Vertical one-and-a-half syndrome in a patient with pecheron artery ischemia: A case report.

Vertical one-and-a-half syndrome (VOHS) is an uncommon presentation resulting from a unilateral thalamomesencephalic stroke with involvement of the rostral interstitial nucleus of the medial longitudinal fasciculus and posterior commissure. The artery of Percheron (aPe) is a branch of the posterior cerebral artery (PCA) and it is a variant that arises as a solitary trunk supplying both medial thalami and upper midbrain. A 78-year-old female patient, presented at the hospital emergency with approximately 12 hours of sudden onset of diplopia, associated with dizziness. Neurological exam revealed torsional nystagmus associated with bilateral upgaze palsy with limitation of infraduction on the left. We describe a rare case of VOHS associated with ischemic alterations at the MRI suggesting an aPe impairment. The conjugate gaze control lies anatomically at the midbrain at the central nervous system (CNS). This report describes a rare type of VOHS and brings a new insight on a possible aPe topography possibly causing this clinical presentation.