Transient Upbeat Nystagmus Due to Unilateral Pontine Infarction

Upbeat nystagmus has been described in bilateral lesions of the medulla, the ventral tegmentum, the anterior cerebellar vermis, the adjacent brachium conjunctivum, and the midbrain. Imbalance of the vertical vestibulo- ocular reflex (VOR) favoring the downward VOR activity would therefore result in upbeat nystagmus. We report a patient with transient upbeat nystagmus due to unilateral pontine infarction that may have disrupted bilateral upward VOR pathways running in the ventral tegmental tracts.

Episodic Central Neurogenic Hyperventilation in an Awake Patient with Unilateral Pontine Infarction

Central neurogenic hyperventilation (CNH) is characterized by sustained tachypnea inspite of an elevated arterial PaO2, pH and a low arterial PaCO2. CNH is common in patients with brainstem injury accompanied by a decreased level of consciousness but this also has been described in some alert patients with an invasive brainstem tumor. We report one case with CNH resulting from a unilateral pontine infarction. His consciousness was clear, and CNH spontaneously disappeared without any medication.