Posttraumatic abducens to oculomotor nerve misdirection.
BACKGROUND
Paradoxical patterns of extraocular muscle, eyelid, or pupillary movements can occur following injury between divisions of the oculomotor nerve, trigeminal and abducens nerves, and trigeminal and oculomotor nerves. We report three cases of unusual ocular motility and eyelid movements that are a result of aberrant connections between the abducens and oculomotor nerves.


METHODS
Three patients with unusual eye movement abnormalities after trauma were studied. A complete ophthalmic examination plus neuroradiologic evaluation were performed.


RESULTS
Each patient manifested an aberrant connection between the 6th and 3rd cranial nerves resulting in third nerve function during sixth nerve stimulation. Two patients demonstrated complete third nerve palsies except for adduction on attempted abduction. The third showed improved bilateral ptosis on abduction.


CONCLUSIONS
The neuroanatomical abnormalities involve intraorbital structures in one patient and central nervous system pathways in the others. Explanations such as retrograde regeneration, ephaptic transmission, or denervation supersensitivity do not appear to explain these unusual eye movements. The most likely mechanism involves some form of peripheral neuronal misdirection. These rare sixth to third nerve misdirection cases add support to the "neuronal misdirection hypothesis" of aberrant eye movements after trauma.
Buckley
Edward G
EG
Duke University Eye Center, Durham, NC, USA
Ellis
Forrest D
FD
Postel
Eric
E
Saunders
Timothy
T
D000010:Abducens Nerve / Q000503:physiopathology*; D020222:Abducens Nerve Injury / Q000503:physiopathology*; D000328:Adult; D001763:Blepharoptosis / Q000209:etiology / Q000503:physiopathology*; D002648:Child; D003941:Diagnostic Techniques, Ophthalmological; D004948:Esotropia / Q000209:etiology / Q000503:physiopathology; D005131:Eye Injuries / Q000503:physiopathology*; D005260:Female; D016489:Head Injuries, Closed / Q000503:physiopathology; D006801:Humans; D008297:Male; D009416:Nerve Regeneration; D009802:Oculomotor Nerve / Q000503:physiopathology*; D061220:Oculomotor Nerve Injuries; D009886:Ophthalmoplegia / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D009915:Orbit / Q000293:injuries; D011681:Pupil Disorders / Q000209:etiology / Q000503:physiopathology