Oculomotor fascicular syndrome involving the right superior rectus and the inferior oblique muscles

Abstract

We report a case of partial oculomotor palsy due to a brainstem infarction. A 70-year-old female noted a sudden onset of double vision. Visual acuity was normal in both eyes. Pupils were round and isocoric. The right eye was hypotropic and showed an elevation deficit. Bell’s phenomenon was not evident in the right eye. MRI showed a low intensity on the T1-weighted image and a high intensity on the T2-weighted image in the right ventrolateral portion of the mesencephalon. The partial oculomotor paresis of this case reflects damage of the oculomotor nerve fascicles that supply the inferior oblique and superior rectus muscles. We diagnosed the case as right oculomotor fascicular syndrome. This case report also suggests that acquired monocular elevation paresis can be caused by a lesion in the midbrain.