Unilateral spatial neglect in degenerative brain pathology

In an attempt to interpret neglect as a disconnection syndrome, it is currently proposed that the disorder results from disorganization of large-scale networks involved in attentional spatial processes rather than of individual brain areas. We hypothesize that as degenerative brain diseases are "system pathologies," degeneration could be restricted to some of the neural subsystems implicated in the functional organization of spatial attention and different neglect syndromes could emerge depending on the patterns of the subsystems involved.

We studied five neglect patients: one with corticobasal degeneration (CBD), three with Posterior Cortical Atrophy (PCA) and one with frontotemporal dementia (FTD).

The patient with CBD and left parietoccipital atrophy showed right allocentric neglect; the three patients with PCA mostly distributed in the right posterior regions showed left egocentric extrapersonal neglect; the patient with FTD, who displayed more severe frontotemporal atrophy on the right, had left motor-executive neglect for both personal and extrapersonal space. All patients also presented a deep breakdown of spatial working memory.

Our data would confirm that left neglect is more frequent than right neglect also in degenerative pathology and that damage to different neural substrates can produce different types of neglect. Our findings are also consistent with the hypothesis that both lateralized and nonlateralized attention disorders contribute to generate the syndrome. We suggest that evidence from degenerative diseases may contribute to construction of models of spatial attention.