Incidence and anatomy of gaze-evoked nystagmus in patients with cerebellar lesions

Background: Disorders of gaze-holding-organized by a neural network located in the brainstem or the cerebellum-may lead to nystagmus. Based on previous animal studies it was concluded that one key player of the cerebellar part of this gaze-holding neural network is the flocculus. Up to now, in humans there are no systematic studies in patients with cerebellar lesions examining one of the most common forms of nystagmus: gaze-evoked nystagmus (GEN). The aim of our present study was to clarify which cerebellar structures are involved in the generation of GEN. Methods: Twenty-one patients with acute unilateral cerebellar stroke were analyzed by means of modern MRI-based voxel-wise lesion-behavior mapping. Results: Our data indicate that cerebellar structures such as the vermal pyramid, the uvula, and the tonsil, but also parts of the biventer lobule and the inferior semilunar lobule, were affected in horizontal GEN. Conclusion: It seems that these structures are part of a gaze-holding neural integrator control system. Furthermore, GEN might present a diagnostic sign pointing toward ipsilesionally located lesions of midline and lower cerebellar structures. Neurology (R) 2011;76:361-365