Transorbital anastomotic pathways between the external and internal carotid systems in children affected by intraocular retinoblastoma

Purpose: It is well known that many anastomoses can join the external carotid system and the ophthalmic artery. However, their frequency has never been reported. Since they can be relevant for interventional radiologists operating in the orbit, we decided to illustrate and determine the frequency of the anastomoses that can be found in children. Methods: A retrospective study of 443 angiographic procedures (via ophthalmic artery and/or external carotid artery) carried out on 97 children affected by intraocular retinoblastoma was made to investigate the arterial anatomy of 106 orbits. Results: Anastomoses were observed in 44.33% of orbits. However, their true frequency is likely much higher as the rate of visualization increased up to 91.11% of orbits when the angiographic study was extended to the external carotid artery. In order of frequency we detected the following anastomoses: lacrimal artery - middle meningeal artery, lacrimal artery - anterior deep temporal artery, ophthalmic artery - middle meningeal artery, ophthalmic artery - facial artery, supraorbital artery - superficial temporal artery, supratrochlear artery - superficial temporal artery, supraorbital artery - middle meningeal artery, dorsal nasal artery - infraorbital artery, supraorbital artery - zygomaticoorbital artery, lacrimal artery - zygomaticoorbital artery. Conclusion: When properly searched, anastomoses between the ophthalmic artery and the external carotid artery are almost constant in children. Depending on the clinical scenario they can represent dangers or valuable alternative routes for collateral circulations and intraarterial chemotherapy.