title: Cell-mediated allergy to a cerebral aneurysm clip: case report.
abstract: BACKGROUND
  Titanium aneurysm clips have superior imaging characteristics and have been supplanting their stainless steel counterparts. We report the case of a 36-year-old woman with a histologically demonstrated cell-mediated reaction to a cobalt alloy aneurysm clip.
  
  
  METHODS
  The patient underwent a craniotomy and clip placement for a ruptured cerebral aneurysm. Both the aneurysm clip and the wires used to fix the craniotomy were made of stainless steel (cobalt and nickel) alloys. Postoperatively, the patient was plagued by intense pruritus.
  
  
  METHODS
  Skin patch testing revealed a severe reaction to nickel and cobalt. Surgical removal of the aneurysm clip and wires resulted in the disappearance of the patient's symptoms. A histological analysis of the tissue adjacent to the clip and wires was consistent with Type IV delayed type hypersensitivity.
  
  
  CONCLUSIONS
  Stainless steel surgical implants in the head can cause diffuse, severe pruritus in susceptible individuals. Although the role of the aneurysm clip, as opposed to the more superficial wires, in the genesis of the patient's symptoms is not certain, this case demonstrates that a cobalt alloy aneurysm clip can activate T cells and cause an immunological reaction in the central nervous system.
authors.affiliation: Section of Neurosurgery, University of Manitoba and Health Sciences Center, Winnipeg, Canada.
authors.forename: I B
authors.initials: IB
authors.lastname: Ross
authors.forename: R J
authors.initials: RJ
authors.lastname: Warrington
authors.forename: W C
authors.initials: WC
authors.lastname: Halliday
mesh_terms: D000328:Adult; D003035:Cobalt / Q000009:adverse effects*; D003875:Drug Eruptions / Q000276:immunology / Q000473:pathology; D005260:Female; D005549:Foreign-Body Reaction / Q000276:immunology / Q000473:pathology; D006801:Humans; D006968:Hypersensitivity, Delayed / Q000276:immunology* / Q000473:pathology; D007111:Immunity, Cellular / Q000276:immunology*; D002532:Intracranial Aneurysm / Q000473:pathology / Q000601:surgery*; D008213:Lymphocyte Activation / Q000276:immunology; D010328:Patch Tests; D012086:Reoperation; D013193:Stainless Steel / Q000009:adverse effects; D013525:Surgical Instruments; D013601:T-Lymphocytes / Q000276:immunology / Q000473:pathology
chemical_list: D013193:Stainless Steel; D003035:Cobalt