DEAR DR. DONOHUE: I have had sciatica for two and a half months. Even though I am better than at I was first, I am taking forever to fully recover. I have had chiropractic treatments and physiotherapy.

My doctor tells me it will go away on its own. Books that I have read say that most recover in six weeks. It’s going on three months for me.

I also had vasculitis (Henoch-Schonlein purpura). I haven’t experienced any symptoms for a couple of years. I have been feeling nauseated and have had loose BMs and the odd stomachache. A red spot appeared on my leg a few days ago. Do you think the vasculitis is playing a role in my delay in recovery? — J.B.

ANSWER: I’ll describe the typical pain of sciatica, and you see if the description fits your pain. The sciatic nerve is the body’s largest and longest nerve. It travels from the lower back, down the leg to the ankle or foot. Pressure on the nerve from a protruding back disk, a bone spur or anything that compresses the nerve brings on sharp or burning pain running down the side and back of the leg to the foot.

Pulling the knees to the chest and holding that position for 20 seconds produces sciatica pain.

The pain of sciatica often lessens and disappears in one or two months.

The X-ray report you included doesn’t rule in or rule out sciatica. If the pain persists, an MRI or CT scan provides additional information. You are improving, so I think eventually you should be pain-free.

Vasculitis is an inflammation of blood vessels, and Henoch-Schonlein (HE-knock SURN-line) purpura is one kind of vasculitis. Children get this illness more than adults do. Red blotches that turn into bruises (purpura) pop up on the buttocks and legs. Joint pain, abdominal pain, nausea, vomiting and diarrhea (or constipation) also arise. In the first year after recovery, relapses are common. If your current stomach troubles worsen or you see more red blotches, get back to the doctor who took care of you before. I don’t believe that HS, if it is returning, is interfering with your recovery from sciatica.

The booklet on back problems describes their common causes and their treatment. Readers can order a copy by writing: Dr. Donohue — No. 303, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.75 U.S./$6 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DEAR DR. DONOHUE: I have a dropped foot (left). What causes this condition? Are there any solutions?

I am 71 and did not have a stroke. — M.L.

ANSWER: Something has gone wrong with the nerves that control the muscles of your left lower leg. Most of the time, that “something” is a neuropathy, a word that simply means “nerve illness or malfunction.” Many conditions cause neuropathy, including diabetes, a loss of the insulation that covers nerves, nerve inflammation and a large number of inherited conditions. Most of the time a doctor must call it “idiopathic,” meaning no cause can be found.

People with your kind of neuropathy have to lift their leg very high to take a step. If they don’t, the foot drops downward and trips them up. That’s a dropped foot. Ordinarily, leg muscles keep the foot parallel to the ground when a person lifts it to take a step.

If a doctor, preferably a neurologist, cannot find a treatable cause for a person’s foot drop, then the doctor has to resort to prescribing braces that hold the foot in position. The person can then walk more normally and without fear of tripping.

Do yourself a favor. Contact the Neuropathy Association at 888-PN-FACTS (toll-free) or online at www.neuropathy.org. The association will provide you with a wealth of information on this common condition.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com.