Cephalgia Following Flow Diversion of Unruptured Intracranial Aneurysms

BACKGROUND: Headaches following treatment of unruptured intracranial aneurysms with flow diverting stents is a known, however under-reported, entity. Prevalence of this phenomenon, its clinical and procedural correlates, as well as its clinical course and correlation to aneurysm location and size have not been reported in the past. This manuscript aims to quantify the prevalence of the phenomenon, describe its natural course, and identify risk factors for its emergence. METHODS: Within our prospectively collected institutional database, we identified 141 consecutive patients treated electively for unruptured intracranial aneurysms by flow diversion between 2015 and 2021 who had a minimum of 2 years of clinical follow-up. The mean patient age was 55.7 (±13) y/o and 120/141 patients (85%) were females. Based on chart review and clinical notes we evaluated the presence of postprocedural headache complaints and correlated these with anatomical and periprocedural data. Additionally we have assessed charts of 88 patient who underwent aneurysm coiling without flow diversion during the same time period. RESULTS: Twenty-four (17%) patients complained of new headaches postflow diversion which were hemicranial or holocranial (n = 17) or retro-orbital (n = 7) in nature. Headaches were most common in paraclinoid, paraophthalmic, and cavernous aneurysms, while retro-orbital pain was correlated to larger aneurysms of same locations mean dimensions and older age (Pearson's correlation, 13 mm ± 5.4, P = 0.04; 65 ± 14, P = 0.048). Two stent constructs were also correlated to retro-orbital headaches (hazard ratio [HR] 3.8, P = 0.03, confidence interval [CI] 1.0-16.4). In addition, in 15 of 24 cases (62.5%) of headache presentations, the stent construct was crossing the dura. In 6 of 7 (87.5%) of patients presenting with retro-orbital headaches the stent construct was crossing the dural ring. The clinical course of the pain syndrome was invariably benign and short-lived (<1 year long). During the same time period only 3 patients (3.4%) in the elective coiling without flow diverter group presented with various duration of holocranial eventually resolving headaches. CONCLUSIONS: In our cohort, new postprocedural headaches following flow-diversion were present in 17% of patients thus constituting a common adverse event that was exclusively related to anterior circulation aneurysms, in contrast to only 3.4% prevalence of new postprocedural headaches following elective aneurysm coiling. The phenomenon was short-lived and benign, related to larger aneurysm size, proximity to the dural ring in the treated segment, double stent construct, and older age. We hypothesize that these headaches may be related to meningeal irritation. We recommend that patients are educated during the consent process of this phenomenon and its clinical course prior to treatment.