Neuroform In-Stent Stenosis: Incidence, Natural History and Treatment Strategies

Abstract

Delayed in-stent stenosis is an important and well characterized complication of angioplasty and stenting for the treatment of intra- and extra-cranial atheromatous disease. The current series describes the incidence and natural history of in-stent stenosis following the deployment of the Neuroform stent within the cerebrovasculature for the treatment of aneurysms. The collaborative CCF-BNI endovascular database was reviewed to identify cases of delayed moderate or severe in-stent stenosis observed during the follow up of cerebral aneurysms treated with the Neuroform stent. The hospital charts, clinic records and operative reports for these patients were reviewed. Out of a total of 156 patients with follow up, 9 cases of moderate or severe delayed (>2 mo) in-stent stenosis were identified (5.8%), including two parent vessel occlusions. In two cases, patients presented three months after stent-supported aneurysm embolization with focal neurological symptoms. Both of these patients were treated with angioplasty. One eventually required surgical bypass. Of the seven asymptomatic patients, three demonstrated some degree of spontaneous resolution at follow up, one progressed to complete occlusion, two are awaiting further follow-up and one patient died of unrelated causes. Of the 9 patients in the series, 5 were treated with “bioactive” coils (Matrix, Hydrocoil, Cerecyte), 3 were treated with bare platinum coils and 1 was treated with stenting alone. The earliest time interval to diagnosis was 2.5 months and 3 months for asymptomatic and symptomatic patients, respectively. The earliest interval documented for spontaneous resolution was 9 months. Delayed Neuroform in-stent stenosis is not a rare phenomenon, occurring in 5.8% of cases. The stenosis can be symptomatic and may require endovascular treatment or surgical bypass. In asymptomatic patients, a strategy of “watchful waiting” may be effective, as many patients may demonstrate partial or complete resolution at follow up. The spontaneous resolution of delayed in-stent stenosis has not been previously described. This may be a phenomenon unique to the application of low radial force, self-expanding stents within the non-atheromatous cerebrovasculature.