The medial longitudinal fasciculus (MLF) is a pair of crossed fibers of axons, on each side of the brainstem that carries information about the direction of eye movement. An ischemic stroke is the most common cause of MLF syndrome. We report a patient with unilateral partial oculomotor paresis associated with internuclear ophthalmoplegia, which is a dysfunction of the MLF in the pontine. A second diffusion-weighted magnetic resonance imaging (DW-MRI) showed a high-signal-intensity lesion in the brainstem. We would like to emphasize that detailed neurological physical examination and imaging control are essential aspects of clinical assessment for the diagnosis of MLF infarction because its detection based on imaging is challenging.
Keywords: Partial oculomotor paresis, brainstem, MLF, MRI