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Original research
Nickels and tines: the myth of nickel allergy in intracranial stents
  1. Kevin N Vanent1,
  2. Emma M Federico2,3,
  3. David I Bass2,
  4. Guilherme Barros2,
  5. Jade Keen2,3,
  6. Michael R Levitt2,3,4,5
  1. 1 School of Medicine, University of Washington, Seattle, WA, USA
  2. 2 Neurological Surgery, University of Washington, Seattle, Washington, USA
  3. 3 Stroke & Applied Neuroscience Center, University of Washington, Seattle, Washington, USA
  4. 4 Radiology, University of Washington, Seattle, WA, USA
  5. 5 Mechanical Engineering, University of Washington, Seattle, WA, USA
  1. Correspondence to Dr Michael R Levitt, Neurological Surgery, University of Washington School of Medicine, Seattle, WA 98104, USA; mlevitt{at}


Background Most intracranial stents contain nickel alloy, and nickel allergy or hypersensitivity is common. Neurological injury following endovascular treatment with a nickel containing intracranial stent has been reported in patients with purported nickel allergy, but it is unclear whether these reactions represent true nickel hypersensitivity. We quantified nickel release from commonly used intracranial stents to investigate whether such stents should be avoided in patients with nickel allergy.

Methods We examined nickel release from seven commonly used intracranial stents: Enterprise, LVIS Jr, Neuroform, Wingspan, Zilver, Pipeline Flex Embolization Device, and Surpass Evolve. We incubated each stent in human plasma-like media for 30 days. Dimethylglyoxime (DMG) spot testing was performed on each stent to detect released nickel at 0 and 30 days. Inductively coupled plasma–optical emission spectroscopy (ICP-OES) was then used to quantify the nickel concentration of the media at 30 days. Nickel currency and nickel standard for atomic absorption spectrometry were used as positive controls.

Results DMG spot tests indicated nickel release only from nickel currency at 0 and 30 days of incubation. No nickel release was detected from any stent at 30 days using ICP-OES.

Conclusions Nickel release from commonly used intracranial stents is negligible. These results suggest that previously reported hypersensitivity to these stents may be misattributed to nickel allergy, and that patients with nickel allergy may be safely treated with select nickel-containing stents.

  • stent
  • aneurysm

Data availability statement

All data relevant to the study are included in the article. Raw data will be made available through any reasonable direct request. Not applicable.

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Data availability statement

All data relevant to the study are included in the article. Raw data will be made available through any reasonable direct request. Not applicable.

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  • Contributors KNV: interpretation of the data and drafting the manuscript. EMF: study conception, study design, and acquisition of the data. DIB and GB: study design and interpretation of the data. JK: acquisition of the data. MRL: study conception, study design, acquisition of the data, interpretation of the data, drafting the manuscript, and guarantor of the study. All authors: critically reviewed the manuscript, provided final approval of the version to be published, and each agrees to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

  • 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 MRL is the recipient of unrestricted educational grants from Stryker and Medtronic, reports equity interest in Synchron, Cerebrotech, Proprio, Fluid Biotech, and Hyperion Surgical, is an advisor for Metis Innovative, and is a consultant for Medtronic. MRL is an assistant editor of social media for Journal of NeuroInterventional Surgery.

  • 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.

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