Cognitive rehabilitation of the hemineglect disorder in chronic patients with unilateral right brain damage

Abstract

Thirteen patients with a stabilized hemineglect symptomatology due to right-hemisphere lesions were subjected to a rehabilitation training specifically aimed at reducing the scanning deficit. The training consisted of four procedures (visual-spatial scanning, reading and copying training, copying of line drawings on a dot matrix, and figure description) which lasted 40 sessions. By the end of therapy, the patients as a group showed significant improvements on several standard tests of hemineglect. The results on a Semi-structured Scale for the Functional Evaluation of Hemineglect pointed to the extension of exploratory improvements to situations similar to those of daily life. In contrast, patients improved very slightly on a variety of standard visual-spatial tests, indicating the specificity of training in reducing the scanning defect. Seven patients were examined at a follow-up several months after the end of therapy and appeared stable on both standard and functional tests of neglect.

The Novelty Effect in Recovered Hemineglect

“…Consistent with previous observations (Friedrieh and Margolin, 1993;Posner et al, 1984), the present study shows that RT testing may reveal a residual spatial bias in patients who had recovered from neglect. The serial analysis of response latencies demonstrated that this residual bias mainly affected the initial phase of the task.…”

“…If the observer voluntarily attends to a stimulus, an abrupt onset at another spatial location is not able to capture his or her attention. These observations fit in a hierarchical model of attentional orienting (see Posner and Petersen, 1990), in which a frontal system, more concerned with volitional orienting, controls more posterior areas, which are in turn responsible for automatic, stimulus-driven orienting. When the anterior system is not employed, then an abrupt onset automatically captures attention through the activation of the posterior system.…”

“…On the other hand, frontal cognitive abilities are also important for recovery from neglect, which is more rapid in patients without injury to the right frontal cortex (Hier et al, 1983), and is related to the restoration of metabolism in the ipsi-and contralesional frontal cortices (Cappa, Perani, Paulesu et al, 1995;Pantano, Di Piero, Fieschi et al, 1992;Perani, Vallar, Paulesu et al, 1993). The notion of neglect recovery as determined by frontal cognitive abilities implies that the anterior attention system does not only act through the modulation of the posterior system, as the hierarchical hypothesis maintains (Posner and Petersen, 1990). Rather, this notion suggests that the two systems are organised in a double architecture, hierarchical and parallel.…”

“…Nevertheless, evidence is accumulating that subtle spatal deficits persist in patients who had recovered from neglect (Campbell and Oxbury, 1976;Friedrich and Margolin, 1993;Goodale, Milner, Jakobson et al, 1990;Kaplan, Cohen, Rosengart et al, 1995;Karnath, 1988;Mattingley, Bradshaw, Bradshaw et al, 1994;Posner, Walker, Friedrich et al, 1984). Karnath (1988) hypothesised a multi-component model of neglect consisting of an initial, automatic orienting of attention toward the ipsilesional side, an impairment in reorienting attention toward the contralesional side and a more general, non-directional attentional deficit.…”

“…As a consequence, performance on tests of this sort should remain impaired when patiens are improved on tests emphasising the exploratory-motor components. Indeed, Pizzamiglio, Antonucci, Judica et al (1992) found that performance on a task based on the Wundt-Jastrow illusion was only slightly improved after neglect rehabilitation, while reading and cancellation tests showed more substantial improvements. Similar results were obtained in a longitudinal study of neglect patients who had not reccived specific rehabilitation (Mattingley et al, 1994).…”