A 3yo M comes into your ED around midnight after a fall off a stool onto his face. He has been vomiting, is bradycardic in triage to the 50s so is brought into your pediatric RESUS bay. Mom states that his eyes “look weird”. On exam, pt is scared but awake and alert, with full EOMI of the L eye, unable to look superiorly or medially with the R eye. PERRL. Mild erythema and tenderness over R inferior orbit. Vision grossly intact to fingers and colors in both eyes. No photophobia. Rest of PE is normal. HR on monitor varies from 80s to the 40s.
CT scan of the head shows no bleed. Orbital cuts show a R inferior orbital fracture suspicious for muscle entrapment. Admitted to PICU for hemodynamic monitoring and continuous neuro checks, and OR in the am. EKG shows sinus bradycardia.
Why is he intermittently bradycardic?
Oculocardiac reflex (also known as Aschner phenomenon, Aschner reflex, or Aschner-Dagnini reflex)
The reflex is mediated by nerve connections between the ophthalmic branch of the trigeminal cranial nerve via the ciliary ganglion, and the vagus nerve of the parasympathetic nervous system. Happens when there is traction on the muscles or on the eyeball itself. Case reports exist of similar phenomena from the maxillary and mandibular branches as well, but most well known in the ophthalmic.
-seen most often in pediatrics and young adults due to baseline increased parasympathetic tone
-can try atropine as a temporary fix (no strong evidence, case reports), it will resolve once the entrapment is surgically fixed
In this case, the patient was stable though intermittently bradycardic, so no atropine given. Kept on monitor and admitted to PICU. Ophthalmology came in from home and the patient was taken to the OR that morning. After surgery, HR back to normal.
Other similar cases have been written about in the literature
http://www.ncbi.nlm.nih.gov/pubmed/24810440
http://www.ncbi.nlm.nih.gov/pubmed/23915493
