Oculocardiac Reflex

The oculocardiac reflex, also known as Aschner phenomenon, Aschner reflex, or Aschner-Dagnini reflex, is a decrease in pulse rate associated with traction applied to extraocular muscles and/or compression of the eyeball. The reflex is mediated by nerve connections between the trigeminal cranial nerve and the vagus nerve of the parasympathetic nervous system. The afferent tracts are derived mainly from the ophthalmic division of the trigeminal nerve, although tracts from the maxillary and mandibular division have also been documented. These afferents synapse with the visceral motor nucleus of the vagus nerve, located in the reticular formation of the brain stem. The efferent portion is carried by the vagus nerve from the cardiovascular center of the medulla to the heart, of which increased stimulation leads to decreased output of the sinoatrial node. This reflex is especially sensitive in neonates and children, and must be monitored, usually by an anaesthesiologist during paediatric ophthalmological surgery, particularly during strabismus correction surgery. However, this reflex may also occur with adults. Bradycardia, junctional rhythm, asystole, and very rarely death, can be induced through this reflex.