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Case series
Medical treatment of polymeric cerebral granulomatous reactions following endovascular procedures
  1. Therese Boyle1,
  2. Suran L Fernando1,2,3,
  3. Brendan Steinfort4,
  4. Jamma Li1,2,3,
  5. Martin Krause5,
  6. Tim Harrington4,
  7. Nazih Assaad6,
  8. Ken Faulder4
  1. 1 Department of Clinical Immunology and Allergy, Royal North Shore Hospital, Sydney, New South Wales, Australia
  2. 2 Immunorheumatology Laboratory, NSW Health Pathology, Royal North Shore Hospital, St Leonards, New South Wales, Australia
  3. 3 Medicine (Immunology and Infectious Diseases), The University of Sydney, Sydney, New South Wales, Australia
  4. 4 Neurosurgery Department-Interventional Neuroradiology Unit, Royal North Shore Hospital, St Leonards, New South Wales, Australia
  5. 5 Department of Neurology, Royal North Shore Hospital, St Leonards, New South Wales, Australia
  6. 6 Neurosurgical Department, Royal North Shore Hospital, St Leonards, New South Wales, Australia
  1. Correspondence to Dr Therese Boyle, Clinical Immunology and Allergy, Royal North Shore Hospital, Sydney, NSW 2065, Australia; thereseboyle{at}


Background Endovascular 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.

Methods We 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.

Results These 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.

Conclusions There 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.

  • aneurysm
  • device
  • embolic
  • inflammation
  • material

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  • Contributors TB collated and analysed information as well as both contributed and co-ordinated the write-up of the article. SLF, JL and MK were the treating specialists. BS, KF, and TH performed the interventional procedures. NA performed the surgical biopsies. All authors assisted with reviewing and editing the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial, or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.