Structure-function relationship between magnetic resonance imaging lesion areas and visual field defects in initial optic neuritis with altitudinal hemianopsia.

PURPOSE: To study the spatial association of magnetic resonance imaging (MRI) contrast enhancement (CE) areas with visual field defect (VFD) asymmetry in initial cases of optic neuritis (ON) with altitudinal hemianopsia (AH) with reference to nonarteritic anterior ischemic optic neuropathy (NAION) with AH. STUDY DESIGN: Multicenter, cross-sectional study. METHODS: The present study comprised 19 ON patients and 20 NAION patients with AH who underwent orbital contrast fat-suppressed MRI. The signal-to-intensity ratio (SIR) was calculated by dividing the maximum CE of the optic nerve by the mean CE of the cerebral white matter in 11 coronal sections at 3-mm intervals from immediately posterior to the eyeball to the optic chiasm. Sections in ON patients with an SIR exceeding the mean plus 2 standard deviations of the SIR at the corresponding section in the NAION group were considered abnormal. The correlation between upper-to-lower CE asymmetry in the maximum SIR section and VFD counterpart was determined. RESULTS: The ON group had significantly higher maximum SIR than that of the NAION group (1.77 ± 0.88 vs. 1.25 ± 0.32; P < .01). Seven of the 19 patients had sections with abnormally high CE extending posteriorly beyond the orbital apex. Significant spatial correspondence was observed between CE and VFD asymmetry (rs = 0.563; P = .015) in the ON group but not in the NAION group (rs = - 0. 048; P = .850). CONCLUSIONS: ON patients with AH frequently show CE even in the intracerebral optic nerve, maintaining a moderate structure-function correspondence.

Giant Recurrence Pituitary Adenoma After Three Times Transphenoidal Removal Surgery, One Craniotomy Procedure, and 30 Doses of External Radiotherapy.

This is a case of 42nd year-old woman with history of sight loss in her both eyes. She experienced headache and visual field decrease gradually since 2014. After several laboratory and imaging examinations, from her dynamic pituitary magnetic resonance imaging (MRI), it is concluded that she had a giant adenoma of the pituitary gland which compressed to her optic chiasm. From her pituitary laboratory hormone panel, it is revealed that the tumor is a non-functioning pituitary adenoma. From the neuro-ophthalmology (campimetry) examinations, she had papillae atrophy in her both eyes and also bilateral temporal hemianopia.

Direct and transsynaptic retrograde degeneration and optic nerve head microvascular changes in patients with hemianopia.

PURPOSE: To investigate optic nerve head (ONH) microvascular changes secondary to transsynaptic retrograde degeneration (TRD), comperatively with direct retrograde degeneration and healthy controls. METHODS: Patients with hemianopia due to intracranial lesion included in the study. Intracranial lesion was categorized by location: postgeniculate (causing TRD), chiasmal (causing direct retrograde degeneration). For the postgeniculate lesions, the eye on the same side of the lesion was defined as the ipsilateral eye and the eye on the opposite side as the contralateral eye. Optic disc microvasculature was evaluated with the help of optic coherence tomography angiography. RESULTS: Sixteen eyes of 16 patients with chiasmal lesion, 28 eyes of 14 patients with postgeniculate lesion, and 30 eyes of 30 healthy subjects were included in the study. Ipsilateral eyes of the patients with postgeniculate lesion had decreased vessel density at the temporal sectors compatible with the affected nasal side of the visual field. Contralateral eyes showed no reduction of the vessel density at the affected nasal sectors. The eyes with chiasmal lesions had decreased vessel density at the peripapillary region and nasal half of the ONH compatible with temporal hemianopia. Vascular changes in the chiasmal lesion were more prominent than those of the postgeniculate lesion. Retinal nerve fiber layer and ganglion cell complex thickness were reduced. CONCLUSION: Vessel density of ONH was reduced in patients with homonymous hemianopia, providing evidence for TRD secondary to acquired postgeniculate lesion. Direct retrograde degeneration was more prominent in affected sectors when compared to TRD.

Functional connectivity of the Precuneus reflects effectiveness of visual restitution training in chronic hemianopia.

Visual field defects in chronic hemianopia can improve through visual restitution training, yet not all patients benefit equally from this long and exhaustive procedure. Here, we asked if resting-state functional connectivity prior to visual restitution could predict training success. In two training sessions of eight weeks each, 20 patients with chronic hemianopia performed a visual discrimination task by directing spatial selective attention towards stimuli presented in either hemifield, while suppressing eye movements. We examined two effects: a sensitivity change in the attended (trained) minus the unattended (control) hemifield (i.e., a training-specific improvement), and an overall improvement (i.e., a total change in sensitivity after both sessions). We then identified five visual resting-state networks and evaluated their functional connectivity in relation to both training effects. We found that the functional connectivity strength between the anterior Precuneus and the Occipital Pole Network was positively related to the attention modulated (i.e., training-specific) improvement. No such relationship was found for the overall improvement or for the other visual networks of interest. Our finding suggests that the anterior Precuneus plays a role in attention-modulated visual field improvements. The resting-state functional connectivity between the anterior Precuneus and the Occipital Pole Network may thus serve as an imaging-based biomarker that quantifies a patient's potential capacity to direct spatial attention. This may help to identify hemianopia patients that are most likely to benefit from visual restitution training.

Neuroanatomic correlates of visual hallucinations in poststroke hemianopic patients.

OBJECTIVES: Homonymous hemianopia (HH) is the most frequent visual-field defect after a stroke. Some of these patients also have visual hallucinations, the origin and frequency of which remain largely unknown. The aims of this work were to determine the occurrence of visual hallucinations among poststroke hemianopic patients in function of the location (Brodmann areas) of the brain lesion, as determined by MRI, and to study the neuroanatomic correlates of these hallucinations by nature, frequency, and type. METHODS: One hundred sixteen patients with HH who had had a stroke in the posterior region, including the occipital lobe, participated in the study. We evaluated the frequency and nature of visual hallucinations with the Questionnaire for Hallucinations in Homonymous Hemianopia. The volume of each patient's brain lesion was modeled in 3 dimensions. RESULTS: Of 116 patients with an HH from a cortical infarction, 85 were excluded due to confounding factors associated with hallucinations. In the final cohort of 31 patients matched for lesion location and etiology, 58% had experienced hallucinations. A significant inverse correlation between lesion size and the frequency of visual hallucinations emerged. The presence of visual hallucinations in poststroke hemianopic patients requires a relatively small lesion that includes, at the very least, loss of the striate cortex but that spares Brodmann area 19, 20, and 37. CONCLUSION: Our results suggest that visual hallucinations might be due to complex interactions between damaged areas and intact areas of the visual cortex. We discuss these findings regarding models of perception and of visual recognition. Our results also have implications for the clinical care of patients with HH who have had a stroke.

Homonymous quadrantanopia associated with hyperosmolar hyperglycemic syndrome.

We encountered a 64-year-old man with hyperosmolar hyperglycemic syndrome, having a sudden-onset homonymous right inferior quadrantanopia. This is the first documentation of such a phenomenon in hyperosmolar hyperglycemic syndrome. We believe this is a variant of hemianopia in patients with hyperglycemic hyperosmolar syndrome.

Functional interactions in patients with hemianopia: A graph theory-based connectivity study of resting fMRI signal.

The assessment of task-independent functional connectivity (FC) after a lesion causing hemianopia remains an uncovered topic and represents a crucial point to better understand the neural basis of blindsight (i.e. unconscious visually triggered behavior) and visual awareness. In this light, we evaluated functional connectivity (FC) in 10 hemianopic patients and 10 healthy controls in a resting state paradigm. The main aim of this study is twofold: first of all we focused on the description and assessment of density and intensity of functional connectivity and network topology with and without a lesion affecting the visual pathway, and then we extracted and statistically compared network metrics, focusing on functional segregation, integration and specialization. Moreover, a study of 3-cycle triangles with prominent connectivity was conducted to analyze functional segregation calculated as the area of each triangle created connecting three neighboring nodes. To achieve these purposes we applied a graph theory-based approach, starting from Pearson correlation coefficients extracted from pairs of regions of interest. In these analyses we focused on the FC extracted by the whole brain as well as by four resting state networks: The Visual (VN), Salience (SN), Attention (AN) and Default Mode Network (DMN), to assess brain functional reorganization following the injury. The results showed a general decrease in density and intensity of functional connections, that leads to a less compact structure characterized by decrease in functional integration, segregation and in the number of interconnected hubs in both the Visual Network and the whole brain, despite an increase in long-range inter-modules connections (occipito-frontal connections). Indeed, the VN was the most affected network, characterized by a decrease in intra- and inter-network connections and by a less compact topology, with less interconnected nodes. Surprisingly, we observed a higher functional integration in the DMN and in the AN regardless of the lesion extent, that may indicate a functional reorganization of the brain following the injury, trying to compensate for the general reduced connectivity. Finally we observed an increase in functional specialization (lower between-network connectivity) and in inter-networks functional segregation, which is reflected in a less compact network topology, highly organized in functional clusters. These descriptive findings provide new insight on the spontaneous brain activity in hemianopic patients by showing an alteration in the intrinsic architecture of a large-scale brain system that goes beyond the impairment of a single RSN.

Homonymous hemiatrophy of ganglion cell layer from retrochiasmal lesions in the visual pathway.

OBJECTIVE: To determine the temporal evolution, morphology, and frequency of macular ganglion cell atrophy in patients with retrochiasmal lesions of the visual pathway. METHODS: In a consecutive retrospective case series, we identified 47 patients with homonymous hemianopia and accessible macular optical coherence tomography scans. We estimated the time of lesion onset and the location of the lesion within the afferent visual pathway. Using semiautomatic layer segmentation, we determined ganglion cell layer thickness in areas projecting to the side of the retrochiasmal lesion and compared it with ganglion cell layer thickness on the healthy side. RESULTS: We found that retrochiasmal lesions at any level may be associated with an atrophy of ganglion cells. This atrophy respects the vertical midline through the fovea and thus the anatomic separation of the nasal and temporal visual field. The vertical line separating the affected from the unaffected side has significantly less tilt as compared with the disc-fovea angle. Lesions of the optic tract are associated with earlier macular ganglion cell atrophy than retrogeniculate lesions. Macular ganglion cell atrophy may be present in cases with normal peripapillary nerve fiber layer analysis and vice versa. CONCLUSIONS: Macular ganglion cell layer thickness shows a topographic hemiatrophy in retrochiasmal lesions, which manifests earlier for tract lesions than for retrogeniculate lesions. This additional examination of ganglion cell homonymous hemiatrophy has a higher sensitivity in detecting retrograde transsynaptic degeneration than the analysis of the peripapillary nerve fiber layer alone.

Using the Principles of Multisensory Integration to Reverse Hemianopia.

Hemianopia can be rehabilitated by an auditory-visual "training" procedure, which restores visual responsiveness in midbrain neurons indirectly compromised by the cortical lesion and reinstates vision in contralesional space. Presumably, these rehabilitative changes are induced via mechanisms of multisensory integration/plasticity. If so, the paradigm should fail if the stimulus configurations violate the spatiotemporal principles that govern these midbrain processes. To test this possibility, hemianopic cats were provided spatially or temporally noncongruent auditory-visual training. Rehabilitation failed in all cases even after approximately twice the number of training trials normally required for recovery, and even after animals learned to approach the location of the undetected visual stimulus. When training was repeated with these stimuli in spatiotemporal concordance, hemianopia was resolved. The results identify the conditions needed to engage changes in remaining neural circuits required to support vision in the absence of visual cortex, and have implications for rehabilitative strategies in human patients.

Cerebral Amyloidoma.

Cerebral amyloidoma is the rarest presentation of amyloid-related diseases of the central nervous system. We present the case of a patient with visual difficulty and an infiltrating lesion in the temporal lobe, shown by magnetic resonance imaging. In as much as a benign clinical course is expected, a knowledge of this entity, along with state-of-the-art imaging and close follow-up, could avoid invasive procedures such as biopsy.

[Traumatic homonymous hemianopsia and ganglion cell complex changes: Report of 3 cases]. / Hémianopsie latérale homonyme post-traumatique et atteinte des cellules ganglionnaires : à propos de 3 cas.

Homonymous lateral hemianopia follows an attack on the contralateral retrochiasmal visual pathways. In three patients with post-traumatic homonymous hemianopia, optical coherence tomographic (OCT) study of the ganglion cell layer thickness showed hemiretinal thinning contralateral to the visual field defect. This involvement could be explained by trans-synaptic degeneration of the pre-geniculate visual pathways, whose cell nuclei correspond to ganglion cells, which synapse with the damaged retrogeniculate visual pathways.

Effects of cortical damage on binocular depth perception.

Stereoscopic depth perception requires considerable neural computation, including the initial correspondence of the two retinal images, comparison across the local regions of the visual field and integration with other cues to depth. The most common cause for loss of stereoscopic vision is amblyopia, in which one eye has failed to form an adequate input to the visual cortex, usually due to strabismus (deviating eye) or anisometropia. However, the significant cortical processing required to produce the percept of depth means that, even when the retinal input is intact from both eyes, brain damage or dysfunction can interfere with stereoscopic vision. In this review, I examine the evidence for impairment of binocular vision and depth perception that can result from insults to the brain, including both discrete damage, temporal lobectomy and more systemic diseases such as posterior cortical atrophy.This article is part of the themed issue 'Vision in our three-dimensional world'.

Visual Plasticity: Blindsight Bridges Anatomy and Function in the Visual System.

Some people who are blind due to damage to their primary visual cortex, V1, can discriminate stimuli presented within their blind visual field. This residual function has been recently linked to a pathway that bypasses V1, and connects the thalamic lateral geniculate nucleus directly with the extrastriate cortical area MT.

Human blindsight is mediated by an intact geniculo-extrastriate pathway.

Although damage to the primary visual cortex (V1) causes hemianopia, many patients retain some residual vision; known as blindsight. We show that blindsight may be facilitated by an intact white-matter pathway between the lateral geniculate nucleus and motion area hMT+. Visual psychophysics, diffusion-weighted magnetic resonance imaging and fibre tractography were applied in 17 patients with V1 damage acquired during adulthood and 9 age-matched controls. Individuals with V1 damage were subdivided into blindsight positive (preserved residual vision) and negative (no residual vision) according to psychophysical performance. All blindsight positive individuals showed intact geniculo-hMT+ pathways, while this pathway was significantly impaired or not measurable in blindsight negative individuals. Two white matter pathways previously implicated in blindsight: (i) superior colliculus to hMT+ and (ii) between hMT+ in each hemisphere were not consistently present in blindsight positive cases. Understanding the visual pathways crucial for residual vision may direct future rehabilitation strategies for hemianopia patients.