Clinical assessment of language development in children at age 3 years that were born preterm

Avaliação da evolução dos aspectos linguísticos em crianças que nasceram prematuras aos 3 anos de idade

Clinical assessment of language development in children at age 3 years that were born preterm

Avaliação da evolução dos aspectos linguísticos em crianças que nasceram prematuras aos 3 anos de idade

Carolina Rizzotto Schirmer^I; Mirna Wetters Portuguez^II; Magda Lahorgue Nunes^III

Division of Neurology - Hospital São Lucas and School of Medicine Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS) Porto Alegre RS - Brazil:

^ILanguage Therapist - Fellow Developmental Outpatient Clinic HSL - PUCRS

^IIMD, Associate Professor of Neurology, PUCRS School of Medicine

^IIIMD, PhD Associate Professor of Neurology and Pediatrics, PUCRS School of Medicine

ABSTRACT

OBJECTIVE: To evaluate the influence of gestational age and birth weight on language development and neurodevelopmental outcome at age 3 years in children born preterm.

METHOD: Cross sectional study including 69 children followed in our developmental outpatient clinic. Patients were consecutively included at the time of the 3 years of age appointment and stratified for birth weight (<1500 grams and between 1500-2500 grams). All patients were assessed for receptive and expressive language , Denver II and Bayley II tests and clinical neurological examination. For analysis patients were divided in two groups normal language acquisition (NLA) and delay in language acquisition (DLA).

RESULTS: NLA children had higher scores on mental and psychomotor (p=<0.01, p=0.012) indexes of Bayley II. Newborns with less than 1500 grams had lower scores on all Bayley scale at age 36 months (p=0.002, p=0.007 and p<0.001). Multivariate analysis suggests an association between gestational age (p=0.032), abnormal behavior (p<0.001) and delay in language acquisition. Denver test at 12 and 24 months of age was a good predictor of delayed receptive and expressive language at three years of age (p=<0.01 and p=<0.01).

CONCLUSION: Children born prematurely with low birth weight had an increased risk of language acquisition delay, and those had also lower cognitive and behavior scores when compared to NLA.

Key words: prematurity, low birth weight, language acquisition, developmental delay, Bayley infant scale, Denver test.

RESUMO

OBJETIVO: Avaliar influência da idade gestacional (IG) e peso ao nascimento na aquisição da linguagem e neurodesenvolvimento em crianças de 3 anos que nasceram prematuras.

MÉTODO: Estudo transversal incluindo 69 crianças acompanhadas no Ambulatório de Seguimento Neonatal. Pacientes incluídos tinham 3 anos e foram estratificados por peso ao nascimento (>1500 gramas e entre 1500-2500 gramas). Todos foram avaliados com relação ao neurodesenvolvimento incluindo avaliação neurológica clínica, Denver II, Bayley II e avaliação da linguagem. Para a analise dividimos em dois grupos com e sem alteração na aquisição de linguagem.

RESULTADOS: Crianças com DAL apresentam melhores índices nos escores de desenvolvimento no Bayley II (p=<0.01 e p=0.012). Crianças que nasceram com peso >1500 gramas tiveram escores menores no Bayley II na idade de 36 m (p=0.002, p=0.007 e p<0.001). Análise multivariada sugere uma associação da IG (p=0,032) e alteração comportamental (p=0,001) com atraso na aquisição da linguagem. Denver II alterado tanto aos 12 m quanto aos 24 m, correlaciona-se com significância estatística a atraso na aquisição de linguagem receptiva e expressiva aos 3 anos de idade (p=<0.01 e p=<0.01).

CONCLUSÃO: Crianças nascidas prematuras e com baixo peso ao nascimento, apresentam maior risco de ter um atraso no desenvolvimento da linguagem. Sendo que as crianças que tem atraso no desenvolvimento de linguagem apresentaram um desempenho cognitivo e psicomotor inferior ao das com desenvolvimento normal.

Palavras-chave: prematuridade, baixo peso ao nascimento, aquisição de linguagem, atraso no desenvolvimento, escala infantil Bayley, teste de Denver.

Even though technical and scientific advances have expressively contributed to the reduction of preterm newborn mortalility, prematurity and low birth weight still rise as the causes of mortality and neonatal morbidity, promoting a strong clinical and epidemiological impact. The risks of deviations in the development of these infants are consistent not only because they are more sensitive to diseases but also because they are exposed to iatrogenic factors such as long time isolation in the incubator, side effects of medications , besides mechanical ventilation and stress due to long handling^1-4. Studies show that the majority of newborns survivors of perinatal complications develop, at a later stage, multiple disorders in the first infancy or school age, including learning and language delay. Preterm low birth weight children may have up to four times more chances of presenting motor coordination and language acquisition delay in the third year of life than those born at a normal gestational age and weight⁵. Within language alterations the most significant is poverty in linguistic skills such as naming, language reception and hearing processing either in preschool age or school age^6-8.

It is well known that language disorders are related to learning disorders and around 50% of children diagnosed as having language disorders at age 2 years will continue to have this problem at ages 3-4 years⁹. As language is considered one of the most important developmental milestone and as outcome studies on preterm low birth weight newborns generally focus on mortality/morbidity and global neurological outcome, we specifically designed this study to access language acquisition^10-12.

The aim of this study was to evaluate the influence of gestational age and birth weight on language development and at global outcome at age 3 years in children born preterm.

METHOD

A cross sectional study was developed in a cohort of newborns admitted at the Neonatal Intensive Care Unit of Hospital São Lucas, the University Hospital of PUCRS Medical School, and followed at the Neonatal Follow up Outpatient Clinic of the same institution. The variables studied were prematurity and low birth weight and the clinical outcomes were the alteration or not of language acquisition besides mental and psychomotor development.

Patients – In this study, 69 children both male and female have been included in a consecutive way when their 3-year old appointment was scheduled at the Neonatal Follow up Outpatient Clinic. These children were born prematurely between January 1999 and April 2001 (gestational age <37 weeks) and with low birth weight (<2500 grams), all of them belonged to lower socioeconomic classes and were admitted by the Brazilian Public Health System (SUS).

Children followed in programs of early stimulation, that were hearing impaired or had malformations of the central nervous system, as well as those who interrupted their follow up in the two first years of life or those whose the current address was unavailable, have been excluded.

The statistical Mann-Whitney test was initially applied to verify if the sample included in this study differed from the total group of children born prematurely and with low birth weight, from 1999 to 2001, in the same unit. The result obtained was that the studied group was similar in relation to gestational age but with lower birth weight.

Procedures – Perinatal clinical data have been revised in the medical records. Children were divided in two groups according to birth weight (very low birth weight <1500 grams and low birth weight between 1500-2500 grams).

For the evaluation of the neuropsychomotor development, the scales of Bayley II Infant Development (BSDI-II)¹³ and the Denver II test^14,15 were used . The cognitive and behavioral development evaluation was performed using Bayley II¹³. These tests are applied routinely in our Neonatal Follow Up Outpatient Clinic.

The information on the mental and neuropsychomotor development in the corrected ages of 12 months and 24 months were obtained retrospectively in the clinic medical records and were performed by the Neuropsychology and Children Neurology teams.

The evaluation at 3 years of age was done in a prospective way, by the same teams, supervised by the researchers (MWP e MLN) and complemented by the language evaluation.

The evaluation of language development was done by the observation technique of language behavior based in the Nicolosi¹⁶ Sequence of Language Development which provides qualitative data that is, if language is adequate or altered. This evaluation was done by the researcher (CRS) that analyzed the infant’s linguistic behavior having as parameters points in receptive and expressive language. The researcher was blind to the study variables.

The exam of the hearing function, which is part of the clinic routine, was done by the Speech Therapy Service, during the first year of life through the otoacustic emission test.

This project was approved by the Ethics Committee of PUCRS.

An analytic study of the frequency for the categorical data and for the comparisons among the groups with absence and presence of language alteration was done. Categorical variables were compared using the chi-square test and continuous variables were compared using the Student T test. Wald test was used for the multivariate analysis.

RESULTS

During the period established for data collection 69 children were included. In the stratification according to birth weight, 39 had low birth weight (<2500g and >1500g) and 30 very low birth weight (<1500g). Regarding language evaluation, 34 presented normal development and 35 presented altered language development.

In the group studied, 23 children had neonatal neurological disorders such as perinatal asphyxia (9), intraventricular hemorrhage grade I (6), congenital infection (4), seizures (3) and bacterial meningitis (1).

The clinical characteristics and the evaluation of the neuropsychomotor development at 3 years of age in children with and without language alterations are described in Table 1.

The group without language alterations have shown better indexes in the mental and psychomotor development (p=<0.01, p=0.012). Alteration in the BSDI-II behavior scale was found in 66% of patients with language alteration (p<0.001). The Denver II test was abnormal in 31.4% of patients with language alteration and in 6% of those with normal language (p=0.012).

Results referring the stratification by weight are described in Table 2.

The children with birth weight lower than 1500 grams and language delay showed the worst performance in all BSDI-II when compared to those without language alteration. Children with birth weight between 1500-2500 grams and language delay showed the worst BSD-I mental score and in the Denver test (p=0.002, p=0.008).

Evaluation of receptive and expressive language acquisition compared to Denver test results are described in Table 3. Altered Denver test either at 12 months or at 24 months, correlates with statistic significance to the delay in the receptive and expressive language acquisition at 3 year-old children (p=<0.01 and p=<0.01).

Language acquisition when compared in all its levels and the Denver II test among groups stratified by birth weight, we observed that the Denver altered at 12 and 24 months in children with birth weight between 2550-1500 grams is correlated with the delay in language acquisition in expressive and receptive levels. In those children with birth weight lower than 1500 grams there was a relation between alteration in the Denver and the receptive language (Table 4).

Multivariate analysis was refered in order to identify the associations among the variables gestational age, birth weight, Denver test result at 12 and 24 months, Bayley test results, Bayley test results at 36 months with the closing of language at 36 months. Only the variables with a significant association are in the multivariate analysis, that is gestational age (p=0.04), Bayley test scores (p=<0.01) and Bayley test behavioral score (p=<0.01).

In the multivariate analysis of the association among the variables GA, Denver test at 12 months (Denver 12), Denver test at 24 months (Denver 24) and alteration in the BSDI-II behavioral score it was observed that the gestational age lower than 32 weeks increases 3 times the risk of delay in language acquisition. Alteration in behavior at 36 months has a 8 times higher risk to show language alteration (Table 5).

DISCUSSION

Prematurity and low weight, per se, are elements that constitute risk factors for development delay and are associated to either global disorders such as brain paralysis or mental retardation or specific disorders such as hearing and /or visual disorders and language alterations^3,17. The impact of prematurity and low birth weight in the neuropsychomotor development (NPMD) was studied by several authors^3,17-22.

Possibly, the most important aspect of our study, was the language evaluation and the valorization of both expressive and receptive level, once most studies of low birth weight premature born children related to children development are based on the mental and psychomotor development^1-3,5,23.

In this investigation, the results found suggested that the premature with language alteration have a tendency to show low birth weight and a smaller gestational age. In this group it was also found lower score indexes for the mental and psychomotor development. Vohr and collaborators¹ in a multicentric study with the objective of detecting risk factors for the altered neurological development in premature children with extreme low weight, between 18 to 22 months of corrected age, verified that 37% showed intelligence bellow expected and 29% showed delayed in the psychomotor development. Ohgi and collaborators³ in a study with low birth premature newborns, observed that, at 5, 19,6% of children were classified as moderate handicap and 9,6% as severe handicap. Stoelhorst and collaborators⁴, in a study with extreme premature newborns, found, at 18 and 24 months of corrected age, prevalence of 40% psychomotor and mental development delay.

Another aspect raised in our investigation, similar to the one described in the literature, is the high prevalence of alteration in the expressive language acquisition process in children born premature and with low birth weight. Grunau and collaborators¹⁹ compared the language development, at 3 years old, of premature children born with birth weight lower than 1000g with term control children paired by social class based on chronological age and corrected age. The pre-term group used less complex expressive language and showed low receptive comprehension, listening memory and verbal reasoning.

Landry and collaborators²² followed the development of low weight premature children up to 8 years of age and verified that the social economic level may influence language development. Children in our study come from a low social economic class and are seen by the Public Health System.

We observed in our study a correlation between gestational age and language development alteration, that is, the more the premature the bigger the chance of showing alteration in language development. These findings agree with Landry and collaborators²².

It seems that the sum of factors that negatively affect the development of low birth weight premature infants involves two aspects, the exposure to unfavorable environmental factors such as, for example, the mother’s low social and economic level^24,25 (that implies in little linguistic stimulation) and the physiological delay in neurobiological maturation, those aspects leads to the conclusion that not even the very active brain plasticity at this period²⁶ can compensate in time the neurodevelopment to the point of making the acquisition of language expression chronologically adequate²⁷.

To conclude, in our sample, low birth weight premature infants showed higher risk of having language delay. Those children that have a delay in language development showed a lower cognitive and psychomotor development compared to those with normal development. Abnormalities previously detected by Denver II test were correlated with statistical significance with delay in the receptive and expressive language acquisition, showing that this test is a good resource to detection and early intervention in cases of prematurity and low birth weight.

Received 22 March 2006, received in final form 4 July 2006. Accepted 10 August 2006.

Dra. Magda Lahorgue Nunes - Division of Neurology - Hospital São Lucas - PUCRS - Avenida Ipiranga 6690 / 220 - CEP 90610-000 Porto Alegre RS - Brasil. E -mail: [e-mail]

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Publication Dates

• Publication in this collection
  21 Dec 2006
• Date of issue
  Dec 2006

History

• Received
  22 Mar 2006
• Reviewed
  04 July 2006
• Accepted
  10 Aug 2006