Q: While growing up just south of the Canadian border, my friends and I spent many winter days playing outside in the cold without adequate protection for our toes and fingers. As a result, we believe that we suffered some degree of frostbite. Now we all suffer numbness and discomfort on those same toes and fingers on cold days in Washington. Could you please comment on these sensations and recommend a remedy?

A: It's very possible that you suffered frostbite injury to some of your fingers and toes, and now are bothered with a residual sensitivity to the cold. I don't have any special remedy to suggest, but can only recommend avoiding further damage from the cold.

Depending on the amount of exposure, frostbite injuries can be superficial or deep. Even superficial frostbite can have lasting effects, such as you seem to be having. Deep injury can lead to wasting of the muscles, scarring, arthritis and gangrene with loss of toes or entire limbs.

When serious frostbite occurs, the best treatment is rapid rewarming in a water bath at 90 to 108 degrees Fahrenheit for 20 to 40 minutes. If outdoors, you shouldn't rub the frostbitten area, especially not with snow. This would only further damage injured tissues. You also shouldn't smoke, because nicotine constricts a critically needed blood supply. If possible, avoid having any frostbitten area thaw and then refreeze again. This freeze-thaw-freeze cycle is particularly damaging.

Q: I'm 42 years old and recently had my first seizure. My doctor didn't find any cause for it, but I had been using large amounts of the artificial sweetener aspartame, up to 20 packets of Equal per day, plus drinking several diet drinks containing aspartame. I've heard that aspartame binds with acids in the stomach and forms poisons that can damage the brain. I've wondered whether my problem was caused by aspartame.

A: Based on theoretical reasons, some scientists have voiced concerns about the safety of the artificial sweetener aspartame, sold as Equal in packages and called NutraSweet in soft drinks. But a great deal of evidence suggests that it's safe to consume.

Aspartame is made from two substances commonly found in protein, phenylalanine and aspartic acid. Phenylalanine may cause problems in people with the uncommon disorder called phenylketonuria (PKU), a condition caused by lack of an important enzyme. But even many people with PKU have no trouble handling aspartame.

Aspartame doesn't bind with acids in the stomach to form poisons, but perhaps you're referring to concerns about aspartic acid in combination with glutamate (a substance found in foods and the flavor enhancer monosodium glutamate, MSG). These concerns arose because both of these substances have caused brain damage in laboratory animals when given in extremely high amounts. But even your 20 packets of Equal a day wouldn't begin to approach toxic levels of phenylalanine or aspartic acid. As an example, you'd have to take about 300 packets of aspartame at one time just to reach half the toxic level of phenylalanine.

Tests show that taking up to 5,000 milligrams for every kilogram (2.2 pounds) of weight produces no ill effects in laboratory animals. To be on the safe side, the Food and Drug Administration cut this dose 100-fold and recommends taking no more than 50 milligrams of aspartame for each kilogram you weigh. For a 130-pound person, this amounts to 85 packets of Equal, or 17 to 21 12-ounce cans of aspartame-sweetened soda, a day.

After reviewing the evidence, both a public board of inquiry and the Food and Drug Administration have concluded that aspartame, either alone or in combination with glutamate, does not cause brain damage. The American Medical Association's Council on Scientific Affairs recently supported the FDA's stamp of safety on aspartame and investigators from the Centers for Disease Control, after interviewing more than 500 people complaining of possible reactions to aspartame, concluded that although some people may have unusual sensitivity to the sweetener, there was no evidence of it causing any seriously harmful effects. Follow-Up

My answer on restless legs prompted several readers to write and may have caused some confusion. That may have been because of the similarities among several leg problems that typically occur at night. To review, here's a list of the ones I've talked about.

*Restless legs syndrome, a disagreeable leg sensation that makes you want to get out of bed and walk around.

*Painful leg cramps, also called a charley horse.

*Nocturnal myoclonus, or leg muscle twitching that occurs during sleep.

*Leg paresthesias, painful or unpleasant leg sensations caused by a nerve problem known as peripheral neuropathy.

But these distinctions aren't as neat as doctors would hope for. There's a lot of overlap among them, especially between restless legs syndrome and peripheral neuropathy.

One reader, a 26-year-old runner, said he relieved his disagreeable leg sensations by leg stretching exercises, a response that suggests his problem was a mild form of nighttime leg cramps. Another reader got relief from leg "spasms" by taking quinine, an over-the-counter remedy for leg cramps. This is the same ingredient in the prescription medicine Quinamm, which is sometimes helpful for this problem.

Others successfully treated restless legs symptoms with regular exercise and -- a new one on me -- vitamin E. Though I can't confirm its effectiveness, I was surprised to learn that vitamin E was a second ingredient in two nonprescription quinine products, Q-vel and Quintrol. Finally, one reader's restless legs symptoms responded very well to treatment by his wife, a massage therapist.