Peripheral Neuropathy and Diabetic Foot Ulcers

 

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What is peripheral neuropathy?

One of the major complications associated with diabetes is peripheral neuropathy. This process of nerve damage gradually takes place after many years of having diabetes and uncontrolled blood sugar. The condition affects the sensory, motor, and autonomic nerves of the body. Muscle strength and balance are diminished with motor neuropathies. While autonomic neuropathies manifest as loss of hair and disfunctioning sweat glands in the lower extremity and can present as erectile dysfunction in very advanced cases. Sensory deficits, which include numbness, tingling or even pain, are often the first symptoms to develop. Many people that are developing the condition may not notice the gradual onset of symptoms. Diabetics may be unaware of of these gradual changes until their doctor informs them that they have the condition. Some may experience shooting pains in their feet that become worse at night, making it difficult to sleep.

 

Lack of sensation in the lower extremity can be very dangerous because it increases the risk of developing sores, open wounds and ulcers on the feet. If the wound becomes infected, there is a likelihood that the infection can spread and amputation of the affected limb may be necessary if it is not treated soon enough. Losing a limb becomes a large burden for patients in their daily activities and adds additional costs to their medical care. Because of this, it is recommended that a comprehensive foot exam be performed annually in all diabetics.

 

Muscle weakening associated with motor neuropathy acts as an added detriment because it can lead to development of foot deformities, such as hammertoes, bunions or limitation of motion in joints of the lower extremity. These defomities may rub on shoe gear and cause skin breakdown. Coupled with a numb foot, these deformities increase the patient’s risk of developing foot wounds.

 

Foot exam

The physical exam involves a thorough review of the skin health, blood supply, nerves and muscle strength of the lower extremity. The skin is assessed for hair growth, any discoloration and wounds. Diabetics have an increased risk of developing poor blood supply also known as peripheral vascular disease. This in turn greatly increases their risk of acquiring a dangerous infection and non-heeling wounds of the feet. The neurological portion of the exam involves measuring the patient’s ability to feel a small flexible fiber under their feet with their eyes closed. Additional testing evaluates their ability to detect vibratory sensation. Patients that develop peripheral neuropathy may not be able to tell the doctor when the bottom of their feet is touched with a monofilament. These patients are at an increased risk of developing unnoticed foot wounds.

 

Diabetic foot wounds – how are they treated?

Repetitive trauma to the foot leads to development of a hard callus, which increases pressure on the foot when the patient walks. The person with a numb foot continues to exert pressure on the callus, which forms a deeper wound that can subsequently lead to infection. An ulcer develops when a break of the skin occurs. The depth of the wound plays a large role in how serious the infection can be and how it can be managed. A rim of callus usually surrounds the wound. Once the wound becomes infected, the foot may become red, leak fluid, and may have a foul smell. As the infection progresses, thick yellow fluid can leak from the wound. It is important that callus and any wound is medically evaluated and appropriate medical treatment is started as soon as possible. Initial treatment involves debriding the wound to remove any dead tissue covering in order to expose the underlying healthy tissue in the wound. Any callus that surrounds the wound is also removed. A culture is obtained to find out which bacteria are involved with the infection so that appropriate medical therapy with antibiotics can be initiated. Negative pressure wound therapy a small vacuum placed over the wound can be used in some cases to quicken the healing process. Some of these infected ulcers may require intervenous antibiotics and hospitalization.

In addition to antibiotics and debridement pressure from the shoe and the ground must be reduced or eliminated to allow the wound to heal. Offloading pressure from the wound sight is accomplished in many ways. Sometimes a wheelchair or crutches are needed to completely remove weight from the foot. An orthotic or shoe insert with cutout areas under the wound can reduce pressure from causing additional damage. There are also many other ankle-foot braces and cast that remove pressure from the foot. One of these braces is the Bledso Boot. This boot has a layer of auto-molding foam in the foot bed, which reduces pressure on the wound. It also prevents movement at the ankle therefore reducing friction that can cause tissue breakdown. Another type of device made to eliminate pressure from the bottom of the foot is called the Toad Brace. This apparatus is molded to fit and grip around the top of the lower leg and the knee. This construct floats the foot off the ground and completely offloads the bottom of the foot. After the wound heals it will be necessary to use an offloading orthotic and a shoe designed to fit this inner sole.

If you have peripheral neuropathy, it is important to check your feet daily for wounds. Areas of your feet that receive high pressure may develop calluses, which increase the risk of a wound forming in that area. Seek help early from your doctor so that a proper treatment regimen can be started. A wound that is deep and does not heal leads to further complications, such as bone or systemic infection. Disregard for the condition of your feet, especially if you are diabetic, can lead to loss of a limb.

 

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