Arterial spin labelling shows functional depression of non-lesion tissue in chronic Wernicke’s aphasia

Robson, H., Specht, K., Beaumont, H., Parkes, L. M., Sage, K., Lambon Ralph, M. A. and Zahn, R. (2017) Arterial spin labelling shows functional depression of non-lesion tissue in chronic Wernicke’s aphasia. Cortex, 92. pp. 249-260. ISSN 0010-9452 doi: 10.1016/j.cortex.2016.11.002

Abstract/Summary

Behavioural impairment post-stroke is a consequence of structural damage and altered functional network dynamics. Hypoperfusion of intact neural tissue is frequently observed in acute stroke, indicating reduced functional capacity of regions outside the lesion. However, cerebral blood flow is rarely investigated in chronic stroke. This study investigated cerebral blood flow in individuals with chronic Wernicke’s aphasia and examined the relationship between lesion, cerebral blood flow and neuropsychological impairment. Arterial spin labelling cerebral blood flow imaging and structural MRIs were collected in 12 individuals with chronic Wernicke’s aphasia and 13 age-matched control participants. Joint independent component analysis (jICA) investigated the relationship between structural lesion and hypoperfusion. Partial correlations explored the relationship between lesion, hypoperfusion and language measures. Joint ICA revealed significant differences between the control and WA groups reflecting a large area of structural lesion in the left posterior hemisphere and an associated area of hypoperfusion extending into grey matter surrounding the lesion. Small regions of remote cortical hypoperfusion were observed, ipsilateral and contralateral to the lesion. Significant correlations were observed between the neuropsychological measures (naming, repetition, reading and semantic association) and the jICA component of interest in the WA group. Additional ROI analyses found a relationship between perfusion surrounding the core lesion and the same neuropsychological measures.