Compared with small aneurysms, treating large aneurysms is technically challenging, with a much higher complication and recanalization rate[8,14]. Long-term angiographic outcomes showed that recurrence rates for large aneurysms treated with coiling alone or stent-assisted coiling were 57.9% and 23.5%, respectively[15], indicating that satisfactory outcomes cannot be achieved via conventional endovascular treatment. Parent artery occlusion can be used to treat large aneurysms, but this requires a negative balloon occlusion test, and new aneurysms occurred in other areas in 4.5% of patients after parent artery occlusion[16]. In addition, when treating LCCAs, our goals are to reduce the risk of rupture and thromboembolism, and relieve cerebral nerve paralysis caused by the aneurysmal mass effect. Recently, higher numbers of large aneurysms are being treated with flow-diverter devices, and the efficacy and safety of these devices are being proven. Flow diverter devices contrast with the traditional treatment concept of intracranial aneurysmal sac tamping, and reconstruct the parental artery, which is a big step in the treatment of intracranial aneurysms (In Table 3, we compared the advantages and disadvantages of the three endovascular treatment modalities). In the present study, we reported our preliminary findings related to the use of TFDs in LCCAs.
In our series, angiographic follow-up data were obtained for all seven patients (Table 2) with a median imaging follow-up period of 57.5 ± 16.7 (range, 6–69) months. All seven patients obtained favorable angiographic follow-up results. Lin et al reported that complete aneurysm occlusion was achieved in a higher proportion of the pipeline plus coils compared with Pipeline only (93.1% VS 74.7%, P =0.03 )[17]. O’Kelly et al reported that for patients presenting with cranial nerve deficits (18 cavernous aneurysms), 11 patients experienced resolution (61%)[18]. In our clinical follow-up, patients achieved even better results, with six patients experiencing complete resolution (85.7%) of the aneurysmal mass effect symptoms.
The use of flow diverter devices theoretically does not require coiling. However, for large, complex aneurysms, additional coils could play a role in improving occlusion rates and decreasing the risk of catastrophic aneurysm rupture after the use of flow diverter stents[17,19]. In our study, every patient was treated with a TFD and coils because we believe that the additional coils accelerate thrombus formation to decrease the pressure from the aneurysmal sac caused by blood retention within the sac after TFD implantation.Jing et al [20]have also reported that adjunctive coiling with the TFD can reduce intra-aneurysmal flow velocity and wall shear stress, promoting thrombosis formation and embolization of aneurysms. In an earlier experience using the Pipeline flow diverter, Siddiqui et al [21] recommended avoiding dense packing of the aneurysmal sac because this can lead to acute thrombotic or compressive occlusion. Our findings were similar; six patients were treated with low coil-packing densities, and their cranial nerve deficits resolved completely. The only patient (patient 4) treated with dense aneurysmal packing obtained subtotal cranial nerve deficit improvement. Although we observed good outcomes for loose embolized aneurysms, because only one patient received dense aneurysmal packing , we still need a larger number of records to reach the conclusion of loose aneurysmal packing does not affect alleviation of the mass effect.
The reported complication rates for ischemia and bleeding following aneurysmal repair are 5.5%–9.76% and 2.0%–6.1% respectively, with morbidity and mortality rates of 9.8%–17.7% and 3.8%–4.9%, respectively[22,23]; the incidence of complications is higher for giant aneurysms[24]. The incidence of complications in the flow diverter device group in our study was lower than that in conventional parent artery occlusion with a single coil and stent-assisted coiling when treating cavernous aneurysms [25]. In our case serious, one patient had occlusion of the parent artery, but showed no signs of ischemia because the left internal carotid artery provided sufficient blood flow for right anterior circulation through the anterior communicating artery. But the result need to be taken seriously, not all patients can compensate adequately after unilateral internal carotid artery occlusion, ischemic events may occur once compensation is insufficient. One meta-analyses indicated ischemic rates after flow diverter implantation was 7.5% [26] and a 9%-10% incidence of ischemic events should be anticipated when using flow diverters for large aneurysms[12]. We did not encounter hemorrhagic complications, and the morbidity and mortality rates were both 0%.
Up to now, there has been no single report on the therapeutic effect of TFD for LCCAs, in a clinical trial of liu et al[12], 37 patients with paraclinoid or cavernous aneurysms (aneurysm size 21.8 7.5, 10.0-45mm) were included, with a 6-month complete embolization rate of 75.7%. The article reported one-year mortality rate of 4.88%, hemorrhagic stroke and ischemic stroke related to target vessel was 6.1% and 9.76% respectively (These calculations include aneurysms of all sites, and was not a simple cavernous segment aneurysm). But no long-term follow-up results were reported.