A lesion of the medial longitudinal fasciculus produces slowed or absent adduction of the ipsilateral eye upon contralateral gaze. This is usually associated with involuntary jerky eye movements (nystagmus) of the abducting eye, a syndrome called internuclear ophthalmoplegia. Because multiple sclerosis causes demyelination of the axons of the central nervous system, it can cause internuclear ophthalmoplegia when medial longitudinal fasciculus axons get demyelinated.Multiple Sclerosis Encyclopaedia This presents as nystagmus and diplopia. Other demyelinating diseases, as well as certain neoplasms and strokes, can also cause the same symptoms.
