I see many patients who suffer from an intense and seemingly inexplicable itch on their arms. Until now, we doctors haven’t been able to explain why this happens- but at last there’s a conclusive answer. Like nostalgia paresthetica, the problem is apparently caused by a nerve impingement in the spine!
For me, this answer is one of my highlights from the 2011 American Academy Of Dermatology’s Annual meeting in New Orleans; when science figures out the cause of some mystery condition that I treat every day, I’m thrilled.
The diagnosis is brachioradial pruritus. It’s another one of those strange conditions where a precise part of the skin itches intensely but yet it looks entirely normal. Patients can actually draw on their skin exactly where the itchy area stops and starts. I’ve been able to give my patients the name of the condition, but it’s been frustrating for all of us because I haven’t been able to give them a good explanation for the problem. Now I can.
Of course there are many other reasons why arm skin can itch, but usually there’s a rash on the arm skin and possibly on other parts of the body too. Common examples include dry skin, a contact allergic reaction like poison oak or wool allergy, psoriasis, etc. But when you have brachioradial pruritus, the intensely itchy skin looks completely normal before you start scratching. My right arm has the itch of brachioradial pruritus so I get to “observe” the condition daily. (There are other conditions where it’s possible to have total body itching with no visible rash on the skin, but in brachioradial pruritus the itching is limited mainly to the arms.)
How do you know if you might have brachioradial pruritus?
Brachioradial pruritus usually begins in adulthood, especially if the skin on your arms is sun damaged. In fact, sun exposure may also trigger the onset of itching. The skin looks normal unless if you’ve been scratching. Unlike nostalgia paresthetica, the central back itch, your arms are right there for you to scratch and the itch is almost irresistible. Years of scratching will cause a callusing and roughness of the skin, ultimately leading to white, red, and brown scars. These are “secondary skin changes” because they’re due to scratching. There are no primary changes (changes due to a rash) because the underlying skin is actually normal.
Both arms are usually affected but often the driver’s side arm is worse. The most common area of your arms to be involved is the forearm near the elbow, but any area on the arms, upper back, and neck can be affected. Itching is usually described by patients as a burning, prickling, or stinging sensation. Like nostalgia paresthetica, the involved skin is hypersensitive to touch. Even light touch can set off the itching process. Sunlight can start it up too.
The new nerve impingement explanation for brachioradial pruritus
We’ve suspected nerve impingement to be the cause of both brachioradial pruritus and notalgia paresthetica, but now it’s conclusive! Since the arms are involved, the impinged nerves are coming out of the cervical spine, so it’s cervical spinal abnormalities that cause the nerve impingement. Also, like notalgia paresthetica, the spinal abnormalities don’t need to be severe; they can be just a slight bulge of a disk, calcium spurs coming of the vertebrae, or other spinal changes that accompany aging.
There also seems to be a role for sun damage in brachioradial pruritus. It may be that both the nerve impingement and the degenerative changes in the skin that occur from sun damage are both necessary to cause the problem.
What can you do to lessen your itchy arms if you have brachioradial pruritus
Treatment is tricky because the skin is actually normal and the message of “itch” emanates from the nerve near the spine, but there are things we can do to lessen the itch.
Sun protect your arm skin. We know that sun plays a role in the problem, so, of course, sun protection is important. The best protection comes from wearing sun protective shirts that cover your arms. If that’s not possible then the mineral micronized zinc oxide sunscreens are best because, unlike chemical sunscreens, heat is not created when the UV rays hit the active sunscreen ingredients. Heat can make the itch worse. My favorite micronized zinc oxide sunscreen for the arms is Solbar Zinc.
Keep your arm skin well moisturized and free of flaky, dry scale. Tickling dry skin scale sets off the itch, so moisturizing is really important. (Think of dry skin scale like tiny feathers brushing over your skin and tickling you.) I described my moisturizing recommendations in my post on nostalgia paresthetica. If your skin is really dry and irritated you will need to start with bland, rich moisturizers. Eventually though, glycolic acid products will work the best to control flaky scale. My favorite way to keep itchy arm skin well moisturized and free from tickling dry scale is with my Anti-Aging Body Kit. The products are used to keep your skin from becoming scaly, not for anti-aging purposes, and they are highly effective at doing the job.
When itching occurs:
- I tell my patients to slap an ice pack on the itchy skin because when the nerve is so busy telling you your skin is cold it can’t tell you that your skin itches.
- I also stress the importance of not scratching! Scratching causes skin nerves to thicken up and send even louder itch messages to your brain in the future.
- Anti-itch creams with pramoxine or menthol sometimes help and can be used on an as needed basis numerous times during the day. If you keep them in the fridge they are cool too, providing additional benefit for your itch.
Scratching also eventually causes scarring and uneven pigmentation. This can be disfiguring, so we need to find some other solution for the itch. If sun avoidance, moisturizing, anti-itch creams, and the occasional ice pack don’t control the itch then I prescribe a topical cortisone cream to apply while my patient is going through an itchy spell. If none of this provides sufficient relief, then just like nostalgia paresthetica, there are strong oral medicines that can help block nerve signals. They have a lot of side effects and I only prescribe them for my patients as a last resort. (If you think you have this diagnosis and need prescription treatment you must discuss your situation with your personal doctor.)
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