Reader response: Teaching Video NeuroImages: Vestibulo-ocular reflex defect in cerebellar stroke.

We read with interest the report “Teaching Video NeuroImages: Vestibulo-ocular reflex defect in cerebellar stroke” by Witsch et al.1 Although this is a well-written case report with a good-quality video, we have an alternative interpretation of the MRI findings. The flocculus is located posterior to the facial and vestibulocochlear nerves and the internal auditory canal at the cerebellopontine level, and the nodulus is located just posterior to the fourth ventricle at the facial colliculus level. Lesions involving the flocculus can cause gaze-evoked nystagmus, impaired smooth pursuit, contraversive ocular tilt reaction, and reduced vestibulo-ocular reflex gain for head impulses directed contralateral to the lesion.2 However, the lesion found by the authors, indicated by the arrow in the diffusion-weighted MRI scan,1 has a more posterolateral location compared with the floccular area on MRIs of previous reports2 and on anatomic templates (figure).