Early magnetic resonance imaging in acute traumatic internuclear ophthalmoplegia. Adduction deficiency following acute head trauma may result not only from orbital damage but also from internuclear ophthalmoplegia, and in most instances this resolves over weeks to months. To date, noninvasive imaging studies during the acute phase following injury have not been definitive in localizing the pathology. Three cases of adduction deficiency following head trauma that were caused by internuclear ophthalmoplegia are reported. A lesion in the brain stem was found in all three cases by magnetic resonance imaging in the subacute post-traumatic period. These lesions were not visible on routine x-ray computed tomography obtained at the time of injury. 