Peripheral type facial palsy in a patient with dorsolateral medullary infarction with infranuclear involvement of the caudal pons.

The corticobulbar tract fibers descend near the corticospinal tract, mostly to the upper medulla, where they decussate and ascend in the dorsolateral medulla to connect with the contralateral facial nucleus. Therefore, central type facial palsy can be present in patients with ipsilateral dorsolateral upper medullar lesion. We describe a 71-year-old man with lateral medullary infarction who showed ipsilateral peripheral type facial palsy. Brain diffusion-weighted image showed hyperintensities on the left dorsolateral portion of upper medulla and adjacent inferomedial tegmentum of the lower pons. Transfemoral cerebral angiography depicted prominence of ipsilateral posterior inferior cerebellar artery with focal stenosis. Left posterior inferior cerebellar artery might supply the inferolateral tegmentum of the lower pons, which is usually supplied from anterior inferior cerebellar artery. The peripheral type facial palsy in our patient may have resulted from facial infranuclear involvement of the caudal pons extended from dorsolateral upper medullary lesion in ascending pathway of corticobulbar tract fibers.