Sciatica, Diabetes, Frostbite: Many Reasons for Foot Problems

Question 1:
I'm 49 years old and have type 2 diabetes. I've had a month of "pins and needles" sensation in my left foot, and my doctor told me I have sciatica. (An X-ray of my back showed degeneration of the discs and deterioration of the sacroiliac joint.) I start physical therapy next week. Is that the only treatment?

Dr. Mitchell answers:
You may have sciatica, a word that describes the aching pain, burning and tingling that is often caused by a herniated disc. Typically, this pain starts at the back and radiates to the buttock or radiates down the back or side of the leg, depending on which disk is affected.

Usually, if symptoms are predominantly in the foot like yours, a disc has trapped a nerve, leaving you not only with "pins and needles" but also muscle weakness and numbness of the foot. (By the way, problems with the sacroiliac joint usually cause pain at that site, that is, in the buttocks or low back.) Along with over-the-counter pain relievers, physical therapy is a good initial approach to sciatic or low back pain.

Since your story is not classic, your pain has lasted a month, and you have a history of diabetes, sciatica may not be the only explanation. You may need an EMG (an electromyogram or nerve test) or other tests to make sure you don't have diabetes-related peripheral neuropathy or a different problem.

Question 2:
I have numbness in both feet on my toes only. My doctor says I have peripheral neuropathy, but I was not given a reason for it (I do not have diabetes). Last winter I was out in the cold (9 degrees for two hours) with only rubber boots and a thin layer of socks. My feet were cold when I came in but did not change in color. It was about a month later that I noticed the numbness. Could this be from the cold?

Dr. Mitchell answers:
Frostbite can certainly be a cause of peripheral neuropathy, but I cannot tell if you indeed had frostbite. Doctors use three categories to describe skin or deeper tissue injuries from cold temperatures: frost nip (numbness and mild color changes), superficial frostbite (numbness and loss of color; then reddening, swelling and clear blisters on rewarming), and deep frostbite (numbness, white color, and stony or woody feel to the feet; then bloody, very swollen blisters on rewarming).

If you had any symptoms of numbness on that cold day, you probably at least had frost nip. About half of people with a history of superficial frostbite will develop an increased sensitivity to cold temperatures, and about a third will have long-term numbness.

Now is the time to remember how to prevent frostbite: dress warmly with all skin covered, particularly the susceptible areas of the feet, hands, ears and nose, do not wear constrictive clothing such as tight socks, keep moving while outdoors, and do not drink alcohol.

If you do have numbness or frostbite, warm up quickly but avoid only partial warming or repeat exposure to cold while the area is recovering. In case of deep frostbite, seek immediate care by a physician.

Julie L. Mitchell, MD, MS, is an Assistant Professor of Medicine at the Medical College of Wisconsin. She practices internal medicine at the Froedtert & Medical College General Internal Medicine Clinic - East. Her column appears in the Milwaukee Journal-Sentinel.