Introduction: Metal allergies manifesting as contact dermatitis are common in the general population. Implanted, metallic endovascular stents corrode and release metal ions into the circulation that may elicit immune reactions in patients with metal allergies. It is unknown whether or not this mechanism contributes to in-stent-stenosis in intracranial stents and flow diverters, such as the Pipeline embolization device (PED), made of cobalt-chrome and platinum-tungsten alloys.
Methods: We report two patients with documented metal allergies and unruptured intracranial aneurysms that underwent treatment with the PED. Both patients had a PED taped to their skin during their preoperative workup. Clinical and angiographic outcomes are described.
Results: A 68-year-old female with documented cutaneous nickel allergy and an incidentally identified, wide-necked left ophthalmic artery aneurysm underwent treatment with a PED (4.5 x 20 mm). Follow-up arteriography at 1 year showed complete obliteration of the aneurysm and no evidence of in-PED-stenosis. A 66-year-old female with documented cutaneous nickel allergy and an incidentally identified, complex left paraclinoidal aneurysm underwent treatment with a PED (4.75 x 25 mm). Follow-up arteriography at 1 year and then again at 20-months showed persistent filling of the aneurysm and no evidence of in-PED-stenosis. She therefore underwent placement of a second PED (4.75 x 14 mm) leading to improved stagnation of aneurysmal flow intra-procedurally. Neither patient developed any clinical signs or symptoms of allergic reaction.
Conclusions: In two patients with known metal allergies and intracranial aneurysms treated with the PED there were no clinically apparent allergic reactions and there was no radiographic in-PED-stenosis.
Patient Care: Neuroendovascular surgeons use metallic stents to treat a variety of cerebrovascular pathologies but there is limited data on the safety of these devices in patients with documented metal allergies. We call attention to our institutional experience with the Pipeline embolization device and patients with known nickel allergies to raise awareness about the management of this complex scenario and to report promising clinical and radiographic outcomes.
Learning Objectives: By the conclusion of this session, participants should be able to: A) Describe the prevalence of metal allergies in the general population and understand the management options for patients with documented metal allergies who will need a stent to be placed; B) Recognize which metals are used to produce commonly-used intracranial stents; and C) Appreciate the controversy surrounding the hypothesis that endovascular metallic stents may cause hypersensitivity reactions that could contribute to in-stent stenosis.