Minor neurological dysfunction and cognition in 9-year-olds born at term

Neurological soft signs are associated with reduced medial-lateral postural control in adolescent athletes

INTRODUCTION

Neurological soft signs (NSS) are minor deviations from the norm in motor performance that are commonly assessed using neurological examinations. NSS may be of clinical relevance for evaluating the developmental status of adolescents. Here we investigate whether quantitative force plate measures may add relevant information to observer-based neurological examinations.

METHODS

Male adolescent athletes (n = 141) aged 13-16 years from three European sites underwent a neurological examination including 28 tests grouped into six functional clusters. The performance of tests and functional clusters was rated as optimal/non-optimal resulting in NSS+/NSS- groups and a continuous total NSS score. Participants performed a postural control task on a Balance Tracking System measured as path length, root mean square and sway area. ANCOVAs were applied to test for group differences in postural control between the NSS+ and NSS- group, and between optimal/non-optimal performance on a cluster- and test-level. Moreover, we tested for correlations between the total NSS score and postural control variables.

RESULTS

There was no significant overall difference between the NSS+ and NSS- group in postural control. However, non-optimal performing participants in the diadochokinesis test swayed significantly more in the medial-lateral direction than optimal performing participants. Moreover, a lower total NSS score was associated with reduced postural control in the medial-lateral direction.

CONCLUSION

Our findings demonstrate that NSS are related to postural control in adolescent athletes. Thus, force plate measures may add a quantitative, objective measurement of postural control to observer-based qualitative assessments, and thus, may complement clinical testing.

Neurological soft signs in adolescents are associated with brain structure

Neurological soft signs (NSS) are minor deviations in motor performance. During childhood and adolescence, NSS are examined for functional motor phenotyping to describe development, to screen for comorbidities, and to identify developmental vulnerabilities. Here, we investigate underlying brain structure alterations in association with NSS in physically trained adolescents. Male adolescent athletes (n = 136, 13–16 years) underwent a standardized neurological examination including 28 tests grouped into 6 functional clusters. Non-optimal performance in at least 1 cluster was rated as NSS (NSS+ group). Participants underwent T1- and diffusion-weighted magnetic resonance imaging. Cortical volume, thickness, and local gyrification were calculated using Freesurfer. Measures of white matter microstructure (Free-water (FW), FW-corrected fractional anisotropy (FAt), axial and radial diffusivity (ADt, RDt)) were calculated using tract-based spatial statistics. General linear models with age and handedness as covariates were applied to assess differences between NSS+ and NSS− group. We found higher gyrification in a large cluster spanning the left superior frontal and parietal areas, and widespread lower FAt and higher RDt compared with the NSS− group. This study shows that NSS in adolescents are associated with brain structure alterations. Underlying mechanisms may include alterations in synaptic pruning and axon myelination, which are hallmark processes of brain maturation.

Patterns of atypical muscle tone in the general infant population - Prevalence and associations with perinatal risk and neurodevelopmental status

BACKGROUND

Muscle tone is an indispensable element in motor development. Its assessment forms an integral part of the infant neurological examination. Knowledge on the prevalence of atypical tone in infancy is lacking.

AIM

To assess the prevalence of atypical muscle tone in infancy and of the most common atypical muscle tone patterns, and associations between atypical tone and perinatal risk and neurodevelopmental status.

STUDY DESIGN

Cross-sectional study.

SUBJECTS

1100 infants (585 boys; gestational age 39.4 weeks (27.3-42.4)), 6 weeks-12 months corrected age, representative of the Dutch population.

OUTCOME MEASURES

Muscle tone and neurodevelopmental status were assessed with the Standardized Infant NeuroDevelopmental Assessment (SINDA). Perinatal information was obtained by questionnaire and medical records. Univariable and multivariable statistics were applied.

RESULTS

Ninety-two infants (8%) had atypical muscle tone in 3-4 body parts (impaired pattern), while atypical muscle tone in 1-2 body parts was observed in 50%. Isolated leg hypotonia and isolated arm hypertonia were most common. Isolated arm hypertonia and the impaired pattern were most clearly but only moderately associated with perinatal risk. These patterns were also most clearly associated with lower neurological scores. Only the impaired pattern was associated with lower developmental scores.

CONCLUSION

Atypical muscle tone in one or two body parts is common in infancy and has in general little clinical significance. This finding corresponds to the well-known high prevalence of a typical but non-optimal neurological condition. Eight percent of infants show atypical muscle tone in 3-4 body parts. This clinically relevant pattern is associated with perinatal risk and less favourable neurodevelopmental status.

Minor neurological dysfunction and associations with motor function, general cognitive abilities, and behaviour in children born extremely preterm

AIM

To study the prevalence of minor neurological dysfunction (MND) at 6 years of age in a cohort of children born extremely preterm without cerebral palsy (CP) and to investigate associations with motor function, cognitive abilities, and behaviour.

METHOD

This study assessed 80 children born at less than 27 weeks of gestation and 90 children born at term age between 2004 and 2007 at a mean age of 6 years 6 months. The assessments included a simplified version of the Touwen Infant Neurological Examination, the Movement Assessment Battery for Children, Second Edition (MABC-2), Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV), the Strengths and Difficulties Questionnaire (SDQ), and the parent version of the Five to Fifteen questionnaire.

RESULTS

Fifty-one of the children born preterm had normal neurology, 23 had simple MND, and six had complex MND compared with 88 who had normal neurology and two simple MND in the term-born group (p<0.001). There were significant differences between the children with normal neurology and MND in the preterm group in MABC-2-assessed motor function (p<0.001), general cognitive abilities with WISC-IV (p=0.005), and SDQ overall behavioural problems and peer problems reported by the parents (p=0.021 and p=0.003 respectively). SDQ teacher-reported overall behavioural and hyperactivity problems were significantly different between children with normal and simple MND (p=0.036 and p=0.019).

INTERPRETATION

Children born extremely preterm, in the absence of CP, are at risk of MND and this is associated with motor function, cognitive ability, and behaviour.

WHAT THIS PAPER ADDS

Extremely preterm birth carries a risk of minor neurological dysfunction (MND). MND in children born extremely preterm is associated with impaired motor function and cognitive abilities, and behavioural problems. Male sex is associated with MND in children born extremely preterm.

Neurological condition assessed with the Hempel examination and cognition and behaviour at 4years

AIM

To investigate associations between neurological condition, assessed with the Hempel examination, in terms of minor neurological dysfunction (MND) and neurological optimality, and cognition and behaviour at 4years.

STUDY DESIGN

Cross-sectional analyses within a prospective, assessor-blinded follow-up study.

SUBJECTS

Four-year-old singletons born to subfertile parents (n=235; 120 boys).

OUTCOME MEASURES

Outcome parameters were complex minor neurological dysfunction (complex MND) and the neurological optimality score (NOS). Cognitive outcome was evaluated with the Kaufman Assessment Battery for Children, resulting in a total intelligence quotient (IQ). Behavioural outcome was evaluated with the Child Behavior Checklist, resulting in a total problem T-score.

RESULTS

Fifty-seven (24.3%) children had complex MND. None of the children showed fine motor dysfunction, suggesting a ceiling effect of the Hempel assessment. Complex MND was not correlated with IQ or total problem T-score. Nevertheless, a higher NOS was correlated with a higher IQ and a lower total problem T-score (adjusted mean estimate [95% confidence interval]: cognition: 0.445 [0.026; 0.865], p=0.038; behaviour: -0.458 [-0.830; -0.087], p=0.016).

INTERPRETATION

At age 4, complex MND assessed with the Hempel assessment was not associated with cognition and behaviour, presumably due to a ceiling effect in the Hempel domain of fine motor function. A more optimal neurological condition was associated with higher IQ and better behaviour.

Neonatal sepsis and simple minor neurological dysfunction

BACKGROUND

This study examined potential risk factors for and consequences of simple minor neurological dysfunction (SMND), in a group of very low-birthweight newborns followed until preschool age.

METHODS

This was a prospective longitudinal study. Children with birthweight <1500 g were assessed at 4-6 years of age. Twenty-eight children with normal neurological examination and 35 children with SMND were included in the final analysis. Risk factors for the development of SMND and its association with certain neuropsychiatric conditions were studied.

RESULTS

Based on neonatal data, in children with SMND, Apgar score at 1 min (6.13 ± 2.37 vs 7.66 ± 1.04, P = 0.008) and at 5 min (8.63 ± 1.29 vs 9.45 ± 0.65, P = 0.019) was lower, duration of hospital stay was longer (45.8 ± 21.8 vs 35.1 ± 18.2 days, P = 0.037), and the frequency of sepsis was higher (73.5 vs 25%, P < 0.001). Sepsis was found to be an independent risk factor for SMND (OR, 7.6; 95% CI: 2.2-26.0; P = 0.001). The children with SMND had lower intelligence quotient and higher prevalence of hyperactivity and refraction error.

CONCLUSION

Postnatal sepsis was the single most important risk factor for the development of SMND, and these children with SMND are at great risk for certain neuropsychiatric conditions. Preventive strategies, particularly for sepsis in the neonatal period, and early diagnosis and rehabilitation of future neuropsychiatric disorders are needed for better management of these cases.

Minor neurological dysfunction in five year old very preterm children is associated with lower processing speed

BACKGROUND

Minor neurological dysfunction (MND) is present in one quarter to one third of children born very preterm (VP). The more severe form, complex (c)-MND has been associated with learning disabilities, behavioural and motor problems.

OBJECTIVE

To study the association between c-MND and neurocognitive and motor disabilities at age five in VP children without CP.

METHODS

Ninety-four children born with gestational age<30weeks and/or a birth weight<1000g were assessed at five years corrected age. MND was classified according to Touwen. The Wechsler Preschool and Primary School Scale of Intelligence (WPPSI-III-NL) was used to measure intelligence. Simple reaction time, focused attention and visuomotor coordination were measured using the Amsterdam Neuropsychological Tasks, and working memory using a Digit Span Task. For motor skills the Movement Assessment Battery for children (M-ABC2) was used.

RESULTS

Eighty-one percent was classified as 'normal' (no or simple (s-)-MND) and 19% as 'abnormal'(c-MND or mild CP). The abnormal group had a significantly lower processing speed quotient (PSQ), M-ABC percentile score and slower simple Reaction Time than the normal group. Verbal IQ, Performance IQ, working memory, focused attention and visuomotor coordination did not differ between groups. Exclusion of the mild CP cases (n=4) led to similar results.

CONCLUSIONS

Five year old VP children with c-MND have lower PSQ, slower reaction time, and poorer motor skills, than those without c-MND. Neurological examination should include identification of MND to help identify children at risk for neurocognitive disabilities.

Minor neurological dysfunction and behaviour in 9-year-old children born at term: evidence for sex dimorphism

AIM

The aim of the study was to assess associations between minor neurological dysfunction (MND) and behaviour, with specific attention to sex differences.

METHOD

This was an observational cohort study in which 341 9-year-old children (177 male, 164 female) without perinatal risk were neurologically assessed, with attention to severity and type of MND. Eight domains of dysfunction were distinguished, including posture and muscle tone, fine manipulative ability and coordination. Severity of MND was based on the number of dysfunctional domains. Behaviour was assessed by parents and teachers using the Child Behavior Checklist and Teacher's Report Form (TRF); outcomes were internalizing and externalizing behaviour and total score of behavioural problems.

RESULTS

Females with complex MND or dysfunctional posture and muscle tone had increased risk for externalizing behavioural problems (OR 4.52, 95% CI 1.01-20.2, and OR 4.05, 95% CI 1.06-15.5, respectively). In males, these associations were absent. However, males with simple MND had an increased risk for behavioural problems indicated by the total TRF-score (OR 7.52, 95% CI 1.36-41.4).

INTERPRETATION

In children without perinatal risk, associations between MND and behaviour are sex-specific. In females, dysfunction of complex neural networks, including the cerebellum, is associated with externalizing behaviour. In males, neurobehavioural relationships are limited, suggesting a larger role of psychosocial factors in the genesis of behavioural problems.