Detection of Isolated Occipital Lobe Anomalies During Early Childhood

Lambert, Scott R.; Kriss, A.; Taylor, David

doi:10.1111/j.1469-8749.1990.tb16964.x

Cited by 16 publications

(6 citation statements)

References 9 publications

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“…Another interesting case was described by Lambert et al. in 1990 56 . A child with a silent prenatal and perinatal history was found to be inattentive to one side at around the age of 6 weeks.…”

Section: Is Recovery Of Normal Conscious Vision Possible?mentioning

confidence: 90%

“…Another interesting case was described by Lambert et al in 1990. 56 A child with a silent prenatal and perinatal history was found to be inattentive to one side at around the age of 6 weeks. The follow-up showed a normalization of the clinical picture with no detectable visual defect from the age of 9 months, and subsequent MRI documented a right occipital lobe hypoplasia.…”

Section: What This Paper Addsmentioning

confidence: 99%

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Plasticity of the visual system after early brain damage

Guzzetta

D’Acunto

Rose

et al. 2010

Develop Med Child Neuro

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The aim of this review is to discuss the existing evidence supporting different processes of visual brain plasticity after early damage, as opposed to damage that occurs during adulthood. There is initial evidence that some of the neuroplastic mechanisms adopted by the brain after early damage to the visual system are unavailable at a later stage. These are, for example, the ability to differentiate functional tissue within a larger dysplastic cortex during its formation, or to develop new thalamo-cortical connections able to bypass the lesion and reach their cortical destination in the occipital cortex. The young brain also uses the same mechanisms available at later stages of development but in a more efficient way. For example, in people with visual field defects of central origin, the anatomical expansion of the extrastriatal visual network is greater after an early lesion than after a later one, which results in more efficient mechanisms of visual exploration of the blind field. A similar mechanism is likely to support some of the differences found in people with blindsight, the phenomenon of unconscious visual perception in the blind field. In particular, compared with people with late lesions, those with early brain damage appear to have stronger subjective awareness of stimuli hitting the blind visual field, reported as a conscious feeling that something is present in the visual field. Expanding our knowledge of these mechanisms could help the development of early therapeutic interventions aimed at supporting and enhancing visual reorganization at a time of greatest potential brain plasticity.Brain plasticity consists of the modifications to the central nervous system in response to environmental stimulation, which allow us to learn new skills, remember new information, and recover from brain injury. 1 Mechanisms of neuronal plasticity are more powerful during early development. For example, children are faster than adults in learning a new language or in achieving complex skills such as playing a musical instrument. 2 Similarly, children lacking proper environmental inputs early in life are more susceptible to an abnormal development of the functions related to those inputs (the principle of sensitive periods 3 ).The presence of more powerful mechanisms of neuronal plasticity during early development should imply that recovery from brain damage is more effective after early lesions than after lesions occurring later in life. This principle was first suggested by Paul Broca in 1865 4 and then more systematically explored by Margaret Kennard in the late 1930s. 5 Since then, most of the studies of different species have supported this general principle, although describing a more complex picture, which takes into consideration several other aspects beyond timing of the insult, including the location and extension of injury (e.g. focal versus diffuse), the clinical phenotype (e.g. presence of seizures), or the genetic susceptibility of the individual. 6 Today, there is general agreement that the way the bra...

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Section: Is Recovery Of Normal Conscious Vision Possible?mentioning

confidence: 90%

Section: What This Paper Addsmentioning

confidence: 99%

Plasticity of the visual system after early brain damage

Guzzetta

D’Acunto

Rose

et al. 2010

Develop Med Child Neuro

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“…In infants and young children with lesions of the visual area of one cerebral hemisphere, a marked VEP asymmetry has been demonstrated for both flash and pattern testing. 345 Patients suspected of hemianopic defects on the basis of cerebral lesions should be tested for the presence of smooth pursuit asymmetry, either with an optokinetic ROP (OKN) target, spinning of the patient, or eye movement recording. Saccadic tracking to the side of the lesion is a helpful diagnostic sign in patients with large lesions involving the parietal lobe.…”

Section: Hemianopic Visual Field Defects In Childrenmentioning

confidence: 99%

“…As mentioned earlier, VEP measurements with hemispheric recordings can help delineate preferential or asymmetric hemispheric disorders associated with hemianopic field defects. 345 Some children with neglect may have a pseudohemianopia (a body-or gaze-dependent defect rather than a retinotopic defect). When looking leftward, these patients are unable to see objects in the left retinotopic field, but when looking rightward, they can see objects in the left field.…”

Section: Hemianopic Visual Field Defects In Childrenmentioning

confidence: 99%

The Apparently Blind Infant

Brodsky

2009

Pediatric Neuro-Ophthalmology

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“…This horizontal symmetric VEP distribution about the midline depends on stimulation of both occipital hemispheres; asymmetric VEP distributions are typically recorded to hemi-field stimulation in normal subjects. The main positive peak of monocular flash VEPs recorded with a mid-frontal (Fz) reference has the same lateralized trans-occipital distribution as monocular pattern reversal VEPs, demonstrated in patients with welldefined unilateral occipital lesions [5,6]. These studies suggest that a trans-occipital difference in peak time of 6 ms or an amplitude reduction of 50% of a flash VEP indicates a hemianopic field defect [7,8].…”

Section: Introductionmentioning

confidence: 99%

Case report: Unilateral optic nerve aplasia and developmental hemi-chiasmal dysplasia with VEP misrouting

et al. 2020

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Purpose To describe the trans-occipital asymmetries of pattern and flash visual evoked potentials (VEPs), in an infant with MRI findings of unilateral optic nerve aplasia and hemi-chiasm dysplasia. Methods A child with suspected left cystic microphthalmia, left microcornea, left unilateral optic nerve aplasia, and hemi-chiasm underwent a multi-channel VEP assessment with pattern reversal, pattern onset, and flash stimulation at the age of 16 weeks. Results There was no VEP evidence of any postretinal visual pathway activation from left eye with optic nerve aplasia. The VEP trans-occipital distribution from the functional right eye was skewed markedly across the midline, in keeping with significant misrouting of optic nerve fibres at the chiasm. This was supported by the anatomical trajectory of the optic chiasm and tracts seen on MRI. Conclusion This infant has chiasmal misrouting in association with unilateral optic nerve aplasia and unilateral microphthalmos. Chiasmal misrouting has not been found in patients with microphthalmos or anophthalmos, but has been reported after early eye loss in animal models. Our findings contribute to our understanding of the discrepancy between the visual pathway physiology of human unilateral microphthalmia and animal models.

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Detection of Isolated Occipital Lobe Anomalies During Early Childhood

Cited by 16 publications

References 9 publications

Plasticity of the visual system after early brain damage

Plasticity of the visual system after early brain damage

The Apparently Blind Infant

Case report: Unilateral optic nerve aplasia and developmental hemi-chiasmal dysplasia with VEP misrouting

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