Dear Dr. K: Do you have anything to share from your recent trip to the Southeastern Allergy meeting?
The meeting was excellent. The presentation I found most provocative was on allergy to medical devices. Unfortunately, this is becoming a more common source of allergic difficulty. The spectrum of reactions has included allergy to joint replacements, fracture-stabilizing metals, spine-straightening rods, cardiac pacemakers, defibrillators and their wires, coronary and other arterial stents and dental products, including implants and orthodontic materials.
Although some reactions are to glues and adhesives, it seems that metal allergy is the primary cause for these reactions. The reaction to metals is found more commonly in people who already have known metal allergy, such as nickel allergy to earring materials. In fact, nickel allergy is the most common metal allergy, followed by chromium and cobalt allergies.
People who have multiple body piercing sites have a greater likelihood of developing metal allergy. The American Academy of Allergy recommends avoiding ear or other piercings until age 10 to lessen the chance for developing metal allergy. It was once thought that titanium was allergenically inert but, unfortunately, allergic reactions are occurring to some titanium alloys.
The most common manifestation of the allergic reaction is a rash in the skin surrounding the implant site, or in the mucous membranes in the mouth in the case of dental allergy. In some patients there can also be sites of remote rash and other systemic symptoms, such as achiness and pain.
A special scenario can exist with arterial stent allergy. Sometimes the only manifestation is what is called rapid re-stenosis. That is, the artery that was reopened with the stent quickly closes again due to the allergic inflammation.
If someone has a known metal allergy and needs an implanted material, it is recommended that a patch test be done with the material prior to its being used. Unfortunately, there are not yet any standardized test kits, so the approach is more seat-of-your- pants in nature. Usually a small piece of the to-be implanted metal can be obtained and a patch test carried out. In some very special cases, instead of a patch test, the test metal is actually surgically placed in a superficial pocket below the skin for several weeks to see if an allergy develops. Obviously, this more invasive test is only undertaken in special high-risk cases.