Vergleich verschiedener endovaskulärer Platinspiral-Embolisationsverfahren zur Therapie zerebraler Aneurysmen : tierexperimentelle Untersuchungen

One of the main causes of spontaneous subarachnoid hemorrhage is the rupture of a cerebral aneurysm situated in the Circulus arteriosus Willisii. Treatment options of ruptured cerebral aneurysms include surgical clipping and endovascular therapies. Endovascular methods, especially coiling became an important alternative to the surgical procedure. The configuration of the aneurysm plays an important role to choose which method is best suited for an individual patient. Problems for endovascular therapies can occur in aneurysms with a wide neck. In these cases, parts of the coil loops can protrude into the parent artery and can become a permanent source of embolisms. Another problem is coil compaction with subsequent growing of a new aneurysm neck. In contrast, the surgical method leads to continuous and stable aneurysm obliteration with reconstruction of the vessel wall. Despite these theoretical considerations, clinical data from a recent large prospective study (International Subarachnoid Trial) point toward a better short-term outcome of endovascular treated aneurysms if both the neurosurgeon and the neuroradiologist think that the given aneurysm can be treated with their respective technique. This study demonstrated significant advantages of the endovascular therapy in regard of morbidity and mortality of the patients. Following recent developments, platinum coils were enhanced with different material laminations and coatings to overcome the still present limitations that were outlined above. The objective of this study is to test in an animal model two newly developed types of coated coils, a) coils coated with a bioabsorbable polymer, so called Matrix coils and, b) hydrogel coated coils, so called Hydro coils that increase their volume and lead to a smooth surface. Following treatment, animals were followed over a period of six months and compared to animals treated with conventional platinum coils (GDC-coils), in order to obtain information about reconstruction of the vessel wall and complete and stable obliteration of the aneurysms. Aneurysms were created in 20 rabbits by intraluminal elastase incubation of the common carotid artery. Five animals each were assigned to the following groups: untreated, coils, matrix coils and hydro coils. After the observation period of 6 month digital subtraction angiography (DSA) was performed. Thereafter the animals were euthanized. Angiography, histological examinations and scanning electron microscopy were used for evaluation. In the untreated group all five aneurysms remained patent for the investigated time of 6 month. The group treated with the GDC-coils demonstrated the well known problems of coil compaction and recanalisation, no aneurysm was completely occluded. From a histological point of view, the Matrix coils gave no evidence of complete aneurysms obliteration, however, an increased intra aneurysmatic reaction of the collagenous tissue was documented. Still, an endothelialization as an indication of vascular remodelling was absent in most cases. Only the group treated with Hydro coils gave evidence of completely obliterated aneurysms. Continuous endothelial lining was detected using scanning electron microscopy and histological analysis. Despite some problems and limitations of this experiment, e.g. the small number of animals per group and the follow-up period of only 6 month, it was possible to find consistent results. Hydro coils lead to a completely and stable aneurysm obliteration, whereas the Matrix coils did not show a complete aneurysm obliteration. In case of the Hydro coils it seems that a new embolisation material has emerged which has the known benefits of endovascular treatments over surgical procedures, as being shown in the ISAT-study, and, that, in addition, leads to a complete and stable aneurysm obliteration combined with a remodelling of the vessel wall. Nevertheless, this progress and the development of new materials and techniques should be observed critically and attentively as it has been pointed out that Hydrogel coating may lead to hydrocephalus in the clinical setting. The long-term results in patients will be of particular interest. These should be clarified in enduring clinical trials. Generally speaking the question, if a neuroradiological or interventionell approach is chosen, is depending on the individual case. A well-rehearsed and adapted team of neuroradiologists and neurosurgeons should clarify this, in order to offer an individual and interdisciplinary treatment concept to the patient.