Visual perceptual impairment in children at 5 years of age with perinatal haemorrhagic or ischaemic brain damage in relation to cerebral magnetic resonance imaging

From Hemispheric Asymmetry through Sensorimotor Experiences to Cognitive Outcomes in Children with Cerebral Palsy

Recent neuroimaging studies allowed us to explore abnormal brain structures and interhemispheric connectivity in children with cerebral palsy (CP). Behavioral researchers have long reported that children with CP exhibit suboptimal performance in different cognitive domains (e.g., receptive and expressive language skills, reading, mental imagery, spatial processing, subitizing, math, and executive functions). However, there has been very limited cross-domain research involving these two areas of scientific inquiry. To stimulate such research, this perspective paper proposes some possible neurological mechanisms involved in the cognitive delays and impairments in children with CP. Additionally, the paper examines the ways motor and sensorimotor experience during the development of these neural substrates could enable more optimal development for children with CP. Understanding these developmental mechanisms could guide more effective interventions to promote the development of both sensorimotor and cognitive skills in children with CP.

Children with Cerebral Palsy Have Altered Occipital Cortical Oscillations during a Visuospatial Attention Task

Dynamically allocating neural resources to salient features or objects within our visual space is fundamental to making rapid and accurate decisions. Impairments in such visuospatial abilities have been consistently documented in the clinical literature on individuals with cerebral palsy (CP), although the underlying neural mechanisms are poorly understood. In this study, we used magnetoencephalography (MEG) and oscillatory analysis methods to examine visuospatial processing in children with CP and demographically matched typically developing (TD) children. Our results indicated robust oscillations in the theta (4-8 Hz), alpha (8-14 Hz), and gamma (64-80 Hz) frequency bands in the occipital cortex of both groups during visuospatial processing. Importantly, the group with CP exhibited weaker cortical oscillations in the theta and gamma frequency bands, as well as slower response times and worse accuracy during task performance compared to the TD children. Furthermore, we found that weaker theta and gamma oscillations were related to greater visuospatial performance deficits across both groups. We propose that the weaker occipital oscillations seen in children with CP may reflect poor bottom-up processing of incoming visual information, which subsequently affects the higher-order visual computations essential for accurate visual perception and integration for decision-making.

Quantitative Analysis of Punctate White Matter Lesions in Neonates Using Quantitative Susceptibility Mapping and R2* Relaxation

BACKGROUND AND PURPOSE

It is difficult to distinguish punctate white matter lesions from focal hemorrhagic lesions in neonates on conventional MR imaging because both kinds of lesions show increased signal intensity on T1-weighted images and, frequently, decreased signal intensity on T2-weighted images. Our aim was to distinguish punctate white matter lesions and focal hemorrhagic lesions using quantitative measures.

MATERIALS AND METHODS

In the current study, we acquired multiecho gradient recalled-echo MR imaging data from 24 neonates with hypoxic-ischemic encephalopathy and postprocessed them as R2* relaxation maps and quantitative susceptibility maps. Seven subjects who were found to have multifocal punctate white matter lesions and/or focal hemorrhagic lesions on R2* maps were included (mean gestational age at birth, 33 ± 4.28 weeks; mean gestational age at scanning, 38 ± 2 weeks). Manually drawing ROIs on R2* maps, we measured R2* and magnetic susceptibility values of the lesions, along with white matter regions within the corpus callosum as healthy comparison tissue.

RESULTS

R2* and magnetic susceptibility values were both found to easily distinguish punctate white matter lesions, focal hemorrhagic lesions, and healthy white matter tissue from each other (P < .05), with a large Hedge g. R2* and magnetic susceptibility values were significantly increased in focal hemorrhagic lesions compared with punctate white matter lesions and healthy white matter tissue. Punctate white matter lesions were also found to have significantly increased values over healthy white matter tissue.

CONCLUSIONS

R2* and quantitative susceptibility maps can be used to help clinicians distinguish and measure focal hemorrhages, punctate white matter lesions, and healthy white matter tissue.

Children with cerebral palsy display altered neural oscillations within the visual MT/V5 cortices

Cortical visual processing in visual MT/V5 is necessary for tracking movement and performing reliable visuomotor transformations. Although the role of this cortical area is well recognized, the activity of the visual MT/V5 cortical area in children with cerebral palsy (CP) has not been examined nor has its potential role in the atypical motor actions of these children been considered. This study used magnetoencephalography to image the neural activity in the motion-sensitive MT/V5 cortices of typically developing (TD) children (n = 21; mean age 14 yrs. ± 2, 12 males) and children with CP (n = 21; mean age 16 yrs. ± 4, 13 males) as they viewed a horizontally moving stimulus. Behavioral measures of visual perception were additionally assessed by having the participants press a button when the visual stimulus changed to moving in vertical direction. Our results showed that the horizontal movement of the visual stimulus evoked changes in the strength of the theta-alpha (5-10 Hz) and alpha-beta (8-20 Hz) oscillations in the visual MT/V5 area of all participants. Compared with the TD children, the children with CP had weaker alpha-beta oscillations in the visual MT/V5 cortices. In addition, the children with CP took longer to perceive a directional change of the visual stimulus and made more errors in detecting the change. Lastly, weaker alpha-beta oscillations were correlated with slower detection of the change in motion direction and less accuracy in identifying the change. This study shows that the uncharacteristic neural oscillations in the visual MT/V5 cortical area may partially account for the abnormal perceptions and motor decisions seen in children with CP.

Basic visual perceptual processes in children with typical development and cerebral palsy: The processing of surface, length, orientation, and position

The present study aims to assess how the processing of basic visual perceptual (VP) components (length, surface, orientation, and position) develops in typically developing (TD) children (n = 215, 4-14 years old) and adults (n = 20, 20-25 years old), and in children with cerebral palsy (CP) (n = 86, 5-14 years old) using the first four subtests of the Battery for the Evaluation of Visual Perceptual and Spatial processing in children. Experiment 1 showed that these four basic VP processes follow distinct developmental trajectories in typical development. Experiment 2 revealed that children with CP present global and persistent deficits for the processing of basic VP components when compared with TD children matched on chronological age and nonverbal reasoning abilities.

Spastic diplegia in preterm-born children: Executive function impairment and neuroanatomical correlates

BACKGROUND

The neuropsychological literature on preterm-born children with spastic diplegia due to periventricular leukomalacia is convergent in reporting deficits in non-verbal intelligence and in visuo-spatial abilities. Nevertheless, other cognitive functions have found to be impaired, but data are scant and not correlated with neuroimaging findings.

AIMS

This study analyzes the neuropsychological strengths and weaknesses in preterm-born children with spastic diplegia (pSD) and their relationships with neuroanatomical findings, investigated by a novel scale for MRI classification.

METHODS AND PROCEDURES

Nineteen children with pSD, mild to moderate upper limb impairment and Verbal IQ>80, and 38 normal controls were evaluated with a comprehensive neuropsychological battery (NEPSY-II), assessing Attention/Executive Functioning, Language, Memory, Sensorimotor, Social Perception and Visuospatial Processing domains. The MRIs were quantitatively scored for lesion severity.

OUTCOMES AND RESULTS

The results showed that, beyond core visuo-spatial and sensory-motor deficits, impairments in attention and executive functions were present in more than half of the sample, particularly in children with damage to the anterior corpus callosum.

CONCLUSIONS AND IMPLICATIONS

The findings are discussed in terms of clinical and rehabilitative implications tailored for pSD subgroups diversified for neuropsychological and neuroanatomical characteristics.

Relationship between Stereoscopic Vision, Visual Perception, and Microstructure Changes of Corpus Callosum and Occipital White Matter in the 4-Year-Old Very Low Birth Weight Children

Aim. To assess the relationship between stereoscopic vision, visual perception, and microstructure of the corpus callosum (CC) and occipital white matter, 61 children born with a mean birth weight of 1024 g (SD 270 g) were subjected to detailed ophthalmologic evaluation, Developmental Test of Visual Perception (DTVP-3), and diffusion tensor imaging (DTI) at the age of 4. Results. Abnormal stereoscopic vision was detected in 16 children. Children with abnormal stereoscopic vision had smaller CC (CC length: 53 ± 6 mm versus 61 ± 4 mm; p < 0.01; estimated CC area: 314 ± 106 mm² versus 446 ± 79 mm²; p < 0.01) and lower fractional anisotropy (FA) values in CC (FA value of rostrum/genu: 0.7 ± 0.09 versus 0.79 ± 0.07; p < 0.01; FA value of CC body: 0.74 ± 0.13 versus 0.82 ± 0.09; p = 0.03). We found a significant correlation between DTVP-3 scores, CC size, and FA values in rostrum and body. This correlation was unrelated to retinopathy of prematurity. Conclusions. Visual perceptive dysfunction in ex-preterm children without major sequelae of prematurity depends on more subtle changes in the brain microstructure, including CC. Role of interhemispheric connections in visual perception might be more complex than previously anticipated.

Visual-motor deficits relate to altered gray and white matter in young adults born preterm with very low birth weight

Individuals born preterm and at very low birth weight (birth weight ≤ 1500 g) are at an increased risk of perinatal brain injury and neurodevelopmental deficits over the long term. This study examined whether this clinical group has more problems with visual-motor integration, motor coordination, and visual perception compared to term-born controls, and related these findings to cortical surface area and thickness and white matter fractional anisotropy. Forty-seven preterm-born very low birth weight individuals and 56 term-born controls were examined at 18-22 years of age with a combined cognitive, morphometric MRI, and diffusion tensor imaging evaluation in Trondheim, Norway. Visual-motor skills were evaluated with the Beery-Buktenica Developmental Test of Visual-Motor Integration-V (VMI) copying test and its supplemental tests of motor coordination and visual perception. 3D T1-weighted MPRAGE images and diffusion tensor imaging were done at 1.5 T. Cortical reconstruction generated in FreeSurfer and voxelwise maps of fractional anisotropy calculated with Tract-Based Spatial Statistics were used to explore the relationship between MRI findings and cognitive results. Very low birth weight individuals had significantly lower scores on the copying and motor coordination tests compared with controls. In the very low birth weight group, VMI scores showed significant positive relationships with cortical surface area in widespread regions, with reductions of the superior temporal gyrus, insula, and medial occipital lobe in conjunction with the posterior ventral temporal lobe. Visual perception scores also showed positive relationships with cortical thickness in the very low birth weight group, primarily in the lateral occipito-temporo-parietal junction, the superior temporal gyrus, insula, and superior parietal regions. In the very low birth weight group, visual-motor performance correlated positively with fractional anisotropy especially in the corpus callosum, inferior fronto-occipital fasciculus bilaterally, and anterior thalamic radiation bilaterally, driven primarily by an increase in radial diffusivity. VMI scores did not demonstrate a significant relationship to cortical surface area, cortical thickness, or diffusion measures in the control group. Our results indicate that visual-motor integration problems persist into adulthood for very low birth weight individuals, which may be due to structural alterations in several specific gray-white matter networks. Visual-motor deficits appear related to reduced surface area of motor and visual cortices and disturbed connectivity in long association tracts containing visual and motor information. We conjecture that these outcomes may be due to perinatal brain injury or aberrant cortical development secondary to injury or due to very preterm birth.

Visuoperceptual sequelae in children with hemophilia and intracranial hemorrhage

BACKGROUND

The goal of this study was to examine the impact of focal brain injuries on the outcomes of visual perception and visuospatial abilities in Mexican children with hemophilia who have experienced intracranial hemorrhages.

METHODS

We assessed ten boys who had hemophilia with intracranial hemorrhage (HIC), six boys who had hemophilia without intracranial hemorrhage (HH), and ten boys without hemophilia (CTL). The Verbal (VIQ), Performance IQs (PIQ), and Full Scale IQs (FSIQ) from the Wechsler Intelligence Scale for Children-Mexican Revision, Visual Perception, and Visuospatial Abilities domains, which are from a neuropsychological assessment battery for Spanish-speaking children (ENI), were employed for our analysis.

RESULTS

The results showed that the HIC group performed in the low-average range on the PIQ and FSIQ, which was lower than the HH group. The HIC group showed low performance on visual perception tests, such as line orientation, fragmented objects, and overlapping figures, compared with their matched controls.

CONCLUSIONS

The results suggest that it is not the ability to recognize objects that is impaired in the HIC group, but the ability to identify objects under less favorable conditions. Our findings may have therapeutic and rehabilitative implications for the management of children with hemophilia and early focal brain lesions.

Limitations on the developing preterm brain: impact of periventricular white matter lesions on brain connectivity and cognition

Brain lesions to the white matter in peritrigonal regions, periventricular leukomalacia, in children who were born prematurely represent an important model for studying limitations on brain development. The lesional pattern is of early origin and bilateral, that constrains the compensatory potential of the brain. We suggest that (i) topography and severity of periventricular lesions may have a long-term predictive value for cognitive and social capabilities in preterm birth survivors; and (ii) periventricular lesions may impact cognitive and social functions by affecting brain connectivity, and thereby, the dissociable neural networks underpinning these functions. A further pathway to explore is the relationship between cerebral palsy and cognitive outcome. Restrictions caused by motor disability may affect active exploration of surrounding and social participation that may in turn differentially impinge on cognitive development and social cognition. As an outline for future research, we underscore sex differences, as the sex of a preterm newborn may shape the mechanisms by which the developing brain is affected.

Assessment of cortical visual impairment in infants with periventricular leukomalacia: a pilot event-related FMRI study

Objective

We wanted to investigate the usefulness of event-related (ER) functional MRI (fMRI) for the assessment of cortical visual impairment in infants with periventricular leukomalacia (PVL).

Materials and Methods

FMRI data were collected from 24 infants who suffered from PVL and from 12 age-matched normal controls. Slow ER fMRI was performed using a 3.0T MR scanner while visual stimuli were being presented. Data analysis was performed using Statistical Parametric Mapping software (SPM2), the SPM toolbox MarsBar was used to analyze the region of interest data, and the time to peak (TTP) of hemodynamic response functions (HRFs) was estimated for the surviving voxels. The number of activated voxels and the TTP values of HRFs were compared. Pearson correlation analysis was performed to compare visual impairment evaluated by using Teller Acuity Cards (TAC) with the number of activated voxels in the occipital lobes in all patients.

Results

In all 12 control infants, the blood oxygenation level-dependent (BOLD) signal was negative and the maximum response was located in the anterior and superior part of the calcarine fissure, and this might correspond to the anterior region of the primary visual cortex (PVC). In contrast, for the 24 cases of PVL, there were no activated pixels in the PVC in four subjects, small and weak activations in six subjects, deviated activations in seven subjects and both small and deviated activations in three subjects. The number of active voxels in the occipital lobe was significantly correlated with the TAC-evaluated visual impairment (p < 0.001). The mean TTP of the HRFs was significantly delayed in the cases of PVL as compared with that of the normal controls.

Conclusion

Determining the characteristics of both the BOLD response and the ER fMRI activation may play an important role in the cortical visual assessment of infants with PVL.

Visual perception in preterm children: what are we currently measuring?

Over the past two decades, cerebral visual impairment has been recognized as a principal deficit in preterm children, and in particular those with cerebral palsy. We review the current knowledge of visual processing deficits in these children, and provide an overview of the tools for assessing cerebral visual impairment. Commercially available instruments are usually directed at evaluating visuospatial skills rather than detecting object recognition difficulties. Particularly in children aged 3 years or younger and in children with multiple handicaps, cerebral visual impairment is difficult to diagnose. This difficulty may be attributable to limitations specific to the instrument, such as a test that is inappropriate for age, or to child-specific limitations such as motor impairment or speech delay. We therefore include an overview of relevant neuroimaging findings reported in these children, focusing on the most recent imaging modalities. Novel techniques such as diffusion tensor imaging may provide sensitive markers of cerebral visual impairment in situations where clinical diagnosis is difficult, and such approaches may allow for early intervention.

Cerebral Visual Impairment: which perceptive visual dysfunctions can be expected in children with brain damage? A systematic review

The current definition of Cerebral Visual Impairment (CVI) includes all visual dysfunctions caused by damage to, or malfunctioning of, the retrochiasmatic visual pathways in the absence of damage to the anterior visual pathways or any major ocular disease. CVI is diagnosed by exclusion and the existence of many different causes and symptoms make it an overall non-categorized group. To date, no discrimination is made within CVI based on types of perceptive visual dysfunctions. The aim of this review was to outline which perceptive visual dysfunctions are to be expected based on a number of etiologies of brain damage and brain development disorders with their onset in the pre-, peri- or postnatal period. For each period two etiologies were chosen as the main characteristic brain damage. For each etiology a main search was performed. The selection of the articles was based on the following criteria: age, etiology, imaging, central pathology and perceptive visual function test. The perceptive visual functions included for this review were object recognition, face recognition, visual memory, orientation, visual spatial perception, motion perception and simultaneous perception. Our search resulted in 11 key articles. A diversity of research history is performed for the selected etiologies and their relation to perceptive visual dysfunctions. Periventricular Leukomalacia (PVL) was most studied, whereas the main tested perceptive visual function was visual spatial perception. As a conclusion, the present status of research in the field of CVI does not allow to correlate between etiology, location and perceptive visual dysfunctions in children with brain damage or a brain development disorder. A limiting factor could be the small number of objective tests performed in children experiencing problems in visual processing. Based on recent insights in central visual information processing, we recommend an alternative approach for the definition of CVI that is based on functional visual processing, rather than anatomical landmarks. This could be of benefit in daily practice to diagnose CVI.

Inversion of Perceived Direction of Motion Caused by Spatial Undersampling in Two Children with Periventricular Leukomalacia

We report here two cases of two young diplegic patients with cystic periventricular leukomalacia who systematically, and with high sensitivity, perceive translational motion of a random-dot display in the opposite direction. The apparent inversion was specific for translation motion: Rotation and expansion motion were perceived correctly, with normal sensitivity. It was also specific for random-dot patterns, not occurring with gratings. For the one patient that we were able to test extensively, contrast sensitivity for static stimuli was normal, but was very low for direction discrimination at high spatial frequencies and all temporal frequencies. His optokinetic nystagmus movements were normal but he was unable to track a single translating target, indicating a perceptual origin of the tracking deficit. The severe deficit for motion perception was also evident in the seminatural situation of a driving simulation video game. The perceptual deficit for translational motion was reinforced by functional magnetic resonance imaging studies. Translational motion elicited no response in the MT complex, although it did produce a strong response in many visual areas when contrasted with blank stimuli. However, radial and rotational motion produced a normal pattern of activation in a subregion of the MT complex. These data reinforce the existent evidence for independent cortical processing for translational, and circular or radial flow motion, and further suggest that the two systems have different vulnerability and plasticity to prenatal damage. They also highlight the complexity of visual motion perception, and how the delicate balance of neural activity can lead to paradoxical effects such as consistent misperception of the direction of motion. We advance a possible explanation of a reduced spatial sampling of the motion stimuli and report a simple model that simulates well the experimental results.

The assessment of visual acuity in children with periventricular damage: a comparison of behavioural and electrophysiological techniques

It has been controversial whether electrophysiology offers better precision than behavioural techniques in measuring visual acuity in children with brain damage. We investigated the concordance between sweep VEPs and Acuity Cards (AC) in 29 children with periventricular leukomalacia (PVL), the most common type of brain damage in preterm infants. An overall good correlation was shown but with relatively better behavioural acuity values. VEP/AC ratio was significantly correlated to corpus callosum posterior thinning. We propose that this result reflects the efficacy of the compensatory mechanisms following early brain damage which may differentially affect the two methods.

White-matter injury is associated with impaired gaze in premature infants

Periventricular leukomalacia is a risk factor for visual impairment in children born prematurely. The impact of diffuse white-matter injury, as detected on magnetic resonance imaging, on early visual function is unknown. We developed two 5-point visual-gaze scores to analyze the association between this clinical assessment and white-matter injury in 93 premature neonates <34 weeks of gestational age at birth. Older postmenstrual age was associated with higher values of the two gaze scores. Infants with moderate or severe white-matter injury had lower scores than their peers without white-matter injury (0.41 points, 95% confidence interval of 0.13-0.69 for visual fixation score; and 0.70 points, 95% confidence interval of 0.30-1.10 for conjugate score, P < 0.005). Using the results from both scales, a score of >or=9 in an infant examined at >or=36 weeks postmenstrual age predicted normal white matter on magnetic resonance examination, with a sensitivity of 84% and a specificity of 100%. These preliminary findings suggest that white-matter injury affects visual function even before term equivalent postmenstrual age.

Inflammation, brain damage and visual dysfunction in preterm infants

Antenatal intrauterine infection and the fetal inflammatory response appear to be important pathogenetic factors in preterm birth and subsequent neonatal disorders of the lung and brain. In this paper, we expand this concept to include visual dysfunction. Although present data tend to support our notion, we suggest that more experimental and epidemiological research is needed to elucidate mechanisms of infection/inflammation-induced damage to the eye and visual brain pathways of preterm infants.

Early brain injury in premature newborns detected with magnetic resonance imaging is associated with adverse early neurodevelopmental outcome

OBJECTIVE

To determine the neurodevelopmental outcome of prematurely born newborns with magnetic resonance imaging (MRI) abnormalities.

STUDY DESIGN

A total of 89 prematurely born newborns (median age 28 weeks postgestation) were studied with MRI when stable for transport to MRI (median age, 32 weeks postgestation); 50 newborns were studied again near term age (median age, 37 weeks). Neurodevelopmental outcome was determined at 18 months adjusted age (median) using the Mental Development Index (Bayley Scales Infant Development II) and a standardized neurologic exam.

RESULTS

Of 86 neonatal survivors, outcome was normal in 51 (59%), borderline in 22 (26%), and abnormal in 13 (15%). Moderate/severe MRI abnormalities were common on the first (37%) and second (32%) scans. Abnormal outcome was associated with increasing severity of white matter injury, ventriculomegaly, and intraventricular hemorrhage on MRI, as well as moderate/severe abnormalities on the first (relative risk [RR] = 5.6; P = .002) and second MRI studies (RR = 5.3; P = .03). Neuromotor abnormalities on neurologic examination near term age (RR = 6.5; P = .04) and postnatal infection (RR = 4.0; P = .01) also increased the risk for abnormal neurodevelopmental outcome.

CONCLUSIONS

In premature newborns, brain abnormalities are common on MRI early in life and are associated with adverse neurodevelopmental outcome.