Transient dystonia in non-handicapped low-birthweight infants and later neurodevelopment

Transient tone anomalies in very preterm infants: Association with term-equivalent brain magnetic resonance imaging and neurodevelopment at 18 months

BACKGROUND

Very preterm (VPT) infants are at risk for neurodevelopmental impairments and early clinical findings such as transient tone anomalies (TTA) might represent potential predictive indicators.

AIMS

The aims of this study were to assess 1) the prevalence of TTA at 6 months corrected age in a population of VPT infants, 2) the association with term-equivalent age (TEA) brain MRI and 3) the neurodevelopmental outcome at 18 months corrected age.

STUDY DESIGN AND SUBJECTS

A prospective case-control cohort of 103 VPT infants (<29 weeks of gestation) was followed up at 6 months and classified into TTA+ or TTA-. TTA+ was defined by the presence of ≥2 criteria among anomalies of posture, anomalies of tone and hyperreflexia.

OUTCOME MEASURES

Conventional and diffusion-weighted MRIs at TEA were analyzed according to a semi-quantitative MRI scoring system and apparent diffusion coefficients (ADC) and fractional anisotropy (FA) were measured in frontal, occipital white matter and posterior limb of the internal capsule (PLIC). Neurodevelopment was assessed at 18 months using Bayley-II scales (Psychomotor Developmental Index: PDI; Mental Developmental Index: MDI).

RESULTS

TTA+ infants represented 29.1% of the total population. They had: 1) significantly higher ADC values in 3 regions of interest (p < 0.001), 2) significant lower FA in the PLIC (p < 0.001), and 3) significant lower PDI score (p < 0.05). No differences were observed regarding MDI scores. Interaction of TTA by cerebellum score was related to lower MDI scores.

CONCLUSIONS

In VPT infants, TTA at 6 months and/or structural brain abnormality at TEA are associated with poorer neurodevelopmental outcome at 18 months.

Early school outcomes for extremely preterm infants with transient neurological abnormalities

AIM

To determine if transient neurological abnormalities (TNA) at 9 months corrected age predict cognitive, behavioral, and motor outcomes at 6 years of age in extremely preterm infants.

METHOD

A cohort of 124 extremely preterm infants (mean gestational age 25.5wks; 55 males, 69 females), admitted to our unit between 2001 and 2003, were classified based on the Amiel-Tison Neurological Assessment at 9 months and 20 months corrected age as having TNA (n=17), normal neurological assessment (n=89), or neurologically abnormal assessment (n=18). The children were assessed at a mean age of 5 years 11 months (SD 4mo) on cognition, academic achievement, motor ability, and behavior.

RESULTS

Compared with children with a normal neurological assessment, children with TNA had higher postnatal exposure to steroids (35% vs 9%) and lower adjusted mean scores on spatial relations (84 [standard error {SE} 5] vs 98 [SE 2]), visual matching (79 [SE 5] vs 91 [SE 2]), letter-word identification (97 [SE 4] vs 108 [SE 1]), and spelling (76 [SE 4] vs 96 [SE 2]) (all p<0.05).

INTERPRETATION

Despite a normalized neurological assessment, extremely preterm children with a history TNA are at higher risk for lower cognitive and academic skills than those with normal neurological findings during their first year of school.

Apgar Scores: Examining the Long-term Significance

The Apgar scoring system was intended as an evaluative measure of a newborn's condition at birth and of the need for immediate attention. In the most recent past, individuals have unsuccessfully attempted to link Apgar scores with long-term developmental outcomes. This practice is not appropriate, as the Apgar score is currently defined. Expectant parents need to be aware of the limitations of the Apgar score and its appropriate uses.

Cerebral MRI and cognition in nonhandicapped, low birth weight adults

This study sought to compare cognitive and cerebral findings of magnetic resonance imaging in young adults with low birth weights and in a control group. One hundred thirteen of 173 (65%) eligible adults with birth weights <2000 g, and 100 of 170 (59%) controls, all without major disabilities, were examined at age 19 years. Cerebral 3.0 T magnetic resonance imaging was performed according to standardized protocols. Prorated intelligence quotient was estimated from two subtests of the Wechsler Abbreviated Scale of Ability, a word comprehension test, and matrices. Prominent lateral ventricles and loss of white matter, and thinning of the corpus callosum, were more common in the low birth weight group than in the control group (40% vs. 15%, respectively; odds ratio, 3.8; P < 0.001; and 31% vs. 7%, respectively; odds ratio, 6.0; P < 0.001). Low birth weight adults exhibited lower mean intelligence quotients (95 vs. 101, respectively; P < 0.001). Low birth weight adults face an increased risk of prominent ventricles, global loss of white matter, and thinning of the corpus callosum. Similar magnetic resonance imaging findings are not uncommon among healthy adults.

Transient tone abnormalities in high risk infants and cognitive outcome at five years

OBJECTIVE

to identify transient tone abnormalities and determine its prevalence in high risk infants and their cognitive outcome at 5 years.

DESIGN

prospective cohort observational study.

SETTING

high risk infants discharged from a level II neonatal unit in a 12 month period, and followed upto 5 years.

METHODS

High risk infants and normal controls were assessed for abnormalities of tone using the method described by Amiel Tison at 3, 6, 9, 12 months. An IQ by Stanford Binet method and a preschool inventory by Ayres, Bobath was done at 5 years. Those infants who had normal tone at 6 and 12 months were called normal high risk (HR) group and those who had abnormalities at 6 months, which disappeared at 12 months, were called the transient tone abnormalities (TTA) group.

RESULTS

out of 190 high risk infants, 113 were normal HR and 67 (35.2%) were labeled as TTA. Ten infants with cerebral palsy had abnormal tone throughout the first year. Controls had normal tone throughout the follow-up period. Although there was no difference in the IQ of the TTA group (98.5 ± 12.4) and the normal HR (99.1 ± 13.1) group, it was significantly less (P=0.04) than that of controls (106.1 ± 9.1). Preschool inventory in TTA children showed poor language development (P=0.014).

CONCLUSION

many of the tone abnormalities detected at 6 months resolve by 12 months, hence a hasty diagnosis of cerebral palsy should not be made. High risk infants with transient tone abnormalities have a normal cognitive outcome at 5 years, except for poor language skills.

Clinimetric properties of the alberta infant motor scale in infants born preterm

PURPOSE

The Alberta Infant Motor Scale (AIMS) is a standardized motor assessment for young infants. This study aimed to examine the reliability of the AIMS in a group of infants born at or before 29 weeks of gestation.

METHODS

Fifty-nine infants born preterm were recruited. Two experienced pediatric physical therapists participated in this reliability study. Infants were assessed at 4, 8, 12, and 18 months corrected age (CA).

RESULTS

Intrarater reliability was high (intraclass correlation coefficient [ICC] > or =0.99). The ICC for interrater reliability varied from 0.85 to 0.97. The ICC was low at 4 and 18 months CA.

CONCLUSIONS

The AIMS is reliable in evaluating motor development in infants born preterm. Clinicians should be cautious about using the AIMS in infants at very young ages and those approaching independent ambulation. Accurate placement of the window on a movement repertoire is crucial. Attention is required when using the AIMS in infants developing atypically.

Motor development from 4 to 8 months corrected age in infants born at or less than 29 weeks' gestation

AIM

Clinically, preterm infants show motor delay and atypical postures compared with their peers born at term. A longitudinal cohort study was designed to describe the motor development of very preterm infants from 4 to 18 months corrected age (CA). The study was also designed to investigate how the atypical postures observed in early infancy in the preterm infants might be related to their later motor development. Here we report the findings in early motor skills from 4 to 8 months CA.

METHOD

Early motor skills were assessed in 62 preterm infants (32 males, 30 females, mean gestation 26.94wks, SD 1.11) and 53 term infants (32 males, 21 females, mean gestation 39.55wks, SD 1.17) using the Alberta Infant Motor Scale (AIMS).

RESULTS

The preterm infants demonstrated different motor behaviours from their term peers, with an uneven progression of motor skills in different positions from 4 to 8 months CA. At 8 months CA, 90%of the term infants were able to sit without arm support, but only 56%of the preterm infants could maintain sitting very briefly without arm support.

INTERPRETATION

This uneven progression may have been due to an imbalance between the active flexor and extensor strength and hence inadequate postural control in these positions. The AIMS has also been shown to be a valid assessment tool to demonstrate unique characteristics in movement quality in the preterm population.

Predictive factors for neuromotor abnormalities at the corrected age of 12 months in very low birth weight premature infants

BACKGROUND: The increase in survival of premature newborns has sparked growing interest in the prediction of their long-term neurodevelopment. OBJECTIVE: To estimate the incidence of neuromotor abnormalities at the corrected age of 12 months and to identify the predictive factors associated with altered neuromotor development in very low birth weight premature infants. METHOD: Cohort study. The sample included 100 premature infants. The outcome was neuromotor development at 12 months classified by Bayley Scale (PDI) and neurological assessment (tonus, reflexes, posture). A multivariate logistic regression model was constructed. Neonatal variables and neuromotor abnormalities up to 6 months of corrected age were selected by bivariate analysis. RESULTS: Mean birth weight was 1126g (SD: 240). Abnormal neuromotor development was presented in 60 children at 12 months corrected age. CONCLUSION: According to the model, patients with a diagnosis including bronchopulmonary dysplasia, hypertonia of lower extremities, truncal hypotonia showed a 94.0% probability of neuromotor involvement at 12 months.

Stability of neuromotor outcomes at 18 and 30 months of age after extremely low birth weight status

BACKGROUND

Extremely low birth weight (< or =1000 g) children have increased rates of cerebral palsy and other abnormal neurologic findings.

OBJECTIVE

To investigate the stability of neuromotor findings between 18 and 30 months' adjusted age in extremely low birth weight infants. METHODS. Seven hundred nineteen extremely low birth weight infants with assessments at 18 and 30 months' adjusted age were included in this analysis. At each visit a neurologic examination, the modified gross motor function classification system, and the Bayley Scales of Infant Development II were administered. Logistic regression models were constructed to assess neonatal factors and neuromotor function at 18 months of age associated with stability in neuromotor function.

RESULTS

Eighty-four percent of the children had agreement in neurologic/motor function at both visits. However, classification changed from normal to abnormal in 6% and from abnormal to normal in 10%. Diagnosis of cerebral palsy was consistent for 91% of the children, and the gross motor function classification system score was consistent for 83%. In multivariate models, factors associated with decreased severity or absence of cerebral palsy diagnosis at 30 months of age were higher gestational age, no periventricular leukomalacia or severe intraventricular hemorrhage, and a gross motor function classification system score of 0 (normal) at the 18-month visit, whereas factors associated with a new cerebral palsy diagnosis at 30 months of age were postnatal steroid use, periventricular leukomalacia or severe intraventricular hemorrhage, a gross motor function classification system score of > or =1 at 18 months of age, and asymmetrical limb movement at 18 months of age.

CONCLUSIONS

Stability of neurologic diagnosis in 84% and cerebral palsy in 91% of the children is reassuring. However, for a significant percentage of children, the neurologic diagnosis changes between 18 and 30 months of age. The diagnosis of cerebral palsy may be delayed in some infants until an older adjusted age.

The development of reaching behavior in low-risk preterm infants

This longitudinal study investigated the development of reaching behavior in the seated position in preterm infants at the ages of 5-7 months by analyzing kinematic variables (straightness and adjustment indexes, movement unit, mean and final velocities). The correlation between kinematic variables and grasping was verified. The participants were nine low-risk preterm infants with no cerebral lesions. Ten fullterm infants served as control. In both groups, kinematic variables remained unchanged over age, except for the adjustment index, which was higher at 6 months in the preterm group. Successful grasping increased in both groups over age and it was shown to be negatively correlated with mean velocity in the preterm infants. At the ages of 6 and 7 months, preterms showed lower mean and final velocities and higher adjustment index when compared with fullterms. The relative constancy in the kinematic variables suggests that, after having explored the action possibilities during the acquisition phase, the infants selected an adaptative pattern to perform the reaching movements. Slower movements and greater adjustments may be functional strategies of preterms to achieve successful grasps.

Quality of reaching and postural control in young preterm infants is related to neuromotor outcome at 6 years

A substantial proportion of the "apparently normal" preterm infants exhibit minor and moderate dysfunctions in neuromotor outcome as they grow older. Birth characteristics, minor abnormalities on the neonatal ultrasound scan of the brain, and motor milestones have only limited value in the early detection of these children. The aim of the present study was to investigate whether nonoptimal reaching and relatively immobile postural behavior at an early age are associated with dysfunctional neuromotor and behavioural development at school age. The preterm children and full-term children of the present follow-up study participated in a previous study on the characteristics of reaching kinematics and the kinetics of posture at 4 and 6 mo corrected age. At the age of 6 y, the children were re-assessed by means of the Touwen neurologic assessment, the Movement ABC, and the Child Behavior Check List. The results demonstrated that in preterm children without cerebral palsy, a lack of successful reaching at 4 mo and a nonoptimal quality of reaching at 6 mo are related to the development of a complex form of minor neurologic dysfunction (MND) and fine manipulative disability at 6 y. Thus, these early signs indicate the presence of clinically significant brain dysfunction. A relatively immobile postural behavior at 4 mo was associated with simple MND, coordination problems, and at 6 mo with a worse score on the Movement ABC and internalizing behavior. This suggests that a relatively immobile postural behavior points to a mild form of brain dysfunction.

Maternal infection and risk of cerebral palsy in term and preterm infants

OBJECTIVE

We tested the hypothesis that term and preterm infants exposed to maternal infection at the time of delivery are at increased risk of developing cerebral palsy (CP).

STUDY DESIGN

A population-based case-control study was conducted using Washington State birth certificate data linked to hospital discharge data. Cases (688) were children <or=6 years old, singleton births, hospitalized during 1987 to 1999 with an ICD-9 diagnosis code for CP. Controls were 3,068 singleton birth infants randomly selected from birth records for the same years without CP-related hospitalizations. Infection information was available only for the birth hospitalization.

RESULTS

Infants of women who had any infection during their hospitalization for delivery were at increased risk of CP (odds ratio (OR) 3.1, 95% confidence interval (CI) 2.3 to 4.2). This was observed for term deliveries (OR 1.8, 95% CI 1.1 to 2.8) and preterm deliveries (OR 2.3, 95% CI 1.3 to 4.2).

CONCLUSIONS

Our results suggest that maternal infection is a risk factor for CP in both term and preterm infants.

The effects of an early physical therapy intervention for very preterm, very low birth weight infants: a randomized controlled clinical trial

PURPOSE

A randomized controlled clinical trial was used to investigate effects of physical therapy (PT) intervention on motor outcome of infants born very preterm with very low birth weight (VLBW).

METHODS

Seventy-two infants born very preterm with VLBW were randomly assigned to a nontreatment (NT) (n = 38) or treatment (T) (n = 34) group. The T group received developmental PT from birth until four months corrected age (CA) weekdays during the infant's neonatal stay and on a needs- and problem-orientated basis thereafter. The NT group received no intervention. Both groups were assessed at four months CA using the Alberta Infant Motor Scale (AIMS) as was a control group of 14 infants born full term. Parental compliance was measured using a parent questionnaire.

RESULTS

PT intervention had no significant effect on the T group's motor performance. However, no T group subjects had abnormal motor development at four months CA when compared to the NT group (16%) and the control group (14%) (p = 0.09). The T group subjects with high levels of parental compliance had better scores on the AIMS than those with lower parental compliance (p = 0.05).

CONCLUSION

PT intervention does not significantly affect motor performance of infants born very preterm with VLBW at four months CA. Parental compliance and intervention frequency may have influenced the outcome. Preliminary evidence suggests that neonatal and early PT may reduce the incidence of motor delay among infants born very preterm with VLBW. Follow-up of this group is recommended to ascertain the long-term benefits of this type of early PT.

Kinematic quality of reaching movements in preterm infants

Many preterm infants may experience so-called minor developmental disorders; however, in general, the problems in motor behavior are not detected until school age. To introduce therapies aimed at the prevention of these problems, we need to increase our knowledge of motor function and dysfunction at early age. The present study focused on the organization of reaching movements in full-term and preterm infants without cerebral palsy. The reaching behavior of premature infants (n = 63) was assessed longitudinally at the corrected ages of 4 and 6 mo. Clinical assessments were made at 6 and 12 mo of age. On the basis of the infant's morbidity during the early stay in the neonatal intensive care unit, the preterm infants were allocated into a high-risk and a low-risk group. Results from a previous study in full-term infants (n = 13) were included. Kinematics of reaching movements in supine position were measured, and the analysis focused on movement velocity and movement units. A compound parameter of kinematic variables was created, reflecting the quality of reaching movements. The present study showed that at the age of 4 mo, low-risk preterm infants showed more often optimal reaching behavior than full-term and preterm high-risk infants. This better reaching performance was related to a better general motor and behavioral development during the first year of life. At the age of 6 mo, the advantage of the low-risk group in reaching behavior had disappeared and a disadvantage in the form of nonoptimal reaching behavior of the high-risk group emerged.

Patterns of motor disability in very preterm children

Motor development in very preterm children differs in several important ways from that of children born at full term. Variability is common, although the anatomic and physiologic bases for that variability are often poorly understood. Motor patterns over the first postnatal year may depend on behaviours learned during often long periods of neonatal intensive care. The normal pattern of development may be modified by disturbances of brain function caused both by the interruption of normal brain maturation ex-utero and the superimposition of focal brain injuries following very preterm birth. Abnormal patterns of development over the first year may evolve into clear neuromotor patterns of cerebral palsy or resolve, as "transient dystonias." Cerebral palsy is associated with identified patterns of brain injury secondary to ischaemic or haemorrhagic lesions, perhaps modified by activation of inflammatory cytokines. Cerebral palsy rates have not fallen as might be expected over the past 10 years as survival has improved, perhaps because of increasing survival at low gestations, which is associated with the highest prevalence of cerebral palsy. Children who escape cerebral palsy are also at risk of motor impairments during the school years. The relationship of these impairments to perinatal factors or to neurological progress over the first postnatal year is debated. Neuromotor abnormalities are the most frequent of the "hidden disabilities" among ex-preterm children and are thus frequently associated with poorer cognitive ability and attention deficit disorders. Interventions to prevent cerebral palsy or to reduce these late disabilities in very preterm children are needed.

Cerebral palsy in very preterm infants: new epidemiological insights

The focus of this review is on new insights from recent epidemiological research on cerebral palsy in preterm infants. These include: 1) a better understanding of issues related to diagnosis and classification; 2) new information about the brain abnormalities underlying cerebral palsy in preterm infants; and 3) a better understanding of biological mechanisms that may underlie previously described epidemiological associations. Ongoing efforts to improve the diagnosis and classification of cerebral palsy have been enhanced by findings from serial examinations of cohorts of very preterm infants. Cranial ultrasonography through the anterior fontanelle of very preterm infants has provided information about grossly evident brain damage, found in about one-half of preterm infants who develop cerebral palsy. Insights into the pathophysiologic basis for certain epidemiologic associations have come from studies of experimental brain damage in animals and clinical studies of neurologic disorders in adults. Much of the current epidemiological research into the causes of cerebral palsy in preterm infants has focused on two potential mechanisms of brain damage. One mechanism involves insufficient cerebral perfusion; the other, cytokine-mediated damage, potentially triggered by events such as maternal infection (e.g., intrauterine or periodontal infection), neonatal infection (e.g., sepsis and necrotizing enterocolitis), and neonatal oxygen- or ventilator-induced lung injury. In addition to the preterm infant's increased exposure to such damaging factors, the high frequency of cerebral palsy in these infants might be due, in part, to insufficient levels of developmentally regulated protective substances, such as thyroid hormone and glucocorticoids. Models of causation currently are being investigated using recently developed methods for quantifying, with small quantities of blood, biomolecules that are suspected to either promote or protect against brain damage in the neonate. Clinical investigations now under way can be expected to identify strategies to be tested in clinical trials that could lower the risk of cerebral palsy in very preterm infants.

Development of postural adjustments during reaching in preterm infants

Preterm infants often show postural abnormalities, such as hyperextension of neck and trunk, which can interfere with motor and cognitive development. Little is, however, known on the pathophysiology of postural development in preterm infants. Therefore, we longitudinally studied the development of postural adjustments during reaching movements in 12 preterm infants between the (corrected) ages of 4 and 18 mo. Five infants showed minor neurological dysfunctions at 18 mo, such as a mild diffuse hypotonia, a mild hypertonia of the legs, or a mild asymmetry in posture and motility, and seven infants were neurologically normal. Each assessment consisted of a simultaneous recording of video-data and surface electromyograms of arm, neck, trunk, and leg muscles during reaching in various lying and sitting positions. Comparable data on postural development in ten full-term infants were available. The preterm infants showed an excessive amount of postural activity during reaching movements at all ages studied. Moreover, the postural adjustments were temporally disorganized and could not be modulated with respect to the velocity of the arm movement and the initial sitting position. We hypothesized that the preterms' disability to modulate their postural adjustments might be due to a reduced capacity to learn from prior experience. In our small group the postural dysfunctions were not related to the presence of hyperextension at early ages, to the neurological outcome at 18 mo, or to the lesions found on the neonatal brain ultrasound scans.