Ipsiversive partial ocular tilt reaction in a patient with acute paramedian thalamic infarctions

The ocular tilt reaction (OTR) consists of skew deviation, ocular torsion and head tilt. A 54-year-old woman developed sudden onset of vertical diplopia. On primary gaze, there was skew deviation with the left eye higher than the right eye. The photography of fundus disclosed 15 degrees of excyclotropia of the right eye and 20 degrees of incyclotropia of the left eye. There was no motor deficit, sensory impairment, ataxia or changes in consciousness. Brain MRI, including T2WI, FLAIR and DWI, revealed two lesions of high signal intensities in bilateral paramedian thalamus, with the much larger and brighter one on the right side. These findings constituted an ipsiversive partial OTR, i.e. skew and torsion toward the side of the lesion. OTR as the only manifestation of paramedian thalamic stroke is rare. A previous report by Dieterich and Brandt indicated that if an OTR occurred in a paramedian thalamic infarct, there should be concurrent ischemia of the interstitial nucleus of Cajal, and it was always contraversive. In contrast, the lesions in our case were quite localized in the paramedian thalamus, not extending into the midbrain. In addition, this report demonstrated an OTR could be ipsiversive under such conditions, opposite to the direction mentioned in previous reports.