Spontaneous recovery of visually-triggered saccades after focal lesions of the frontal and parietal eye fields: A combined longitudinal oculomotor and fMRI study

Abstract

Objective To analyze oculomotor recovery in a patient with ischemic lesions restricted to the left frontal eye field (FEF) and the left parietal eye field (PEF). Methods Two, three, and four weeks after the stroke, saccades were measured and mean gain and latency were calculated. At the same time intervals and 2 months after stroke, the same oculomotor paradigm was performed during fMRI. Bilateral FEF and PEF were identified and defined as volumes of interest (VOI). Both cluster size and mean percentage blood oxygenation level-dependent (BOLD) signal changes were computed for each VOI. Results Initially, rightward saccades were hypometric and showed bilaterally increased latencies that recovered within 4 weeks ( Talairach and Tournoux, 1988). FMRI revealed important changes in cluster size and percentage BOLD signal change in the contralesional and ipsilesional hemisphere. A persisting high activation was found in the contralesional intact FEF and PEF, whereas in the lesioned FEF and PEF, the initially absent or reduced activity increased. Two months after stroke symmetric activations in both FEF and PEF were found. Conclusions Saccade deficits completely and rapidly recovered due to functional rearrangements within the ipsi- and contralesional hemispheric oculomotor network. Significance This study shows the importance of the contralesional and ipsilesional hemispheres in oculomotor recovery.