Infant Neurologic Assessment.
Central nervous system (Growth)
|Publication:||Name: Journal of Neuroscience Nursing Publisher: American Association of Neuroscience Nurses Audience: Professional Format: Magazine/Journal Subject: Health care industry Copyright: COPYRIGHT 2001 American Association of Neuroscience Nurses ISSN: 0888-0395|
|Issue:||Date: August, 2001 Source Volume: 33 Source Issue: 4|
|Geographic:||Geographic Scope: United States Geographic Code: 1USA United States|
Abstract: Infant neurologic assessment reflects the ongoing
maturation of the central nervous system. Traditional approaches to
assessment cannot be used. Key factors are accurate observation and
flexibility in obtaining the data. A case example using a 4-month-old
infant illustrates specific approaches to assessment.
Infant neurologic assessment reflects the ongoing maturation of the central nervous system (CNS). This maturation is demonstrated by the infant's appropriate acquisition of developmental milestones. Traditional approaches to assessment cannot be used in the infant. Key to pediatric neurologic assessments are accurate observation, flexibility in obtaining data, and appreciation of the role of embryology. After a brief review of pertinent embryological factors, a case example is used to illustrate the framework for assessment.
Formation of the basic structures of the CNS begins at 3-4 weeks postconception with the appearance of the neural plate. A neural grove appears and then undergoes an invagination process. This process occurs in a zipper-like fashion beginning at medullary levels and proceeding cephalad and caudad for formation of the brain and spinal cord.
Once the basic structures are in place, neural cells proliferate at approximately 3 months postconception and then migrate to their final locations by 6 months of fetal life. At the end of this process all neurons are present. Interference in either phase can lead to a number of abnormalities such as neural tube defects (e.g., spina bifida, meningomyelocele), microcephaly (i.e., small brain), or lisencephaly (i.e., smooth brain).
Development of the white matter begins at varying stages of fetal life and continues, in the case of oligodendrocytes, to many years postnatal. Oligodendrocyte function, in fact, does not cease until myelinization is complete.
Jane was a 4 1/2-month-old female with presenting complaints of "weakness" and failure to gain developmental milestones. No studies had been done to evaluate these problems. Nursing evaluation begins with the history and neurological assessment.
Similar to all neurologic assessment, a critical factor in pediatric evaluation is the history. This begins with the chronology of the presenting complaint(s) and previous evaluations. Specific to pediatrics are the pre-, peri-, and the postnatal events (Table 1) as well as the family history (Table 2). As the history is obtained, the infant should be observed for normal movements and interactions. In an older infant or young child, this allows them to become accustomed to you. If your approach provokes a screaming/crying or fearful response, you may need to ask the parent to take a more active role in assessment.
The assessment should proceed from the least to the most painful or intrusive to maximize the infant's cooperation. This necessitates a blending of the assessment rather than use of the traditional approach (e.g., cranial nerve then motor). Use of familiar toys or objects and making a game out of the assessment also may promote cooperation from the infant.
Jane was the 3-kg product of her mother's first pregnancy. In retrospect, her mother noted fewer fetal movements than she expected during the pregnancy. No peri-or postnatal problems were noted, and Jane went home with her mother at 2 days of age. A review of the family history revealed that a paternal cousin expired at 6 months for unknown reasons. The mother is 16 years old and the father is 17 years old. They are not related. Jane had had regular appointments with her pediatrician. Her parents became concerned when Jane was not rolling over by 4 months of age. They requested an evaluation.
At the time of the pediatric visit, Jane had no sucking or swallowing difficulties and had a robust appetite. She had no history of frequent respiratory problems or pneumonia. She was noted to be hypotonic. Jane was then referred to neurology for further evaluation.
Examination: Level of Consciousness
Evaluating level of consciousness (LOC) is as critical in pediatric as in adult assessment. The challenge is in determining the LOC of a non-verbal infant. The quality of time the infant is awake (smiling, looking around, interacting with parents) and ease in arousing from the sleeping state should be described as well as sleep patterns.
Jane slept all night and during the day and would awaken easily from naps and remain awake for several hours. While awake she was alert, maintained eye contact with her parents, and smiled appropriately.
Examination: Cranial Nerves
Cranial nerve function can be tested in the infant; however, the method of obtaining a response varies by the age and developmental level of the infant. Many of the techniques are similar to adult assessment. Elements of cranial nerve testing are as follows:
* Ability to smell is not evaluated in the infant.
* Pupillary reactions to light are determined after notation of pupillary size in a dim light. Resting pupil size is determined by the amount of ambient light available. Prompt constriction to the light stimulus should be noted. Infants do not focus on command. Talking to the infant or having a parent in the infant's visual field while applying the light stimulus will help to obtain a reliable response.
* The funduscopic examination also is affected by the infant's inability to focus on an object for prolonged periods. The best approach is for the examiner to remain stationary and catch glimpses of the fundi as it moves by. If further definition of the fundi is required, dilation of the pupils or an ophthalmology consult may be needed.
* Extraocular movements are obtained by having the infant follow a favorite or bright-colored object. Some infants may prefer to fix on a face so that fixation on the examiner's face also may be used. If these maneuvers are unsuccessful, the oculocephalic maneuver should be used. Infants of 4 months should have an orthophoric resting gaze.
* If needed for the evaluation, a touch of a wisp of cotton to the cornea will elicit the corneal response in infants. However, the response may be the Bell's phenomenon rather than eye closure. The Bell's phenomenon is an upward deviation of the eyes after the stimulus is applied.
* Strength of masseter muscles is determined by noting the strength of the infant's suck on a pacifier, examiner's thumb, or bottle.
* Facial symmetry is noted when the infant spontaneously smiles or cries. It is very difficult to assess forehead movement in the infant and may be possible only when the infant is forcibly crying.
* Strength of eyelid closure can be noted during the funduscopic examination when it becomes impossible to open the eyes.
* Noting an alerting response to voice or bell tests hearing. A stimulus that creates airflow such as clapping of the hands is not the preferred stimulus. If hand clapping is used, it should be done from a distance so that the response noted is to the sound rather than the airflow over the face.
* The gag reflex is tested as in adults. Always check time of last feeding with parents. Infants may vomit when gag reflex is tested immediately after a feeding. Testing of this reflex will give an indirect evaluation of the infant's ability to swallow. An occupational therapy consult may be required for a full evaluation of swallowing.
* Palate elevation and symmetry can be assessed when the infant yawns or cries.
* Indirect evidence for cranial nerve XI can be obtained by noting symmetry of head position when placed in the sitting position.
* In infants, observations for worm-like movements of the tongue (i.e., fasciculation) is critical, particularly when the presenting symptom is weakness. This is best observed at the edges of the tongue. You must observe the tongue at rest, not on forced protrusion from the mouth.
Jane had an unremarkable funduscopic examination, and pupillary response to light was intact. Her gag and corneal responses were present. She was noted to have a strong suck. Examination of the tongue revealed fasciculations. Jane's extraocular movements were intact, her facial movement was symmetric, and she attempted to turn her head to the sound of a bell.
Motor examination of the infant focuses on tone, strength, and deep tendon reflexes (DTRs). Observation of the infant's resting posture is a critical part of this examination because the infant is developmentally unable to participate in the more traditional approach to the motor examination. At rest, infants will normally have a slightly flexed posture at the hips, knees, and arms. They should be able to move their extremities to a full stretch. Abnormal tone is present when this normal stretch is absent, with persistence of increase in tone or the absence of flexion in a flaccid posture. Frequently, flaccidity or decreased tone is evidenced by an outward rotation at the hips with the legs externally rotated in a frog leg position.
Individual muscle testing is not possible. However, several muscle groups may be assessed for tone:
* Notation of neck tone is accomplished by the traction maneuver. With the infant lying supine on a flat surface, the infant is pulled to a sitting position. At 4-5 months of age the infant should be able to maintain the head in a neutral position. Abnormal tone is indicated by the head falling backward or requiring support.
* Shoulder tone is assessed by holding the infant in vertical suspension with the examiner's hands under the arms at the armpits. The infant should hold in that position with the arms remaining flexed and no rise in the shoulders. Inability to maintain that position is known as "slipping through" and is an abnormal response.
* Finally, placing the infant in the vertical position with his or her feet placed on the examining surface assesses leg tone. The 4-month-old infant should be at least momentarily able to support his or her weight. Inability to support any weight implies decreased tone. Increased tone is manifested by an extensor posture to the legs with preference for placement on the toes and a crossing or scissoring of the legs.
Strength in the infant is tested by the infant's ability to move his or her muscles against gravity.
DTRs are obtained at the biceps, triceps, Achilles, and patellar tendons. The Achilles reflex is present but difficult to elicit in young infants. Plantar (Babinski) responses are obtained by stroking the dorsum (i.e., outside edge) of the foot. In infants, a plantar grasp response can be elicited if the stimulus is applied to the center of the foot. There is some controversy about at what age an extensor (e.g., movement of great toe upward with fanning of other toes) response is abnormal. Most authors continue to suggest that the extensor response may be normal up to 1 year of age.
Muscle bulk and consistency are evaluated by palpation of the arm and leg muscles. In a 4-month-old infant the muscles have a degree of firmness. Determination of muscle bulk is a subjective estimate of the volume of muscle.
Jane had markedly decreased tone and strength. In the resting position she maintained a frog leg posture. She had marked head lag on the traction maneuver, no weight bearing in vertical suspension, and an inability to support her weight at the shoulders. Muscle bulk was normal but palpation revealed a doughy consistency.
She could not lift her extremities against gravity and, in fact, only demonstrated minimal to-fro motion at the wrist. DTRs were absent. Plantar responses were flexor.
Sensory examination of infants is limited to responses to pain or touch. Normal responses in a 4-month-old infant will demonstrate generalized movement of the extremity away from the stimulus. Infants are developmentally unable to remove the source of the stimulus or indicate the degree of the stimulus.
Jane responded to painful stimuli by crying and waving her hands.
Developmental evaluations provide the most detail about the cognitive level of the child. Specific intelligence testing is not feasible until the child reaches a minimum of 2 1/2-3 years of age. There is a sequential accrual of developmental reflexes that reflect the maturation of the CNS. For example, in the neonatal period, the only function not on the basis of a reflex are is the placing response. More skills are learned as the infant matures. Developmental testing reflects both the accrual of skills and the notation of developmental reflexes.
At 4 months of age infants should be able to hold their heads up and push up on their arms when prone. A social smile should be present, hands should come to the midline, and laughter as well as vowel sounds should be present. The Denver II Developmental Screening Test (DDST) is the most widely used developmental screening tool for this type of assessment.
Developmental reflexes present at 4 months include the following:
* Moro reflex. The infant's head is allowed to fall back as he or she is held in the examiner's hands. Normally, there will be an abduction and extension followed by an adduction and flexion of the upper extremities. The movement should be symmetric. This reflex begins to disappear at 4 months. A muted or incomplete response may therefore be seen at this age.
* Palmar reflex. The infant's hand will close around the examiner's finger when the finger is placed in the hand.
* Tonic neck reflex. The fencing posture is assumed by the infant when his or her head is turned quickly to one side in the supine position. The 4-month-old infant should be able to overcome this position.
Jane had no head control and could not bring her hands to midline. She had a social smile and was making cooing sounds. The Moro and tonic neck responses were absent. Jane had a palmar reflex.
In summary, Jane was a 4-month-old female with abnormal cranial nerve (lingual fasciculations) and motor examination. Her DDST also was delayed, evidenced by her inability to perform gross and fine motor skills. Specific genetic studies were sent and a diagnosis of infantile spinal muscular atrophy was made.
The neurological examination changes as infants develop. The most marked changes occur during the first year of life. The cranial nerve and level of consciousness examination remain the most stable over time. The gross and fine motor assessments are the most affected because myelin formation and cognitive development are essential to the development of these skills. Once the child is approaching school age, components of the neurologic evaluation will more closely resemble those of the adult. It is not until adolescence that they parallel the adult examination.
[1.] Bowden VR, Dickey SB, Greenberg CS (editors): Children and Their Families: A Continuum of Care. WB Saunders, 1998.
[2.] Frankenburg W, Dodds J, Archer P, et al: Denver II Screening Manual. Denver Developmental Materials, Inc, 1990.
[3.] Volpe JJ: Normal and abnormal human brain development. Clinics in Perinatology 1977; 4(1): 3-30.
Questions or comments about this article may be directed to: Elizabeth Hobdell, PhD CRNP CNRN, Section of Pediatric Neurology, St. Christopher's Hospital for Children, Front Avenue at Erie Street, Philadelphia, PA 19134-1095. She is a nurse practitioner in child neurology at St. Christopher's Hospital for Children.
Copyright (C)2001 American Association of Neuroscience Nurses 0047-2606/01/3304/00190$5.00
Table 1. Birth History Prenatal * Maternal health, adequacy of prenatal care * Placental function * Exposure to teratogens Perinatal * Position of fetus * Progress of labor * Premature rupture of membranes * Condition of cord * Monitoring abnormalities Postnatal * APGARs * Meconium staining/inhalation * Growth parameters * Laboratory evidence of hypoxia Table 2. Family History * Early deaths * Genetic conditions such as tuberous sclerosis, neurofibromatosis * Frequent miscarriages * Problems similar to those of infant * Hypotonia * Cerebral palsy * Epilepsy * Mental retardation * Diabetes * Cardiac problems
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