Pendular nystagmus corresponds to an enduring to and fro eye oscillation without resetting
quick phases. The most common causes of acquired pendular nystagmus (APN) are multiple
sclerosis (MS) and focal brainstem lesions (oculopalatal tremor, OPT). Based on
pathophysiological hypothesis, pharmacological treatments of acquired nystagmus have been
thoroughly proposed over different publications of cases, series, reviews or expert opinions.
Acquired pendular nystagmus underwent the most rigorous treatment trials, leading to the
proposal of gabapentin or memantine as valuable drugs. Whether gabapentin and memantine are
effective in APN associated with OPT remains unclear, since none of the previous studies has
evaluated the effect of these medications in a group of OPT patients. However, this is an
important issue in prospect to a clinical use of these medications. In the current study, the
investigators aim is to evaluate the effect of gabapentin and memantine on the mean velocity,
amplitude and frequency of pendular nystagmus, as well as on visual acuity and
vision-specific health-related quality of life score, in a group of OPT patients