Reduced Peripapillary and Macular Vessel Density in Unilateral Postgeniculate Lesions With Retrograde Transsynaptic Degeneration.

BACKGROUND: Retrograde transsynaptic degeneration (RTSD) of the retinal ganglion cells and retinal nerve fiber layer after postgeniculate injury has been well documented, but to the best of our knowledge, associated retinal microvascular changes have not been examined. The purpose of our study was to assess vessel density (VD) at macular and peripapillary regions in patients with RTSD. METHODS: Cross-sectional study including 16 patients with homonymous visual field defects secondary to unilateral postgeniculate visual pathway injury and 18 age-matched controls. All participants were examined with AngioVue optical coherence tomography angiography to measure the peripapillary vessel density and macular vessel density (pVD/mVD) as well as the peripapillary retinal nerve fiber layer (pRNFL) and macular ganglion cell complex (GCC) thicknesses. The pRNFL and macular ganglion cell-inner plexiform layer (GCIPL) thicknesses also were evaluated using Cirrus OCT. A normalized asymmetry score (NAS) was calculated for GCIPL and GCC thickness, and mVD. RESULTS: Average pRNFL and macular GCIPL/GCC thicknesses were significantly thinner in both eyes of patients compared with control eyes (all P ≤ 0.05). Eight patients (50%), who showed a RTSD of the GCIPL map, had a relative thinning of the GCIPL/GCC ipsilateral to the brain lesion in both eyes (represented by a positive GCIPL-NAS/GCC-NAS). The mean pVD and mVD also were significantly reduced in patients (all P ≤ 0.05). There was a strong correlation between GCIPL-NAS/GCC-NAS and mVD-NAS index in both eyes (all r > 0.7, P = 0.001). Furthermore, there was a similar spatial pattern of damage for the macular GCC thickness and VD values. CONCLUSIONS: We demonstrated a significant VD decrease in peripapillary and macular areas of patients with RTSD because of postgeniculate lesions. The structural and microvascular asymmetry indexes were significantly correlated. These findings provide new insights regarding transsynaptic degeneration of the visual system.

Petroclival Meningioma Presenting With an Ipsilateral Sixth Nerve Palsy and a Contralateral Homonymous Quadrantanopia: A Unique and Topographically Localizing Syndrome.

An 84-year-old woman reported onset of headaches, diplopia, and blurred vision. On examination, she was found to have a left sixth nerve palsy and an incongruous right homonymous hemianopia. Brain MRI demonstrated a left petroclival meningioma, causing this unusual combination of clinical findings. The patient was treated with radiation therapy and has remained stable over 4 years of follow-up.

Homonymous Hemianopia in Children and Adolescents: An MRI Study.

AIM: Diagnosing homonymous hemianopia (HH) in children can be difficult due to inability to comply with perimetry. Therefore, HH can often only be suspected by magnetic resonance imaging (MRI) showing lesions to the retrochiasmatic visual pathways. The aim of our retrospective observational cross-sectional study was to improve the radiologic detection of HH. METHODS: MRIs of 21 subjects (5-17 years old) with ophthalmologically confirmed HH (14 complete, 7 incomplete hemianopias) were analyzed. In addition, we asked four questions looking at everyday problems possibly related to the HH. The questions asked for (1) problems in avoiding objects/people, (2) bumping into objects/people, (3) difficulties in judging stairs, and (4) difficulties in grasping objects. RESULTS: We found neuroanatomical correlates of the HH in all 21 participants, with the optic radiation being involved in almost all participants (20/21). Everyday problems possibly related to the HH were reported for all nine patients with postneonatally acquired complete hemianopias. In contrast, no such problems were reported for seven patients with incomplete HH (7/7) and for 3/5 patients with complete hemianopias due to pre-, peri- or neonatally acquired brain lesions. INTERPRETATION: A dedicated radiologic analysis of the retrochiasmatic optic pathway should routinely be performed in children with brain lesions to identify children with HH. Early onset and incomplete HH are predictors for successful compensation.

Vertebrobasilar dolichoectasia causing homonymous hemianopia: a case report and review of the literature.

A 73-year-old man was diagnosed with an incidental finding of right homonymous hemianopia and presyncopal spells. Magnetic resonance imaging revealed a vertebrobasilar dolichoectasia (VBD) with compression of the left optic tract. VBD is defined as an elongation and dilatation of the basilar artery. Only a few cases have been described in the literature of VBD causing optic tract compression. So far no treatment option has been described for these cases, while surgical options exist for compressions of other cranial nerves, most commonly the trigeminal nerve. VBD can further cause stroke or cerebral and subarachnoid bleeding.

Improvement of Glucose Metabolism in the Visual Cortex Accompanies Visual Field Recovery in a Patient with Hemianopia.

Damage to the visual cortex or the geniculostriatal pathways could cause homonymous visual field (VF) defects at the contralateral side of the lesion. In clinical practice, it is known that the VF defects are gradually recovered over months on the cases. We report a case with recovered homonymous hemianopia following an infarction in the visual cortex by positron emission tomography (PET) with (18)F-fluorodeoxyglucose (FDG) and (11)C-flumazenil (FMZ). A 58-year-old man experienced defect of left VF, and magnetic resonance imaging (MRI) revealed a localized infarction in the right occipital lobe. Goldmann VF perimetry revealed left homonymous hemianopia, but central VF was intact. Three months after the onset of infarction, we measured cerebral glucose metabolism with FDG and FMZ binding using PET. FMZ binding reflects the density of surviving neurons. Moreover, eight months after the onset, FDG-PET scan was performed. Goldmann VF perimetry was also performed at the same times of PET examinations. Decrease of cerebral glucose metabolism in the right anterior striate cortex was observed at three months after onset, while FMZ binding in the same area did not decrease in the patient. At eight months after onset, we observed recovery of VF and improvement of cerebral glucose metabolism in the anterior striate cortex. We presented change of cerebral glucose metabolism using PET accompanying improvement of VF. Evaluation of cerebral glucose metabolism and FMZ binding in the striate cortex is useful for estimating the prognosis of hemianopia caused by organic brain damage.

Role of corpus callosum in unconscious vision.

The existence of unconscious visually triggered behavior in patients with cortical blindness (e.g., homonymous hemianopia) has been amply demonstrated and the neural bases of this phenomenon have been thoroughly studied. However, a crosstalk between the two hemispheres as a possible mechanism of unconscious or partially conscious vision has not been so far considered. Thus, the aim of this study was to assess the relationship between structural and functional properties of the corpus callosum (CC), as shown by probabilistic tractography (PT), behavioral detection/discrimination performance and level of perceptual awareness in the blind field of patients with hemianopia. Twelve patients were tested in two tasks with black-and-white visual square-wave gratings, one task of movement and the other of orientation. The stimuli were lateralized to one hemifield either intact or blind. A PT analysis was carried out on MRI data to extract fiber properties along the CC (genu, body, and splenium). Compared with a control group of participants without brain damage, patients showed lower FA values in all three CC sections studied. For the intact hemifield we found a significant correlation between PT values and visual detection/discrimination accuracy. For the blind hemifield the level of perceptual awareness correlated with PT values for all three CC sections in the movement task. Importantly, significant differences in all three CC sections were found also between patients with above-vs. chance detection/discrimination performance while differences in the genu were found between patients with and without perceptual awareness. Overall, our study provides evidence that the properties of CC fibers are related to the presence of unconscious stimulus detection/discrimination and to hints of perceptual awareness for stimulus presentation to the blind hemifield. These results underline the importance of information exchange between the damaged and the healthy hemisphere for possible partial or full recovery from hemianopia.

Measurement of Cerebral Glucose Metabolism in the Visual Cortex Predicts the Prognosis of Hemianopia.

BACKGROUND AND OBJECTIVE: Homonymous hemianopia caused by cerebrovascular disease may improve over time. This study investigated whether functional neuroimaging can predict the prognosis of hemianopia due to cerebral infarction. METHODS: We studied 19 patients (10 men and 9 women) with homonymous hemianopia and compared them with 34 healthy subjects (20 men and 14 women). Cerebral glucose metabolism was measured by 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), 1 to 6 months after the onset. Bilateral regions of interest (ROIs) were selected from the posterior and, anterior striate cortices, extrastriate cortex, and thalamus. Furthermore, semi-quantitative data on cerebral glucose metabolism were obtained for ROIs and compared with the data obtained for homologous regions in the contralateral hemisphere by calculating the ipsilateral/contralateral (I/C) ratio. RESULTS: The I/C ratio for the cerebral glucose metabolism in the posterior striate cortex was high (>0.750) in 8 patients, and the central visual field of these patients improved or showed macular sparing. The I/C ratio for cerebral glucose metabolism in the anterior striate cortex was high (>0.830) in 7 patients, and the peripheral visual field of these patients improved. However, no improvement was observed in 9 patients with a low I/C ratio for cerebral glucose metabolism in both the posterior and anterior striate cortices. CONCLUSION: Measurement of cerebral glucose metabolism in the striate cortex is useful for estimating visual field prognosis. Furthermore, FDG-PET is useful in predicting the prognosis of hemianopia.

Intravenous thrombolysis in ischemic stroke patients with isolated homonymous hemianopia.

BACKGROUND: Patients with posterior ischemic stroke were usually excluded from thrombolytic treatment in clinical trials and clinical practice, and little is known about effectiveness of thrombolysis treatment in such patients who may end up with severe disability. AIMS OF THE STUDY: We aimed to describe the outcome of acute ischemic stroke patients presenting with isolated homonymous hemianopia and treated with intravenous thrombolysis. METHODS: A case report of three patients presenting with homonymous hemianopia owing to posterior circulation stroke treated with intravenous thrombolysis at the Helsinki University Central Hospital. Main outcome measures were modified Rankin Scale and neuropsychological examination at 3 months after thrombolysis. We further evaluated Goldmann visual field examination at 6 months. RESULTS: No acute findings appeared on admission non-contrast head-computed tomography scan. All patients had a perfusion deficit on admission-computed tomography perfusion imaging. All patients scored 0 on 3-month modified Rankin Scale, and their neuropsychological evaluation was normal. Goldmann examination revealed no visual field deficit in both female patients, and a modest visual field defect was detected in the male patient. CONCLUSIONS: Our experience encourages application of intravenous thrombolytic treatment (especially when supported with multimodality neuroimaging) in patients with homonymous hemianopia, for which rehabilitation options are limited.

Clinical Reasoning: An 80-Year-Old Woman With a Homonymous Hemianopsia.

An 80-year-old woman who was experiencing visual symptoms for 2 years was found to have a left homonymous hemianopsia (HH). On further evaluation the following month, she was noted to have simultanagnosia and alexia. MRI of the brain did not reveal a structural etiology for the symptoms. [18F]-fluorodeoxyglucose (FDG) PET-CT was performed to aid in the diagnostic investigation. This case of posterior cortical atrophy highlights the differential diagnosis of a HH in the absence of a structural lesion on MRI and the role of FDG PET-CT imaging in such patients.

Detection of post-stroke visual field loss by quantification of the retrogeniculate visual pathway.

Visual field loss is associated with poor post-stroke functional outcomes. However, early detection of visual field loss is often challenging in patients with disabling stroke. This study explored the association between the microstructural integrity of the retrogeniculate pathway and visual field loss in disabling stroke patients undergoing inpatient rehabilitation. Thirty patients with stroke lesions involving the retrogeniculate visual pathway were included. The degree of visual field loss was determined by the visual field index and mean deviation using automated perimetry. The fractional anisotropy (FA) values were obtained for the lateral geniculate nucleus and optic radiation; the FA laterality indices, representing the degree of degeneration, were calculated. The FA values were compared between the affected and unaffected hemispheres. The patients were categorized into complete and incomplete hemianopia groups, and their FA values were compared. The relationship between the FA laterality index and the degree of visual field loss was assessed. FA values of the lateral geniculate nucleus and optic radiation were lower on the affected side than on the unaffected side (P < 0.001 and P < 0.001, respectively). The affected optic radiation in the complete hemianopia group showed a lower FA value than in the incomplete group (P = 0.006). The FA laterality index of the optic radiation was positively correlated with the degree of visual field loss (visual field index, ρ = 0.629; mean deviation, ρ = 0.568). The quantification of the retrogeniculate visual pathway may aid in detecting post-stroke visual field loss. The microstructural integrity of the optic radiation is associated with the severity of visual field loss.

Anatomical variant of origin of ophthalmic artery: case report.

We report on one case of variant origin of right ophthalmic artery (OA) from C4 choroidal segment of the right supraclinoid internal carotid artery. A 41-year-old woman affected by bitemporal hemianopsia performed Magnetic Resonance Imaging with gadolinium showing tuberculum sellae meningioma. During angiography we observed this variant of origin of OA. At surgical dissection, we observed this variant in carotid cistern.

Avoidance and Improvement in Visual Field Defect After Surgery for Metastatic Brain Tumors in the Parietal and the Occipital Lobe.

OBJECTIVE: Visual field defects occasionally occur secondary to tumors in the parietal and the occipital lobes. The aim of this study was to analyze the efficacy of improvement in hemianopsia after surgery for metastatic brain tumors involving or adjacent to the optic radiation (OR). METHODS: The study included 49 patients with brain metastasis in the parietal and occipital lobes in the present study. Preoperative and postoperative neurological assessments included visual field, Mini-Mental State Examination, and Karnofsky performance scale. RESULTS: Of 49 patients, 33 (67.3%) presented with preoperative homonymous hemianopsia. Of these 33 patients, the visual field was improved postoperatively in 17 patients (51.5%). In all patients regardless of preoperative hemianopsia, postoperative visual fields did not deteriorate. Tractography demonstrated that the OR was split by the tumor (n = 6) and fanning of fibers expanded along the lateral side of the tumor (n = 11). All tumors were removed via surgical access toward the medial side of the tumor. Gross total resection was achieved in most tumors in the group with visual improvement (n = 16/17; 94.1%). Improvement in the visual field was attributed to tumor location in the subcortical white matter, removal rate of the tumor, and higher postoperative Karnofsky performance scale score. CONCLUSIONS: The OR tended to deviate to the lateral side of the tumor in the parieto-occipital junction. The postoperative visual field improved even in cases of an occipital tumor. Based on the present study, total resection via an appropriate surgical route should be considered to preserve the OR, leading to improvement in the postoperative visual field.

Visuo-spatial attention to the blind hemifield of hemianopic patients: Can it survive the impairment of visual awareness?

The general aim of this study was to assess the effect produced by visuo-spatial attention on both behavioural performance and brain activation in hemianopic patients following visual stimulus presentation to the blind hemifield. To do that, we tested five hemianopic patients and six age-matched healthy controls in an MRI scanner during the execution of a Posner-like paradigm using a predictive central cue. Participants were instructed to covertly orient attention toward the blind or sighted hemifield in different blocks while discriminating the orientation of a visual grating. In patients, we found significantly faster reaction times (RT) in valid and neutral than invalid trials not only in the sighted but also in the blind hemifield, despite the impairment of consciousness and performance at chance. As to the fMRI signal, in valid trials we observed the activation of ipsilesional visual areas (mainly lingual gyrus - area 19) during the orientation of attention toward the blind hemifield. Importantly, this activation was similar in patients and controls. In order to assess the related functional network, we performed a psychophysiological interactions (PPI) analysis that revealed an increased functional connectivity (FC) in patients with respect to controls between the ipsilesional lingual gyrus and ipsilateral fronto-parietal as well as contralesional parietal regions. Moreover, the shift of attention from the blind to the sighted hemifield revealed stronger FC between the contralesional visual areas V3/V4 and ipsilateral parietal regions in patients than controls. These results indicate a higher cognitive effort in patients when paying attention to the blind hemifiled or when shifting attention from the blind to the sighted hemfield, possibly as an attempt to compensate for the visual loss. Taken together, these results show that hemianopic patients can covertly orient attention toward the blind hemifield with a top-down mechanism by activating a functional network mainly including fronto-parietal regions belonging to the dorsal attentional network.

The Chiasmal Compression Index: An Integrative Assessment Tool for Visual Disturbances in Patients with Pituitary Macroadenomas.

OBJECTIVE: Visual status is routinely evaluated by neuro-ophthalmologic examination and computerized visual field (VF) tests in patients with chiasmal compression secondary to pituitary macroadenoma. Currently, no relevant data exists to accurately quantify the extent of optic apparatus compromise to further guide clinical decision-making. We aimed to assess for a possible quantitative correlation between optic chiasm geometric properties on magnetic resonance imaging (MRI) and VF deficits. METHODS: Visual assessments and concurrent MRI scans were retrospectively reviewed from patients treated for pituitary macroadenoma in a single medical institution. Chiasm width, chiasm minimal and maximal height, and chiasm angle were measured on MRI coronal plane images by 3 independent reviewers (for the sake of variability analysis). VF numerical summary parameters were also retrieved. RESULTS: A total of 30 patients were included in the final analysis. Average VF index was 70% (±30), and averaged mean deviation was 10.0 db (±9). Chiasm angle and width (which together represents the bending and stretching of the chiasm by the upward directed compression; both of which demonstrated high inter- and intraobserver agreement) showed strong correlation with VF loss. Chiasmal compression index derived from those parameters showed even stronger correlation. CONCLUSIONS: The strong correlation demonstrated by our results of this relatively simple radiologic measurement with VF status, despite the relatively small cohort, calls for further investigation in this promising direction, and may facilitate with basic assessment and clinical decision-making for patients with equivocal neuro-ophthalmologic evaluation, as well as with poor compliance.

Extrageniculate vision in hemianopic humans: saccade inhibition by signals in the blind field.

The functional competence of extrageniculate visual pathways in hemianopic humans was demonstrated by showing that distractor signals in the blind half of the visual field could inhibit saccades toward targets in the intact visual field. This inhibitory effect of unseen distractors in patients occurred only when distractors were presented in the temporal half of the visual field, was specific to oculomotor responses, and did not occur in normal subjects. These results show that a peripheral visual signal activates retinotectal pathways to prime the oculomotor system and that these pathways can mediate orienting behavior in hemianopic humans.

[Homonymous hemianopia and posterior cortical atrophy]. / Hémianopsie latérale homonyme et atrophie corticale postérieure.

INTRODUCTION: Posterior cortical atrophy (PCA) is a clinically and radiologically defined syndrome, in which predominant symptoms focus on higher visual dysfunction with progressive course and association with cortical atrophy or hypometabolism that predominates in the posterior part of the hemispheres. Homonymous hemianopia (HH) has rarely been described in this syndrome. METHODS: We report on six patients (four females, two males, aged 63 to 80) referred for visual disorder which led to demonstration of HH using perimetry testing. These patients were followed for 1 to 5 years after discovery of HH. Brain imaging with MRI or CT scan was obtained in the six cases and a SPECT scan was performed in four cases. RESULTS: HH was left-sided in four cases and right-sided in two cases. Associated symptoms related to higher visual dysfunction were simultagnosia, alone or as part of a full Balint's syndrome, alexia, constructional apraxia, dressing apraxia, visual form agnosia, prosopagnosia and hemispatial neglect. These symptoms were mild at onset but invariably worsened with disease progression. Dementia eventually developed in all cases. The clinical diagnosis was probable Alzheimer's disease in five cases and corticobasal degeneration in one case. Radiology showed posterior cortex atrophy in all cases as well as reduced cerebral blood flow in the same region, with an asymmetrical pattern compatible with the side of HH. CONCLUSION: Elementary cortical lesions in PCA can develop mainly in the associative visual areas and even in the primary visual area, resulting in HH. HH has rarely been documented in PCA, but its prevalence would probably be higher if systematic search was conducted. Apparently isolated HH of insidious onset should suggest PCA and lead to neuropsychological testing and search for discrete atrophic changes of the posterior cortex on MRI as well as for metabolic alterations with SPECT or PET.

Nomogram Using Optical Coherence Tomography and Visual Field Parameters to Predict Brain Lesions in Patients with Bitemporal Hemianopia.

PURPOSE: This study aims to develop a nomogram to predict brain lesions in patients with complete or incomplete bitemporal hemianopia by combining results from optical coherence tomography (OCT) and visual field (VF) testing. MATERIAL AND METHODS: We reviewed the medical records of patients who underwent magnetic resonance imaging (MRI) to identify brain lesions due to bitemporal hemianopia between January 2010 and March 2017, retrospectively. The patients were divided into two groups based on MRI findings: brain-lesion (+) group that had brain lesions on MRI (n = 63), and brain-lesion (-) group without brain lesions on MRI (n = 16). We compared OCT and VF findings between the two groups to find factors that could predict a brain lesion. Multiple logistic regression analysis was performed to select prognostic factors, and we constructed a nomogram to predict brain lesions on MRI. RESULT: The VF mean deviation was lower (p = 0.011) and all sectors of peripapillary retinal nerve fiber layer thickness except the temporal region were thicker in the brain-lesion (+) group. However, there was no statistically significant difference in macular ganglion cell-inner plexiform layer between the two groups. The area under the receiver operating characteristic curve of the nomogram for predicting brain lesions on MRI was 0.916. CONCLUSION: We developed a nomogram using VF and OCT examinations as a novel and accurate screening method to predict brain lesions in patients with bitemporal hemianopia and aid ophthalmologists and other clinicians in deciding whether to further evaluate a patient by MRI.