Onset-to-treatment time and aneurysmal regression predict improvement of cranial neuropathy after flow diversion treatment in patients with symptomatic internal carotid artery aneurysms

BACKGROUND: Although flow diversion plays a pivotal role in treating internal carotid artery aneurysms presenting with cranial neuropathy, predictors of symptom improvement have not been established. OBJECTIVE: To investigate improvement of symptoms after flow diversion treatment in patients with internal carotid artery aneurysms causing cranial neuropathy, with sufficient follow-up period. Additionally, to examine factors associated with improvement of symptoms. METHODS: This retrospective multicenter study examined patients with unruptured internal carotid artery aneurysms presenting with cranial neuropathy who were treated using flow diversion and followed up for at least 12 months. Study outcomes were transient worsening of symptoms and symptom status 12 months after treatment. Patient and aneurysm characteristics were statistically analyzed. RESULTS: Seventy-seven patients were included. Data needed for outcome analysis were available for 66 patients. At the 1-, 3-, 6-, 12-month, and last follow-ups, the proportion of patients with resolved or improved symptoms was 26% (20/77), 51% (39/77), 74% (57/77), 83% (64/77), and 79%(62/77), respectively. Symptom onset-to-treatment time <6 months (OR=24.2; 95% CI 3.09 to 188.84; p=0.002) and aneurysmal regression (OR=23.1; 95% CI 1.97 to 271.75; p=0.012) were significantly associated with symptom improvement. Transient symptom worsening and worse symptoms at 12 months occurred in 19/77 (25%) and 2/77 (3%) patients, respectively. CONCLUSIONS: The rate of cranial neuropathy symptom improvement after flow diversion increased over the first 12 months after treatment, but not thereafter. Treatment within 6 months of symptom onset and aneurysmal regression were predictors of symptom improvement.