Quantifying the pattern of optic tract degeneration in human hemianopia

Millington, Rebecca S.; Yasuda, Clarissa L.; Jindahra, Panitha; Jenkinson, Mark; Barbur, John L.; Kennard, Christopher; Cendes, Fernando; Plant, Gordon T.; Bridge, Holly

doi:10.1136/jnnp-2013-306577

Cited by 36 publications

(42 citation statements)

References 29 publications

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“…Whether this represents a form of visual disuse atrophy, a consequence of retrograde degeneration of neurons in the dorsal lateral geniculate nucleus (dLGN) and retina, 27–31 or whether patients learned to ignore weak, unreliable vision near their blind field remains to be determined. That worsening was not systematically reported previously may be due to HVF analyses in prior studies lacking sensitivity to such changes.…”

Section: Discussionmentioning

confidence: 99%

Visual discrimination training improves Humphrey perimetry in chronic cortically induced blindness

Cavanaugh

Huxlin

2017

Neurology

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Objective:To assess if visual discrimination training improves performance on visual perimetry tests in chronic stroke patients with visual cortex involvement.Methods:24-2 and 10-2 Humphrey visual fields were analyzed for 17 chronic cortically blind stroke patients prior to and following visual discrimination training, as well as in 5 untrained, cortically blind controls. Trained patients practiced direction discrimination, orientation discrimination, or both, at nonoverlapping, blind field locations. All pretraining and posttraining discrimination performance and Humphrey fields were collected with online eye tracking, ensuring gaze-contingent stimulus presentation.Results:Trained patients recovered ∼108 degrees2 of vision on average, while untrained patients spontaneously improved over an area of ∼16 degrees2. Improvement was not affected by patient age, time since lesion, size of initial deficit, or training type, but was proportional to the amount of training performed. Untrained patients counterbalanced their improvements with worsening of sensitivity over ∼9 degrees2 of their visual field. Worsening was minimal in trained patients. Finally, although discrimination performance improved at all trained locations, changes in Humphrey sensitivity occurred both within trained regions and beyond, extending over a larger area along the blind field border.Conclusions:In adults with chronic cortical visual impairment, the blind field border appears to have enhanced plastic potential, which can be recruited by gaze-controlled visual discrimination training to expand the visible field. Our findings underscore a critical need for future studies to measure the effects of vision restoration approaches on perimetry in larger cohorts of patients.

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Section: Discussionmentioning

confidence: 99%

Visual discrimination training improves Humphrey perimetry in chronic cortically induced blindness

Cavanaugh

Huxlin

2017

Neurology

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“…Whilst surgery still remains the most effective course of action to drug resistant epilepsy (Schmidt and Stavem, 2009;Jobst and Cascino, 2015), it is well known that the brain shifts position during surgery, and this has been addressed using tractography during neurosurgical procedures (Nimsky et al, 2005;Winston et al, 2012;Yang et al, 2017). It has also been documented that there is degeneration of the visual system over time following damage to postchiasmal visual pathways (Millington et al, 2014). In some cases, the long-time interval between the pre-surgical scan and surgery may have resulted in changes in the position of the visual pathways by the time surgery was performed, as well as in other brain regions reflecting brain plasticity (Yogarajah et al, 2010).…”

Section: Limitations and Future Directionsmentioning

confidence: 99%

Microstructural Investigations of the Visual Pathways in Pediatric Epilepsy Neurosurgery: Insights From Multi-Shell Diffusion Magnetic Resonance Imaging

et al. 2020

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Background: Surgery is a key approach for achieving seizure freedom in children with focal onset epilepsy. However, the resection can affect or be in the vicinity of the optic radiations. Multi-shell diffusion MRI and tractography can better characterize tissue structure and provide guidance to help minimize surgical related deficits. Whilst in adults tractography has been used to demonstrate that damage to the optic radiations leads to postoperative visual field deficits, this approach has yet to be properly explored in children.Objective: To demonstrate the capabilities of multi-shell diffusion MRI and tractography in characterizing microstructural changes in children with epilepsy pre-and post-surgery affecting the occipital, parietal or temporal lobes.Methods: Diffusion Tensor Imaging and the Spherical Mean Technique were used to investigate the microstructure of the optic radiations. Furthermore, tractography was used to evaluate whether pre-surgical reconstructions of the optic radiations overlap with the resection margin as measured using anatomical post-surgical T1weighted MRI.Results: Increased diffusivity in patients compared to controls at baseline was observed with evidence of decreased diffusivity, anisotropy, and neurite orientation distribution in contralateral hemisphere after surgery. Pre-surgical optic radiation tractography overlapped with post-surgical resection margins in 20/43 (46%) children, and where visual data was available before and after surgery, the presence of overlap indicated a visual field deficit. Frontiers in Neuroscience | www.frontiersin.org 1 April 2020 | Volume 14 | Article 269 Lacerda et al. Visual Pathways in Pediatric SurgeryConclusion: This is the first report in a pediatric series which highlights the relevance of tractography for future pre-surgical evaluation in children undergoing epilepsy surgery and the usefulness of multi-shell diffusion MRI to characterize brain microstructure in these patients.

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“…2 This analysis used control data to derive a group OT mask for FA collection from their participants rather than direct OT identification in individuals. 2 This analysis used control data to derive a group OT mask for FA collection from their participants rather than direct OT identification in individuals.…”

Section: Identification Of Lesions and Visual System Compromisementioning

confidence: 99%

“…RTD in the visual system was initially reported in 1963 in a macaque following occipital lobectomy. Optic nerve atrophy is evident on T1 sequences, 2,8,9 although not until 18 months following injury. [4][5][6] The 2 neuron visual pathway may represent a simplified model for the investigation of mechanisms guiding global neurodegeneration.…”

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confidence: 99%

Early diffusion evidence of retrograde transsynaptic degeneration in the human visual system

et al. 2016

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Quantifying the pattern of optic tract degeneration in human hemianopia

Abstract: We conclude that TRD of the OT occurs in acquired and congenital hemianopia, is correlated with visual field loss, and is most severe in congenital cases. Understanding the pattern of TRD may help to predict effects of any visual rehabilitation training.

Cited by 36 publications

References 29 publications

Visual discrimination training improves Humphrey perimetry in chronic cortically induced blindness

Visual discrimination training improves Humphrey perimetry in chronic cortically induced blindness

Microstructural Investigations of the Visual Pathways in Pediatric Epilepsy Neurosurgery: Insights From Multi-Shell Diffusion Magnetic Resonance Imaging

Early diffusion evidence of retrograde transsynaptic degeneration in the human visual system

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