In our former study,15 recurrent aneurysms were classified into the following five types: I, pure recanalization inside the aneurysm sac; II, pure coil compaction without aneurysm growth; III, new aneurysm neck formed without coil compaction; IV, new aneurysm neck formed with coil compaction; and V, newly formed aneurysm neck and sac. showed that each recurrent aneurysm was wrapped by a thrombus and the aneurysm wall; some coils protruded from the pseudocapsule in some ruptured aneurysms. Microscopically, H&E staining showed that three types of thrombi (fresh thrombus, granulation tissue, and scar tissue) coexisted in one section. In addition, characteristic unstable and unorganized thrombi with empty spaces were found in the neck cavity. Immunohistochemical staining showed that this SMA stain was discontinued and incomplete, and CD68+ antibody?and H&E staining revealed inflammatory infiltrate in the aneurysm wall. Conclusion The coexistence of three types of thrombi is the main characteristic of recurrent aneurysms. The formation of stable thrombus may be one of the key points of aneurysm recurrence. Smooth muscle cell damage and infiltration of inflammatory cells in the aneurysm wall probably contribute to the recanalization. strong class=”kwd-title” Keywords: coil, aneurysm, vessel wall, intervention Introduction Unruptured intracranial aneurysms (IAs) are common cerebrovascular conditions. Aneurysm rupture results in subarachnoid hemorrhage (SAH), which is an important subtype of stroke with high mortality and morbidity rates.1 Therefore, appropriate intervention is necessary for IAs.2 The initial intervention method was microscopic aneurysm clipping. After the development of catheterization techniques with cerebral angiography, endovascular coiling has become another way of treating IAs. LW6 (CAY10585) Moreover, endovascular therapy improves patient quality of life immediately Rabbit polyclonal to APCDD1 after treatment and during follow-up, and has a lower mortality rate than surgical clipping.3 4 Although endovascular therapy has been verified as safe and effective, IA recurrence may occur even after complete coil embolization of the aneurysm. 5 The recurrence rate is usually relatively high after coiling alone and after stent-assisted coil embolization. 6 7 IAs often recur early after endovascular treatment. Nearly 50% of IA recurrences occur within 6 months after coiling in humans.8 The mechanism of IA recurrence is complex and the specific processes are still unclear. Many hypotheses have been proposed for IA recanalization, including: (1) growth of the aneurysm itself,5 9 (2) coil compaction,5 10 (3) degradation and recanalization of LW6 (CAY10585) fresh and unstable thrombotic tissue, (4) continuous blood flow through the intraluminal coils and thrombosis complex,11 (5) lack of neointima formation across the neck of the aneurysm,12 (6) lack of smooth muscle in the IA wall, leading to organized thrombus reduction.13 14 To solve the problem of IA recurrence, this study investigated the pathology of specimens collected from patients who underwent clipping after unsuccessful coil embolization. Patients and methods Between June 2019 and January 2021, eight patients with nine recurrent saccular aneurysms underwent surgery in our hospital. All patients had received previous embolization treatment before undergoing surgical clipping. Four patients with five recurrent aneurysms experienced SAH after embolization. The other four recurrent aneurysms in four patients were detected on follow-up imaging. In our former study,15 recurrent aneurysms were classified into the following five types: I, pure recanalization inside the aneurysm sac; II, pure coil compaction without aneurysm growth; III, new aneurysm neck formed without coil compaction; IV, new aneurysm neck formed with coil compaction; and V, newly formed aneurysm neck and sac. Types C can be resolved with endovascular treatment, while types C require surgical clipping. This strategy results in a satisfactory cure rate and compactions. In the present study, four recurrent IAs (two type , one type , and one type ) and five ruptured IAs in eight patients were analyzed. Patient and aneurysm information is usually presented in table 1. Table 1 Basic patient and recurrent aneurysm characteristics thead Aneurysm br / NoFirst coiling reasonEndovascular treatment timesLast implant time (months)*Clipping reasonLocationSize/neck br / (mm)Imaging LW6 (CAY10585) findingsType? /thead 1Headache22aSAHAComA13.3/4.5Aneurysm growth2Headache22aSAHRMCA12.2/4.2Aneurysm growth3aSAH135?RecurrenceRMCA4.3/2.2Coil compaction4Dizziness16RecurrencePComA25.0/8.4Coil compaction5aSAH2102?aSAHRCA C78.2/4.5None6aSAH17RecurrenceAComA5.2/2.4Aneurysm growth7aSAH28RecurrenceAComA5.3/2.2Coil compaction8aSAH171?aSAHLCA C76.3/2.2Aneurysm growth9aSAH2111?aSAHLCA C713.4/4.5Aneurysm growth and coil compactionIV Open in a separate window *Last implant time means the interval between the last endovascular treatment and clipping. ?The type of recurrent aneurysm is classified into the following five types: I, pure recanalization inside the aneurysm sac;.