ISCHEMIC AND HEMORRHAGIC BRAIN-STEM LESIONS MIMICKING DIABETIC OPHTHALMOPLEGIA

Two patients with diabetes mellitus, one of them with an isolated thir d cranial nerve palsy and the other with an isolated sixth cranial ner ve palsy, are presented. MRI investigations including diffusion-weight ed MRI revealed a small ischemic brain stem lesion in the former and a small hemorrhagic brain stem lesion in the latter. In the former case wallerian degeneration of the nerve fascicle within the mesencephalon was also detected. These cases indicate that vascular accidents of th e brain stem may masquerade as fascicular or infranuclear disturbance of the oculomotor or abducens nerve; therefore, it is important to inc lude brain stem lesions into the differential diagnosis of isolated op hthalmoplegia. Thorough investigation by MRI including diffusion-weigh ted MRI is helpful for correct diagnosis.