Cerebral visual impairment in periventricular leukomalacia

The relation between neuroimaging and visual impairment in children and adolescents with cerebral palsy: A systematic review

OBJECTIVE

The structure-function relation between magnetic resonance imaging (MRI) and visual impairment (VI) in children with cerebral palsy (CP) has not been fully unravelled. The present systematic review aims to summarize the relation between brain lesions on MRI and VI in children and adolescents with CP.

METHODS

PubMed, Embase, Web of Science Core Collection, and Cochrane Database were systematically searched according to the PRISMA checklist. A total of 45 articles met the inclusion criteria.

RESULTS

White matter lesions were most frequently associated with VI. Only 25 studies described lesions within specific structures, mainly in the optic radiations. Only four studies reported on the thalamus. 8.4% of children with CP showed no brain abnormalities on MRI. Diffusion-weighted MRI studies showed that decreased structural connectivity in the optic radiations, superior longitudinal fasciculus, posterior limb of the internal capsule, and occipital lobe is associated with more severe VI.

CONCLUSIONS

All types of brain lesions lead to visual dysfunctions, arguing for a comprehensive visual assessment in all children with CP. Whereas white matter damage is a well-known contributor, the exact contribution of specific visual structures requires further investigation, to enable early prediction, detection, and intervention.

Myelination of preterm brain networks at adolescence

Prematurity and preterm stressors severely affect the development of infants born before 37 weeks of gestation, with increasing effects seen at earlier gestations. Although preterm mortality rates have declined due to the advances in neonatal care, disability rates, especially in middle-income settings, continue to grow. With the advances in MR imaging technology, there has been a focus on safely imaging the preterm brain to better understand its development and discover the brain regions and networks affected by prematurity. Such studies aim to support interventions and improve the neurodevelopment of preterm infants and deliver accurate prognoses. Few studies, however, have focused on the fully developed brain of preterm born infants, especially in extremely preterm subjects. To assess the long-term effect of prematurity on the adult brain, myelin related biomarkers such as myelin water fraction and g-ratio are measured for a cohort of 19-year-old extremely preterm born subjects. Using multi-modal imaging techniques that combine T2 relaxometry and neurite density information, the results show that specific brain regions associated with white matter injuries due to preterm birth, such as the posterior limb of the internal capsule and corpus callosum, are still less myelinated in adulthood. Furthermore, a weak positive relationship between myelin water fraction values and Full-Scale Intelligence Quotient (FSIQ) scores was found in multiple brain regions previously defined as less myelinated in the Extremely Preterm (EPT) cohort. These findings might suggest altered connectivity in the adult preterm brain and explain differences in cognitive outcomes.

Visual impairment and periventricular leukomalacia in children: A systematic review

BACKGROUND

Thanks to Magnetic Resonance Imaging (MRI) it is now possible to diagnose lesions of the central nervous system (CNS) such as periventricular leukomalacia (PVL) from the first days of life. However, there are still few studies aimed at describing the relationship between MRI and the outcome of visual function in patients with PVL.

AIM

To systematically review and investigate the relationship between MRI neuroimaging and visual impairment arising from PVL.

METHODS AND PROCEDURES

Three electronic databases (PubMed, SCOPUS, Web of Science) were consulted from 15 June 2021-30 September 2021. Of the 81 records identified, 10 were selected for the systematic review. The STROBE Checklist was used to assess the quality of the observational studies.

OUTCOME AND RESULTS

PVL on MRI was found to have a strong association with visual impairment in the various aspects of visual function (visual acuity, ocular motility, visual field); in 60% of these articles, the selected subjects also reported damage to optical radiations.

CONCLUSION AND IMPLICATIONS

there is a clear need for more extensive and detailed studies on the correlation between PVL and visual impairment, in order to set up a personalized early therapeutic-rehabilitation plan. WHAT THIS PAPER ADDS?: Over the past decades numerous studies have reported increasing evidence that one of the most frequent sequelae in subjects with PVL, in addition to motor impairment, is the impairment of visual function even if it is still not clear what different authors mean with the term visual impairment. This systematic review presents an overview of the relationship between structural correlates of MRI and visual impairment in children with periventricular leukomalacia. Interesting correlations emerge between MRI radiological finding and consequences on visual function especially between damage to the periventricular white matter and the impairment of various aspects of visual function and also between the impairment of optical radiation and visual acuity. Thanks to this literature revision, it is now clear that MRI plays an important role in the screening and diagnosis of significant intracranial brain changes in very young children in particular about the outcome of visual function. This is of great relevance since that visual function represents one of the main adaptive functions in the development of the child.

Optic cupping secondary to periventricular leukomalacia: A potential mimic for normal pressure glaucoma

We herein present a case of periventricular leukomalacia (PVL) with secondary optic pathway denervation atrophy, which was initially labeled as normal tension glaucoma. However, given the discordant clinical and ophthalmologic findings, brain magnetic resonance imaging was requested which proved PVL to be the underlying process to the patient's decreased visual acuity. In addition to presenting the ophthalmologic findings, we are emphasizing the pivotal role of neuroimaging in ruling out central causes of optic atrophy/hypoplasia and making this clinical distinction by demonstrating optic pathway atrophy associated with PVL.

Ultrasound imaging of preterm brain injury: fundamentals and updates

Neurosonography has become an essential tool for diagnosis and serial monitoring of preterm brain injury. Preterm infants are at significantly higher risk of hypoxic-ischemic injury, intraventricular hemorrhage, periventricular leukomalacia and post-hemorrhagic hydrocephalus. Neonatologists have become increasingly dependent on neurosonography to initiate medical and surgical interventions because it can be used at the bedside. While brain MRI is regarded as the gold standard for detecting preterm brain injury, neurosonography offers distinct advantages such as its cost-effectiveness, diagnostic utility and convenience. Neurosonographic signatures associated with poor long-term outcomes shape decisions regarding supportive care, medical or behavioral interventions, and family members' expectations. Within the last decade substantial progress has been made in neurosonography techniques, prompting an updated review of the topic. In addition to the up-to-date summary of neurosonography, this review discusses the potential roles of emerging neurosonography techniques that offer new functional insights into the brain, such as superb microvessel imaging, elastography, three-dimensional ventricular volume assessment, and contrast-enhanced US.

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.

Visual Impairment and Functional Classification in Children with Cerebral Palsy

BACKGROUND

Cerebral palsy (CP) is the most common motor impairment in childhood and often accompanied by a broad spectrum of comorbidities. Data are sparse concerning visual impairment (VI) and functional classification among CP children.

OBJECTIVE

The objective of this study was to analyze the prevalence of VI among children with CP and to investigate a possible association between VI and Gross Motor Function Classification System (GMFCS) and the Bimanual Fine Motor Function (BFMF).

METHODS

In this hospital-based study, records of 200 children with CP aged 2 to 17 years were reviewed.

RESULTS

Overall, VI was found in 59.5% of children with CP. Prevalence of VI was higher when compared with non-CP children. A correlation between GMFCS as well as BFMF and severity of VI was found. Children with severe CP were at greater risk for severe VI, especially cerebral VI compared with children with mild CP.

CONCLUSION

VI is a significant problem in children with CP and is correlated with motor function. Children with CP should undergo detailed ophthalmologic and orthoptic assessment to enable early intervention.

Clinical Spectrum of Ocular and Visual Dysfunction in Children with Periventricular Leukomalacia: A Need for an Interdisciplinary Approach

The study aimed to evaluate the ocular motility and visual and optic disc abnormalities in children diagnosed with periventricular leukomalacia (PVL). A retrospective analysis was performed on 51 consecutive children who had ophthalmic symptoms and were diagnosed with PVL by using magnetic resonance imaging. The patients were assessed for visual function, strabismus, cycloplegic refraction, fundus examination, and if appropriate, spectral-domain optical coherence tomography and visual field testing were applied. The primary outcome measures were the prevalence and visual and ocular motility dysfunctions. Mean age was 5.72 ± 2.6 years (range = 1–12), median birth weight was 2,740 g (range = 1,240–3,460), and median gestational age was 34 weeks (range = 28–38). In total, 21 patients (39.6%) had neurological deficit, 11 (21.5%) had intellectual disability, and 19 (37.2%) had no neurological symptom. In the spherical equivalent refractive error and cylinder power analysis, 10 patients had ≥3.0 D myopia, 15 had ≥3.0 D hyperopia, and eight had ≥2.50 D astigmatism. Thirteen (25.4%) children had a best-corrected visual acuity between 20/40 and 20/20 for Snellen card, while 9 (17.6%) had strabismic amblyopia and 6 (11.7%) had anisometropic amblyopia. Manifest strabismus was present in 35 patients (68.6%); of whom 12 had esotropia (23.5%), 16 had exotropia (31.3%) and 6 had vertical deviation (11.7%). Manifest or latent nystagmus was detected in 14 patients (27.4%). In 28 patients (54.9%), there was optic nerve abnormality. Two patients had hypoplastic disc, 14 had optic disc pallor, 7 had large cupping, and 5 had total optic atrophy. Six subjects underwent reliable visual field (VF) examinations, and all six had abnormal VFs, with inferior fields being most affected. Ocular motility disorders, optic nerve abnormalities, VF defects, and low visual acuity are common findings in this cohort of PVL patients and maybe the only presenting signs of the disease. The recognition of the visual disabilities and implementation of early rehabilitation may have a significant benefit in these children.

Cerebral visual impairment-related vision problems in primary school children: a cross-sectional survey

AIM

To estimate how many children in mainstream primary schools have cerebral visual impairment (CVI)-related vision problems and to investigate whether some indicators might be useful as red flags, if they were associated with increased risk for these problems.

METHOD

We conducted a survey of primary school children aged 5 to 11 years, using whether they were getting extra educational help and/or teacher- and parent-reported behaviour questionnaires to identify children at risk for CVI. These and a random 5% sample were assessed for CVI-related vision problems. We compared the usefulness of potential red flags using likelihood ratios.

RESULTS

We received questionnaires on 2298 mainstream-educated children and examined 248 children (152 [61%] males, 96 females [39%]; mean age 8y 1mo, SD 20mo, range 5y 6mo-11y 8mo). We identified 78 out of 248 children (31.5% of those examined, 3.4% of the total sample), who had at least one CVI-related vision problem. The majority (88%) were identified by one or more red flag but none were strongly predictive. Fewer than one in five children with any CVI-related vision problem had reduced visual acuity.

INTERPRETATION

Children with CVI-related vision problems were more prevalent than has been appreciated. Assessment of at-risk children may be useful so that opportunities to improve outcomes for children with CVI-related vision problems are not missed.

What assessments are currently used to investigate and diagnose cerebral visual impairment (CVI) in children? A systematic review

PURPOSE

Cerebral visual impairment (CVI) is the leading cause of childhood visual impairment in the developed world. Despite this, there are no agreed clinical guidelines for the investigation and diagnosis of the condition. Before development of such guidelines can commence, it is important to recognise which approaches are currently employed. This systematic review evaluated the literature to identify which methods of assessment are currently used to investigate and diagnose childhood CVI.

METHODS

Medline, Embase, CINAHL, Scopus and the Cochrane Library databases were systematically searched in January 2020 using defined search terms. Articles were included if they: (i) were research papers, conference abstracts or research protocols published in peer-reviewed scientific journals, or relevant textbooks; (ii) included a clinical investigation of CVI in children; (iii) provided an explanation or criteria to diagnose CVI and (iv) were specifically investigating cerebral/cortical visual impairment. Methods used to a) assess and b) diagnose CVI were extracted from included articles. 'Assessment scores' were assigned for each method employed by researchers to investigate and diagnose CVI to quantify and compare approaches between articles. A quality grading was also applied to each article.

RESULTS

Of 6454 identified articles, 45 met the inclusion criteria. From these, 10 categories of assessment utilised within included articles were identified: (1) Medical history, (2) Vision assessment/ophthalmologic examination, (3) Neuroimaging, (4) Visual behaviour and direct observation, (5) Structured history-taking, (6) Visual perception tests, (7) Ocular movement and posture assessment, (8) Intelligence/IQ assessment, (9) Clinical electrophysiology and (10) Neurodevelopmental tests. In terms of diagnostic criteria, the most commonly reported approach was one of exclusion, i.e., CVI was diagnosed when visual dysfunction could not be attributed to abnormalities detected in the anterior visual pathway.

CONCLUSION

There is a lack of common practice in the approaches used by clinicians to investigate and diagnose CVI in children. At present, a 'diagnosis of exclusion' remains the most common means to diagnose CVI. Development of clinical guidelines for assessment and diagnosis are necessary to ensure consistency in the diagnosis of CVI and the timely implementation of support to alleviate the impact of CVI on the child's daily living.

Structural brain damage and visual disorders in children with cerebral palsy due to periventricular leukomalacia

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There is a strong correlation between brain lesion severity and visual function, evident also with a Structural MRI.

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It is confirmed the validity of MRI semi-quantitative scale published by Fiori et al. (2014).

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There is a frequent association of PVL with thalamic lesions with important repercussion on visual function.

Aim

To systematically explore the relationship between type and severity of brain lesion on Magnetic Resonance Imaging (MRI) and visual function in a large cohort of children with periventricular leukomalacia (PVL).

Methods

94 children with bilateral cerebral palsy (CP) and history of PVL were recruited at Stella Maris Scientific Institute in Pisa (Italy). We included data of participants (72) with at least one MRI after the age of three years and an evaluation of visual function including fixation, following, saccades, nystagmus, acuity, visual field, stereopsis and color perception.

Brain lesions location and extent were assessed by a semi-quantitative MRI-scale for children with CP.

Results

Brain lesion severity strongly correlated with visual function total score (global MRI score p = .000; hemispheric score p = .001 and subcortical score p = .000). Moreover, visual acuity, visual field, stereopsis and colour were compromised when a cortical damage was present, while ocular motricity (and in particular fixation and saccades) were compromised in presence of subcortical brain damage.

Interpretation

Structural MRI is valuable for understanding the relationship between brain lesion severity and visual function in children with CP.

Relationship between brain structure and Cerebral Visual Impairment in children with Cerebral Palsy: A systematic review

BACKGROUND

Cerebral Visual Impairment (CVI) is very common yet often unrecognised visual dysfunction in children with Cerebral Palsy (CP). Magnetic Resonance Imaging (MRI) is the diagnostic tool in the investigation of brain lesions in children with CP and CVI.

AIM

The aim of this systematic review is to evaluate the relationship between brain structure and CVI, as determined by MRI in children with CP.

METHODS AND PROCEDURES

A comprehensive search of 5 database (PubMed, EMBASE, SCOPUS, CINAHL and Cochrane Database) was undertaken up until June 2019. The PRISMA checklist was then utilised to report on the process of selecting eligible papers. A total of 30 observational studies met the full inclusion criteria. Further, STROBE checklist was employed to report on the observational studies.

OUTCOMES AND RESULTS

Periventricular leucomalacia on MRI was found to have a strong association with CVI in all 30 studies. Only 13 (43 %) studies described dorsal and/ ventral stream dysfunction. There was ambiguity in the definition of CVI.

CONCLUSIONS AND IMPLICATIONS

The overall level of evidence correlating different patterns of CVI and CP (based on GMFCS, motor type and distribution) and MRI was low. Further studies utilising advances in MRI are needed to understand brain reorganisation and patterns of CVI and suggest rehabilitation therapy inclusive of vision.

Preterm white matter injury: ultrasound diagnosis and classification

White matter injury (WMI) is the most frequent form of preterm brain injury. Cranial ultrasound (CUS) remains the preferred modality for initial and sequential neuroimaging in preterm infants, and is reliable for the diagnosis of cystic periventricular leukomalacia. Although magnetic resonance imaging is superior to CUS in detecting the diffuse and more subtle forms of WMI that prevail in very premature infants surviving nowadays, recent improvement in the quality of neonatal CUS imaging has broadened the spectrum of preterm white matter abnormalities that can be detected with this technique. We propose a structured CUS assessment of WMI of prematurity that seeks to account for both cystic and non-cystic changes, as well as signs of white matter loss and impaired brain growth and maturation, at or near term equivalent age. This novel assessment system aims to improve disease description in both routine clinical practice and clinical research. Whether this systematic assessment will improve prediction of outcome in preterm infants with WMI still needs to be evaluated in prospective studies.

Impact of prematurity on neurodevelopment

The consequences of prematurity on brain functional development are numerous and diverse, and impact all brain functions at different levels. Prematurity occurs between 22 and 36 weeks of gestation. This period is marked by extreme dynamics in the physiologic maturation, structural, and functional processes. These different processes appear sequentially or simultaneously. They are dependent on genetic and/or environmental factors. Disturbance of these processes or of the fine-tuning between them, when caring for premature children, is likely to induce disturbances in the structural and functional development of the immature neural networks. These will appear as impairments in learning skills progress and are likely to have a lasting impact on the development of children born prematurely. The level of severity depends on the initial alteration, whether structural or functional. In this chapter, after having briefly reviewed the neurodevelopmental, structural, and functional processes, we describe, in a nonexhaustive manner, the impact of prematurity on the different brain, motor, sensory, and cognitive functions.

Visuospatial Attention and Saccadic Inhibitory Control in Children With Cerebral Palsy

Cerebral palsy (CP) is a non-progressive syndrome due to a pre-, peri- or post-natal brain injury, which frequently involves an impairment of non-motor abilities. The aim of this article was to examine visuospatial attention and inhibitory control of prepotent motor responses in children with CP showing a normal IQ or mild cognitive impairment, measuring their performance in oculomotor tasks. Ten children (9–16-year-old) with spastic CP and 13 age-matched, typically developing children (TDC) participated in the study. Subjects performed a simple visually-guided saccade task and a cue-target task, in which they performed a saccade towards a peripheral target, after a non-informative visual cue was flashed 150 ms before the imperative target, either at the same (valid) or at a different (invalid) spatial position. Children with CP showed severe executive deficits in maintaining sustained attention and complying with task instructions. Furthermore, saccadic inhibitory control appeared to be significantly impaired in the presence of both stimulus-driven and goal-directed captures of attention. In fact, patients showed great difficulties in suppressing saccades not only to the cue stimuli but also to the always-present target placeholders, which represented powerful attentional attractors that had to be covertly attended throughout the task execution. Moreover, impairment did not affect in equal manner the whole visual field but showed a marked spatial selectivity in each individual subject. Saccade latencies in the cue-target task were faster in the valid than in the invalid condition in both child groups, indicating the preservation of low-level visuospatial attentive capabilities. Finally, this study provides evidence that these impairments of executive skills and in inhibitory control, following early brain injuries, manifest in childhood but recover to virtually normal level during adolescence.

Alterations in the Structural and Functional Connectivity of the Visuomotor Network of Children With Periventricular Leukomalacia

Children born preterm with periventricular leukomalacia (PVL) demonstrate increased difficulties with tasks requiring visuomotor integration. The visuomotor integration network encompasses brain regions within frontal, parietal, and occipital cortices. Because of their proximity to the lateral ventricle the underlying white matter pathways are at a high risk of damage following PVL-related hypoxic-ischemic white matter injury. This study provides an exploratory analysis of the structural and functional connections within the visuomotor integration network, along with an a priori evaluation of the superior longitudinal fasciculus, inferior fronto-occipital fasciculus, and frontal aslant tract. For each pathway, tracts within both hemispheres revealed decreased volume and number of reconstructed fibers and an increase in quantitative anisotropy and generalized fractional anisotropy. The connectivity results also indicate that there may be changes to both the structural integrity and functional integration of neural networks involved with visuomotor integration functions in children with PVL.

Systemic 7,8-Dihydroxyflavone Treatment Protects Immature Retinas Against Hypoxic-Ischemic Injury via Müller Glia Regeneration and MAPK/ERK Activation

Purpose

Perinatal hypoxic-ischemic (HI) injury causes significant damages in the immature retina. The brain-derived neurotrophic factor is well known for its neuroprotective role but has limited clinical applications. A selective agonist of tyrosine kinase receptor B, 7,8-dihydroxyflavone (DHF), is a powerful therapeutic tool, when administered systemically. However, it remains unclear whether DHF treatment can protect the immature retinas against HI injury.

Methods

Postnatal (P) day 7 rat pups were intraperitoneally injected with DHF or vehicle 2 hours before and 18 hours after being subjected to HI injury. The outcomes were assessed at various timepoints after injury by electroretinography and histologic examinations. Neurogenesis was assessed by double-labeling of retinal sections with 5-bromo-2'-deoxyuridine and different neuronal markers.

Results

At P8, 24-hours postinjury, brain-derived neurotrophic factor mRNA levels in the retina decreased significantly. DHF treatment partially protected immature retinas at both histologic and functional levels between P14 and P30 but did not prevent apoptosis, inflammation, or damage of the blood-retinal barrier (BRB) at P8. On the other hand, DHF treatment promoted the survival of proliferating inner retinal cells, including Müller glia, and enhanced their transdifferentiation to bipolar cells at P17. Moreover, DHF treatment rescued the levels of extracellular signal-regulated kinase (ERK) phosphorylation, which were significantly decreased after injury. The neuroprotective effects of DHF were markedly eliminated by inhibition of ERK phosphorylation.

Conclusions

Early systemic DHF treatment has neuroprotective effects against HI injury in immature retinas, possibly via promoting neurogenesis through the tyrosine kinase receptor B/ERK signaling pathway.

Chinese Abstract.

Is there consensus in defining childhood cerebral visual impairment? A systematic review of terminology and definitions

The childhood condition of visual difficulties caused by brain damage, commonly termed cortical or cerebral visual impairment (CVI), is well established but has no internationally accepted definition. Clarification of its core features is required to advance research and clinical practice. This systematic review aimed to identify the definitions of childhood CVI in the original scientific literature to describe and critically appraise a consensual definition of the condition. MEDLINE, EMBASE, PsychINFO, CINAHL and AMED databases were searched in January 2017. Studies were included if they (1) were published original research, (2) contained a childhood CVI sample, (3) contained a definition of CVI and (4) described their CVI identification/diagnostic method. Thematic analysis identified concepts within definitions and narrative synthesis was conducted. Of 1150 articles, 51 met inclusion criteria. Definitions were subdivided according to detail (descriptive definition, description not reaching definition status and diagnostic/operationalising criteria). Three themes concerning visual deficits, eye health and brain integrity were identified (each containing subthemes) and analysed individually across definitions. The most common themes were ‘visual impairment’ (n=20), ‘retrochiasmatic pathway damage’(n=13) and ‘normal/near normal eye health’ (n=15). The most consensual definition identified here may not be the best quality for advancing our understanding of CVI. We argue for the alternative definition: CVI is a verifiable visual dysfunction which cannot be attributed to disorders of the anterior visual pathways or any potentially co-occurring ocular impairment. We propose reporting guidelines to permit comparison across studies and increase the evidence base for more reliable clinical assessment and diagnosis.

Subplate in a rat model of preterm hypoxia-ischemia

Objective

Hypoxia–ischemia (HI) in preterm infants primarily leads to injuries in the cerebral white matter. However, there is growing evidence that perinatal injury in preterms can also involve other zones including the cortical gray matter. In a neonatal rat model of HI, selective vulnerability of subplate has been suggested using BrdU birth-dating methods. In this study, we aimed to investigate the neuropathological changes of the subplate and deep layers of the cortex following cerebral HI in neonatal rats with specific cell markers.

Methods

P2 rats underwent permanent occlusion of the right common carotid artery followed by a period of hypoxia. P8 rats were analyzed using immunohistochemistry; subplate and deep layers cells were quantified and compared with sham-operated case.

Results

A large variability in the extent of the cerebral injury was apparent. For the three analyzed subplate populations (Nurr1+, Cplx3+, and Ctgf+ cells), no significant cell reduction was observed in mild and moderate cases. Only in severe cases, subplate cells were strongly affected, but these injuries were always accompanied by the cell reductions in layers VI and V.

Interpretation

We could therefore not confirm a specific vulnerability of subplate cells compared to other deep layers or the white matter in our model.

Neural stem/progenitor cell transplantation for cortical visual impairment in neonatal brain injured patients

The purpose of this study was to investigate the clinical efficacy of neural stem/progenitor cell (NS/PC) transplantation to treat severe cortical visual impairment (CVI), a sequela of neonatal brain injury. Fifty-two patients with cerebral injury and CVI were randomly divided into two groups: the treatment group (n = 25, with the median age of 18 months) and the control group (n = 27, with the median age of 19.5 months). The treatment group received intracerebroventricular transplantation of human NS/PCs and rehabilitation training. The control group received rehabilitation only. The visual function was assessed by Holt's method at various time points after transplantation. One in five patients with fundus abnormalities accompanied by blindness regained light perception. The visual functions of 75% of the patients with normal fundus were improved by one level or more in a 2-year follow-up. The median efficacy appeared 60 days posttransplantation. The total effective rate of cell transplantation on visual improvement was 64% (16 patients of 25), among which one blind patient regained light perception, five (31.2%) CVI patients improved by one level, and 10 (62.5%) improved by more than one level. Functional magnetic resonance imaging (fMRI) in a subpopulation of patients showed enhanced signals in the occipital lobe, visual pathway, and apical lobe after transplantation. In the control group, four patients with fundus abnormalities showed no improvement. Nine of 23 CVI patients with normal fundus improved visual function by more than one level. At the 2-year follow-up, no blind patients showed visual improvement. The total effective rate was 33.33% (9 of 27 patients). Among those showing visual improvement in the control group, six patients (66.67%) improved by one level, and three (33.33%) by more than one level. The median efficacy occurred in 365 days. Human NS/PC transplantation is effective to treat patients with severe CVI after neonatal brain injury. Compared with the traditional rehabilitation training, cell transplantation showed not only earlier visual improvement but also higher improvement rates and degrees. This article is published as part of the International Association of Neurorestoratology (IANR) supplement issue of Cell Transplantation.

Visual function in preterm infants: visualizing the brain to improve prognosis

Considerable development of the visual system occurs in the third trimester of life, a time when very preterm-born infants are in a neonatal intensive care unit (NICU). Their very early birth during a period of rapid and marked neurodevelopment and their clinical course makes them a very high-risk population. A range of different events impacts brain development and the visual system, leading to significant long-term visual dysfunction. Improved neuroimaging techniques provide an important window on the early brain and visual system development of these vulnerable infants. Greater understanding of the etiology of visual impairment subsequent to preterm birth and the timing of critical processes will allow early recognition and the earlier implementations of interventions. In the longer term, this will help clinicians optimize NICU practice to reduce the incidence of visual dysfunction in these children.

Neuro-ophthalmological disorders in cerebral palsy: ophthalmological, oculomotor, and visual aspects

AIM

Cerebral visual impairment (CVI) is a disorder caused by damage to the retrogeniculate visual pathways. Cerebral palsy (CP) and CVI share a common origin: 60 to 70% of children with CP also have CVI. We set out to describe visual dysfunction in children with CP. A further aim was to establish whether different types of CP are associated with different patterns of visual involvement.

METHODS

A total of 129 patients (54 females, 75 males; mean age 4 y 6 mo, SD 3 y 5 mo; range 3 mo-15 y) with CP (51 with diplegia, 61 with tetraplegia, and 17 with hemiplegia; 62 [48%] of participants were able to walk) and CVI enrolled at the Centre of Child Neuro-ophthalmology (at the Department of Child Neurology and Psychiatry, IRCCS 'C. Mondino Institute of Neurology', University of Pavia) underwent an assessment protocol including neurological examination, developmental and/or cognitive assessment, neuro-ophthalmological evaluation including ophthalmological assessment, evaluation of visual acuity, contrast sensitivity, optokinetic nystagmus, visual field and stereopsis, and neuroradiological investigations.

RESULTS

Visual dysfunction in diplegia was characterized mainly by refractive errors (75% of patients), strabismus (90%), abnormal saccadic movements (86%), and reduced visual acuity (82%). The participants with hemiplegia showed strabismus (71%) and refractive errors (88%); oculomotor involvement was less frequent (59%). This group had the largest percentage of patients with altered visual field (64%). Children with tetraplegia showed a severe neuro-ophthalmological profile, characterized by ocular abnormalities (98%), oculomotor dysfunction (100%), and reduced visual acuity (98%).

INTERPRETATION

Neuro-ophthalmological disorders are one of the main symptoms in CP. Each clinical type of CP is associated with a distinct neuro-ophthalmological profile. Early and careful neuro-ophthalmological assessment of children with CP is essential for an accurate diagnosis and for personalized rehabilitation.

Visual performance and brain structures in the developing brain of pre-term infants

The presence of abnormal visual function has been related to overt lesions in the thalami, peritrigonal white matter (such as cavitational-necrotic periventricular leucomalacia) and optic radiations, and also to the extent of occipital cortex involvement. The normal development of visual function seems to depend on the integrity of a network that includes not only optic radiations and the primary visual cortex but also other cortical and subcortical areas, such as the frontal or temporal lobes or basal ganglia, which have been found to play a topical role in the development of vision. Therefore, the complex functions and functional connectivity of the developing brain of premature infants can be studied only with highly sophisticated techniques such as diffusion tensor tractography. The combined use of visual tests and neonatal structural and functional neuroimaging, which have become available for newborn infants, provides a better understanding of the correlation between structure and function from early life. This appears to be particularly relevant considering the essential role of early visual function in cognitive development. The identification of early visual impairment is also important, as it allows for early enrolment in intervention programmes. The association of clinical and functional studies to newer imaging techniques, which are being increasingly used also in neonates, are likely to provide further information on early aspects of vision and the mechanisms underlying brain plasticity, which are still not fully understood. Early exposure to a difficult postnatal environment together with early and unexpected removal from a protective milieu are exclusive and peculiar factors of prematurity that interfere with the normal development of the visual system in pre-term babies. The problem is further compounded by the influence of different perinatal brain lesions affecting the developing brain of premature babies. Nevertheless, in the last few decades, there have been considerable advances in our understanding of the development of vision in pre-term infants during early infancy. This has mainly been due to the development of age-specific tests assessing various aspects of visual function, from ophthalmological examination to more cortical aspects of vision, such as the ability to process orientation or different aspects of visual attention [1-7]. Improvements in understanding very early and specific neurological impairments in neurological functions have been reported in pre-term infants, known to be at risk of developing visual and visual-perceptual impairment. These impairments are due not only to retinopathy, a common finding in premature infants, but also to cerebral (central) visual impairment, secondary to brain lesions affecting the central visual pathway.

Quantitative fiber tracking of the optic radiation is correlated with visual-evoked potential amplitude in preterm infants

BACKGROUND AND PURPOSE

Children born preterm are at risk for adverse outcome, including visual impairment. We examined the relationship between neonatal DTI and sVEP in children born preterm to determine whether visual outcomes are related to early measurements of brain microstructure.

MATERIALS AND METHODS

Subjects were born at <34 weeks gestation and imaged before term-equivalent age. DTI fiber tracking was used to delineate the optic radiations and measure tract-specific average FA, D(av), and parallel and transverse diffusivity. Visual-evoked response amplitudes were measured as a function of spatial frequency, contrast, and vernier offset size with sVEP at 6-20 months after birth. The association between DTI and sVEP was assessed by using the Spearman correlation coefficient and linear regression for repeated measures.

RESULTS

Nine children with 15 scans were included. The peak response amplitudes for spatial frequency sweeps were associated with increasing FA and decreasing D(av) and transverse diffusivity (P ≤ .006) but not with parallel diffusivity (P = 1). There was only modest association with the swept contrast condition and no detectable association with the vernier offset sweeps.

CONCLUSIONS

Microstructure of the optic radiations measured shortly after birth is associated with quantitatively measured responses elicited by moderate-to-high contrast spatiotemporal gratings in infancy. These findings are in keeping with studies showing a relationship between brain microstructure and function. While the clinical impact is not known, quantitative neuroimaging of white matter may ultimately be important for predicting outcome in preterm neonates.

Neonatal cerebral hypoxia-ischemia impairs plasticity in rat visual cortex

Ocular dominance plasticity (ODP) following monocular deprivation (MD) is a model of activity-dependent neural plasticity that is restricted to an early critical period regulated by maturation of inhibition. Unique developmental plasticity mechanisms may improve outcomes following early brain injury. Our objective was to determine the effects of neonatal cerebral hypoxia-ischemia (HI) on ODP. The rationale extends from observations that neonatal HI results in death of subplate neurons, a transient population known to influence development of inhibition. In rodents subjected to neonatal HI and controls, maps of visual response were derived from optical imaging during the critical period for ODP and changes in the balance of eye-specific response following MD were measured. In controls, MD results in a shift of the ocular dominance index (ODI) from a baseline of 0.15 to -0.10 (p < 0.001). Neonatal HI with moderate cortical injury impairs this shift, ODI = 0.14 (p < 0.01). Plasticity was intact in animals with mild injury and in those exposed to hypoxia alone. Neonatal HI resulted in decreased parvalbumin expression in hemispheres receiving HI compared with hypoxia alone: 23.4 versus 35.0 cells/high-power field (p = 0.01), with no change in other markers of inhibitory or excitatory neurons. Despite abnormal inhibitory neuron phenotype, spontaneous activity of single units and development of orientation selective responses were intact following neonatal HI, while overall visual responses were reduced. Our data suggest that specific plasticity mechanisms are impaired following early brain injury and that the impairment is associated with altered inhibitory neuronal development and cortical activation.

Understanding brain injury and neurodevelopmental disabilities in the preterm infant: the evolving role of advanced magnetic resonance imaging

The high incidence of neurodevelopmental disability in premature infants requires continued efforts at understanding the underlying microstructural changes in the brain that cause this perturbation in normal development. Magnetic resonance imaging (MRI) methods offer great potential to fulfill this need. Serial MR imaging and the application of newer analysis techniques, such as diffusion tensor imaging (DTI), volumetric MR analysis, cortical surface analysis, functional connectivity MRI (fcMRI) and diffusion tractography, provide important insights into the trajectory of brain development in the premature infant and the impact of injury on this developmental trajectory. While some of these imaging techniques are currently available in the research setting only, other measures, such as DTI and brain metric measures can be used clinically. MR imaging also has an enormous potential to be used as a surrogate, short-term outcome measure in clinical studies evaluating new therapeutic interventions of neuroprotection of the developing brain. In this article, we review the current status of these advanced MR imaging techniques.

Functional MRI of postnatal visual development in normal and hypoxic-ischemic-injured superior colliculi

The superior colliculus (SC) is a laminated subcortical structure in the mammalian midbrain, whose superficial layers receive visual information from the retina and the visual cortex. To date, its functional organization and development in the visual system remain largely unknown. This study employed blood oxygenation level-dependent (BOLD) functional MRI to evaluate the visual responses of the SC in normally developing and severe neonatal hypoxic-ischemic (HI)-injured rat brains from the time of eyelid opening to adulthood. MRI was performed to the normal animals (n=7) at postnatal days (P) 14, 21, 28 and 60. In the HI-injured group (n=7), the ipsilesional primary and secondary visual cortices were completely damaged after unilateral ligation of the left common carotid artery at P7 followed by hypoxia for 2 h, and MRI was performed at P60. Upon unilateral flash illumination, the normal contralateral SC underwent a systematic increase in BOLD signal amplitude with age especially after the third postnatal week. However, no significant difference in BOLD signal increase was found between P14 and P21. These findings implied the presence of neurovascular coupling at the time of eyelid opening, and the progressive development of hemodynamic regulation in the subcortical visual system. In the HI-injured group at P60, the BOLD signal increases in both SC remained at the same level as the normal group at P28 though they were significantly lower than the normal group at P60. These observations suggested the residual visual functions on both sides of the subcortical brain, despite the damages to the entire ipsilesional visual cortex. The results of this study constitute important evidence on the progressive maturation of visual functions and hemodynamic responses in the normal subcortical brain, and its functional plasticity upon neonatal HI injury.

Subplate neurons: crucial regulators of cortical development and plasticity

The developing cerebral cortex contains a distinct class of cells, subplate neurons, which form one of the first functional cortical circuits. Subplate neurons reside in the cortical white matter, receive thalamic inputs and project into the developing cortical plate, mostly to layer 4. Subplate neurons are present at key time points during development. Removal of subplate neurons profoundly affects cortical development. Subplate removal in visual cortex prevents the maturation of thalamocortical synapse, the maturation of inhibition in layer 4, the development of orientation selective responses in individual cortical neurons, and the formation of ocular dominance columns. In addition, monocular deprivation during development reveals that ocular dominance plasticity is paradoxical in the absence of subplate neurons. Because subplate neurons projecting to layer 4 are glutamatergic, these diverse deficits following subplate removal were hypothesized to be due to lack of feed-forward thalamic driven cortical excitation. A computational model of the developing thalamocortical pathway incorporating feed-forward excitatory subplate projections replicates both normal development and plasticity of ocular dominance as well as the effects of subplate removal. Therefore, we postulate that feed-forward excitatory projections from subplate neurons into the developing cortical plate enhance correlated activity between thalamus and layer 4 and, in concert with Hebbian learning rules in layer 4, allow maturational and plastic processes in layer 4 to commence. Thus subplate neurons are a crucial regulator of cortical development and plasticity, and damage to these neurons might play a role in the pathology of many neurodevelopmental disorders.

Somatosensory and visual evoked potentials in children with cerebral palsy: Correlations and discrepancies with MRI findings and clinical picture

PURPOSE

To determine if there is any association between the findings of visual evoked potentials (VEPs), somatosensory evoked potentials (SEPs), and magnetic resonance imaging (MRI) findings with the neurodevelopment and severity in children with cerebral palsy (CP).

METHODS

The present study included 15 children with spastic diplegic CP and five children with spastic hemiplegic CP and 42 healthy children as controls. The number of the controls was two-times greater than the study group to increase statistical power of this study. VEPs and SEPs were recorded in the CP children and compared with healthy controls. All MR scans were obtained using a 1.5 T MR scanner.

RESULTS

A significant difference was found in the latencies P100 (VEP) between the CP and controls. No correlations between increased P100 latencies and asphyxia, prematurity, the CP severity, MRI findings and mental retardation were noted. A significant difference in N13-N20 conductions (SEPs) between the subjects with CP and the control group was found. SEPs were positively correlated with mental retardation in CP children. The brain lesions in MRI showed a significant correlation with the CP severity scores and mental retardation.

CONCLUSION

The differences in VEPs and SEPs were determined between CP children and healthy children. The MRI findings were positively correlated with the CP severity and mental retardation.

Abnormal fast activity in infancy with paroxysmal downwards gaze

We report here on 8 infants who showed paroxysmal downwards gaze (PDG). The time of initial appearance of PDG ranged from one month to five months (mean: 2.7 months) of corrected age. Seven out of eight patients showed interictal spikes in EEG, so they were started on prophylactic therapy with antiepileptic drugs. In five of the eight patients, PDG ceased, either spontaneously or with antiepileptic drug treatment, by four to eight months of corrected age. Six out of eight patients showed localized spikes and peculiar abnormal fast activity (AFA) in the occipital area and five of these patients later developed West syndrome. These AFA were observed on EEGs recorded at the time of initial PDG appearance, before hypsarrhythmia was observed and before tonic spasms appeared. We were able to exclude the possibility that PDG was a subtle epileptic seizure by confirming the temporal discordance between individual episodes of PDG and AFA with video-EEG monitoring. Yet topographic data showed that AFA in these patients was characteristically located in the occipital area, with a distribution similar to that of the fast activity which accompanied the tonic spasms that later developed in these patients. As a risk factor for developing WS, we propose the clinical symptom of PDG with characteristic occipital AFA visible in the EEG, both of which represent damage to the occipital region including the optic radiation.

Transient cell-cell interactions in neural circuit formation

The wiring of the nervous system requires a complex orchestration of developmental events. Emerging evidence suggests that transient cell-cell interactions often serve as positional cues for axon guidance and synaptogenesis during the assembly of neural circuits. In contrast to the relatively stable cellular interactions between synaptic partners in mature circuits, these transient interactions involve cells that are not destined to be pre- or postsynaptic cells. Here we review the roles of these transient cell-cell interactions in a variety of developmental contexts and describe the mechanisms through which they organize neural connections.

Neurodevelopmental evolution of West syndrome: a 2-year prospective study

OBJECTIVE

The aim of this study was to evaluate the epileptic and developmental evolution in infants with West syndrome.

METHODS

A prospective study of 21 infants was performed, with a follow-up at 2 years. Serial assessment included long-term EEG monitoring, visual and auditory evaluation and assessment of neurodevelopment.

RESULTS

Neurosensory and developmental impairments at the spasm onset were transitory in seven cases, including four cryptogenic forms. In all other cases, there was a progressive worsening in neurosensory and developmental impairments. The epileptic evolution was generally better: in 11 of the 16 infants without seizures at outcome, spasms had already disappeared by 2 months after disease onset. Statistic analysis of results showed a correlation between neurosensory impairment and development throughout the whole follow-up. In addition, visual function at T1 resulted significant predictor of developmental outcome. Among the epileptic features, disorganization of slow sleep was an unfavorable prognostic factor.

CONCLUSION

Some forms of West syndrome are confirmed to have a benign evolution: among them there are not only cryptogenic cases but also symptomatic ones without significant neurodevelopmental impairment. Abnormalities of sleep organization, expression of the pervasive epileptic disorder, seem to play a role in determining a developmental deterioration. Neurosensory impairment since the onset of the disease could be a relevant cause of the developmental disorder.

[Primary exotropia: importance of cerebral MRI]

INTRODUCTION

Primary exotropia is a divergent strabismus that appears from the first day of life to the second year. It can be isolated or associated with a pathological context requiring cerebral imaging to determine diagnosis and prognosis. The objective of this study was to report the sensorimotor state and the result of MRI in infantile exotropia.

PATIENTS AND METHOD

Forty-seven children with primary exotropia had a complete ophthalmologic assessment (visual acuity, binocular vision, refraction with cycloplegia, eye fundus) and cerebral MRI (average age, 16 months). Deviation was classified into four categories<4 degrees, > or =4<10 degrees, > or =10<20 degrees, > or =20 degrees. MRI results were classified into seven categories: white matter abnormalities (gliosis, delay of maturation, periventricular leukomalacia, aspecific hyperintense signal, and necroses); Virchow-Robin enlargement space and enlarged subarachnoid space; gray matter abnormalities (necroses, cerebral atrophy, occipital cortex, basal ganglia); ventriculomegaly; thin corpus callosum; cerebellar injury; and tumor.

RESULTS

There was a statistically significant increase in the rate of pathological MRI as the angle deviation increased: 76.6% of patients had a pathological ophthalmologic exam (amblyopia, ptosis, head posture, Duane's syndrome, cataract, albinism, or pigmentary retinopathy). We found 38% nystagmus and 38% optic nerve hypoplasia. There was a real pathological context in 61.7% of the exotropia cases: 27.7% prematurity, 31.9% fetal distress, 21.3% facial dysmorphy (plagiocephaly), 12.8% psychomotor delay, and 14.9% epilepsy. Only three children had isolated exotropia. Thirty-four cerebral MRI (72.3%) were not normal. In pathological MRI, there was 61.8% white matter injury, 41.2% gray matter injury, and 17.6% thin corpus callosum.

CONCLUSION

This study demonstrates the fundamental contribution of cerebral MRI in infantile exotropia. The greater the deviation, the more abnormal the MRI results are. The pathological context and ophthalmological abnormalities are important in infantile exotropia.

Long-term follow-up of visual functions in prematurely born children--a prospective population-based study up to 10 years of age

INTRODUCTION

Prematurely born children have an increased risk of ophthalmologic problems. There is still no consensus on how they should be followed. The purpose of this study was to evaluate predictive factors for problems in premature children at ten years of age and to discuss follow-up recommendations.

MATERIALS AND METHODS

One hundred ninety-nine children with a birth weight of 1500 g or less were screened for retinopathy of prematurity (ROP) in the neonatal period and thereafter ophthalmologically examined at 6 months, 1.5, 2.5, 3.5, and 10 years of age. "Visual dysfunction" at ten years of age was defined as visual acuity > or =0.1 logMAR and/or strabismus and/or subnormal contrast sensitivity. Multiple regression analyses were used to evaluate risk factors at an early age, which could predict problems at ten years of age.

RESULTS

Twenty-five percent of the cohort had visual dysfunction at ten years of age. Neurological complications, cryotreated ROP, anisometropia, and astigmatism were risk factors. The sensitivity was 75.5%, and the specificity 80.7% for the detection of visual dysfunction at ten years of age when all children with neurological complications, cryotreated ROP, strabismus, anisometropia > or =1 diopters (D) at 2.5 years, and astigmatism > or =2 D at 2.5 years were included in further follow-up.

CONCLUSIONS

Repeated ophthalmologic follow-up of prematurely born children should be performed in those with treated ROP and/or neurological conditions. For a third group without such problems, at least one follow-up is recommended. Such an examination also provides a good opportunity to identify neurological problems that warrant further ophthalmologic follow-up.

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.

Comorbidities and clinical determinants of outcome in children with spastic quadriplegic cerebral palsy

The objective of this study was to determine the major comorbidities in patients with spastic quadriplegic (SQ) cerebral palsy (CP) and their possible clinical associations. Medical records of patients with SQ CP from a pediatric neurology practice over a 14-year period were retrospectively and systematically reviewed. Variables examined included demographics, prenatal, perinatal, and postnatal risk factors. Comorbidities documented included those involving hearing, vision, feeding status, and epilepsy. Binomial logistic regression analyses were applied to identify clinical associations of the comorbidities. Ninety-two children were included in this study of whom 39 were born preterm. Mean age of presentation was 2 months (SD 3.5) and males comprised 60% of the group. A total of 57% had a Gross Motor Function Classification Score (GMFCS) of Level IV or V. The four documented comorbidities occurred at a high frequency: 66 out of 83 children (80%) had a visual impairment with 13 (21%) having a substantial impairment; 37 out of 86 children (40%) had a hearing deficit; 43 out of 92 children (47%) had epilepsy; and 29 (33%) required assisted feeding. A GMFCS Level of IV or V and documented microcephaly was associated with the need for assisted feeding (odds ratio [OR] 8.1; 95% confidence interval [CI] 2.1-29.8, p=0.002 and OR 4.9, 95% CI 1.7-14.8, p=0.004 respectively). Epilepsy was associated with the occurrence of neonatal encephalopathy (OR 2.3, 95% CI 1.0-55; p=0.05), microcephaly (OR 4.9, 95% CI 1.6-14.8; p=0.004), periventricular leukomalacia (OR 7.4, 95% CI 1.6-35.0; p=0.012), and perinatal asphyxia (OR 3.6, 95% CI 1.5-8.9; p=0.005). There is a high frequency of comorbidity in the setting of SQ CP which can impact on quality of life and burdens of care. Few clinical associations of this burden appear, thus necessitating systematic programmatic follow-up of these children to facilitate early identification and intervention.

The development of vision

Disorders of visual function are common findings in children with neonatal brain lesions of antenatal and perinatal onset. In the last few years the development of age appropriate batteries for assessing visual function in the first years and the combined use of neuroimaging and neurophysiological techniques have allowed to achieve better understanding of the mechanisms underlying development of vision in low risk infants and in those with brain lesions. We will review the main models of visual development and the tests available to assess visual function in infancy, focusing on the recently described battery of tests for assessing early visual abilities in preterm and full term infants.

Cortical visual impairment: etiology, associated findings, and prognosis in a tertiary care setting

PURPOSE

To evaluate the etiology, prognosis, and associated neurological and ophthalmologic findings of children with cortical visual impairment (CVI) at a tertiary care referral facility.

METHODS

Records from patients visiting the Vanderbilt University Pediatric Ophthalmology Center during 2002 to 2005 were reviewed, and 98 patients were identified with an International Classification of Disease (9th ed.) coding of CVI (377.75). The charts were reviewed to assess presenting symptoms. The clinic and imaging notes were correlated with visual function (graded on a scale of I to VI).

RESULTS

The most common etiologies were perinatal hypoxia (35%), prematurity (29%), hydrocephalus (19%), structural central nervous system abnormalities (11%), and seizures (10%). Many children (69%) had multiple etiologies. Associated ophthalmic abnormalities included esotropia (19%), exotropia (40%), nystagmus (21%), and optic atrophy (42%). Significant refractive error (> +3.00 D or < -2.00 D) was common (20%). Associated neurological findings included seizures (60%), cerebral palsy (37%), periventricular leukomalacia (12%), hemiparesis (21%), and hearing loss (11%). Fifty-three percent of children initially diagnosed with CVI were followed for a period of 0.5 to 10 years. Forty percent of the patients showed no improvement in visual function; 34% had minimal improvement, and 17% had mild improvement. Only 6% of the patients had significant improvement in visual function. Eight patients had fixing and following or better acuity at last follow-up.

CONCLUSIONS

The major risk factors for CVI are perinatal hypoxia, premature birth, and hydrocephalus. Most patients have associated serious neurological and ophthalmologic abnormalities. While many patients have some recovery in vision acuity, most never see well. Patients with the most improvement in visual function were those having better initial acuity.

The development of visual object recognition in school-age children

This study documents the age-dependent development of visual object recognition abilities in 115 children aged 6 to 11 years, using a battery of neuropsychological tests based on Marrs model (Efron test, Warringtons Figure-Ground Test, Street Completion Test, Poppelreuter-Ghent Test, a selection of stimuli from the Birmingham Object Recognition Battery, a series of color photographs of objects presented from unusual perspectives or illuminated in unusual ways). The results suggest a maturation of complex visual perceptual abilities, possibly related to the development of the cerebral processes involved in object recognition, and could be the starting point for future investigations of these skills in impaired populations.

Spectrum of visual disorders in children with cerebral visual impairment

Cerebral visual impairment is a visual function deficit caused by damage to the retrogeniculate visual pathways in the absence of any major ocular disease. It is the main visual deficit in children in the developed world. Preperinatal hypoxic-ischemic damage is the most frequent cause of cerebral visual impairment, but the etiology is variable. The authors set out to evaluate the presence of visual disorders not attributable to any major ocular pathology in a sample of children with central nervous system disease and to describe the clinical picture of cerebral visual impairment in this cohort. One hundred twenty-one patients with central nervous system damage and visual impairment underwent a protocol developed at the authors' center that included neurologic, neurophthalmologic, and neuroradiologic assessments (brain magnetic resonance imaging). Reduced visual acuity was found in 105 of 121 patients, reduced contrast sensitivity in 58, abnormal optokinetic nystagmus in 88, and visual field deficit in 7. Fixation was altered in 58 patients, smooth pursuit in 95, and saccadic movements in 41. Strabismus was present in 88 patients, and abnormal ocular movements were found in 43 patients. Of the 27 patients in whom they could be assessed, visual-perceptual abilities were found to be impaired in 24. Fundus oculi abnormalities and refractive errors were frequently associated findings. This study confirms that the clinical expression of cerebral visual impairment can be variable and that, in addition to already well-documented symptoms (such as reduced visual acuity, visual field deficits, reduced contrast sensitivity), the clinical picture can also be characterized by oculomotor or visual-cognitive disorders. Cerebral visual impairment is often associated with ophthalmologic abnormalities, and these should be carefully sought. Early and careful assessment, taking into account both the neurophthalmologic and the ophthalmologic aspects, is essential for a correct diagnosis and the development of personalized rehabilitation programs.

Thalamic atrophy in infants with PVL and cerebral visual impairment

The aim of this retrospective study was to establish the presence and severity of cerebral visual impairment in preterm infants with PVL. We also wished to establish whether abnormalities of visual function are related to brain MRI findings and more specifically not only to the involvement of optic radiations and occipital cortex but also to changes in the thalami, that are often affected in infants with PVL. Twelve infants with cystic PVL were assessed at 1 year (+2) corrected age with a battery of tests specifically designed to assess various aspects of visual function in infancy, such as ocular movements, visual acuity, visual fields and fixation shift. All infants also had a brain MRI. Eleven of the 12 had involvement of the optic radiations: all had some abnormalities of visual function and visual impairment was more severe in infants with more extensive involvement of the optic radiations. The child with normal optic radiations had normal visual function. Six of the 12 infants also had obvious signs of atrophy of the thalami and all had severe and wide-ranging abnormalities of visual function in all testing domains. Two children had equivocal atrophy of the thalami, both had some abnormalities of visual function. Four children had normal thalami and had normal visual function or only minor abnormalities on one of the visual tests. Our results suggest that the atrophy of the thalami may play an additional role in the abnormal development of visual function in infants with PVL and abnormal optic radiations.

Cognitive assessment in epilepsy surgery of children

INTRODUCTION

Although the neurocognitive assessment in children as in the adults is an important step before and after surgery, in the literature, the data about pre- and postoperative neurocognitive evaluations in children are very few.

OBJECTIVE

The purpose of this paper is to consider some peculiar aspects of the neurocognitive assessment during development, and report literature data about neuropsychological outcome of epileptic children treated with focal resection and hemispherectomy.

RESULTS AND DISCUSSION

The second section concerns our personal experience about a cohort of 45 children with refractory epilepsy operated on before 7 years. The results suggest that early surgical treatment is generally effective for seizure control and behavior improvement in children with refractory epilepsy. Concerning cognitive outcome, we found that the neurocognitive level was unchanged in the majority of the patients.

CONCLUSION

We underline the importance of multicentric studies with standardized neuropsychological assessments in large series of young children.

Argon laser photocoagulation for retinopathy of prematurity: long-term outcome

PURPOSE

To assess the visual, refractive, ocular structural, and neurodevelopmental outcome in a group of children who were screened, treated with laser photocoagulation for threshold retinopathy of prematurity (ROP), and followed up at our institution.

METHODS

The 21 survivors of a cohort of 23 children were recalled at the age of 5 years or more. They underwent a full ophthalmologic examination. A paediatric neurologist and/or developmental paediatrician performed a neurodevelopmental assessment and a neuropsychologist performed psychological testing.

RESULTS

A total of 30 eyes (71.4%) had a best-corrected visual acuity (BCVA) of 20/40 or better. In all, 26 (62%) eyes were myopic; the overall mean spherical equivalent was -4.95 D. No eye had Stage 4 findings and only one eye (2.4%) progressed to stage 5 despite photocoagulation. In total, 14 patients (66.6%) showed evidence of stereopsis. Strabismus was seen in six patients (28.5%) and nystagmus in three (14.3%). Periventricular leukomalacia (PVL) was identified in five patients (23.8%), cerebral palsy (CP) in seven (33.3%), and intraventricular haemorrhage (IVH) in 13 (62%). Cerebral palsy and IVH associated strongly with visual acuity of less than 20/40 (P=0.009 and 0.047). There was also a strong association between visual acuity of 20/40 or above and a better cognitive outcome (P=0.013).

CONCLUSIONS

Retinal scarring and detachment are relatively rare causes of visual morbidity 5 years or more after laser treatment for threshold ROP, but the neurological sequelae of extreme prematurity and amblyopia remain important causes of impaired visual function.