Endovascular recanalization for symptomatic chronic internal carotid artery occlusion: proposal of a modified angiographic classification and clinical outcomes.

Purpose: To stratify angiographic images of chronic internal carotid artery occlusion (CICAO) into a newly modified angiographic classification, and identify suitable candidates for endovascular recanalization.

Methods: This study included 51 consecutive patients with symptomatic CICAO who underwent endovascular recanalization at our institution. Patients' clinical information, angiographic findings, procedural results, and outcomes were recorded. We attempted to stratify all angiographic images into categories based on morphological occlusive patterns and distal internal carotid artery (ICA) lumen reconstitution on digital subtraction angiography (DSA).

Results: Four types (I-IV) of CICAO were identified based on angiographic characteristics. We defined type I as having a tapered (IA) or blunt stump (IB) and distal ICA lumen reconstitution with collateral filling; type II as having no stump but with distal ICA lumen reconstitution; type III as having a tapered (IIIA) or blunt stump (IIIB) but no distal ICA lumen reconstitution; type IV as having no stump and no distal ICA lumen reconstitution. The rate of successful recanalization was 90.3 % for type I, 60.0 % for type II, 50.0 % for type III, 0 % for type IV, respectively (P = 0.002). The overall intraoperative complication rate was 11.8 %, and none of them led to severe neurological damage or death. The follow-up modified Rankin Scale (mRS) scores were significantly decreased in successfully revascularized patients, whilst there were no significant changes in the other failed patients.

Conclusion: For symptomatic CICAO, our newly modified angiographic classification may be comprehensive and useful in selecting suitable patients for recanalization and grading the difficulty of the procedures.