Anastamoses between internal and external carotid arteries
Multiple, highly-variable anastamoses exist between the internal and external carotid arteries. These anastamoses may not be evident on non-invasive imaging or even catheter angiography, and may only be demonstrable with elevated intra-arterial pressures or high-flow states. ICA-ECA collaterals may enlarge following occlusion of the ICA and have been implicated in the development of dural AV fistulas.
A non-exhaustive list of sites include:
- Ophthalmic artery (ICA) – middle meningeal artery (ECA)
- The ophthalmic artery most commonly arises from the supraclinoid (C6) segment of the ICA but may arise from the middle meningeal artery or middle cerebral artery
- Ophthalmic artery may have collaterals with the middle mengingeal artery or with the deep temporal artery or infraorbital artery (from the maxillary artery)
- Cavernous sinus
- Ethmoidal sinuses
- Dorsal nasal artery (ICA) – nasal branches of the facial artery (ECA)
- Dorsal nasal artery is branch of the ophthalmic artery
- Recognition is important in epistaxis embolization
Collateral pathways are also present between the occipital artery (from the ECA) and muscular branches of the vertebral arteries around the C1 and C2 vertebrae.
- Dangerous Extracranial–Intracranial Anastomoses and Supply to the Cranial Nerves: Vessels the Neurointerventionalist Needs to Know S. Geibprasert, S. Pongpech, D. Armstrong, T. Krings American Journal of Neuroradiology Sep 2009, 30 (8) 1459-1468; DOI: 10.3174/ajnr.A1500
- Mokin M., Siddiqui A.H. (2016) ICA–ECA Collaterals. In: Saba L., Raz E. (eds) Neurovascular Imaging. Springer, New York, NY. https://doi-org.ezproxy.library.uq.edu.au/10.1007/978-1-4614-9029-6_1
- Geibprasert, Pongpech, Armstrong, Krings; Dangerous Extracranial–Intracranial Anastomoses and Supply to the Cranial Nerves: Vessels the Neurointerventionalist Needs to Know; AJNR Am J Neuroradiol 30:1459–68; (2009)