Diagnosis of Transient Ischemic Attack: Sex-Specific Differences From a Retrospective Cohort Study

BACKGROUND AND PURPOSE

Research suggests that women and men may present with different transient ischemic attack (TIA) and stroke symptoms. We aimed to explore symptoms and features associated with a definite TIA/stroke diagnosis and whether those associations differed by sex.

METHODS

We completed a retrospective cohort study of patients referred to The Ottawa Hospital Stroke Prevention Clinic in 2015. Exploratory multinomial logistic regression was used to evaluate candidate variables associated with diagnosis and patient sex. Backwards elimination of the interaction terms with a significance level for staying in the model of 0.25 was used to arrive at a more parsimonious model.

RESULTS

Based on 1770 complete patient records, sex-specific differences were noted in TIA/stroke diagnosis based on features such as duration of event, suddenness of symptom onset, unilateral sensory loss, and pain.

CONCLUSIONS

This preliminary work identified sex-specific differences in the final diagnosis of TIA/stroke based on common presenting symptoms/features. More research is needed to understand if there are biases or sex-based differences in TIA/stroke manifestations and diagnosis.

Quality of care evaluation in non-functioning pituitary adenoma with chiasm compression: visual outcomes and timing of intervention clinical recommendations based on a systematic literature review and cohort study

PURPOSE

Surgery in patients with non-functioning pituitary macroadenomas (NFMA) is effective in ameliorating visual function. The urgency for decompression, and preferred timing of surgery related to the preoperative severity of dysfunction is unknown.

METHODS

Systematic review for evidence to provide clinical guidance for timing of surgical decompression of the optic chiasm, and a cohort study of 30 NFMA patients, in whom mean deviation (MD), and severity of visual dysfunction was assessed.

RESULTS

Systematic review 44 studies were included with a total of 4789 patients. Postoperatively, visual field defects improved in 87.0% of patients, stabilized in 12.8% and worsened in 1.0%. Specific protocols regarding timing of surgery were not reported. Only seven studies (16.7%) reported on either the duration of visual symptoms, or diagnostic, or treatment delay. Cohort study 30 NFMA patients (50% female, 60 eyes, mean age 58.5 ± 14.8 years), had a median MD of - 5.3 decibel (IQR - 3.1 to - 10.1). MD was strongly correlated with clinical severity (r =  - 0.94, P < 0.0001), and were used for severity of defects cut-off values: (1) normal >  - 2 dB, (2) mild - 2 dB to - 4 dB, (3) moderate - 4 to - 8 dB, (4) severe - 8 to - 17 dB, (5) very severe <  - 17 dB.

CONCLUSION

Surgical decompression is highly effective in improving visual function. Uniform, quantitative grading of visual dysfunction was lacking. MD is a promising quantitative outcome measure. We provide recommendations for the evaluation of timing of surgery, considering severity of visual impairment, which will need further validation based on expert clinical practice.

Reliability in reporting perceptual experience: Behaviour and electrophysiology in hemianopic patients

Patients with hemianopia can present with the so called blindsight phenomenon: the ability to perform above chance in the absence of acknowledged awareness. Proper awareness reports are, thus, crucial to distinguish pure forms of blindsight from forms of conscious, yet degraded, vision. It has, in fact, been recently shown that 1) dichotomous and graded measures to assess awareness can lead to different behavioural results in patients with hemianopia and that 2) different grades of perceptual clarity show different electrophysiological correlates in healthy participants. Here, in hemianopic patients, we assessed awareness by means of the four-point Perceptual Awareness Scale (PAS) and investigated its neural correlates with Event Related Potentials (ERPs). Results showed that patients, in most of the cases, can rate the clarity of their perceptual experience in a graded manner. Moreover, graded perceptual experiences correlated with the amplitude of deflections in ERPs. These results call for the need to assess perceptual awareness with graded measures and for the importance to use electrophysiological data to correlate behaviour with neural processing.

Visually evoked responses from the blind field of hemianopic patients

Hemianopia is a visual field defect characterized by decreased vision or blindness in the contralesional visual field of both eyes. The presence of well documented above-chance unconscious behavioural responses to visual stimuli presented to the blind hemifield (blindsight) has stimulated a great deal of research on the neural basis of this important phenomenon. The present study is concerned with electrophysiological responses from the blind field. Since previous studies found that transient Visual Evoked Potentials (VEPs) are not entirely suitable for this purpose here we propose to use Steady-State VEPs (SSVEPs). A positive result would have important implications for the understanding of the neural bases of conscious vision. We carried out a passive SSVEP stimulation with healthy participants and hemianopic patients. Stimuli consisted of four black-and-white sinusoidal Gabor gratings presented one in each visual field quadrant and flickering one at a time at a 12Hz rate. To assess response reliability a Signal-to-Noise Ratio analysis was conducted together with further analyses in time and frequency domains to make comparisons between groups (healthy participants and patients), side of brain lesion (left and right) and visual fields (sighted and blind). The important overall result was that stimulus presentation to the blind hemifield yielded highly reliable responses with time and frequency features broadly similar to those found for cortical extrastriate areas in healthy controls. Moreover, in the intact hemifield of hemianopics and in healthy controls there was evidence of a role of prefrontal structures in perceptual awareness. Finally, the presence of different patterns of brain reorganization depended upon the side of lesion.

High prevalence of strabismic visual field expansion in pediatric homonymous hemianopia

If homonymous hemianopia develops in childhood it is frequently accompanied by strabismus. In some of these cases the strabismus increases the size of the binocular visual field. We determined how prevalent visual-field-expanding strabismus is in children who have homonymous hemianopia. Medical records were examined from 103 hemianopic patients with exotropia (XT) or esotropia (ET). For each participant, we determined whether their strabismus was in a direction that resulted in visual field expansion (i.e. left exotropia with left homonymous hemianopia). Ages at which hemianopia and strabismus were first noted were compared to determine which developed first. The prevalence of XT (24%) and ET (9%) with homonymous hemianopia were both much higher than in the general population (1.5% and 5%, respectively). More strabismic eyes pointed to the blind than seeing side (62 vs 41, 60% vs. 40%, p = 0.02). Exotropic eyes were five times more likely to point to the blind side than esotropic eyes (85% vs 15%). Strabismus, especially exotropia, is much more common in pediatric homonymous hemianopia than in the general population. The strabismus is significantly more often in a visual field-expanding direction. These results support an adaptive role for the strabismus. Patients with HH and exotropia or esotropia should be aware that their visual field could be reduced by strabismus surgery.

No Useful Field Expansion with Full-field Prisms

SIGNIFICANCE

Full-field prisms that fill the entire spectacle eye wire have been considered as field expansion devices for homonymous hemianopia (HH) and acquired monocular vision (AMV). Although the full-field prism is used for addressing binocular dysfunction and for prism adaptation training after brain injury as treatment for spatial hemineglect, we show that the full-field prism for field expansion does not effectively expand the visual field in either HH or AMV.

PURPOSE

Full-field prisms may shift a portion of the blind side to the residual seeing side. However, foveal fixation on an object of interest through a full-field prism requires head and/or eye rotation away from the blind side, thus negating the shift of the field toward the blind side.

METHODS

We fit meniscus and flat full-field 7Δ and 12Δ yoked prisms and conducted Goldmann perimetry in HH and AMV. We compared the perimetry results with ray tracing calculations.

RESULTS

The rated prism power was in effect at the primary position of gaze for all prisms, and the meniscus prisms maintained almost constant power at all eccentricities. To fixate on the perimetry target, the subjects needed to turn their head and/or eyes away from the blind side, which negated the field shift into the blind side. In HH, there was no difference in the perimetry results on the blind side with any of the prisms. In AMV, the lower nasal field of view was slightly shifted into the blind side with the flat prisms, but not with the meniscus prisms.

CONCLUSIONS

Full-field prisms are not an effective field expansion device owing to the inevitable fixation shift. There is potential for a small field shift with the flat full-field prism in AMV, but such lenses cannot incorporate refractive correction. Furthermore, in considering the apical scotoma, the shift provides a mere field substitution at best.

Field Expansion for Acquired Monocular Vision Using a Multiplexing Prism

SIGNIFICANCE

Acquired monocular vision (AMV) is a common visual field loss. Patients report mobility difficulties in walking due to collisions with objects or other pedestrians on the blind side.

PURPOSE

The visual field of people with AMV extends more than 90° temporally on the side of the seeing eye but is restricted to approximately 55° nasally. We developed a novel field expansion device using a multiplexing prism (MxP) that superimposes the see-through and shifted views for true field expansion without apical scotoma. We present various designs of the device that enable customized fitting and improved cosmetics.

METHODS

A partial MxP segment is attached (base-in) near the nose bridge. To avoid total internal reflection due to the high angle of incidence at nasal field end (55°), we fit the MxP with serrations facing the eye and tilt the prism base toward the nose. We calculated the width of the MxP (the apex location) needed to prevent apical scotoma and monocular diplopia. We also consider the effect of spectacle prescriptions on these settings. The results are verified perimetrically.

RESULTS

We documented the effectivity of various prototype glasses designs with perimetric measurements. With the prototypes, all patients with AMV had field-of-view expansions up to 90° nasally without any loss of seeing field.

CONCLUSIONS

The novel and properly mounted MxP in glasses has the potential for meaningful field-of-view expansion up to the size of normal binocular vision in cosmetically acceptable form.

Effects of visual search training in children with hemianopia

BACKGROUND

This study investigates the effect of a new computer-based visual search training (VST) that was adapted for children with homonymous hemianopia (HH).

METHODS

22 children with HH (median age 11 years, 8 months: 6y6m-19y2m) trained at home for 15 minutes twice/day, 5 days/week, for 6 weeks. To assess performance before training (T1), directly after training (T2) and 6 weeks after the end of training (T3), we measured search times (STs) during on-screen search (with eye tracking), and in a real life search task. Additional variables analyzed during on-screen search were numbers, amplitudes, and durations of saccades, their directional patterns and the proportional number of saccades into the non-seeing field. The latter was the main variable during free viewing. Sixteen healthy age-matched children, who did not undergo the training, served as comparison group. Quality of Life (QoL)-questionnaires were also applied.

RESULTS

STs of the patients decreased significantly during the training and all search performance tests. This improvement persisted 6 weeks after the end of the training. Saccade amplitudes increased, total number of saccades to find the target decreased, and the proportional number of saccades to the non-seeing side increased. These changes were maintained at T3. Saccade durations did not change. During free viewing, saccades were equally distributed to both sides before and after training. Patients reported improvements in QoL and activities of daily living. Performance in the healthy children did not change by simply repeating the visual search test.

CONCLUSIONS

The improvement in STs in all search tasks, larger and fewer saccades, and an improved search strategy after VST suggests that the children with HH benefited from the training. The maintained improvement at T3 and the improvement in the real life search task indicate that the newly developed search strategy persists and can be applied to everyday life.

Visual rehabilitation training alters attentional networks in hemianopia: An fMRI study

OBJECTIVE

Hemianopia is a visual field defect following post-chiasmatic damage. We now applied functional magnetic resonance imaging (fMRI) in hemianopic patients before and after visual rehabilitation training (VRT) to examine the impact of VRT on attentional function networks.

METHODS

Seven chronic hemianopic patients with post- chiasmatic lesions carried out a VRT for five weeks under fixation control. Before vs. after intervention, we assessed the area of residual vision (ARV), contrast sensitivity function (CSF) and functional MRI data and correlated them with each other.

RESULTS

VRT significantly improved the visual function of grating detection at the training location. Using fMRI, we found that the training led to a strengthening of connectivity between the right temporoparietal junction (rTPJ) to the insula and the anterior cingulate cortex (ACC), all of which belong to the cortical attentional network. However, no significant correlation between alterations of brain activity and improvements of either CSF or ARV was found.

CONCLUSION

Visual rehabilitation training partially restored the deficient visual field sectors and could improve attentional network function in hemianopia.

SIGNIFICANCE

Our MRI results highlight the role of attention and the rTPJ activation as one, but not the only, component of VRT in hemianopia.

Neurorehabilitation of saccadic ocular movement in a patient with a homonymous hemianopia postgeniculate caused by an arteriovenous malformation: A Case Report

RATIONALE

Visual therapy, which includes a restorative and compensatory approach, seems to be a viable treatment option for homonymous defects of the visual field in patients with postgeniculate injury of the visual pathway, due to occipital arteriovenous malformation (AVM). Until now, the Mexican population suffering from homonymous hemianopia did not have health services that provided any type of visual therapy for their condition.

PATIENT CONCERNS

A 31-year-old patient, who underwent a surgical procedure for resection of the AVM, was referred with posterior low vision on the left side.

DIAGNOSES

The patient was diagnosed with left homonymous hemianopia.

INTERVENTIONS

Visual neurorehabilitation therapy (NRT), which integrated restorative and compensatory approaches, was administered for 3 hours each week. NRT included fixation, follow-up, search, peripheral vision, and reading.

OUTCOMES

The NRT did not change visual field defects and, retinotopocally, the same campimetric defects remained. However, after training the tracking ocular movements improved to standard values on the ENG, further, the visual search became more organized. The reading reached a level without mistakes, with rhythm and goog intonation. The Beck test demostrated an improvement in depression symptoms. Regarding the daily life activities, the patient reported significant improvements.

LESSONS

Visual NRT can significantly improve eye movements, as well as the quality of life and independence of the patient. This integral approach could be an effective therapeutic option for homonymous defects of the visual field.

Late emergence of macular sparing in a stroke patient: Clinical Case Report

RATIONALE

Occlusive cerebrovascular disease is the most common cause of homonymous hemianopia (HH) with macular sparing.

PATIENT CONCERNS

A 61-year-old man came to our ophthalmology clinic complaining of right-side hemianopia. Ophthalmic examination, visual field (VF) examination, and brain magnetic resonance imaging (MRI) were performed.

DIAGNOSES

He had right HH without macular sparing on the initial VF test. And brain MRI 6 days after the visual symptoms began revealed a left occipital infarction.

INTERVENTIONS AND OUTCOMES

Thirty-seven days after the onset, his follow-up 24-2 VF examination showed HH with bilateral macular sparing, which was not apparent in the initial VF examination. About 4 months after the stroke, his central 10-2 VF examination also showed HH with bilateral macular sparing.

LESSONS

We report a case of HH with a dramatic improvement in central vision several days after an occipital infarction. To our knowledge, this is the first case to show macular sparing developing after several days.

Homonymous Hemianopia and Vision Restoration Therapy

Homonymous hemianopia from stroke causes visual disability. Although some patients experience spontaneous improvement, others have limited to no change and may be left with a severe disability. Current rehabilitation strategies are compensatory and cannot restore function. Animal studies suggest that central nervous system plasticity could allow for redirection of lost visual function into undamaged areas of cortex. A commercial therapy system was developed, from which claims of visual field expansion were disputed by independent researchers. The treatment remains controversial with seemingly contradictory data being generated. Continued research is underway to demonstrate the (non-)efficacy of this treatment method.

The Effects of Compensatory Scanning Training on Mobility in Patients with Homonymous Visual Field Defects: Further Support, Predictive Variables and Follow-Up

Introduction

People with homonymous visual field defects (HVFD) often report difficulty detecting obstacles in the periphery on their blind side in time when moving around. Recently, a randomized controlled trial showed that the InSight-Hemianopia Compensatory Scanning Training (IH-CST) specifically improved detection of peripheral stimuli and avoiding obstacles when moving around, especially in dual task situations.

Method

The within-group training effects of the previously reported IH-CST are examined in an extended patient group. Performance of patients with HVFD on a pre-assessment, post-assessment and follow-up assessment and performance of a healthy control group are compared. Furthermore, it is examined whether training effects can be predicted by demographic characteristics, variables related to the visual disorder, and neuropsychological test results.

Results

Performance on both subjective and objective measures of mobility-related scanning was improved after training, while no evidence was found for improvement in visual functions (including visual fields), reading, visual search and dot counting. Self-reported improvement did not correlate with improvement in objective mobility performance. According to the participants, the positive effects were still present six to ten months after training. No demographic characteristics, variables related to the visual disorder, and neuropsychological test results were found to predict the size of training effect, although some inconclusive evidence was found for more improvement in patients with left-sided HVFD than in patients with right-sided HFVD.

Conclusion

Further support was found for a positive effect of IH-CST on detection of visual stimuli during mobility-related activities specifically. Based on the reports given by patients, these effects appear to be long-term effects. However, no conclusions can be drawn on the objective long-term training effects.

Multisensory training reverses midbrain lesion-induced changes and ameliorates haemianopia

Failure to attend to visual cues is a common consequence of visual cortex injury. Here, we report on a behavioural strategy whereby cross-modal (auditory-visual) training reinstates visuomotor competencies in animals rendered haemianopic by complete unilateral visual cortex ablation. The re-emergence of visual behaviours is correlated with the reinstatement of visual responsiveness in deep layer neurons of the ipsilesional superior colliculus (SC). This functional recovery is produced by training-induced alterations in descending influences from association cortex that allowed these midbrain neurons to once again transform visual cues into appropriate orientation behaviours. The findings underscore the inherent plasticity and functional breadth of phylogenetically older visuomotor circuits that can express visual capabilities thought to have been subsumed by more recently evolved brain regions. These observations suggest the need for reevaluating current concepts of functional segregation in the visual system and have important implications for strategies aimed at ameliorating trauma-induced visual deficits in humans.

Optokinetic nystagmus in artificial hemianopsy

Optokinetic nystagmus in cases of artificial hemianopsy was studied. Hemianopsy was produced by using a combination of a projector, an erasing device and DC ENG. The effect of the condition of foveal vision in hemianopsy, whether reserved or involved, was discussed. When foveal vision was reserved, nystagmus during stimulation in cases of hemianopsy was essentially the same as in the normal eye. In cases of hemianopsy in which foveal vision was involved, there was a remarkable difference between the mystagmus induced by foveofugal stimulation and that induced by foveopetal stimulation. In the former case the nystagmus was very fine and irregular, in spite of the fact that the nystagmus was well induced (it was nearly the same as in the normal eye in the latter case). Foveal vision is very important for the formation of the slow component of optokinetic nystagmus. Foveopetal movement of the image on the peripheral retina is very important for the formation of the quick component. Foveofugal movement on the peripheral retinal has, on the contrary, only a small effect in attracting the eye.

Lack of multisensory integration in hemianopia: no influence of visual stimuli on aurally guided saccades to the blind hemifield

In patients with visual hemifield defects residual visual functions may be present, a phenomenon called blindsight. The superior colliculus (SC) is part of the spared pathway that is considered to be responsible for this phenomenon. Given that the SC processes input from different modalities and is involved in the programming of saccadic eye movements, the aim of the present study was to examine whether multimodal integration can modulate oculomotor competition in the damaged hemifield. We conducted two experiments with eight patients who had visual field defects due to lesions that affected the retinogeniculate pathway but spared the retinotectal direct SC pathway. They had to make saccades to an auditory target that was presented alone or in combination with a visual stimulus. The visual stimulus could either be spatially coincident with the auditory target (possibly enhancing the auditory target signal), or spatially disparate to the auditory target (possibly competing with the auditory tar-get signal). For each patient we compared the saccade endpoint deviation in these two bi-modal conditions with the endpoint deviation in the unimodal condition (auditory target alone). In all seven hemianopic patients, saccade accuracy was affected only by visual stimuli in the intact, but not in the blind visual field. In one patient with a more limited quadrantano-pia, a facilitation effect of the spatially coincident visual stimulus was observed. We conclude that our results show that multisensory integration is infrequent in the blind field of patients with hemianopia.

Enhanced effective connectivity in mild occipital stroke patients with hemianopia

Plasticity-based spontaneous recovery and rehabilitation intervention of stroke-induced hemianopia have drawn great attention in recent years. However, the underlying neural mechanism remains unknown. This study aims to investigate brain network disruption and reorganization in hemianopia patients due to mild occipital stroke. Resting-state networks were constructed from 12 hemianopia patients with right occipital infarct by partial directed coherence analysis of multi-channel electroencephalograms. Compared with control subjects, the patients presented enhanced connectivity owing to newly formed connections. Compensational connections mostly originated from the peri-infarct area and targeted contralesional frontal, central, and parietal cortices. These new ipsilesional-to-contralesional inter-hemispheric connections coordinately presented significant correlation with the extent of vision loss. The enhancement of connectivity might be the neural substrate for brain plasticity in stroke-induced hemianopia and may shed light on plasticity-based recovery or rehabilitation.

Bitemporal hemianopia; its unique binocular complexities and a novel remedy

Bitemporal hemianopic visual field impairment frequently leads to binocular vision difficulties. Patients with bitemporal hemianopia with pre-existing exophoria complain of horizontal diplopia, sometimes combined with vertical deviation (with pre-existing hyperphoria). The symptoms are a result of the phoria decompensating into a tropia (hemi-slide) due to the lack of retinal correspondence between the remaining nasal fields of both eyes. We measured these effects using a dichoptic perimeter. We showed that aligning the eyes with prisms could prevent diplopia if the bitemporal hemianopia is incomplete. We also describe the successful use of a novel fusion aid - the 'stereo-typoscope' - that utilizes midline stereopsis to prevent diplopia resulting from hemi-sliding in patients with complete bitemporal hemianopia.

Driving with binocular visual field loss? A study on a supervised on-road parcours with simultaneous eye and head tracking

Post-chiasmal visual pathway lesions and glaucomatous optic neuropathy cause binocular visual field defects (VFDs) that may critically interfere with quality of life and driving licensure. The aims of this study were (i) to assess the on-road driving performance of patients suffering from binocular visual field loss using a dual-brake vehicle, and (ii) to investigate the related compensatory mechanisms. A driving instructor, blinded to the participants' diagnosis, rated the driving performance (passed/failed) of ten patients with homonymous visual field defects (HP), including four patients with right (HR) and six patients with left homonymous visual field defects (HL), ten glaucoma patients (GP), and twenty age and gender-related ophthalmologically healthy control subjects (C) during a 40-minute driving task on a pre-specified public on-road parcours. In order to investigate the subjects' visual exploration ability, eye movements were recorded by means of a mobile eye tracker. Two additional cameras were used to monitor the driving scene and record head and shoulder movements. Thus this study is novel as a quantitative assessment of eye movements and an additional evaluation of head and shoulder was performed. Six out of ten HP and four out of ten GP were rated as fit to drive by the driving instructor, despite their binocular visual field loss. Three out of 20 control subjects failed the on-road assessment. The extent of the visual field defect was of minor importance with regard to the driving performance. The site of the homonymous visual field defect (HVFD) critically interfered with the driving ability: all failed HP subjects suffered from left homonymous visual field loss (HL) due to right hemispheric lesions. Patients who failed the driving assessment had mainly difficulties with lane keeping and gap judgment ability. Patients who passed the test displayed different exploration patterns than those who failed. Patients who passed focused longer on the central area of the visual field than patients who failed the test. In addition, patients who passed the test performed more glances towards the area of their visual field defect. In conclusion, our findings support the hypothesis that the extent of visual field per se cannot predict driving fitness, because some patients with HVFDs and advanced glaucoma can compensate for their deficit by effective visual scanning. Head movements appeared to be superior to eye and shoulder movements in predicting the outcome of the driving test under the present study scenario.

Influence of hemianopic visual field loss on visual motor control

BACKGROUND

Homonymous hemianopia (HH) is an anisotropic visual impairment characterized by the binocular inability to see one side of the visual field. Patients with HH often misperceive visual space. Here we investigated how HH affects visual motor control.

METHODS AND FINDINGS

Seven patients with complete HH and no neglect or cognitive decline and seven gender- and age-matched controls viewed displays in which a target moved randomly along the horizontal or the vertical axis. They used a joystick to control the target movement to keep it at the center of the screen. We found that the mean deviation of the target position from the center of the screen along the horizontal axis was biased toward the blind side for five out of seven HH patients. More importantly, while the normal vision controls showed more precise control and larger response amplitudes when the target moved along the horizontal rather than the vertical axis, the control performance of the HH patients was not different between these two target motion experimental conditions.

CONCLUSIONS

Compared with normal vision controls, HH affected patients' control performance when the target moved horizontally (i.e., along the axis of their visual impairment) rather than vertically. We conclude that hemianopia affects the use of visual information for online control of a moving target specific to the axis of visual impairment. The implications of the findings for driving in hemianopic patients are discussed.

Potential proneness of fetal-type posterior cerebral artery to vascular insufficiency in parent vessel occlusion of distal posterior cerebral artery aneurysms

OBJECT

The purpose of this study was to report the potential proneness of a fetal-type posterior cerebral artery (PCA) to develop vascular insufficiency in parent vessel occlusion of distal PCA aneurysms.

METHODS

Between January 2005 and January 2011, 19 patients (9 females and 10 males) with 20 distal PCA aneurysms (16 dissecting and 4 saccular) were treated with endovascular parent vessel occlusion. The ages of the patients ranged from 5 to 71 years, with a mean age of 40.2 years. Of the 20 aneurysms, 4 were ruptured and 16 were unruptured. One of the unruptured aneurysms was additional to another ruptured aneurysm, and 15 were incidentally discovered. Five aneurysms were smaller than 10 mm, and the other 15 were 10 mm or larger.

RESULTS

All aneurysms were successfully treated with simultaneous coil occlusion of the aneurysm and the parent PCA. One patient had hemianopia at the initial presentation, and 2 patients had new persistent hemianopia due to insufficient leptomeningeal collateral circulation; in 16 patients with an intact visual field, no hemianopia developed because there was sufficient leptomeningeal collateral circulation. A fetal-type PCA was involved in all 3 patients with hemianopia, which was initially presented or caused by parent vessel occlusion. However, in the patients without hemianopia, an adult-type PCA was involved in all cases.

CONCLUSIONS

Endovascular treatment via coil occlusion of the aneurysm as well as the parent artery can be used to cure distal PCA aneurysms. A fetal-type PCA could be an important predictive factor for vascular insufficiency in parent vessel occlusion treatment.

Passive auditory stimulation improves vision in hemianopia

Techniques employed in rehabilitation of visual field disorders such as hemianopia are usually based on either visual or audio-visual stimulation and patients have to perform a training task. Here we present results from a completely different, novel approach that was based on passive unimodal auditory stimulation. Ten patients with either left or right-sided pure hemianopia (without neglect) received one hour of unilateral passive auditory stimulation on either their anopic or their intact side by application of repetitive trains of sound pulses emitted simultaneously via two loudspeakers. Immediately before and after passive auditory stimulation as well as after a period of recovery, patients completed a simple visual task requiring detection of light flashes presented along the horizontal plane in total darkness. The results showed that one-time passive auditory stimulation on the side of the blind, but not of the intact, hemifield of patients with hemianopia induced an improvement in visual detections by almost 100% within 30 min after passive auditory stimulation. This enhancement in performance was reversible and was reduced to baseline 1.5 h later. A non-significant trend of a shift of the visual field border toward the blind hemifield was obtained after passive auditory stimulation. These results are compatible with the view that passive auditory stimulation elicited some activation of the residual visual pathways, which are known to be multisensory and may also be sensitive to unimodal auditory stimuli as were used here.

Pathways involved in human conscious vision contribute to obstacle-avoidance behaviour

Human patients with visual field defects following damage to their primary visual cortex (V1) will often misperceive the midpoint of a horizontal line. They tend to shift the midpoint away from the real position towards their blind field. In patients with unilateral neglect, where midpoint shifts can also be observed, these perceptual errors do not lead to errors in an obstacle-avoidance task, which also requires the ability to find the midpoint between two obstacles. This dissociation in neglect patients was taken as evidence that obstacle-avoidance performance is guided by visual information from the dorsal visual stream. Recently it was shown that a patient with hemianopia could avoid an obstacle presented in his blind field. This suggests that obstacle-avoidance behaviour can be guided by subconscious vision alone involving a direct route from extrageniculate structures in the brain to dorsal stream areas. To investigate whether obstacle avoidance relies only on this subconscious route or also uses information from pathways involved in conscious vision, we examined the effect of the hemianopic shift on obstacle-avoidance behaviour. This shift is found in tasks where a conscious visual judgement is required and presumably arises in pathways underlying conscious vision (V1 and ventral stream areas). We compared the performance of six patients with left hemianopia with the performance of six patients with right hemianopia. We found a clear bias in both groups, which also affected obstacle-avoidance performance. It is thus concluded that obstacle avoidance does not bypass the system for conscious vision completely.

The neural correlates of impaired collision avoidance in hemianopic patients

PURPOSE

The aim of this study was to assess the brain regions associated with impaired performance in a virtual, dynamic collision avoidance task, in a group of patients with homonymous visual field defects (HVFDs) because of unilateral vascular brain lesions.

METHODS

Overall task performance was quantitatively assessed as the number of collisions while crossing an intersection at two levels of traffic density. Twenty-six patients were divided into two subgroups using the median split method: patients with 'performance above average' (HVFD(A), i.e. lower number of collisions) and patients with 'performance below average' (HVFD(B), i.e. higher number of collisions). In order to identify the anatomical structures that might be specifically affected in HVFD(B) patients but spared in HVFD(A) patients, overlap, subtraction and voxel-based lesion-symptom mapping analyses were performed using the MRIcron software.

RESULTS

No significant difference in collision avoidance between patients with left- and right-hemispheric lesions was revealed. Separate lesion analysis in 12 patients with right- and 14 patients with left-hemispheric lesions showed that the cortical structures associated with impaired collision avoidance were the parieto-occipital region and posterior cingulate gyrus in the right hemisphere and the inferior occipital cortex and parts of the fusiform (occipito-temporal) gyrus in the left hemisphere.

CONCLUSION

In the present collision avoidance paradigm, impaired performance of patients with right-hemispheric lesions is associated with damage in the dorsal processing stream and potential impact on the visual spatial working memory (WM), while impaired performance of patients with left-hemispheric lesions is associated with damage in the ventral stream and potential impact on the visual object WM.

Cortical networks of hemianopia stroke patients: a graph theoretical analysis of EEG signals at resting state

Visual cortical stroke patients may have hemianopia symptom, which affects a number of visual functions. Most studies on hemianopia stroke have mainly focused on cortical activation during visual stimulation, leaving the pattern of functional connectivity between different brain regions uncovered yet. In the present study, we investigate the resting neural networks of hemianopia stroke patients by graph theoretical analysis of functional brain networks constructed with phase synchronization indexes of multichannel electroencephalography (EEG) signals. Our results showed that although the global network topological metrics, i.e., weighted clustering coefficient and characteristic path length of patients and healthy controls are comparable, the left primary visual cortex of patients tend to be less active than that of age-matched healthy subjects. However, hemianopia patients showed greater activation in the ipsilesional (left) temporopolar and orbit frontal areas and the contralesional (right) associative visual cortex. These results may offer new insight into neural substrates of the hemianopia stroke, and the further study of neural plasticity and brain reorganization after hemianopia.

Reflections on blindsight: neuroimaging and behavioural explorations clarify a case of reversed localisation in the blind field of a patient with hemianopia

Blindsight refers to residual visual abilities of patients with primary visual cortex lesions. Most of this research uses single case studies, most famously patient GY. We examined a patient (DC) after surgical resection of V1 who demonstrated robust but reversed blind field target localisation, mislocalising midline blind field targets to the periphery and vice versa. This pattern was reliable across multiple sessions and was not because of extraocular light scatter. We then used functional magnetic resonance imaging to examine neural responses to blind field motion stimuli with no evidence of motion-selective activation in DC's extrastriate cortex in the damaged hemisphere, in stark contrast to GY who showed robust bilateral activation in response to blind field stimuli. This suggests that DC's blind field performance may not represent true blindsight. Follow-up testing with the target--background contrast reversed (i.e., black targets/white background), eliminated DC's reversed localisation, strongly suggesting that she was employing an unusual decision criterion based on intraocular light scatter. DC's failure to demonstrate true blindsight may be related to the age at which she acquired her lesion--much later in life than GY.

Neglect and Hemianopia Superimposed

In patients with posterior-parietal brain damage it is often difficult to decide whether left-sided omissions in perimetry are due to primary visual loss or due to visual neglect. We investigated 11 patients with combined neglect/hemianopia and 11 patients with pure hemianopia using a visual search task with single or double stimulation conditions. The second stimulus was either the fixation point itself (like in perimetry) or a distractor appearing in the hemifield opposite to the target. The fixation point did not worsen left-sided perception, but its disappearance led to a bias of exploration towards the right side in neglect patients but not in pure hemianopics. A distractor in the intact hemifield worsened the performance to left-sided stimuli, that is, neglect patients behaved as if they were completely hemianopic, even in intact parts of the visual field (VF). Three of the neglect patients showed unconscious processing of the distractor in the left VF, suggesting that the visual field defect was produced by neglect mechanisms rather than primary visual loss. This visual search paradigm appears to be helpful in understanding of the nature of hemianopia versus neglect deficits in individual patients.

Neuropsychology of acute stroke

Neuropsychology includes both the psychiatric manifestations of neurological illness (primary brain-based disorders) and neurobiology of "idiopathic" psychiatric disorders. Neurological primary brain disorders provoke broad spectrum of brain pathophysiology that cause deficit sin human behaviour, and the magnitude of neurobehavioral-related problems is a world wide health concern. Speech disorders of aphasic type, unilateral neglect, anosognosia (deficit disorders), delirium and mood disorders (productive disorders) in urgent neurology, first of all in acute phase of stroke are more frequent disorders then it verified in routine exam, not only in the developed and large neurological departments. Aphasia is common consequence of left hemispheric lesion and most common neuropsychological consequence of stroke, with prevalence of one third of all stroke patients in acute phase although exist reports on greater frequency. Unilateral neglect is a disorder that mostly effects the patient after the lesion of the right hemisphere, mostly caused by a cerebrovascular insult (infarct or haemorrhage affecting a large area - up to two thirds of the right hemisphere), and in general the left-side neglect is the most widespread neuropsychological deficit after the lesion of the right cerebral hemisphere. Reports on the incidence of visual neglect vary and they range from 13 to 85%. Anosognosia is on the second place as neuropsychological syndrome of stroke in right hemisphere, characterized by the denial of the motor, visual or cognitive deficit. This syndrome, defined as denial of hemiparesis or hemianopsia, is a common disorder verified in 17-28% of all patents with acute brain stoke. There are different reports on frequency of delirium in acute stroke, from 24 to 48%, and it is more frequent in hemorrhagic then ischemic stoke. Post stroke depression (PSD) is one of the more frequent consequences on the stroke, and the prevalence of PSD has ranged from 5 to 63% of patients in several cross-sectional studies, peaking three to six months after a stroke.

[Delayed postanoxic encephalopathy with visual field disturbance after strangulation: a case report]

We report the case of a 30-year-old woman with delayed postanoxic encephalopathy and visual field disturbance caused by strangulation. Although she was normal up to the sixth day after strangulation, she developed quadrantic hemianopia on the seventh day. The results of magnetic resonance imaging (MRI) showed high-intensity T(2) and fluid-attenuated inversion recovery (FLAIR) signals in the bilateral striatum; on the basis of these findings, she was diagnosed with delayed postanoxic encephalopathy. Associated with quadrantic hemianopia, an area with low-intensity FLAIR signals was noted in the subcortical region of the right occipital cortex. Single-photon emission computed tomography (SPECT) revealed decreased blood flow in the right occipital lobe and striatum. By day 41 after strangulation, the low-intensity area in the subcortical region of the right occipital cortex disappeared, and high-intensity FLAIR signals were observed in the right occipital cortex. The quadrantic hemianopia and occipital lesion that were revealed by MRI regressed 4 months later. Respiratory dysfunction or circulatory dysfunction causes ischemia of the entire brain; however, strangulation does not lead to disturbances in the blood flow in the regions supplied by the vertebrobasilar artery. However, in the case of the present patient, a lesion was noted in the occipital lobe after strangulation. It has been reported that the autonomic control in the vertebrobasilar artery is weak, and the control of blood pressure in this artery is limited. In the case of this patient, not only the ischemia resulting from the stricture of the artery and the trachea, but also congestion resulting from disturbances in the venous blood flow might be associated with the brain damage and might have thus led to the development of the occipital lesion.

Relationships between brain tumor and optic tract or calcarine fissure are involved in visual field deficits after surgery for brain tumor

PURPOSE

Diffusion tensor tractography provides useful information regarding the surgical strategy for brain tumors. The goal of the present study was to analyze relationships between visual field deficits and the locations of brain tumors compared with optic tracts as visualized by tractography, and compared with the calcarine fissure.

METHODS

Subjects comprised 11 patients with brain tumor in the occipital lobe or atrium of the lateral ventricle who underwent surgery between October 2006 and February 2009. Tumors were categorized as Type A, with almost all the optic tract in the occipital lobe or atrium of the lateral ventricle running close to and stretched by the brain tumor; and Type B, with the optic tract running at least partially distant to the brain tumor and remaining unstretched.

RESULTS

Those type A optic tracts that were laterally compressed by brain tumors (Cases 1-3) displayed hemianopsia after surgery. When the brain tumor was located rostro-medial to the calcarine fissure and optic tracts were compressed caudally by the tumor, lower quadrant hemianopsia remained after surgery (Cases 4, 5). In other cases, the visual field remained or improved to normal after surgery.

CONCLUSION

The relationship between optic tracts or the calcarine fissure, and brain tumors in the occipital lobe or atrium of the lateral ventricle is related to visual field deficits after surgery. In particular, those Type A optic tracts that are compressed laterally show hemianopsia of the visual field after surgery.

Residual neurovascular function and retinotopy in a case of hemianopia

INTRODUCTION

For occipital cortex strokes resulting in vision disorders, questions about the viability of residual visual cortex remain.

CLINICAL PICTURE

In a patient with a one-year-old, left, complete, homonymous hemianopia due to a right, posterior cerebral artery, ischaemic infarct, we assessed the visual cortex with fMRI retinotopic mapping prior to starting vision restoration therapy.

OUTCOME

The patient was found to have residual neurovascular function and retinotopic representation in the surviving visual cortex around the infarcted area.

CONCLUSION

The ability to respond to stimuli in part of the blind field, though not consciously perceived, suggests the potential for recovery.

Reaction Test for Competence in Visual Pathway Lesions

Performance in the visual environment was evaluated with a central fixation or a search target in 11 positions within 34 degrees on a CRT, superimposed on a landscape. Reaction times were recorded. We examined 24 patients aged 26-83, with lesions of the visual pathways and homonymous visual field defects, and 18 normal subjects aged 23-79. This simple test takes about 1 minute in normal subjects and four or more minutes in neurological patients. The test may be used to quantify saccadic adaptation to disability from homonymous field defects and to monitor the training effects of visual rehabilitation.

[Neuro-ophthalmological manifestations of pituitary adenomas. The usefulness of optical coherence tomography]

INTRODUCTION

Pituitary adenomas are a frequently occurring pathology that require multidisciplinary management by several different specialists. Their neuro-ophthalmological manifestations vary widely and sometimes appear as the presenting symptom.

AIM

To gather the main ophthalmological signs and symptoms of these tumours so that specialists who find themselves before any of them will suspect this pathology.

DEVELOPMENT

This survey was based on the clinical experience of the neuro-ophthalmological unit at the Hospital Clinic de Barcelona, with over 350 patients who had suffered from pituitary tumours. A bibliographical search was also carried out on Medline for papers published on pituitary adenomas in the literature in both English and Spanish. We focused mainly on those that reported on the ophthalmological manifestations of such tumours. A number of articles were found dealing with isolated ophthalmological manifestations of these tumours, many of them as presenting symptoms. We also found review articles in English. Apart from oculomotor disorders and other less common findings, visual field defects stand out as the guiding symptom of this condition.

CONCLUSIONS

Improved diagnostic techniques are allowing pituitary tumours to be detected at increasingly earlier stages, but cases are still seen with neuro-ophthalmological symptoms as the presenting symptoms. Familiarity with these syndromes is crucial. In addition to the clinical and visual field examination, optical coherence tomography is particularly useful for the diagnosis and follow-up of these patients. Prospective studies are needed to establish factors for predicting the visual recovery in these patients.

Linking physiology with behaviour: Functional specialisation of the visual field is reflected in gaze patterns during visual search

Based on neurophysiological findings and a grid to score binocular visual field function, two hypotheses concerning the spatial distribution of fixations during visual search were tested and confirmed in healthy participants and patients with homonymous visual field defects. Both groups showed significant biases of fixations and viewing time towards the centre of the screen and the upper screen half. Patients displayed a third bias towards the side of their field defect, which represents oculomotor compensation. Moreover, significant correlations between the extent of these three biases and search performance were found. Our findings suggest a new, more dynamic view of how functional specialisation of the visual field influences behaviour.

[Non-convulsive status with hemianopsia and ictal headaches: an uncommon manifestation of parieto-occipital epilepsy]

INTRODUCTION

Parieto-occipital epilepsy is uncommon disease that usually occurs with positive symptoms such as illusions, visual hallucinations. The pericital headache, with or without migraine-type characteristics, is common symptoms (amaurosis, hemianopsia) are rare.

CLINICAL CASE

A 21 year-old woman with a previous medical history of Rendu-Osler disease was admitted to the hospital because of migraine-type headache. Examination revealed homonymous hemianopsia which had not been previously observed. During admission, brief episodes of ocular and cephalic deviation to the left were observed. An electroecephalogram showed frequent seizures arising from the right parieto-occipital region. Symptoms disappeared with antiepileptic drug treatment.

CONCLUSION

We report a case of parieto-occipital epilepsy with headache and hemianopsia as ictal symptoms. Differential diagnosis must be done basically with migraine attacks. This type of epilepsy may be underdiagnosed.

Long-term effects of prism adaptation on chronic neglect after stroke

Previous studies have discussed the effectiveness or ineffectiveness of prism adaptation for neglect patients.

PURPOSE

The aim of present study was to determine the long-term effect of prism adaptation with activity performance instead of pointing performance on chronic neglect patients.

SUBJECTS

Seven patients with chronic unilateral spatial neglect were recruited.

METHODS

We performed an 8-week intervention using prismatic glasses. Changes in eye movement before and after intervention were measured using an eye mark recorder system. We also assessed intentional spatial bias in terms of center of gravity in the standing position using a tactile sensor scan system. Additionally, regional cerebral blood flow was measured using SPECT (IMP) before and after intervention.

RESULTS

Eye movements significantly improved on the neglected side (p<0.01), and the effects were sustained for up to 6 weeks after the removal of the prism. The center of gravity significantly moved to the left and forward. Furthermore, rCBF showed a significant increase at the parietal cortex, pericalleosal area of the left hemisphere (P<0.05).

CONCLUSION

These results suggest that intervention using prismatic glasses could improve eye movement on the neglected side and correct intentional spatial bias. Prism intervention might be one valuable method for the activation of the important areas of the brain in neglect patients.

Cortical activation in hemianopia after stroke

Changes in neuronal activity of the visual cortex have been described in patients with hemianopia. The anatomical areas that are involved in neuroplastic changes have not been studied in a larger group of stroke patients with a homogenous structural pathology of the visual cortex. Brain activation was measured in 13 patients with a single ischemic lesion of the striate cortex and partially recovered hemianopia and in 13 age-matched control subjects using blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI). Differences in activation between rest and visual hemifield stimulation were assessed with statistical parametric mapping using group and multi-group studies. In normal subjects, the most significant activation was found in the contralateral primary visual cortex (area 17) and bilaterally in the extrastriate cortex (areas 18 and 19). In patients, these areas were also activated when the intact hemifield was stimulated. During stimulation of the hemianopic side, bilateral activation was seen within the extrastriate cortex, stronger in the ipsilateral (contralesional) hemisphere. Stimulation of the hemianopic visual field is associated with ipsilateral activation of the extrastriate visual cortex. This pattern of activation suggests extensive neuronal plasticity within the visual cortex after postgeniculate ischemic lesions and may have implications for therapeutic interventions.

Object-based neglect for the near peripersonal space in drawing tasks

We report a patient with a right cortical and subcortical temporo-occipital lesion who showed spatial neglect mainly involving the left and the near peripersonal space. In drawing tasks the patient omitted the elements closer to him within each figure. A copying task with pairs of radially aligned line drawings demonstrated that the patient's radial neglect was based on within-object coordinates. This novel observation extends the egocentric-allocentric distinction to the radial dimension.

Fluctuation in spontaneous recovery of left visual neglect: a 1-year follow-up

Spontaneous recovery and possible fluctuation in left visual neglect, and its relation to stroke severity, basic activities of daily living (ADL) and extended ADL were examined at 10 days, at 3, 6, and 12 months after onset. Twenty-one of 56 right hemisphere stroke patients had visual neglect. Three visual neglect recovery groups were identified: continuous, fluctuating and poor recovery. We concentrated on the comparison of the continuous and the fluctuating recovery groups. At the acute phase the fluctuating recovery group had larger infarcts, more severe neglect and stroke, and a lower level of basic ADL compared to the continuous recovery group. In the continuous recovery group stable recovery was detected up to 6 months, whereas in the fluctuating recovery group recovery was incoherent in neglect and in extended ADL. A minimum follow-up period of 6 months including the evaluation of extended ADL is recommended for neglect patients due to possible fluctuation in visual neglect.