oculomotor synkinesis
Last reviewed 01/2018
Oculomotor synkinesis is a regenerative phenomenon of the third cranial nerve that occurs as a result of both misdirection of sprouting axons and of ephaptic transmission - cross-talk between axons without covering sheaths. Features are variable and may include:
- lid elevation on attempted downgaze - levator palpebrae superioris fires as inferior rectus fires
- adduction on attempted upgaze - medial rectus fires as superior rectus fires
- retraction on attempted upgaze - recti act as retractors and fire together
- pseudo-Argyll Robertson pupil - pupil constricts when eye is adducted - pupillary innervation from medial rectus
- pseudo-Von Graefe's sign - no lid lag on downgaze but lid retraction due to innervation of levator palpebrae superioris from fibres distributed to inferior rectus
- monocular vertical optokinetic nystagmus response