Thread by @YoungNIR

Our inaugural #tweetorial on #DangerousAnastomoses is READY for the #NeuroEndovascularFellows. We will discuss the HIGH YIELD POINTS.We hope this serves as a springboard for collaborative learning amongst NIR fellows. Please tweet interesting/classic cases. We hope you enjoy.

@AmeerEHassan @DanTonettiMD @DrJeremyStoneMD @svinsociety @SNISinfo @BrianHoward_MD @youngneuros @eytanraz @AshuPJadhav @shazamhussain (1/15)As a fellow, it’s crucial to understand the collateral circulation between the intracranial(IC)and extracranial(EC) territories, especially when we are embolizing for the first time to avoid complications such as embolic stroke or even cranial nerve palsies.

@AmeerEHassan @DanTonettiMD @DrJeremyStoneMD @svinsociety @SNISinfo @BrianHoward_MD @youngneuros @eytanraz @AshuPJadhav @shazamhussain (2/15)Always remember 3 main regions of potential anastomotic routes between the EC/IC arteries when you embolize or “CROP”:
1. (C)ervical (R)egion 2. (O)rbital 3.(P)etrocavernous.

@AmeerEHassan @DanTonettiMD @DrJeremyStoneMD @svinsociety @SNISinfo @BrianHoward_MD @youngneuros @eytanraz @AshuPJadhav @shazamhussain (3/15) 3 situations to remember when anastomoses could open up:
1. Increased IA pressure (eg, during embolization procedures or superselective injections
2. High-flow shunts as a consequence of the “sump effect,” 3. Occlusions of large arteries with collaterals

@AmeerEHassan @DanTonettiMD @DrJeremyStoneMD @svinsociety @SNISinfo @BrianHoward_MD @youngneuros @eytanraz @AshuPJadhav @shazamhussain (4/15)Whenever embolizing in the Orbital region, remember you can make the patient BLIND if not careful. Remember to always identify the choroidal blush as your landmark because of the potential to occlude the central retinal artery, which can lead to BLINDNESS!

@AmeerEHassan @DanTonettiMD @DrJeremyStoneMD @svinsociety @SNISinfo @BrianHoward_MD @youngneuros @eytanraz @AshuPJadhav @shazamhussain (5/15)Beware of the Meningo-Ophthalmic Artery. If you don’t see the ophthalmic artery filling on the ICA run and instead see it filling on the ECA run this likely means the MMA is the only supply to the ophthalmic artery.

@AmeerEHassan @DanTonettiMD @DrJeremyStoneMD @svinsociety @SNISinfo @BrianHoward_MD @youngneuros @eytanraz @AshuPJadhav @shazamhussain (6/15)Pathways particles can reach the Ophthalmic Artery: 1. MMA-->Lacrimal Arteries 2. Septal/Sphenopalatine Arteries-->Ethmoidal Arteries 3. STA/Facial Artery-->Supraorbital and dorsonasal arteries.

@AmeerEHassan @DanTonettiMD @DrJeremyStoneMD @svinsociety @SNISinfo @BrianHoward_MD @youngneuros @eytanraz @AshuPJadhav @shazamhussain (7/15)Although the sphenopalatine artery has an ophthalmic artery anastomosis, it can safely be embolized in epistaxis and JNA cases due to the anastomosis being <80 microns in diameter and therefore large particles are safe.

@AmeerEHassan @DanTonettiMD @DrJeremyStoneMD @svinsociety @SNISinfo @BrianHoward_MD @youngneuros @eytanraz @AshuPJadhav @shazamhussain (8/15)Ascending Pharyngeal Artery(APA)’s pharyngeal trunk anastomoses with the eustachian tube circle which connects with the mandibular artery from the petrous ICA and with the accessory meningeal artery(AMA) and the pterygovaginal artery from the distal IMA.

@AmeerEHassan @DanTonettiMD @DrJeremyStoneMD @svinsociety @SNISinfo @BrianHoward_MD @youngneuros @eytanraz @AshuPJadhav @shazamhussain (9/15)The inferior tympanic artery of the MHT may anastomose with the caroticotympanic artery of the petrous ICA. This may not be seen on the angiogram pre-embolization, but it has the potential to open up post-embolization.

@AmeerEHassan @DanTonettiMD @DrJeremyStoneMD @svinsociety @SNISinfo @BrianHoward_MD @youngneuros @eytanraz @AshuPJadhav @shazamhussain (10/15)The major anastomotic route for the MMA and Accessory Meningeal Artery(AMA) is via the ILT to the cavernous ICA. MMA’s cavernous branches anastamose with tentorial branches of ILT. Recall, MMA anastomoses with ophthalmic artery as well as with anteromedial branch of ILT.

@AmeerEHassan @DanTonettiMD @DrJeremyStoneMD @svinsociety @SNISinfo @BrianHoward_MD @youngneuros @eytanraz @AshuPJadhav @shazamhussain (11/15)The occipital artery represents an embryologic remnant between the vertebrobasilar and ECA circulations. This connection is present via the radicular branches.They can become important during carotid artery ligation or occlusion.

@AmeerEHassan @DanTonettiMD @DrJeremyStoneMD @svinsociety @SNISinfo @BrianHoward_MD @youngneuros @eytanraz @AshuPJadhav @shazamhussain (12/15)The APA is the primary anastomotic connection with the vertebral artery via the musculospinal and prevertebral branches.

@AmeerEHassan @DanTonettiMD @DrJeremyStoneMD @svinsociety @SNISinfo @BrianHoward_MD @youngneuros @eytanraz @AshuPJadhav @shazamhussain (13/15)Important ECA supplies to the cranial nerves are to CN 7 and CN 9-12.The Petrosal branch of MMA and the stylomastoid branch of the posterior auricular artery supply CN7 ganglion. The APA supplies 9&10: Jugular branch.
11: Musculospinal branch(NMT). 12: Hypoglossal branch.

@AmeerEHassan @DanTonettiMD @DrJeremyStoneMD @svinsociety @SNISinfo @BrianHoward_MD @youngneuros @eytanraz @AshuPJadhav @shazamhussain (14/15)You can always use mechanical blockage of the collateral branch or flow reversal methods (balloon occlusion) to ensure that embolic material does not enter unwanted territories and prevent unwanted complications.

@AmeerEHassan @DanTonettiMD @DrJeremyStoneMD @svinsociety @SNISinfo @BrianHoward_MD @youngneuros @eytanraz @AshuPJadhav @shazamhussain (15/15)Finally, trainees ALWAYS obey your attendings and seniors while embolizing. Their experience, judgment and wisdom have made them successful. Don’t be a cowboy. Always think about the potential adverse risk of stroke, blindness or CN palsy with what you are doing.