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Content: Rostral (upper) pontomesencephalic lesions cause ipsilesional hypertropia, and caudal (lower) pontomedullary lesions cause contralesional hypertropia. Skew deviation can also occur in cerebellar lesions (Wong and Sharpe, 2005). Skew deviation is rarely associated with vestibular lesions and suggested by some to be specific for vestibular "pseudoneuritis" -- a brainstem lesion emulating vestibualr neuritis(Cnyrim, Newman-Toker, et al. 2008). . However, it is not a specific sign as there is good evidence that it occurs in purely peripheral lesions (Vibert. et al., 1996)
Acutely, utricular damagecan also cause hyperdevation. It would seem to us that saccular damage might also cause hyperdeviation, but this has not been reported in the literature to our knowledge. Alternating skew deviation, in which the hypertropic eye occurs on the side of horizontal gaze direction, is associated with lesions of the cervicomedullary junction or cerebellar pathways. Ocular tilt reaction
In normal humans, static lateral head tilt causes sustained low-amplitude counter-roll of the eyes and a small vertical misalignment, so that the lower eye is a little higher than the upper eye.