Diagnosis

Diagnosis of Cerebral Palsy
Since cerebral palsy is not one diagnosis but instead includes a spectrum of disorders with a variety of physical findings, presentations and causes, it is not surprising that a specific diagnosis can sometimes be a challenge. Studies found that of those with cerebral palsy, approximately 30-40 percent had prenatal, 30-40 percent perinatal and 5 percent postnatal onset.

History Findings and Risk Factors
History findings and risk factors for cerebral palsy may include: maternal factors (mental retardation, epilepsy, hyperthyroidism, prior fetal deaths, twin pregnancy), sibling with motor problems, infections, toxins, prematurity, low birth weight, bleeding in the brain, seizures, low Apgar score (reflects condition of newborn), third-trimester bleeding, pre-eclampsia (maternal hypertension with protein in urine), premature placenta separation, low placenta weight, asphyxia/hypoxia (lack of oxygen), abnormal fetal position at birth, congenital malformations, fetal bradycardia (slow heart rate), hyperbilirubinemia (increased levels of bilirubin, a breakdown product of red blood cells), trauma and clotting disorders

However, most children do not necessarily present with these risk factors. A large study called the National Collaborative Perinatal Project looked at high risk factors and found that 97 percent of those with the high-risk profile will not end up having cerebral palsy, and 63 percent of children who end up with a diagnosis of cerebral palsy will not have a high-risk profile. The risk factors studied included a birth weight less than 2500 grams, gestation less than 32 weeks, intrauterine growth retardation, intracranial hemorrhage (bleeding in the brain) and trauma. Having a single risk factor has much less of an impact than having more than one factor.

Eight percent of infants born between 22 and 32 weeks gestation develop cerebral palsy with the prevalence increasing with decreased gestational age. Four percent of infants born at 32 weeks gestation develop cerebral palsy and 20 percent of infants born at less than 27 weeks gestation develop cerebral palsy. If children have bilateral cystic periventricular leukomalacia (brain injury from decreased blood flow), 75 percent of them will develop cerebral palsy.

In the 1800s, Freud first described an increased risk of cerebral palsy in multiple births. Twins are 1.6 percent of all births but 5 to 10 percent of children with cerebral palsy, with a relative risk of five times for a twin versus a single birth. Babies who are born as triplets have 12.7 times the risk of cerebral palsy. This is partly due to the smaller birth weight of multiple birth babies. Babies less than 1500 grams are less than 1 percent of single births, 10 percent of twins, 32 percent of triplets and 73 percent of quadruplets. Twins who are monozygotic are smaller than those who are dizygotic. The fetal death of a twin has been associated with severe problems of the surviving co-twin, including cerebral palsy, which is more common with twins who were monochorionic.

The risk of cerebral palsy in a twin whose co-twin died in utero is 10 percent with higher risk regardless of birth weight and higher in same-sex twins. If a twin dies in infancy, there is an even higher risk of cerebral palsy than if the twin died in utero. This is an even higher risk factor compared to low birth weight, being part of a twin pregnancy or being twins of the same gender. Using ultrasound in early gestation, it has been found that there is a first trimester loss of a twin in 13-78 percent of pregnancies. This is called the “vanishing twin phenomenon” and it is hypothesized that this may actually be a cause of cerebral palsy in infants who are thought to be single births. It is felt that monochorionic twins are at more risk for this phenomenon because they share placental vascular structures. This increases the risk by having twin-to-twin blood transfusion as well as a higher incidence of preterm births, lower birth weight and risk of thromboembolus (blood clot) from the dead to the surviving fetus.

There is also an increased risk of cerebral palsy in pregnancies that are a result of assisted technology due to an increase in multiple births from this technology. It is felt that there is an 8 percent increase in the risk of cerebral palsy in the United States due to multiple births with assistive reproductive technology. This has lead to new guidelines regarding the number of embryos implanted at any one time.

Physical Findings

General
Early on, infants with cerebral palsy may be indistinguishable from those without it. Others, however, may show signs of cerebral palsy such as irritability, difficulty with sleeping or feeding and spasticity. As noted above, sometimes there is actually early hypotonia (decreased muscle tone) which later becomes hypertonia (increased muscle tone). A problematic history may be when parents proudly announce that their child rolled over right away or always wants to stand up or is incredibly strong. These are red-flags, possibly signaling increased tone and the possibility of cerebral palsy. Developmentally, babies should not immediately be rolling over or wanting to stand all of the time. Along with the appearance of the muscles being extremely tight, this may be a manifestation of hypertonicity.

Difficulties with feeding may be seen if there is difficulty with oral motor control with tongue thrusts or with difficulty in coordinating to close the mouth around a nipple and to have coordinated suction for drinking. At times there is central hypotonia, with the head and trunk floppy, with decreased ability to lift them up or maintain control of them, even with hypertonia of arms and legs. There may be developmental delay because of the poor motor control, along with either hypotonic or hypertonic muscles. Hypertonicity may actually cover up weakness and is definitely not a sign of strength. Many times parents will report that when the baby crawls, he uses his arms sometimes in an unusual position and pulls his legs along behind him. This is known as combat crawling and is a sign of hypertonicity of the legs. Similarly, parents may report that when they hold their child up they always cross the legs straight out below them (scissoring) which is another manifestation of hypertonicity. Sometimes children have limited movements due to the primitive reflexes that interfere with their voluntary movements. As children grow, there are normal stages of reflexes that come and go through development. In cerebral palsy many times these do not go away at the proper time frame so these reflexes can actually block the developmental progress.

It is important to remember some normal milestones in child development when considering development in a child with cerebral palsy or whose development is questionable. Supported sitting is generally present by about 7 months of age. Crawling occurs about 10 months, along with standing briefly and cruising (holding on to furniture and walking along it). Walking alone classically is at 14 months. Rolling over to supine (face up) occurs at 4 months and rolling to prone (face down) is at 7 months. Therefore, if any of these occur at a very unusual time or out of order, it is something to be aware of and consider the potential significance in development. For example, one sign of dramatic spasticity is that of a baby who “wants to stand up all of the time” from the moment they come home from the hospital.

There are primitive (early) reflexes that are important in both the diagnosis of cerebral palsy and in treatment. The Moro reflex is present from birth until 4-6 months. With sudden neck extension (bending backwards), there is abduction (opening up) of the shoulders, elbow and finger extension (straightening) followed by arm flexion (bending) at the elbow. This persists beyond six months in cerebral palsy and other CNS abnormalities. The startle reflex is the same physiologic response, occurring in response to a sudden noise, that also is suppressed at 4-6 months with similar reasons for continuing. Positive support reflex is one that occurs when there is pressure or weightbearing on the bottom of the feet, which causes the legs to extend and partially support the body weight. This should be suppressed by 3-5 months of age and replaced by purposeful weightbearing with support when the child wants to do this. When this is hyperactive or continues too long at any age, this is abnormal or if it persists beyond the fifth month, this is an early sign of spasticity. It has been reported to be associated with scissoring legs later in walking.

The asymmetric tonic neck reflex (ATNR) is elicited by turning the head to the side. When this occurs, the arm and leg on that side where the face turns is straightened out and they bend (flex) on the side of the back of the head. This should be extinguished by 6-7 months of age and again is abnormal if it sustains at any age or persists after seven months. A symmetric tonic neck reflex (STNR) shows the arms flexing and the legs extending with neck flexion, conversely with having the neck extended, the arms extend and the legs flex. This extinguishes by 6-7 months as well. These reflexes, if (abnormally) persistent, all create difficulty in motor development in children with spastic cerebral palsy. Having the Moro or startle reflex interrupts attempts to use the arms or maintain a sitting position, which is quite problematic in development. If the asymmetric or symmetric tonic neck reflex persists, then the positioning of the arm is out of one’s control for attempting to sit, maintain balance or use the hands for functional activity. The positive supporting response can interfere with learning to walk because the position of the leg is then reflexively directed, not something the child controls as he tries to learn to stand or move. There is automatic reflex walking that is seen at the newborn age and lasts for three to four months. This is not something that is under control, but it can be confusing to see these alternating steps when the foot is placed on a surface and the body is tilted. These reflexes are gone by 3-4 months of age.

 

Remember that one of the traditional ways of classifying cerebral palsy is into spastic, dyskinetic, ataxic, hypotonic, and mixed groups.  Following are the presentations of the first 3 types. 

Spastic Cerebral Palsy
Spastic cerebral palsy is characterized by increased reflexes in the arms and legs (which includes crossed reflexes or overflow from side to side of reflexes) along with continuation of primitive reflexes, normally present in early development of infants but which generally disappear with maturity. These may remain in children with spastic cerebral palsy. They also may have clonus, which is shown by rapid up-and-down beats of movement at the ankle (or elsewhere in the leg or arm), either spontaneously or with testing of reflexes or changing of position. Spasticity can have a significant impact with making developmental progress more difficult. It may lead to early hand dominance. Usually, there is no hand dominance before 1.5 to 2 years of age. It may have an impact on crawling, and some children will scoot instead of crawl. There may be a delay in the ability to sit. Scissoring is a classic gait change in children with spastic cerebral palsy, as their hips are pulled together (adducted) with over straightening (hyperextension) of their knees and pointing of the toes (plantarflexion). This makes walking difficult so that the legs can actually cross over one another and block forward movement as the child attempts to progress the legs to walk. Spasticity of the hands can have an adverse impact on developmental activities.

Children with hemiparetic cerebral palsy frequently have sparing of the facial muscles because of bilateral cortical representation of the face in most people. There may be decreased two-point discrimination and astereognosis (the decreased ability to recognize objects that are held in one’s hand by shape, size and texture). In many cases, the arm is more affected than the leg. The hypertonicity may be more dramatic or may be more subtle and only show up with running or under stress.

Classically in tetraplegic or quadriplegic cerebral palsy, the legs are more involved than the arms. If the arms are more involved than the legs, it is sometimes called double hemiplegia. The term diplegia is inaccurate in that all four limbs are felt to be involved, though the arms are so much more mildly affected than the legs that the name has remained since it was first used by Freud. The vast majority of premature babies of low birth weight will have diplegic cerebral palsy.

Dyskinetic Cerebral Palsy
Dyskinetic cerebral palsy has been reported to include 10 to 15 percent of children with cerebral palsy. Approximately 80 percent of children with dyskinetic cerebral palsy have dystonic cerebral palsy and 20 percent with choreoathetotic cerebral palsy. Motor disability in dyskinetic cerebral palsy is frequently severe with changes in muscle tone, posture and involuntary movement with preservation of primitive reflexes. Spasticity is commonly present but is not the dominant feature. Dystonia is generally more severe in the arms than legs, is less commonly present in the mouth and rarely affects the eye. Dysarthria is quite common, sometimes requiring the use of alternative communication. Learning disability is present in the majority of children and generally is more severe as the motor disability increases. It is also possible, however, that some children with very severe motor disability do not have a learning disability. Seizure disorder is common in this subgroup of children with cerebral palsy. Visual impairment is common in those with the most severe motor impairment. Abnormalities of the basal ganglia are typically found. There are adverse events that occur in the perinatal, neonatal and late gestation periods. At these points in time, the basal ganglia is especially vulnerable because of high metabolic demands. Kernicterus (high bilirubin in the blood) causes selective injury to the globus pallidus, while hypoxia and ischemia cause injury to the putamen and thalamus.

Children with dyskinetic cerebral palsy tend to have higher scores on the Gross Motor Function Classification System (GMFCS) with approximately 10 percent at levels 1 and 2, 10 percent at level 3, 20 percent at level 4 and 60 percent at level 5. It is not uncommon that children with dystonic cerebral palsy have feeding issues. PEG tubes are sometimes used.

A typical child with dyskinetic cerebral palsy is born at 38 weeks gestation with no prenatal, perinatal, or neonatal adverse events. There were no reports of placental abruption and uterine rupture associated. Requirement for assisted ventilation is more common than in children with spastic cerebral palsy. Children with dyskinetic cerebral palsy who had neonatal seizures, emergent Cesarean section and Apgar score of less than 5 had more severe impairment of gross motor function testing than others.

Ataxic Cerebral Palsy
In children with ataxic cerebral palsy, there is a wide-based gait and they have difficulty performing rapid repetitive movements. They frequently show functional improvement as they mature and develop more coordination and motor skills. It has been reported that alcohol and sedatives tend to increase ataxia.

Radiographic

Ultrasound
Brain neuroimaging plays a critical role in diagnosis of cerebral palsy. Cranial ultrasound is the study of choice in high-risk premature infants. This is best performed on infants less than 30 weeks gestation, from one to two weeks of age and also near their due date to identify ventriculomegaly (abnormal enlargement of brain cavity) and periventricular leukomalacia (PVL) (brain injury from decreased blood flow). These findings are associated with increased risk of subsequent cerebral palsy.

Decreased blood flow leading to either focal or global ischemia in the periventricular white matter leads to PVL. The immature brain is vulnerable at the arterial watershed areas (areas with naturally less blood supply) due to its lack of completed blood vessels. It is also difficult for the developing brain to regulate its blood flow early on, so with decreased oxygenation, this area is vulnerable. The classic finding of PVL in a premature infant is predictive of spastic diplegia; however, there can be a spectrum of findings from a mild neurologic disease to severe quadriplegic cerebral palsy. Approximately one quarter of infants found to have PVL will develop cerebral palsy in the future.

Cystic lesions may develop in PVL after several weeks and these findings are easily noted on ultrasound. The cyst may be absorbed into the brain in a few weeks with only a slightly larger ventricle as a sign of any brain abnormality. With this injury comes a loss of future potential brain connections, which could have far-reaching effects. It has been reported that those infants who have small cysts on both sides have a one in three chance of cerebral palsy as they grow up, with those who have large cysts having a 90 percent chance of cerebral palsy in the future. The cysts that are farthest back are associated with having a worse prognosis for additional deficits, including vision problems.

Of infants who are born very early, advanced ultrasound technology is now showing hemorrhage in the cerebellum. This is reported in infants less than 28 weeks gestation and affects the lateral portions of the cerebellum.

Infants with very low birth weights are also currently recommended to have an ultrasound.

Ultrasound can be performed through both anterior and posterior fontanels (normally unfused portions of infant skull). It is less sensitive than MRI and CT scans, but show PVL, hemorrhage and posterior fossa malformations. It can be done quickly and with no sedation required, unlike other imaging tests. However, this test is not sensitive, meaning there will be many false negative findings (many children with cerebral palsy will have a normal test).

Magnetic Resonance Imaging (MRI)
MRIs are useful in diagnosis of cerebral palsy, especially in mixed, quadriplegic and diplegic types. In term infants with abnormal neurological findings such as increased reflexes, feeding disorder, breathing problems and seizures, neonatal encephalopathy may be diagnosed. In these term infants with known encephalopathy, MRIs done in the first several days of life frequently shows abnormalities of the basal ganglia and thalamus. Abnormalities of the posterior limb of the internal capsule in term infants with encephalopathy are powerful predictors of abnormal neuro-developmental outcomes. One study described that 13 percent of survivors of neonatal encephalopathy had cerebral palsy, which also had more severe impairment, more cognitive impairment and seizure disorder than children with cerebral palsy without neonatal encephalopathy. However, the majority of infants born at term that develop cerebral palsy will not have a known encephalopathy; therefore this test will likely not be ordered by the treating doctor.

Another type of cerebral palsy is from hyperbilirubinemia (increased bilirubin, breakdown product of red blood cells) which affects the globus pallidus leading to athetoid cerebral palsy. This is much less common in the United States due to a decrease in Rh blood type incompatibility, but it is found in other geographic locations and can be found in the United States from hemolysis or meningitis. Hypoxic encephalopathy more commonly affects the putamen and thalamus. MRI can delineate these relatively well.

On MRI, children with spastic cerebral palsy generally show white matter injury while children with extrapyramidal syndromes (dyskinetic) more commonly show basal ganglia abnormalities. Some of these include genetic disorders causing abnormalities of the caudate and putamen and mitochondrial disorders affecting globus pallidus, caudate and putamen.

MRI has a higher yield of information that may be helpful with defining cause and timing of brain injury. It can be more helpful in determining prenatal, perinatal and postnatal onsets of cerebral palsy. Seventy to ninety percent of children with cerebral palsy have abnormalities on MRI. MRI is the most sensitive test for PVL as well as other perinatally acquired lesions and subtle congenital abnormalities.

MRIs use magnets; therefore, there is no x-ray exposure. Gadolinium, an inert contrast material, may be used to show vascular structures and breakdown in the blood-brain barrier. It helps define anatomy, structural abnormalities and brain pathology. Unfortunately, MRIs are expensive and require sedation. Chloral hydrate is commonly used in infants. Sometimes general anesthesia may be required. 

MRI is most useful at term between 38 and 42 weeks gestation because the posterior limb of the internal capsule is myelinated after 37 weeks. Abnormalities in this area correlate with neurologic outcome for premature infants. MRI is more sensitive for focal white matter lesions than ultrasound.

Computed Tomography (CT)
CT scans in children with cerebral palsy show abnormalities more commonly in children with hemiplegic cerebral palsy more than ataxic cerebral palsy and less commonly in mixed diplegic and quadriplegic cerebral palsy. Mental retardation is more common if the CT scan is abnormal than if it is normal. These studies are not very specific in most cases, however, meaning there will be many false positives (many children who have abnormalities on the test will not have cerebral palsy). 

CT can be performed in several minutes, therefore it can often be performed without sedation. It does have x-ray exposure however, which is particularly problematic in repeated studies. It is less costly than MRI. It shows calcifications which may not be seen on MRI.

Emerging Radiographic Examinations
Diagnostic imaging is an exploding field. As improvements in technology continue, it is expected there will be more specific evaluations available that will lead to more specific diagnosis and treatment and information for families. Currently diffusion-weighted imaging is being tested that may show earlier information on brain injury than currently is available, which may lead to early neuroprotective treatment. A functional MRI is used to look at brain patterns during activities and may also have an impact in evaluation and treatment as this progresses. PET scans and SPEC scans are not routinely used but may also show future use in this group of children.

Electroencephalogram (EEG)
Serial EEGs may indicate risks for cerebral palsy. Tests with background depression on days one and two have a high correlation of development of cerebral palsy; however, there is a very high false-positive rate and even the worst EEG abnormality leads to only 50 percent of children developing cerebral palsy. Hypoxic ischemic encephalopathy (HIE) is a type of encephalopathy usually felt to occur in-utero. Children with these difficulties and abnormal brain imaging or EEG are at higher risk for developing cerebral palsy. However, this is very nonspecific and many children with an abnormal EEG will not develop cerebral palsy.