Cerebral haemodynamic changes accompanying cognitive impairment in primary lateral sclerosis

Our objective was to elucidate the relationship between cognitive decline and cerebral haemodynamics in patients with PLS. We examined 18 patients with PLS and contrasted both neuropsychological and cerebral perfusion findings with seven age- and education-matched non-PLS controls. PLS patients were stratified into two groups based on the number of abnormal neuropsychological test scores: 1) cognitively intact PLS patients (PLS; those having zero or one abnormal scores (n =14)), and 2) cognitively-impaired PLS patients (PLSci; those having two or more abnormal test scores (n =4)). There was considerable heterogeneity in level of cognitive functioning with four patients meeting the criteria for cognitive impairment. The findings were highly consistent with a frontotemporal lobar dysfunction. Using CT perfusion to assess cerebral haemodynamics, the PLSci group had increased cerebral blood volume (CBV) and mean transit time (MTT) with reduced cerebral blood flow (CBF). More specifically, MTT was significantly increased (p<0.05) in the PLSci group compared with controls in all regions and affected both grey and white matter, with the exception of the temporal lobe and subcortical parietal white matter. These observations suggest that a subset of PLS patients is subject to cognitive decline and that this process is associated with changes in cerebral haemodynamics.