Diagnosing cerebral palsy--the earlier the better

Diagnosing cerebral palsy--the earlier the better

By Forrest C. Bennett, MD

Recognizing cerebral palsy in the first yearof life has substantial benefits for both the infant and the family.Here are the risk factors and motor signs to look for.

Cerebral palsy is a nonprogressive disorder of movement andposture that is caused by brain damage or defect. Such injurymay result from an extrinsic brain insult (hypoxic-ischemic, traumatic,infectious, toxic) or an intrinsic developmental defect that occursduring the period of brain growth and maturation extending fromthe prenatal period through approximately three to five yearsafter birth. Cerebral palsy is thus a clinical syndrome with numerousspecific etiologies.^1,2 Because signs and symptomsof the original brain injury change as the brain grows and develops,we also define cerebral palsy as a static encephalopathy witha developmental presentation.

The main purpose of this article is to persuade the primarycare physician of the importance of diagnosing cerebral palsyearly--during the first year of life or, in severe cases, duringthe first six months. To that end, it presents some useful assessmentstrategies and clues to assist in making the diagnosis and differentiatingthe two major types of cerebral palsy--spastic (pyramidal) andextrapyramidal.

Why emphasize early detection?

In recent years, physicians, therapists, and others who workwith children who have cerebral palsy have made ever-strongerpleas for early diagnosis of the disorder. This goal often goesunrealized throughout the United States today. The average ageat diagnosis of spastic diplegia--one of the most common typesof cerebral palsy--is around 18 months, and many mildly affectedchildren remain undiagnosed until their preschool years.

Why stress the earliest possible identification of cerebralpalsy? The primary reason is so that treatment--which means primarilyphysical therapy--can begin as soon as possible. Professionalswho work closely with children who have cerebral palsy generallyagree that the largest gains are obtained if intervention startsduring infancy, even though many questions about the long-termresults of physical therapy remain unanswered.

Furthermore, the parents of an infant who is developing signsof cerebral palsy often encounter difficulties and frustrationsrelated to the feeding, handling, sleeping, and temperament ofthe infant. Their distress and concern deserve prompt attention.A diagnosis of cerebral palsy, however dismaying, at least shedslight on the reasons their infant has been so "difficult"and lets them plan for long-term treatment. Early interventionthus benefits both the child and the family.

Unfortunately, medical training programs and critical reviewsof the effectiveness of early intervention often have underemphasizedthe benefits. Consequently, some physicians still think that littlecan be done for a child who has cerebral palsy and that earlydiagnosis is of little value. Unless we acknowledge that one ofour primary roles as physicians is to manage, even if not usuallycure, children with complex disabilities and to provide supportto their families, our patients will not receive the comprehensivecare they require.

A practical approach--and a warning

The basic precepts that should guide your approach to evaluatingpatients for cerebral palsy are outlined on the left. A thoroughfamiliarity with normal child development, particularly earlymotor development, is essential for early recognition of abnormaldelays or deviations from the expected pattern. Table 1 liststhe major elements of normal motor development.

Before discussing the diagnostic process, a caveat about treatmentis in order: Don't succumb to the misconception that therapeuticefforts cannot begin until you have made a conclusive diagnosis.Too-strict adherence to the medical disease model may preventyou from recommending functional interventions that are possibleduring infancy. Moreover, delaying physical therapy until thechild's spasticity is well established can both reduce the eventualphysiologic benefit of treatment and impair the child's emotionalresponses to it. A more rational approach is to confront the child'sdevelopmental problems as they arise, even though they may notbe completely expressed.

Early symptoms: The history

Infants whose prenatal, perinatal, or postnatal histories containcertain risk factors merit close developmental follow-up and especiallythorough developmental and neurologic examination at regular intervals.The premature infant--prematurity is still the number one riskfactor for cerebral palsy--and the full-term infant who has sustainedperinatal asphyxia both should raise red warning flags in yourmind. So should a maternal history of intrauterine infection.Many infants who develop cerebral palsy are considered to be lowrisk at birth, however, so it is important to examine all babiesin your practice systematically, regardless of the presence orabsence of risk factors.

Certain key behavioral symptoms, described by parents earlyin their child's life, should arouse your suspicion of evolvingcerebral palsy even before you can observe a distinct lag in motordevelopment.

Excessive irritability, constant crying, and sleeping difficulties.As many as 30% of infants who are eventually found to have cerebralpalsy demonstrate severe "colic" during the first threemonths of life.

Early feeding problems. Difficulties in coordinating suckingand swallowing, inability to nurse adequately, frequent spittingup, and consequent poor weight gain and failure to thrive arecommon problems in infants with cerebral palsy.

"Jittery" or "jumpy" behavior. Such symptomsare much less likely to indicate brain involvement if the infantis jittery only when hungry. Low-birth-weight infants, especially,may be jittery just before feeding time.

Easily startled behavior. Infants startled readily by noisesand changes in posture may have a low sensory threshold. Thisresponse most often takes the form of an exaggerated Moro reflex,often accompanied by crying.

Stiffness when handled. The infant may show excessive rigidity,especially during dressing (making it difficult to get the armsinto the sleeves), diapering (making it difficult to abduct thethighs to clean the anal area), handwashing (the baby keeps thehands tightly fisted), and at the start of bathing. Dislike ofthe bath is a particularly common complaint. The infant tendsto arch the back rigidly as soon as the feet touch the side ofthe tub. Once the baby adjusts to the water, however, the bathtypically becomes a soothing, even therapeutic, environment.

Paradoxically "precocious" development. The infantwith cerebral palsy may roll over early, but the maneuver is asudden, reflexive "log-roll" rather than the volitional,segmental rolling of a normal child. Likewise, the infant withspastic diplegia (legs more affected than arms) may stand, stiff-leggedand with support, before he is able to maintain balance whilesitting. Parents may liken the child's tendency to stand on tiptoesto that of a ballet dancer. Exaggerated hand preference in reaching,manipulating toys, and feeding also is usually abnormal. It maybe the first indication of a spastic hemiplegia .

Any of these subjective symptoms, taken alone, can appear inan infant whose motor development is perfectly appropriate. Theirimportance increases when two or more occur together and particularlywhen they appear in an infant whose history suggests risk forcerebral palsy.

The definitive characteristic of infantile cerebral palsy isretarded motor development, with delayed achievement of motormilestones. Even without behavioral symptoms like those enumerated,the parent of an infant with cerebral palsy sooner or later becomesconcerned about a definite lag in the infant's motor progress.

Parental concern is likely to vary according to the severityof the manifestations. Another important factor is the extentto which the parents understand the sequence and timing of normaldevelopment.

An infant who is developing severe spastic quadriplegia (withall four extremities affected equally), often shows stiffnesseven in the neonatal period, with opisthotonic posturing (bodyrigidly extended) and obvious delays in ability to control thehead and roll over. Regardless of previous experience, most parentsof such an infant become worried almost immediately. On the otherhand, a premature infant who develops spastic diplegia may notbe diagnosed until the second year of life, when delays in sitting,crawling, and walking can no longer be explained by the child'sprematurity and expected need to "catch up."

In short, when motor problems are more severe and developmentaldeviations are greater, parents generally notice them earlier.Similarly, parents who have raised older children or are familiarwith other infants their baby's age are likely to suspect a problemat an earlier stage of the disorder.

Although an infant who is developing the signs and symptomsof cerebral palsy often shows delays in acquiring nonmotor aswell as motor skills, sometimes the history shows a dissociationin development, with the nonmotor skills appearing well beforethe motor abilities. Such a historical finding is important. Anyinfant or child whose linguistic, adaptive, and social developmentis normal but whose gross-motor development is significantly delayedshould alert you to the strong possibility of cerebral palsy.

In an infant of normal intelligence who has spastic diplegia,fine-motor function may be intact despite a prominent gross-motordelay. Thus, when you screen your young patient with a tool suchas the Denver II, the infant may exhibit failure only in the gross-motorarea.

Gross-motor delays that are diagnostically important include:

• inability to bring the hands together in midline from a supine position by 4 months of age
• head lag (head lolls back when infant is pulled up from supine position) persisting beyond 6 months of age
• no volitional rolling by 6 months
• inability to sit straight independently by 8 months
• no hands-and-knees crawling by 12 months.

Early signs: The examination

During physical examinations through the first year of life,you should focus on four specific neuromotor areas:

• quality of muscle tone
• frequency and quality of volitional movement
• disappearance of primitive reflex patterns according to normal schedule
• appearance of infantile automatic reactions--including righting (head control), equilibrium (balance), and protective (parachute) reactions--according to schedule and to normal extent.

These key aspects of the examination will allow you to diagnosecerebral palsy during the first year of life. In addition, lookat such elements of the traditional neurologic examination asknee and biceps stretch reflexes and search for ankle clonus andother pathologic reflexes.³

The neonatal period

During the first month, only the severest forms of spasticcerebral palsy are readily diagnosable. Affected infants exhibitlittle spontaneous movement. They are clearly hypertonic and mayassume the characteristic posture of opisthotonus. They show strongextensor tone rather than the preponderance of flexor tone normalat this stage. They may have abnormal episodic movements suchas myoclonic jerks.

When lying on their backs, severely affected infants have stifflyextended legs that resist passive flexion and abduction. Theyexhibit extension of the head and neck and retraction of the shouldersand arms (an exaggerated tonic labyrinthine reflex), and theyhave strong asymmetric tonic neck reflexes (the "fencing"reflex, marked by ipsilateral extension and contralateral flexion,elicited when the head is turned to the side while the infantis supine).

In severe cerebral palsy, these tonic reflexes are often obligatory--theinfant is unable to break out of them. The hands are usually fisted,the arms flexed at the elbows and abducted at the shoulders. Ifyou try to move the arms forward at the shoulder and extend themat the elbow, you will encounter strong resistance of a clasp-knifetype. The movement and posture of such a severely affected infantare completely opposite to those normally encountered in the neonatalperiod.

The majority of infants who develop cerebral palsy do not showsuch marked and definite signs of spasticity as newborns, however.They are more likely to exhibit varying degrees of abnormal hypotoniain these early days.

You may note additional warning signs, including:

• unusual state on arousal (either depressed or jittery)
• high-pitched, weak ("cerebral") cry
• poor sucking and rooting response with resultant poor feeding and nutrition
• accentuated stretch reflexes in conjunction with abnormal (high or low) muscle tone.

The first six months

Except in unusually severe cases, you are likely to have difficultyidentifying cerebral palsy in the infant between 1 month and 6months old. As the disorder develops, neonatal hypotonia may havesubsided, but the infant may not yet be clearly hypertonic orspastic. Muscle tone may seem to fluctuate between hypotonia,evident at rest, and hypertonia, which becomes apparent when theinfant is handled and moved.

You can learn much about the infant's muscle tone at this stageby taking these simple steps: First, carefully observe the restingchild. Next, evaluate the baby's response to palpation and passivemovement, and shake each extremity. Finally, move the infant inspace, suspending him or her in both prone and upright positions.

The muscles of a hypotonic infant often feel flabby, whilethose of a hypertonic infant feel firm and hard. When evaluatingresistance to passive movement, take care to differentiate increasedpassive resistance from the active resistance of the normal infant.To do this, attempt to distract the baby while examining him orher in a safe comfortable setting such as the mother's lap.

It's important to determine range of movement at certain joints.The degree of abduction of the thigh at the hip is increased inhypotonic and reduced in hypertonic infants. A tightened heelcord, signifying restricted dorsiflexion of the foot at the ankle,is a common early sign of spasticity. As you shake the child'slimbs, note the range of motion of the hands and feet. The rangeis increased in hypotonic infants and decreased in hypertonicones.

To assess posture in prone suspension (to elicit the Landaureaction), hold the infant free in space, supported under theabdomen. At 2 to 3 months of age, the normal infant holds thehead well up. If spasticity is developing, however, the child'shead droops because of associated hypotonia in the neck and trunk.

To assess posture in vertical suspension, hold the infant uprightunder the axillae. In the normal infant, the lower limbs are flexed,whereas those of the hypertonic infant may be unduly extendedand adducted. The classic "scissoring" movement of theextended legs in response to this test is a very ominous signat any age.

To sum up, if the infant has a "floppy" head andtrunk at rest, if the limbs feel firm and resist repeated attemptsto move them, and if the child stiffens when actively handled,with head, shoulders, and legs in thrust extensor posture, youmust entertain a high suspicion of developing cerebral palsy.

Certain primitive reflexes in the infant indicate a delay inmotor development if they persist beyond a certain point. Testingfor these reflexes, which normally appear and disappear in sequentialfashion, is of paramount importance.

With the onset of spasticity, you will observe an increasein the strength of several important tonic reflexes. Instead ofdisappearing with time as they should, they gradually gain strengthand eventually dominate the infant's motor activities. These primitivereflexes coexist with spasticity, and their persistence preventsfurther maturation of the child's motor behavior.

When you are trying to make an early diagnosis, look particularlyfor signs of three tonic reflexes that normal infants "outgrow"by age 4 months or earlier. In milder cases, these reflexes haveinsidious manifestations that must be elicited by special handling.⁴

The tonic labyrinthine reflexes (prone and supine) producemaximal flexor tone throughout the body in the prone positionand maximal extensor tone in the supine position (Figure 1). Evenin newborns, however, these reflexes are rarely physiologicallyobvious. If persistent, they prevent the infant from rolling overin the normal fashion.

The asymmetric tonic neck reflex (ATNR) consists of an increasein extensor tone in the limbs on the side toward which the faceis turned and an increase in flexor tone in the limbs on the oppositeside (Figure 2). This reflex, which appears within the first month,normally diminishes enough by the fourth month to allow the supineinfant to bring the hands together nicely in the midline. TheATNR inhibits normal rolling over if it remains strong after thefourth month. The normal infant resists the ATNR position andactively tries to assume a neutral position of the arms and legs.A neurologically impaired infant may not be able to break outof this posture despite active effort and crying for 30 secondsor more.

The positive supporting reflex produces rigid extension ofthe legs whenever the balls of the feet touch a solid surface(Figure 3). This posture normally diminishes by 2 to 3 monthsof age and disappears by 4 months. If the reflex is strong, youmay see automatic placing of the feet, stepping, and walking.

Other reflexes that may be helpful in making an early diagnosisinclude the familiar Moro reflex (upon rapid head extension, thearms extend, abduct, then converge) and the palmar grasp reflex.If there is no Moro response during the first three months, orif the Moro reflex persists after the first six months, the infantvery likely has an abnormality of the brain. Reflex palmar graspingoften lasts beyond 4 months of age in the infant who is developingcerebral palsy. It inhibits voluntary grasping and releasing ofobjects.

Head-righting, equilibrium (balance), and protective reactionsshould appear when expected and progress normally during the firstsix months. These so-called automatic reactions appear to developas primitive reflex activity disappears. They form the basis forthe maturing child's ability to maintain positions and posturesagainst the force of gravity. As these reactions develop (Table2), the infant acquires basic patterns of movement such as headand trunk control, ability to support the body on the arms, androtation from front to back and side to side. These patterns,which are prerequisites for such activities as rising to a sittingposition, maintaining balance while sitting, and standing upright,typically are absent or of poor quality in the infant with developingcerebral palsy.

Abnormalities or asymmetric retention of the primitive reflexes(particularly the Moro, palmar grasp, and ATNR), as well as asymmetryof spontaneous movement, should alert you to developing hemiplegia.Additional signs include one-sided shortening or muscle wastingof an upper or lower limb, and coldness to touch (caused by vasomotorinstability) of the affected side.

Thus, by 6 months of age, most infants likely to develop moderateto severe cerebral palsy should have exhibited highly suspicioussigns during careful examination, even though a firm diagnosisstill may not be possible. The infant with mild cerebral palsymay show only very subtle signs and symptoms at this early age.

Two cautionary observations about the evaluation at 6 monthsof age: First, normal infants vary greatly in muscle tone, spontaneousmotor activity, and timing of disappearance of primitive reflexes,making it difficult to draw definite conclusions. Second, duringthese six months we have no reliable way to separate infants whoseabnormal early signs will gradually regress from those whose abnormalitieswill progress to a fully developed cerebral palsy by 8 to 12 monthsof age. Spontaneously regressing neurologic abnormalities areparticularly common in infants born prematurely, a phenomenonthat has been termed transient dystonia of the low birth-weightinfant. When evaluating the effectiveness of early interventionefforts, therefore, always consider the possibility of spontaneousphysiologic recovery from the insults of prematurity.

Beyond 6 months

Identifying cerebral palsy grows easier as the infant growsolder. In almost all affected children (except very mild cases),the diagnosis should become apparent between 6 and 12 months ofage. When an infant is developing spastic cerebral palsy, hypertoniabecomes increasingly obvious, with extensor muscle tone reachinga peak between 6 and 18 months of age.

The scissoring position of the legs may become prominent whenthe infant is held up vertically, especially in spastic diplegia.Also at this time, the Landau reaction becomes abnormal. Whenthe normal infant is supported in prone suspension at the ageof 6 to 8 months, the child will extend the spine and legs aswell as lift the head. The infant developing cerebral palsy usuallywill neither raise the head nor extend the spine and hips. Ifextensor spasticity is marked, however, the knees may be extended.

The brain-damaged infant often resists being seated with thelegs extended straight out. Excessive extensor tone commonly causesthe baby to thrust with the legs and thus fall backward from thesitting position. If the child tends to rise onto the fronts ofthe feet in a stiff standing posture when pulled to the sittingposition, it is an important sign of spasticity and should notbe interpreted as "advanced" motor development.

The older infant with cerebral palsy may show other signs ofhypertonia. The hip adductors may tighten, limiting abductionat the hip joint. Tightening heel cords further limit dorsiflexionat the ankle. Indirect signs of hypertonia include accentuatedstretch reflexes and sustained or easily elicited ankle clonuswith a strong extensor plantar response (Babinski reflex).

Isolated ankle clonus, however, usually has no diagnostic significance.It can't be said that a given number of "beats" of ankleclonus is abnormal; rather, your interpretation should dependon the association of other signs with the ankle clonus.

During infancy, an isolated extensor plantar response is usuallynot significant. Similarly, brisk knee or biceps jerks mean littlein themselves, but they should alert you to look carefully forother abnormal signs.

Persistence of the major primitive reflexes beyond 6 monthsof age is clearly abnormal. It interferes with normal righting,balance, and protective reactions, significantly impeding motordevelopmental progress. The affected infant frequently sits withhead and trunk curved, legs spread, and arms propped in the midlinefor balance and support, producing a "tripod" appearance.An infant who is developing cerebral palsy, particularly spasticdiplegia, often creeps on the elbows and forearms, pulling thelegs stiffly behind "commando-style."

Signs of extrapyramidal cerebral palsy

An infant who develops extrapyramidal (athetoid or ataxic)cerebral palsy during the first year of life shows certain differencesfrom an infant developing spastic (pyramidal) cerebral palsy.Recognizing these differences is important to an accurate diagnosis.

The hallmark of extrapyramidal cerebral palsy is fluctuating(decreased, then increased) muscle tone, with a much longer periodof initial hypotonia than in spastic cerebral palsy. In some cases,in fact, no hypertonia--except possibly for accentuated stretchreflexes--appears until after 12 months of age.

Such infants may move scarcely at all while very young, lyingquietly on the back. When picked up, they have no control overthe head or trunk. The legs are usually flexed and widely abducted,with exaggerated dorsiflexion of the ankles--a very differentpicture from that of an infant with early spasticity.

An infant with athetoid cerebral palsy often is included inthe "floppy infant" category, and a possible lower motor-neuronlesion (such as myopathy or neuropathy) may be strongly considered.Eventually, the initial limpness and flaccidity begin to alternatewith transient phases of stiffening. These become stronger andmore frequent, even to the point of rigidity, as the infant developsand whenever the child tries to move and maintain posture againstgravity. Such babies often wave their arms aimlessly and seemunable to direct them toward an object when reaching for it.

Other early signs of extrapyramidal cerebral palsy includemarked persistence of primitive reflexes, especially the ATNR;occasional opisthotonic posturing and extensor thrusting (againsta background of hypotonia); and poor feeding, sucking, chewing,and tongue control. Often, the tongue is thrust from a wide-openmouth, and prolonged drooling accompanies abnormal speech development(dysarthria).

Interestingly, the choreoathetotic, involuntary movements typicalof extrapyramidal disorders rarely appear during infancy and maynot develop until 18 months to 3 years of age, occurring firstin hand and tongue movements. Thus, the condition of an infantdeveloping extrapyramidal cerebral palsy during the first yearhas been termed athetoid cerebral palsy without athetosis. Untilthe adventitious movements typical of athetosis appear, however,you cannot entertain a definite diagnosis of athetoid cerebralpalsy, even though you may strongly anticipate it.

An achievable goal

Most infants developing spastic cerebral palsy should be recognizedas abnormal by 1 year of age, so that appropriate interventioncan start. Very mild spastic diplegia or very subtle spastic hemiplegia,however, may elude even careful examination until the infant attemptsto stand and walk independently at around 12 months. Most infantswho develop extrapyramidal cerebral palsy should show clear evidenceof abnormality by the end of the first year, even though athetosisand ataxia may not yet be apparent. With the approach outlined,and with an increase in our index of suspicion in the case ofat-risk infants, we can hope to identify nearly all infants withcerebral palsy early enough to institute appropriate and lifeenhancing management.

THE AUTHOR is Professor of Pediatrics and Director of theHigh Risk Infant Program at the University of Washington Schoolof Medicine, Seattle.

REFERENCES

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2. Taft LT: Cerebral palsy. Pediatr Rev 1984;6:35

3. Bums YR, O'Callaghan M, Tudehope DI: Early identificationof cerebral palsy in high-risk infants. Aust Pediatr J 1989;25:215

4. Capute AJ, Accardo PJ, Vining EPG, et al: Primitive ReflexProfile. Monographs in Developmental Pediatrics, Volume 1. Baltimore,University Park Press, 1978