Harris, Susan R. PT, PhD, FAPTA, FCAHS
A previous line of research showed that parents (or other primary caregivers) are quite accurate in identifying developmental concerns in their own infants or young children1–3 and that their initial concerns are often corroborated by subsequent professional assessments.4–8 The knowledge that parents “know their children best” has formed the basis for family-directed care and has been embraced and adopted as a guiding principle by early intervention and early child development professionals. This knowledge has encouraged the use of parent report as a cost-effective and family-centered strategy for screening children’s development, so that appropriate referrals for further assessment and intervention can be made.9
The Harris Infant Neuromotor Test (HINT) is a norm-referenced screening tool designed to discriminate typical from atypical development in infants from 2.5 to 12.5 months of age.10 The HINT comprises 3 parts. In addition to collecting background information on the pregnancy and delivery (part I), the HINT includes 5 questions for the parent or caregiver asking their opinions about their infant’s movement and play (part II; Table 1). After completion of the first 2 parts of the HINT score sheet, the examiner then administers 21 items that compose part III of the test, which, when summed, determine the total HINT score. Items in part III primarily involve observational assessment of the infant’s ability to move in the prone, supine, sitting, and standing (or supported standing) positions. Passive range of motion is also assessed in the prone and supine positions in an attempt to rate muscle tone that is based also on the observation of antigravity movement. Other items include posture of the hands and feet, frequency and variety of movements, the infant’s overall behavior and cooperation during testing, the presence of any stereotypical behaviors, and measurement of head circumference.
Because 3 infants were referred to the author by their parents because of parental concerns about possible motor delays, this provided an opportunity to examine the validity of those parents’ concerns compared with outcomes on the HINT and on the Bayley-II Motor Scale.11 Second, administration of both the screening test (the HINT) and the more comprehensive developmental assessment, the Bayley-II Motor Scale, allowed the author to determine whether both norm-referenced tests were similar in categorizing the degree of motor delay across the 3 infants.
Consequently, the primary purpose of this clinical report was to qualitatively compare the parents’ concerns, as recorded on the second part of the HINT, with norm-referenced scores on the third part of the HINT (total HINT score) and those on the Bayley-II Motor Scale. The second purpose was to determine whether there was concordance or agreement in categorizing the degree of the infants’ delays on the 2 standardized tests.
Description of the Infants
All 3 infants were girls, born at term, with appropriate weight and length for gestational age, although infant 2 was borderline small-for-gestational age. There were no difficulties surrounding any of the pregnancies or deliveries. Each infant was referred to the author for developmental evaluation because of expressed parental concerns about their infants of possible motor delays, floppiness or low muscle tone, and/or possible cerebral palsy. Additional details about the infants are provided in Table 2.
The 2 tests administered were the HINT and the Bayley-II Motor Scale. The HINT is a norm-referenced neuromotor screening tool with strong reliability and known-groups validity.12,13 The Bayley-II is a more comprehensive norm-referenced developmental assessment that has been used in many previous studies to assess cognitive and motor development of at-risk infants or toddlers14,15 or those with known developmental disabilities.16 The reliability and validity of the Bayley-II Motor Scale are reported in the test manual11; concurrent validity has also been assessed by other researchers.17,18 The Bayley-II served as the criterion test to examine the concurrence of its categorical outcomes, ie, degree of motor delay, with the comparable categorical outcomes on the HINT.
The higher the HINT total score, the greater is the delay in motor skills. Based on comparisons with the HINT normative data, the infant is deemed to be developmentally appropriate if the score is within ±1 SD from the mean for his/her age group. Infants who score greater than 1 SD above the mean are referred for follow-up screening or a more comprehensive assessment, eg, Bayley Motor Scale, whereas infants who score greater than 2 SD above the mean should receive a comprehensive assessment that may then result in referral for early intervention services.
Assessment on the Bayley-II Motor Scale results in a Psychomotor Developmental Index (PDI) with a mean of 100 and a SD of 15. According to the Bayley-II manual,11 infants who score 1 to 2 SD below the mean are categorized as having mild delays, whereas those scoring greater than 2 SD below the mean are classified as having significant delays.
Both tests were administered by a pediatric physical therapist with more than 30 years of clinical experience as well as a background in reliable administration of each test. Because the HINT is a screening test, it was administered first, followed by the Bayley-II Motor Scale. All infants were assessed in a university classroom with carpeted floors to allow for placement of the infants on the floor to observe gross motor activities. Each infant’s mother was present for the assessment and completed the 5 parent/caregiver questions on the HINT before the motor portion of the test was administered by the therapist.
Demographic information about the infants is provided in Table 2, with ages at testing and test scores reported in Table 3. Comparison between the parents’ levels of concern and the test results in terms of degree of delay is described qualitatively within the results. The levels of agreement between the HINT and Bayley-II Motor Scale in categorizing the infants by number of SD from the mean are also described in the Results section. Because only 3 infants were included in this clinical report, statistical analyses were deemed inappropriate.
Parent Concerns and Developmental Test Scores
Infant 1, age 9.5 months and a firstborn child, was accompanied to the assessment by both her mother and father. Both parents and their family physician had first noted concerns when the baby was 6–7 months of age, ie, that she was small (weight compared with length) and was not yet sitting independently. At 7–8 months of age, the mother described her baby as “floppy” and not wanting so sit or to bear weight through her legs in supported standing. A recent evaluation by a pediatrician included referral for tests of creatine phosphokinase levels, kidney and liver function, and abdominal and cranial ultrasound scans. According to the parents, all test results were within normal limits. However, neither the family physician nor the pediatrician had recommended a developmental assessment. That request was initiated by the mother.
On the HINT parent questionnaire, the parents differed somewhat in their responses. Whereas the father felt that the infant’s movement and play (question 2) was “just great,” the mother responded that she was “a little worried.” When asked to compare their baby’s movement and play with that of other babies of the same age (question 3), the father felt that the baby was “slightly delayed,” whereas the mother responded to this question as “very delayed,” With regard to question 4, the father had no additional concerns, but the mother expressed concerns about the infant’s limited ability to move against gravity and her “great dislike” of being placed in the prone position. The mother also described the baby as “floppy” and stated that she “didn’t want to bear weight through her legs” when in supported standing. In response to question 5, the mother reported that the family physician was concerned that the baby was not yet sitting or “using her legs.”
Based on administration of part III of the HINT, this infant’s total risk score was 30, which is >3 SD above the mean for her normative age group. Her Bayley-II PDI was 50, which is >3 SD below the mean. Qualitatively, the test scores represent greater delays than expressed by the father (slightly delayed) but comparable with those expressed by the mother (very delayed) in response to question 3.
Assessed initially at 9 months 21 days of age, infant 2 was referred to the author by her mother who had expressed concerns that the infant had been “floppy since birth,” was delayed in attaining motor milestones, and might possibly have cerebral palsy. This infant had a 4.5-year-old sister who was developing typically. Because of the mother’s long-standing concerns, this infant had also been referred by the family physician to a pediatrician who ordered (per mother’s report) an electroencephalogram, computed tomography scan, and various blood and urine tests. According to the infant’s mother, all test results were within normal limits.
On question 1 (for which multiple answers are allowed), the mother described her baby as “soft and cuddly,” “somewhat floppy or loose,” and “somewhat stiff,” ie, that the infant arched her back when sitting. Her response to question 2 addressing the baby’s overall movement and play was “okay, but I am a little worried” and to question 3, “slightly delayed/slightly behind.” In answering question 5, she reported that her own mother and sister were also concerned about the baby as was her best friend, a pediatric occupational therapist.
The total HINT score for infant 2 was 15 or >2.2 SD above the mean. Her Bayley-II PDI was 56, which is 2.9 SD below the mean. The categorical classifications on the 2 tests suggest a greater degree of delay than was reported by the mother on part II (question 3) of the HINT, ie, slightly delayed.
The oldest of the 3 infants assessed, infant 3 was 13 months 3 days at the time of assessment and was the only child in this family. Although she was technically older than the age range covered by the HINT, it was still possible to compute a neuromotor age equivalent and to compare her HINT total score with the normative data on 12-month-old infants. This baby’s mother had expressed concerns that she thought her infant might have “low tone” and that both parents were worried that, at 13 months of age, the baby was not yet crawling, pulling to stand, cruising at furniture, or standing independently. On the HINT parent/caregiver questionnaire, the mother described her infant as “soft and cuddly” (question 1). She was “a little worried” about the baby’s overall movement and play (question 2) and felt that her daughter was “slightly delayed” in her movement and play compared with other same-age infants (question 3). In response to question 4, she commented that she was concerned that the baby was not yet pulling herself up on furniture. For question 5 (is anyone else concerned about your baby?), she noted that her husband was “slightly worried.”
The HINT total score for infant 3 was 23, which is >6 SD above the mean for 12-month-old infants (the closest age band on the test). On the Bayley-II, the baby’s PDI was <50 (>3 SD below the mean). Categorical results on the 2 tests suggest significant motor delays, whereas the mother expressed that she was only “a little worried” on question 2 and thought that her infant was only “slightly delayed” in her movement and play (question 3).
Concordance in Categorization of Delay on the 2 Tests
Table 3 displays the categorization of delay on the 2 norm-referenced tests, the HINT and the Bayley-II Motor Scale, for each of the 3 infants. HINT scores reflect the number of SD above the mean, as higher scores indicate less optimal or less mature performance, whereas the index scores (PDI) on the Bayley-II reflect SD below the mean. Although there is not perfect agreement, both tests showed significant delays, ie, >2 SD from the mean, for all 3 infants. Whereas the number of SD from the mean for the 2 tests was nearly identical for infant 1 (3.2 SD on the HINT and 3.3 SD on the Bayley-II), infant 2 performed better on the HINT, ie, somewhat closer to the mean, and infant 3 fared considerably worse on the HINT than on the Bayley-II.
The 3 infants in this clinical report all showed significant motor delays based on the administration and scoring of 2 norm-referenced developmental tests, corroborating concerns expressed initially by their parents. It is important to note, however, that the parents’ level of concern on part II of the HINT (with the exception of the mother of infant 1) were more consistent with “slight” delays than with the significant delays shown on the 2 standardized tests. There was reasonable concurrence on the categorical results of the 2 tests administered, thus supporting the clinical validity of the HINT as a screening test for motor delay. If the HINT screening had been performed in isolation, all 3 infants would have been referred for more comprehensive assessment based on the decision rules included on the last page of the score form.
What is interesting about these infants is the lack of any prenatal, perinatal, or postnatal risk factors for the developmental delays. All were born at term and of appropriate size, although infant 2 was borderline small for gestational age (Table 2). Based on the detailed background information provided by the parents on part I of the HINT, there were no additional risk factors, eg, prenatal difficulties, problems during the delivery, need for oxygen or ventilator support, or referral to a neonatal intensive care unit. Although all 3 infants had been followed since birth by family physicians and/or pediatricians, none had been assessed for possible developmental delays. All 3 referrals seeking developmental assessment were generated by the parents themselves because of long-standing concerns about their infants’ “floppiness” and delayed motor milestones.
A considerable body of research supports the validity of parental impressions or concerns about their children’s development.1–6 Based on that line of research, the HINT was developed to include questions to the parent or caregiver to elicit any concerns that they might have, particularly about their infant’s movement or play. Research involving an earlier version of the HINT showed a high degree of concurrence between parents’ impressions or concerns reported from the HINT questions and scores on the Bayley Motor Scale.6 In that study, 4 possible parental responses to question 3 (Table 1) were dichotomized into 2 descriptive categories for 2 × 2-analyses of sensitivity and specificity: normal (ahead of schedule or right on target) or delayed development (slightly delayed or very delayed). Consequently, the findings in the earlier study mirror those of these 3 infants, albeit 3 of the 4 parents of the current infants checked slightly delayed, whereas the PDI scores showed significant delays.
In keeping with the latest developmental screening and surveillance policy statement issued by the American Academy of Pediatrics,9 pediatric health professionals should be cognizant of parental questionnaires that elicit parental concerns, such as the Parents’ Evaluation of Developmental Status19 and the Ages and Stages Questionnaire,20 as well as tests like the HINT that incorporate parental impressions along with developmental motor observations. Such types of screening tests if results are positive for delays warrant further developmental and medical evaluations with the possibility of referral for early intervention services.21
Despite the fact that the 3 infants in this report had significant motor delays that were of concern to their parents, none had received previous developmental screening (or had been referred for developmental assessment). As a result of the 2 tests administered through parental referral to a pediatric physical therapist and the concurrence of the 2 tests in showing significant motor delays, all 3 infants were referred shortly thereafter for early intervention services.
Because these 3 infants were initially assessed by the author, they all have had numerous medical, imaging, genetic, and other laboratory tests in an effort to determine the causes of the motor delay. Despite these further examinations, no causes have been identified. Based on parent report, all 3 continue to show generalized hypotonia and significant motor delays; infant 1 is now 46 months of age, infant 2 is 38 months of age, and infant 3 is 23 months of age. In fact, infant 2 was reassessed by the author at 20 months of age and her PDI had dropped slightly (from 56 to 50). However, the infants and their families have likely benefited from receiving early intervention services and developmental motor therapies.21
Pediatric physical therapists should listen carefully to parents’ concerns about their children and take steps to provide developmental screening and surveillance and, when appropriate, refer children for further comprehensive assessment and/or early intervention services.
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