PRECÍSNeurological endovascular coils used for aneurysm embolization may be composed of nickel alloys that can cause transient allergic contact reactions.
DISCUSSIONA 39-year-old woman with a history of skin irritation to jewelry presented for patch testing because of abnormally enhancing white matter lesions observed on magnetic resonance imaging (MRI) and neurologic symptoms attributed to inflammation secondary to recently placed endovascular coil components (Fig. 1). After embolization of a left supraclinoid carotid ophthalmic artery aneurysm with 4 detachable Stryker (Stryker Corporation, Kalamazoo, MI) endovascular coils, she immediately developed transient numbness and tingling of her left face and a persistent left-sided headache. An MR image was unremarkable at this time. Three months later, additional paresthesias of the right extremities prompted an extensive negative infectious and rheumatologic work-up by neurology, but a lumbar puncture detected 15 oligoclonal bands, suggesting central nervous system inflammation corroborated by newly enhancing MRI white matter lesions. Etiologies such as multiple sclerosis or acute disseminating encephalomyelitis were ruled out based on inconsistent cerebral spinal fluid patterns. Her symptoms completely resolved after 2 weeks of systemic steroid treatment. At the time of her presentation for patch testing 1 year later, her MRI lesions had completely resolved.Patch testing was performed with the Chemotechnique Diagnostics North American 80 Comprehensive Series and Metal series (Chemotechnique MB Diagnostics AB, Vellinge, Sweden).The tests showed positive reactions to nickel (2+ at 96 hours) and sodium tetrachloropalladate (II) hydrate (2+ at 96 hours) (Fig. 2). Further inquiry into the composition of the coils confirmed the presence of stainless steel alloys with nickel components but no palladium. Repeated requests for a sample of the coil to use for patch testing went unanswered.There have been reports of hypersensitivity to nickel-containing dental, orthopedic, and cardiac medical devices presenting with systemic symptoms, but few cases implicate neurological endovascular devices. The coils placed in our patient were partially composed of type 316 low carbon vacuum melt (LVM) stainless steel. Coil packaging warnings include the possibility of developing allergic reactions to 316LVM stainless steel in patients with metal hypersensitivity. 1 Type 316LVM stainless steel is a chromium, nickel, and molybdenum alloy that is commonly used for implantable medical devices but has been hypothesized to release nickel ions in the past. 2 These factors combined with the temporal course of our patient's presentation suggest a hypersensitivity response, although causation is difficult to prove without patch testing a coil sample. Figure 1. Patch testing results at 72 hours showing positive response to palladium and nickel.