Aberrant regeneration of the third nerve following orbital trauma. Synkinesis of the iris sphincter.
A patient had aberrant regeneration of the inferior branch of the third nerve following penetrating orbital trauma. Examination of the right eye showed no light perception and a pupil that was nonreactive to accommodation, direct, and consensual light stimuli. However, on downgaze, there was marked constriction of the pupil in the blind eye. The phenomenon of oculomotor misdirection is discussed with respect to aberrant regeneration, ephaptic transmission, chromatolysis-induced nuclear reorganization, and recent neurophysiologic studies. Our case provides strong support for the concept of peripheral aberrant regeneration as the mechanism underlying some instances of oculomotor misdirection after third-nerve palsy.
D003389:Cranial Nerve Diseases / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D007498:Iris / Q000294:innervation; D008297:Male; D008875:Middle Aged; D009416:Nerve Regeneration; D009469:Neuromuscular Junction / Q000502:physiology*; D009802:Oculomotor Nerve / Q000503:physiopathology; D061220:Oculomotor Nerve Injuries; D009915:Orbit / Q000293:injuries*; D013569:Synapses / Q000502:physiology