Clinical Communications

Probable delayed-type hypersensitivity to nickel-containing cerebral aneurysm clip associated with neurologic deficits

Contact dermatitis (CD) is a common skin condition caused by contact with an exogenous agent that elicits an inflammatory response. Although history and physical examination can be helpful in distinguishing between irritant CD and allergic CD (ACD), the gold standard for diagnosing ACD is patch testing. Although the actual patch test (PT) procedure and application is relatively straightforward, the decisions involving which allergens to use, interpretation of results, determination of relevant allergens, and subsequent patient management require more skill and expertise. Often, the distribution of the presenting dermatitis can provide insight into the potential causative allergens and should be taken into account when selecting PT allergens. Commercially available PT panels and personal care products can be used for patch testing. Determining the clinical relevance of PT results is a critical component of the PT procedure. Patients must be educated on avoidance of relevant allergens and given guidance on alternative products available for use. Special populations, including children with ACD and occupational CD, and patients with biomedical devices have unique allergen considerations, and PT panels should be directed as such to address all potential allergens.

Nickel is the most common metal allergen and predominantly affects women. It is also the ubiquitous component in the alloys used to manufacture intracranial devices for aneurysm treatments, including aneurysm clips, self-expanding stents, flow-diverting stents, and endosaccular occlusion devices. Adverse events related to nickel allergy after deployment of such devices are uncommon but can be severe, resulting in dilemmas in the choice of treatment strategies and devices in managing nickel-sensitive patients with intracranial aneurysms.

A literature search was performed in accordance with the PRISMA guidelines to identify studies reporting on nickel-related adverse events in patients being treated for cerebral aneurysm. The materials of the culprit devices, clinical presentation, histological features, and treatments were reviewed. Clinical considerations and management options for nickel allergy patients were evaluated.

Nickel is a major component of the cobalt alloy used in aneurysm clips and also of nitinol, which is commonly used in flow diverters and intracranial stents. Our literature review identified 9 articles reporting 10 unique cases of nickel-related adverse events after aneurysm treatment. Five of the cases occurred after aneurysm clipping, and the other 5 were attributed to endovascular devices. Two patients presented with dermatologic manifestations and 8 with neurologic manifestations, including cerebral edema and cerebritis.

Neurologic complications related to nickel in cerebral aneurysm treatments are rare but remain concern owing to the high prevalence of nickel allergy in the population. Surgeons and interventionists should consider the metal allergy history and its potential clinical significance in managing nickel-allergic patients with aneurysms.