Post-pipeline headache after flow-diverting stenting for unruptured intracranial aneurysms: clinical, radiological findings, and proposed scoring system

Background and objectives: Headache after flow diverter (FD) treatment for unruptured intracranial aneurysms (UIAs), historically referred to as post-pipeline headache, is increasingly recognized but remains poorly characterized and lacks standardized diagnostic criteria. We aimed to investigate the prevalence, clinical features, and predictors of post-pipeline headache and to internally validate a structured scoring system for this entity. Methods: In this single-center cohort study, we included consecutive adult patients undergoing FD treatment for UIAs between 2021 and 2025. Headache characteristics before and after treatment were assessed using structured interviews. A composite post-procedural headache score was developed to identify post-pipeline headache (post-pipe score). Content validity index (CVI) was calculated. Diagnostic performance was assessed with receiver operating characteristic (ROC) curve analysis against independent neurologist classifications. Multivariable logistic regression was performed to identify predictors of post-procedural headache. Results: Among 137 patients (mean age 58.3 ± 12.7 years; 19% male), post-pipeline headache occurred in 29 (21.2%), including 12 patients with new-onset headache and 17 with worsening of pre-existing headache. The scoring system demonstrated excellent content validity (CVI = 0.96) and good diagnostic discrimination across raters (AUC range 0.84–0.91), supporting a threshold ≥ 9 points to identify post-pipeline headache. Larger aneurysm neck size was independently associated with post-procedural headache (OR 1.47, 95% CI 1.04–2.07, p = 0.025), while dome size was also larger in patients with post-pipeline headache (p = 0.042). Discussion: Post-pipeline headache is a common clinical phenomenon affecting approximately one-fifth of patients following FD treatment for UIAs. Larger aneurysm neck size appears to be an independent predictor of post-pipeline headache, supporting a potential role for local vascular remodeling and inflammatory mechanisms.