HELP ON DIABETES

NERVE INJURY TO FEET

The most common type of nervous system injury in diabetes is to the nerves that innervate the muscles of the feet and transmit sensory information from the feet to the spinal cord. Feet affected first because the nerves to the feet are longer. Usually the symptoms start at the toes and gradually go up the foot and leg to the knee (known as stocking distribution). Early on, the injury may pre­sent with occasional tingling or slight electrical shocks. As it progresses, the symp­toms may get worse with more persistent tingling or burning sensation or feeling cold. With even further damage, the burning and uncomfortable sensation gets bet­ter, but then there may be more numbness. Early on, the numbness might be quite mild, but later on the numbness may be so profound that pain cannot be felt. It is this severe form of nerve injury that is of most concern, because a person with this condition may not be aware of the foot injury.

Paralysis of the small muscles of the foot due to diabetic nerve injury can alter the shape of the foot with clawing of the toes and flattening of the arches. When this happens, calluses can develop over pressure points, and then the pressure from the calluses causes ulcers in the tissue underneath.

Treatment

There are a variety of treatments for pain due to neuropathy, and finding the best treatment is really a matter of trying them out. Good glucose control is important because the pain is worse with poor control. Simple things such as acetaminophen (Tylenol) at night might be sufficient. Your doctor may also prescribe tricyclic anti­depressants such as amitriptyline (Elavil) taken one to two hours before bedtime to help the pain. Amitriptyline causes drowsiness, and this can be a good thing for a good night’s sleep. Sometimes, however, the sleepiness extends into the day, in which case your doctor may ask you to try another tricyclic antidepressant that causes less drowsiness. Other side effects that can occur include dry eyes and dry mouth, constipation, and difficulty urinating. If these side effects cannot be toler­ated, then one of the newer anticonvulsants, gabapentin (Neurontin), can be used. The common side effects of gabapentin are drowsiness, fatigue, and imbalance. Recently, a medicine related to gabapentin, called pregabalin (Lyrica), was approved for painful neuropathy. There is no evidence that it is any better than gabapentin. Duloxetine (Cymbalta) is another antidepressant that is also useful in treating neuropathy.

Capsaicin, a chemical found in hot peppers, can be used to treat the pain from diabetic neuropathy. The capsaicin cream Zostrix (available over the counter) is rubbed on the painful areas of the feet two to four times a day. Initially the burning feels worse and there may be redness, but if you persist, the burning gets much bet­ter by about the second week. You do have to wash your hands carefully after using it (or use gloves), otherwise you may end up with burning eyes or face.

For a very small number of people, none of these treatments are sufficient to con­trol the pain, and it may be necessary to take stronger pain medicines such as tram­adol (Ultram) or morphine, preferably under the supervision of physicians at a pain control clinic.

Foot Ulcers

Foot ulcers occur in about 5 percent of people with diabetes. It is important to emphasize that foot ulcers can almost always be prevented, and there are many people with neuropathy and circulation problems of their feet who never get foot ulcers.

People with diabetes are at higher risk for foot ulcers for the following reasons:

• Diabetic nerve injury changes the shape of the foot and leads to callus formation at pressure points. 
• Diabetic nerve injury impairs sensation, and you may be unaware of injury. For example, you may step on something sharp and not realize it. 
• Nerve injury to the sweat glands in the feet can lead to dry feet and cracks in skin. 
• Damage to the small blood vessels causes swelling of the feet. 
• Damage to the large blood vessels reduces blood flow to the foot and impairs healing .  

Prevention of Foot Ulcers

Foot ulcers can be prevented in the following way

1) If you have evidence of diabetic neuropathy or foot circulatory problems, see a podiatrist who has an interest in treating diabetic feet. The podiatrist can

• Trim the calluses and reduce the pressure on the underlying tissues. 
• Prescribe custom orthotics that spread the foot pressures and so prevent the development of new calluses. 
• Treat fungal infection if present and recommend moisturizing creams for dry skin. 
• Prescribe custom, extra-depth shoes if the shape of your foot is altered so that it cannot fit into a normal shoe. 
• Counsel on proper foot care. 

2) It is important not to walk barefoot when there is severe numbness. Socks and shoes should be worn at all times. Examine the inside of your shoes regularly (at least daily) to make sure that there are no pebbles, grit, or other objects in the shoes.

3) Examine your feet daily for cuts, swelling, and blisters. Toenails should be cut straight across to avoid the problem of ingrowing toenails.

4) New shoes should be comfortable and well fitting and initially worn only a few hours at a time.

5) If severe foot deformity and numbness is present, then non-weight-bearing exercise, such as riding a stationary bicycle, may be better than weight-bearing exercises such as walking and jogging.

If a blister or foot ulcer develops, it is important to seek medical attention imme­diately. Depending on the cause, treatments include removal of calluses and dead skin, antibiotics, limiting walking, and treating circulatory problems.