Table 3:

Localization of motility abnormalities

Motility DisturbanceLocalization/Etiology
Weber syndrome (Third-nerve palsy and hemiparesis)Anterior midbrain
Benedikt syndrome (third-nerve palsy and contralateral tremor)Red nucleus and third-nerve fascicle
Isolated pupil-involving third-nerve palsyPosterior communicating artery aneurysm
Pupil-sparing third-nerve palsyMicrovascular ischemia of the third nerve
Isolated fourth-nerve palsyDoral midbrain/anterior medullary velum
Microvascular ischemia
Isolated sixth nerve palsyPons or sixth-nerve fascicle
Demyelination/microvascular ischemia
Gaze palsy and facial weaknessDorsal pons/facial colliculus
Bilateral sixth-nerve palsiesElevated intracranial pressure
Third-, fourth-, and sixth-nerve palsiesCavernous sinus
Third-, fourth-, sixth-nerve palsies, and optic neuropathyOrbital apex
Multiple cranial neuropathiesSubarachnoid space
Internuclear ophthalmoplegiaMedial longitudinal fasciculus
Gaze palsyDorsal pons
Parinaud syndrome (upgaze palsy, eyelid retraction)Dorsal midbrain