The effects of 4‐aminopyridine on cognitive function in patients with multiple sclerosis

Abstract

<b><i>Background:</i></b> The BOLD signal in functional MRI (fMRI) is closely related to neural activity. <b><i>Objective:</i></b> To investigate if this relationship is disrupted after ischemic stroke. <b><i>Methods:</i></b> BOLD activity during tactile exploration of objects was measured with fMRI at 1 week (subacute), 2 to 4 weeks (early chronic), and after 1 month (chronic) after the first completed brain infarction affecting the sensorimotor cortex in eight patients. Functional integrity of the motor cortical output system was assessed with transcranial magnetic stimulation (TMS). <b><i>Results:</i></b> Early after infarction the BOLD-response occurred in the adjacent cortical vicinity related to finger movements of the affected hand. However, during the early chronic stage there was a transient lack of this activation despite clinical improvement of hand function and preserved motor evoked potentials. The BOLD activity reappeared after further improvement in the chronic stage. <b><i>Conclusions:</i></b> Our findings suggest a transient hemodynamic-electrical decoupling in the post-ischemic cerebral cortex during the early phase of spontaneous clinical recovery.