Unilateral internuclear ophthalmoplegia with upbeat nystagmus from ischemic origin: evidence for the paramedian tract neurons as a vertical neural integrator?

Only a few cases with unilateral internuclear ophthalmoplegia have been reported presenting vertical nystagmus, and few of them provides convincing evidence for the paramedian tract neuron to be a vertical neural integrator. We report a patient who suffered from confined dorsal mid-upper pontine infarction showing unilateral internuclear ophthalmoplegia with upbeat nystagmus in primary position. This case possibly provide evidence that paramedian tract neurons may act as a vertical neural integrator in human.