Brain SPECT imaging and left hemispatial neglect covaried using partial least squares: The Sunnybrook Stroke Study

Hemispatial neglect, characterized as failure to attend to contralesional s pace, is hypothesized by current neuroanatomical models to result from dama ge to a network involving the frontal, parietal, and cingulate cortices, ba sal ganglia, and thalamus. This study investigated this model of neglect in 81 right hemisphere-damaged acute stroke patients using Tc-99m-HMPAO singl e photon emission-computed tomography (SPECT). In order to exploit the inhe rent collinearity of SPECT regional brain ratios, a novel statistical techn ique, partial least squares (PLS), was utilized. It makes use of high corre lations to identify biologically relevant patterns of brain activity. Avera ged ipsilesional cerebellar ratios from 152 brain segments were covaried wi th performance on subtests of the Sunnybrook Neglect Battery. In this patie nt sample, the most influential region identified by PLS corresponded to th e area surrounding the right temporal-parietal-occipital (TPO) junction tha t included the right lateral occipital, temporal, and inferior parietal lob es. Hypoperfusion in the medial frontal cortex, including the anterior cing ulate, also emerged as significantly associated with more severe neglect. T hus, hypoperfusion in only two of the five hypothesized network regions eme rged as significantly associated with hemispatial neglect on SPECT imaging. This work converges with structural imaging studies to suggest that damage to the TPO junction, not just the parietal lobe, may be the critical regio n for hemispatial neglect. Our study demonstrated the utility of PLS for an alyzing functional imaging and behavioral data sets in a clinical populatio n in relation to current neuroanatomical models of neglect. Hum. Brain Mapp ing 7:244-253, 1999. (C) 1999 Wiley-Liss, Inc.