Negligência unilateral pós-acidente vascular encefálico: atuação da Terapia Ocupacional

Unilateral Neglect Syndrome is one of the consequences of cerebral vascular accident (CVA) generally following right parietal lobe lesion, leading to the impairment of perceptive visual, spatial and attention functions. The patient affected does not realize the environmental stimuli on the contralesional hemibody. Occupational therapy plays an important role in caring for this patient, seeking the recovery of perception, attention and social engagement. This study aimed to describe and evaluate the results of occupational therapy intervention and treatment in a single Unilateral Neglect Syndrome post CVA patient. Data were obtained from a survey of the patient’s medical records and interviews of his therapist and caretaker. The analysis of the patient’s medical records and his therapist’s report showed that the patient responded satisfactorily to treatment, presenting a decrease of the left unilateral neglect at the end of the study period. The favorable outcome of the patient outlined the relevance of evaluating the effects of Occupational Therapy interventions for clinical unilateral neglect syndrome.

Preserved obstacle avoidance during reaching in patients with left visual neglect

We asked 12 patients with left visual neglect to bisect the gap between two cylinders or to reach rapidly between them to a more distal target zone. Both tasks demanded a motor response but these responses were quite different in nature. The bisection response was a communicative act whereby the patient indicated the perceived midpoint. The reaching task carried no imperative to bisect the gap, only to maintain a safe distance from either cylinder while steering to the target zone. Optimal performance on either task could only be achieved by reference to the location of both cylinders. Our analysis focused upon the relative influence of the left and right cylinders on the lateral location of the response. In the bisection task, all neglect patients showed qualitatively the same asymmetry, with the left cylinder exerting less influence than the right. In the reaching task, the neglect group behaved like normal subjects, being influenced approximately equally by the two cylinders. This was true for all bar two of the patients, who showed clear neglect in both tasks. We conclude that the visuomotor processing underlying obstacle avoidance during reaching is preserved in most patients with left visual neglect. (C) 2004 Elsevier Ltd. All rights reserved.

Dopaminergic genotype biases spatial attention in healthy children

In everyday life, our sensory system is bombarded with visual input and we rely upon attention to select only those inputs that are relevant to behavioural goals. Typically, humans can shift their attention from one visual field to the other with little cost to perception. In cases of, unilateral neglect', however, there is a persistent bias of spatial attention towards the same side as the damaged cerebral hemisphere. We used a visual orienting task to examine the influence of functional polymorphisms of the dopamine transporter gene (DAT1) on individual differences in spatial attention in normally developing children. DAT1 genotype significantly influenced spatial bias. Healthy children who were homozygous for alleles that influence the expression of dopamine transporters in the brain displayed inattention for left-sided stimuli, whereas heterozygotes did not. Our data provide the first evidence in healthy individuals of a genetically mediated bias in spatial attention that is related to dopamine signalling.

A new clinical sign probably associated to left hemiplegia with left hemineglect syndrome: the crossed legs

Objetivo : Descrever um novo sinal clínico associado à síndrome de negligência unilateral (SNU) em pacientes com acidente vascular cerebral isquêmico (AVCi). Método : Em 150 pacientes com acidente vascular cerebral isquêmico, foram realizadas tomografias de crânio e aplicada a National Institute of Health Stroke Scale. Aqueles pacientes com lesões vasculares à direita, hemiplegia esquerda e perna direita persistentemente cruzada sobre a esquerda, foram submetidos a testes específicos para SNU. Trinta pacientes também com lesões vasculares à direita, hemiplegia esquerda, porém sem evidências de permanecerem com as pernas cruzadas, foram submetidos aos mesmos testes clínicos. Resultados : Entre 150 pacientes com AVCi, 9 apresentaram lesão vascular cerebral à direita, hemiplegia esquerda e tendência em permanecer com a perna direita cruzada sobre a esquerda. Em 8 deles, testes específicos realizados nos primeiros dias de internação, confirmaram SNU à esquerda. Um paciente morreu antes que os testes pudessem ser aplicados. Dos 30 pacientes que não cruzaram as pernas, os testes foram normais em 20. Dez pacientes apresentaram alterações mínimas, insuficientes para o diagnóstico de SNU. Conclusão : A perna direita cruzada sobre a esquerda pode representar um novo sinal semiológico associado à hemiplegia esquerda e SNU à esquerda.

Prolonged neglect following unilateral disruption of a prefrontal cortical-dorsal striatal system.

We investigated the potential function of the system formed by connections between the medial prefrontal cortex and the dorsomedial striatum in aspects of attentional function in the rat. It has been reported previously that disconnection of the same corticostriatal circuit produced marked deficits in performance of a serial, choice reaction-time task while sparing the acquisition of an appetitive Pavlovian approach behaviour in an autoshaping task (Christakou et al., 2001). Here, we hypothesized that unilateral disruption of the same circuit would lead to hemispatial inattention, contrasting with the global attention deficit following complete disconnection of the system. Combined unilateral lesions of the medial prefrontal cortex (mPFC) and the medial caudate-putamen (mCPu) within the same hemisphere produced a severe and long-lasting contralesional neglect syndrome while sparing the acquisition of autoshaping. These results provide further evidence for the involvement of the medial prefrontal-dorsomedial striatal circuit in aspects of attentional function, as well as insight into the nature of neglect deficits following lesions at different levels within corticostriatal circuitry.

Carbon leakage revisited: unilateral climate policy with directed technical change

Using a stylized theoretical model, we argue that current economic analyses of climate policy tend to over-estimate the degree of carbon leakage, as they abstract from the effects of induced technological change. We analyse carbon leakage in a two-country model with directed technical change, where only one of the countries enforces an exogenous cap on emissions. Climate policy induces changes in relative prices, that cause carbon leakage through a terms-of-trade effect. However, these changes in relative prices also affect the incentives to innovate in different sectors. This leads to a counterbalancing induced-technology effect, which always reduces carbon leakage. We therefore conclude that the leakage rates reported in the literature may be too high, as these estimates neglect the effect of price changes on the incentives to innovate.

Evaluación y tratamiento basados en realidad virtual de la negligencia espacial unilateral: análisis del estado de la cuestión y demostración de enfoques alternativos

En el siguiente trabajo se presenta en primer lugar de forma detallada la enfermedad denominada negligencia espacial unilateral (síntomas, tipos, causas, evaluación y tratamientos) para proporcionar una mejor comprensión del principal objetivo del estudio, que es el análisis de las soluciones virtuales, existentes en la literatura, aplicadas al tratamiento de esta enfermedad, incluyéndose una amplia descripción de cada estudio encontrado sobre el tema. A continuación, se han realizado tres implementaciones en realidad virtual de tres técnicas clásicas de rehabilitación llevadas a cabo en un entorno virtual, que son la estimulación optocinética, eye patching, y adaptación prismática y se ha desarrollado una aplicación 3D para evaluar el grado y tipo de negligencia sufrida por los pacientes. Que de forma conjunta, constituyen un primer paso hacia un enfoque alternativo para el tratamiento de la enfermedad, más personalizado y eficaz. Por último, en las conclusiones, se analizan las principales ventajas y desventajas encontradas en el uso de estas tecnologías aplicadas a la enfermedad y los trabajos futuros que pueden derivar de este trabajo.---ABSTRACT---The following work starts by presenting in detail a disease called unilateral spatial neglect (symptoms, types, causes, assessment and treatment) to provide the background for this study's main objective, which is the analysis of the virtual solutions existing in the literature for the treatment of this disease. The document includes an extensive description of the previous work found in this topic. Afterwards, three implementations of three classical rehabilitation techniques were performed in virtual reality: optokinetic stimulation, eye patching and prism adaptation, as a proof-of-concept, and a 3D application was implemented to assess the degree and type of negligence suffered by patients. Altogether, they constitute a first step towards an alternative approach for the treatment of disease, more personalized and effective. Finally, the conclusions analyze the main advantages and disadvantages encountered in the use of these technologies when applied to this disease and suggest future work.

Neural fate of seen and unseen faces in visuospatial neglect: A combined event-related functional MRI and event-related potential study

To compare neural activity produced by visual events that escape or reach conscious awareness, we used event-related MRI and evoked potentials in a patient who had neglect and extinction after focal right parietal damage, but intact visual fields. This neurological disorder entails a loss of awareness for stimuli in the field contralateral to a brain lesion when stimuli are simultaneously presented on the ipsilateral side, even though early visual areas may be intact, and single contralateral stimuli may still be perceived. Functional MRI and event-related potential study were performed during a task where faces or shapes appeared in the right, left, or both fields. Unilateral stimuli produced normal responses in V1 and extrastriate areas. In bilateral events, left faces that were not perceived still activated right V1 and inferior temporal cortex and evoked nonsignificantly reduced N1 potentials, with preserved face-specific negative potentials at 170 ms. When left faces were perceived, the same stimuli produced greater activity in a distributed network of areas including right V1 and cuneus, bilateral fusiform gyri, and left parietal cortex. Also, effective connectivity between visual, parietal, and frontal areas increased during perception of faces. These results suggest that activity can occur in V1 and ventral temporal cortex without awareness, whereas coupling with dorsal parietal and frontal areas may be critical for such activity to afford conscious perception.

"mind the gap": The size-distance dissociation in visual neglect is a cueing effect

There is a growing body of evidence that the processes mediating the allocation of spatial attention within objects may be separable from those governing attentional distribution between objects. In the neglect literature, a related proposal has been made regarding the perception of (within-object) sizes and (between-object) distances. This proposal follows observations that, in size-matching and bisection tasks, neglect is more strongly expressed when patients are required to attend to the sizes of discrete objects than to the (unfilled) distances between objects. These findings are consistent with a partial dissociation between size and distance processing, but a simpler alternative must also be considered. Whilst a neglect patient may fail to explore the full extent of a solid stimulus, the estimation of an unfilled distance requires that both endpoints be inspected before the task can be attempted at all. The attentional cueing implicit in distance estimation tasks might thus account for their superior performance by neglect patients. We report two bisection studies that address this issue. The first confirmed, amongst patients with left visual neglect, a reliable reduction of rightward error for unfilled gap stimuli as compared with solid lines. The second study assessed the cause of this reduction, deconfounding the effects of stimulus type (lines vs. gaps) and attentional cueing, by applying an explicit cueing manipulation to line and gap bisection tasks. Under these matched cueing conditions, all patients performed similarly on line and gap bisection tasks, suggesting that the reduction of neglect typically observed for gap stimuli may be attributable entirely to cueing effects. We found no evidence that a spatial extent, once fully attended, is judged any differently according to whether it is filled or unfilled.

Body representation alterations in personal but not in extrapersonal neglect patients

There is still a matter of debate around the nature of personal neglect. Is it an attention disorder or a body representation disorder? Here we investigate the presence of body representation deficits (i.e., the visuo-spatial body map) in right and left brain-damaged patients and in particular in those affected by personal neglect. 23 unilateral brain-damaged patients (5 left-brain-damaged and 18 right-brain-damaged patients) and 15 healthy controls took part in the study. The visuo-spatial body map was assessed by means of the “Frontal body-evocation subtest (FBE),” in which participants have to put tiles representing body parts on a small wooden board where only the head is depicted as a reference point. In order to compare performance on the FBE with performance on an inanimate object that had well-defined right and left sides, participants also performed the “Car test.” Group statistical analysis shows that the performance of patients with personal neglect is significantly worse than that of the controls and patients without personal neglect in the FBE but not in the Car test. Single case analyses of the five patients with pure personal neglect confirm the results of group analysis. Our data supports the hypothesis that personal neglect is a pervasive body representation disorder.

Unilateral pseudogerontoxon

Peripheral corneal opacities are a common clinical finding. In this case report we describe the routine presentation of a young adult male patient with unilateral opacities in the peripheral cornea resembling a corneal arcus. These opacities were confined to the level of the anterior corneal stroma. The patient also exhibited bilateral signs of mild keratoconus and reported a history of vernal keratoconjunctivitis as a child. A diagnosis of unilateral pseudogerontoxon was made. Pseudogerontoxon is an opacity of the peripheral cornea resembling corneal arcus that typically occurs in patients with a history of allergic eye disease. The clinical features and differential diagnoses of this relatively uncommon cause of peripheral corneal opacity are discussed.