Medical treatment of polymeric cerebral granulomatous reactions following endovascular procedures

Abstract

BackgroundEndovascular procedures are standard of care for an increasing range of cerebrovascular diseases. Many endovascular devices contain plastic and are coated with a hydrophilic polymer which has been rarely described to embolize, resulting in distal granulomatous inflammatory lesions within the vascular territory.MethodsWe reviewed three cases of cerebral granulomatous reactions that occurred after endovascular intervention for internal carotid aneurysms. The patient procedure details, presentation, relevant investigations, and treatment course are described. We also provide a literature review on endovascular granulomatous reactions.ResultsThese three cases represent the largest biopsy proven series of cerebral granulomatosis following endovascular intervention. We highlight the variable clinical presentation, with two of the three cases having an unusually delayed onset of up to 4 years following the intervention. We show the characteristic histological findings of granulomatous lesions with foreign body material consistent with a type IV reaction, radiological abnormalities of enhancing lesions within the vascular territory of the intervention, and the requirement of prolonged immunosuppression for maintenance of clinical remission, with two of the three patients requiring a corticosteroid sparing agent. In comparison with the available literature, in addition to hydrophilic gel polymer, we discuss that plastic from the lining of the envoy catheter may be a source of embolic material. We also discuss the recommendations of the Food and Drug Administration and the implementation of novel biomaterials for the prevention of these reactions in the future.ConclusionsThere is a need for increased awareness of this severe complication of cerebral endovascular procedures and further longitudinal studies of its prevalence, optimal management and preventative measures.

Delayed leukoencephalopathy from suspected polymer embolism after neuroendovascular procedures

“…The flow diverter device has been reported as being safe, 16 but a recent case series has described symptoms 4 years after flow diverter stenting of an internal carotid aneurysm. 17 Multiple differential diagnoses should be eliminated, such as central nervous system (CNS) infection, lymphoma and neurosarcoidosis.…”

Incidence, clinical spectrum, and immunotherapy of non-ischemic cerebral enhancing lesions after endovascular therapy

“…In previously published cases, a mean delay to symptoms’ onset or discovery of asymptomatic lesions of 12 weeks (range 2 weeks to 12 months) has been reported (summarized in Shotar et al 8 ). However, intervals up to 4 years in cases with characteristic histological findings of granulomatous lesions with foreign body material have been reported, 16 indicating a highly variable time period between EVT and disease manifestation. Affected patients in our cohort became symptomatic with diverse symptoms: headache and focal neurological signs were prevalent in all patients, epileptic seizures and cognitive deficits in some.…”

“… 2 , 11 Whereas cases resolving completely without any treatment have been described, 7 , 11 most patients reported were treated with GCS. 4 , 8 , 11 , 12 , 16 In some cases, GCS treatment resulted in complete remission, 4 , 11 , 12 but in others it did not. 2 , 5 To our knowledge, there are only single reports on the use of immunosuppressants other than GCS, two reports on the use of MMF, 16 , 17 one report on MTX 16 and two reports on 4 patients treated with AZA.…”

“…As recently published, MTX up to 20 mg weekly, combined with GCS, resulted in resolution or reduction of lesions and regression of symptoms after EVT; however, after a total of 27 months of immunosuppression, new lesions were detected, so the authors considered a treatment change. 16 …”

“…Successful treatment with glucocorticosteroids (GCS) has been described in many cases, other immunosuppressants like mycophenolate mofetil (MMF) or azathioprine (AZA) in few cases only. 13 , 16 , 17 However, data on long-term follow-up and response to long-term treatments are scarce and have not been reported in detail in many cases.…”