Introduction: The pathophysiology and sequelae of transient ischaemic attacks (TIA) merit further study,. Particular challenges arise from the on-going debate on diagnostic criteria and the fact that few studies use the modern tissue-based definition. Differences in functional connectivity have previously been identified in a number of conditions, including stroke, have been implicated in the symptom profile and are known to vary during recovery. In this pilot study we investigate whether there were functional connectivity differences between TIA patients and healthy controls.
Methods: Patients were referred for a standard clinical magnetic resonance imaging (MRI) neurovascular protocol, with the addition of a resting state functional MRI (fMRI) sequence. Eight patients diagnosed with a TIA (4 women, 57±9) were recruited, along with eight healthy controls (4 women, 30±5). Independent component analysis was used to isolate the networks before performing non-parametric two-sample t-test using both threshold-free cluster enhancement (TFCE) and voxel-wise statistics.
Results: Significant differences (p<0.05, FWE-corrected) emerged using TFCE, in particular increased connectivity was noted in the mid-cingulate area with contrasting decreases in the cerebellum within the sensorimotor network. Additionally clusters of decreased connectivity were noted in the right insula in an attentional component, the pre-cuneus within the default mode network and the supplementary motor area in a visual component. No significant differences between the TIA and control group were above the threshold using voxel-wise statistics.
Conclusion: In line with previous research in groups of stroke patients, this study has identified evidence of differences in neural connectivity associated with TIA, which cannot be explained by age. Differences in the sensorimotor network may be linked to the symptoms experienced by patients, with the mid-cingluate area being implicated in memory and learning. Alterations in functional connectivity may be relevant for recovery, including the on-going cognitive deficits reported in TIA patients. These findings suggest an important area for further research with a larger cohort.