor control (dysphagia, dysarthria, apraxia of speech), vision deficits (cortical visual impairment, esotropia), and sensorineural hearing loss. Patients may have seizures, cognitive problems, sensory impairments, muscle weakness, movement disorders, abnormal motor control, and spasticity.

Seizures are most commonly seen in those with spastic hemiplegia or quadriplegia. Seizure presentation can vary and may progress to epilepsy. A study by Humphreys and coworkers found an association between the development of epilepsy and the presence of neonatal seizures in CP patients with periventricular leukomalacia.

Sensory impairments can also be seen in patients with CP. Difficulties with proprioception, two-point discrimination, and stereognosis may be present. This is most common in those with the spastic hemiplegic subtype. Recent literature supports these findings and notes a correlation between sensory impairment and involvement of the thalamocortical pathways.

The predominant neurologic findings in those with CP are changes in tone or movement. This is evident by the way in which CP is classified: spastic, dyskinetic (dystonic or choreoathetotic), or ataxic. Spasticity is defined as a velocity-dependent increase in resistance to passive movement (see Chapter 154 ). The dystonic pattern seen in dyskinetic CP is characterized by involuntary muscle contractions that can be sustained or intermittent, leading to twisting or repetitive movements or abnormal postures. The choreoathetotic pattern is characterized by the combination of athetoid (slow, writhing) and choreiform (abrupt, jerky) movements. The ataxic subtype is characterized by uncoordinated movements. Hypotonia may be seen early in infancy, although it may still be present intermittently with dyskinetic CP.

Other

Sleep may be affected in those with CP as a result of sleep anxiety, night wakings, parasomnias, sleep disordered breathing, intellectual impairment leading to difficulty in self-soothing to sleep, altered light perception, reduced melatonin secretion, epilepsy, or pain. Active epilepsy in children with CP has had the strongest correlation with sleep disorders, specifically with excessive daytime sleepiness. Lower quality of life has been associated with insomnia and excessive daytime sleepiness.

Wayte and coworkers reported that persons with CP needed parental support at night most commonly for restless sleep and turning over in bed. This need for parental support led to increased caregiver burden and depression. Depression has also been reported in patients with CP.