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Nickel allergy: a reason for concern?
  1. Sunil Jeswani,
  2. Michael J Alexander
  1. Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, California, USA
  1. Correspondence to Dr Michael J Alexander, Department of Neurosurgery, Cedars-Sinai Medical Center, 8631 West Third Street, Suite 800E, Los Angeles, CA 90048 USA; michael.alexander{at}

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As the usage of intracranial stents continue to expand for wide-neck intracranial aneurysms, symptomatic intracranial atherosclerotic disease and other pathologies, an enigmatic problem that remains is in-stent stenosis (ISS). Most commonly, this phenomenon seems to take place as a result of neointimal proliferation. However, it has been postulated that the constituents of the metal alloys used in intracranial stents may also induce an inflammatory reaction that results in ISS. Thus, nickel ions, which are present in many of the metal alloys in intracranial stents, may cause a delayed-type hypersensitivity reaction leading to ISS. Studies examining the rate of ISS secondary to hypersensitivity reactions induced by nickel ion release in coronary stents have been equivocal. Based on the available data, we cannot conclude that prescreening for nickel sensitivity before the intracranial stent deployment is indicated, but further studies may be indicated, since the amount of nickel in coronary stents is far less than in the nitinol stents used in the cerebral circulation.

Applications of intracranial stent

The use of intracranial stents has expanded significantly over the past few years, especially with the advent of more flexible nitinol stents.1 Intracranial stents have been shown to be an effective and safe method of revascularization in intracranial vessel disease secondary to atherosclerotic lesions and dissections.2–6 Many studies have shown greater efficacy in revascularization of intracranial stenoses than just angioplasty alone, as well as a decrease in rate of complications such as distal embolization and dissection.7

Additionally, the use of intracranial stents in the treatment of aneurysms has grown dramatically. Studies as early as 1994 demonstrated the use of stents in the cerebrovascular circulation for dissecting aneurysms.5 In 1997, Higashida et al demonstrated the use of an intracranial stent as a scaffold through which coils were placed into an aneurysm in order to treat a …

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  • Competing interests None.

  • Patient consent Obtained.

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