Figure 13 A highly conspicuous lesion in the midbrain tegmentum just ventral to the cerebral aqueduct (left image; arrow) and a highly characteristic lesion in the MLF of the pontomesencephalic junction (right image; arrow) (3 mm thick, axial proton density weighted sequences) was noted

Both images were derived from patients with multiple sclerosis and bilateral internuclear ophthalmoparesis. Both lesions demonstrate the eloquence principal of periventricular demyelinating lesions that are localized to the brainstem, in contrast to the non-eloquence of many cerebral periventricular lesions (that often do not correspond to any concomitant clinical manifestations).