Non-invasive simultaneous recording of neuronal and vascular signals in subacute ischemic stroke

In acute focal cerebral ischemia blood flow and neuronal activity change dramatically. A better understanding of the pathophysiological interactions of these two important parameters is limited owing to the lack of noninvasive techniques to simultaneously measure these parameters in humans. In this feasibility study, we used DC-magnetoencephalography and near-infrared spectroscopy to find out whether blood flow and neuronal activity as well as neurovascular coupling can be analyzed in patients suffering from subacute ischemic stroke. In a simple motor test condition, six patients with subacute ischemic stroke performed self-paced finger movements (30-s periods of movement, separated by 30-s periods of rest; for a total of 15 min). Combined DC-magnetoencephalography and near-infrared spectroscopy were recorded over the affected and unaffected hemispheres. As a control group, four healthy subjects were investigated. In four out of six patients, the time courses of both signals closely followed the motor task cycles revealing significant differences between movement and rest periods. The vascular signal reached a maximum 1-5 s later than the neuronal signals. This proof-of-principle study demonstrates that it has become feasible to simultaneously and noninvasively monitor neuronal and vascular signal changes in patients in the subacute state of ischemic stroke.