Appearance and disappearance of unilateral spatial neglect for an object: influence of attention-attracting peripheral stimuli

Why are some patients with severe neglect able to copy a cube? The significance of verbal intelligence

Cube-copying is often used to assess constructional ability of brain-damaged patients and the influence of unilateral spatial neglect is often pointed out in patients with right hemisphere lesions. However, some patients with severe neglect perform cube-copying satisfactorily. The aim of the present study is to identify the factors that affect the performance of cube-copying in patients with left unilateral spatial neglect. Constructional performance was investigated in 100 patients with unilateral spatial neglect using a task to copy the Necker cube. The relationship of the patients' cube-copying performance to the severity of their neglect, as well as other factors (verbal intelligence, age, duration after onset of the disease, educational level, lesion site, piecemeal approach, and side of starting to copy) was analyzed. Twenty-two normal subjects also participated in this study as controls. Among many factors adopted for analysis, neglect severity and verbal intelligence were found to be primary factors affecting the cube-copying performance of the patients with unilateral spatial neglect. The effect of neglect severity on cube-copying performance was apparent in the patients whose verbal intelligence was deteriorated, but was not observed in the patients with preserved verbal intelligence. Similarly, the effect of verbal intelligence on cube-copying performance was apparent in the patients with severe neglect, but not in the patients with mild neglect. We conclude that constructional ability in the copying of a cube is determined by verbal intelligence, as well as by the severity of unilateral spatial neglect.

Effektivität experimenteller und rehabilitativer Interventionen bei visuellem Neglect - Eine Metaanalyse

Zusammenfassung: Präsentiert wird eine Metaanalyse zur Wirksamkeit neuropsychologischer Interventionen bei visuellem Hemineglect. Es wurden die publizierten Outcome-Ergebnisse Experimental- und Rehabilitationsstudien zur Modifikation und Modulation des Neglectsyndroms quantitativ integriert. 133 identifizierte Studien wurden in sechs Klassen eingeteilt. Studien-, Interventions- und Patientenmerkmale dienten zur Bestimmung moderierender Einflüsse, über Sensitivitätsanalysen wurde die Robustheit der Ergebnisse abgeschätzt. Die mittlere Gesamteffektivität der Interventionen liegt um 0.8 Standardeinheiten Symptomverbesserung gegenüber dem Prä-Niveau bei Patienten mit chronischem Neglect. Spontanremissionseffekte sind aufgrund der durchschnittlichen Erkrankungsdauer als gering zu veranschlagen und konnten empirisch nicht nachgewiesen werden. Explorationstrainings, personale Intervention und Hinweisreiz-Verfahren stellen sich als überdurchschnittlich effektiv und signifikant effektiver als bloße Reduktion der Umweltanforderungen heraus.

Unassociated responses to two related task demands: a negative factor for improvement of unilateral spatial neglect

Patients with relatively mild unilateral spatial neglect underwent the line bisection task with self-estimation, where they were asked two different questions about the relationship of their subjective midpoint to the line. For the first trial, all patients responded by "yes" when asked whether their subjective midpoint was placed at the center of the line, but by "left" or "right" when asked to indicate the longer segment of the bisected line. In the subsequent trials, they repeatedly reported that their subjective midpoints were placed at the true center, even after they had recognized their bisection errors when indicating the longer segment. Of the 32 patients, 28 kept on showing this pattern of responses in almost all the 30 trials. Moreover, the patients who could estimate the longer segment showed no improvement of line bisection throughout the trials. Their performances strongly depended upon the task demand regarding the subjective midpoint. These results demonstrate that the patients treated the two related tasks as independent. Accordingly, they could not improve their performances on one task with the feedback from their performances on the other. The lack of association between the responses to two related task demands may be one of the factors that prevent patients with unilateral spatial neglect from improving the deficit.

Disappearance of unilateral spatial neglect following a simple instruction

OBJECTIVES

To clarify the reason why patients with left unilateral spatial neglect fail to copy the left side of a daisy like flower, not continuing to draw petals all around.

METHODS

A flower was simplified and a figure was made that consisted of a large central circle and small circles surrounding it. Four patients with typical left unilateral spatial neglect performed copying and arrangement tasks to make this figure. In the arrangement task, they were instructed to arrange small circles all around the printed central circle.

RESULTS

The patients' identification of the composition seemed flawless. In the copying task, they showed neglect, leaving a space on the left side. They seemed to adhere to their plan to place the same number of small circles as those of the model figure. By contrast, neglect disappeared in the arrangement task.

CONCLUSION

Patients with neglect can draw the figure satisfactorily if they use a spatial strategy to arrange small circles all around. This strategy seems to improve motivation for drawing and awareness for the left space. It is considered that in the copying of figures such as a daisy, failure to use a spatial strategy plays an important part in the appearance of left unilateral spatial neglect.