Neurogenic ulcers (also known as neuropathic and diabetic ulcers; mal perforans) will affect approximately 15% of individuals with diabetes during their lifetime. The pathogenesis of these ulcers is multifactorial and has to do with peripheral vascular disease, peripheral neuropathy, repetitive trauma, and mechanical change in the bony architecture of the foot over time. They occur over pressure points on the feet of individuals who have had diabetes for many years.
While the overwhelming majority of neurogenic ulcers occur in individuals with diabetes, any condition resulting in polyneuropathy (alcohol use disorder, arsenic poisoning, etc) or local neuropathy (eg, herpes zoster, Hansen disease) will predispose an individual to their formation.
Neurogenic ulcers are difficult to treat, frequently recur, and result in significant morbidity in the form of loss of function and, often, loss of limb.
ICD10CM: E13.621 – Other specified diabetes mellitus with foot ulcer
SNOMEDCT: 15074003 – Neurogenic ulcer
Differential Diagnosis & Pitfalls
Keep in mind that many conditions that lead to skin ulceration may coexist within the same patient.
Neurogenic ulcers, also known as diabetic ulcers, are ulcers that occur most commonly on the bottom of the foot. People with diabetes are predisposed to peripheral neuropathy, which involves a decreased or total lack of sensation in the feet. Feet are naturally stressed from walking, and someone who has decreased sensation will not necessarily feel that they have an area of skin breakdown occurring. Coupled with this lack or absence of sensation is a decrease in circulation to the feet as well. Wounds that do not get proper blood flow are not only slower to heal but also at an increased risk for infection. A small cut, scrape, or irritated area in a patient with diabetes can turn into an ulcer for these reasons. It is common for these types of ulcers to keep coming back in patients with diabetes.
Who’s At Risk
Approximately 15% of patients with diabetes will be affected by neurogenic ulcers. The more serious or severe a person's diabetes is and the more out of control or higher their blood sugar is, the more likely they are to develop ulcers. Other risk factors include obesity, heart disease, and tobacco use.
While neurogenic ulcers most often occur in patients with diabetes, any condition resulting in peripheral neuropathy will predispose a person to getting them.
Signs & Symptoms
An ulcer is an open wound that can be deep enough that you can see down to the bone. Diabetic foot ulcers commonly occur on the pressure points of the foot: the ball, heel, and side of the foot if a person's shoes are too tight. However, an ulcer can form in any location that gets cut or scraped if it fails to heal properly.
The key is to prevent ulcers from forming:
Inspect feet daily, including the areas between the toes, to look for any breaks in the skin; blisters; or red, irritated areas. A mirror can help you see the bottoms of your feet, or have a family member or caregiver do this.
Trim toenails regularly.
Make sure to wear well-fitting, cushioned shoes and pressure-reducing hosiery - indoors and outdoors - to reduce risk of injury. If you wear socks, make sure that any folds in the socks are smoothed out before putting shoes on. Avoid wearing flip-flops and wearing shoes without socks.
Do not go barefoot: there is significantly more pressure on bare feet than feet in properly fitting, cushioned shoes.
Do not use medicated pads to treat corns, calluses, or warts on the feet, as these pads can cause ulcers; instead, speak to a professional about removal.
Test bath water with your fingers instead of stepping in it; if your feet lack sensation, they may get burned by water that is too hot.
It is important to note that if you have had an ulcer previously, it is very common to get more. You should follow the tips above and consider decreasing pressure on your feet by trying to walk less (try non-weight bearing exercise, such as swimming, cycling, or rowing), getting cushioned shoes (your insurance may pay for them), and considering changing to a job that does not require much walking or standing.
Additionally, smoking can worsen blood flow, further slowing down healing. It is very important to make sure that you keep your blood sugar under tight control, as elevated blood glucose actually reduces the body's ability to fight infection and slows down wound healing.
When to Seek Medical Care
People can develop peripheral neuropathy without even being aware of it, so it is important for patients with diabetes to be examined by their doctor every 6 months. The doctor will use a special test, called a monofilament test, to assess the sensation on the bottoms of your feet.
All ulcers should receive treatment. Also see your health care provider if you feel a lack of sensation in your feet, there is any discoloration, pain, swelling, redness, oozing, or fever.
Neurogenic ulcers can lead to amputation if care is delayed, so it is important to be seen by your physician as soon as possible.
In the case of a new ulcer, your doctor may want to take an X-ray of the area to make sure that there is no infection (osteomyelitis), fracture of the bone, or foreign objects lodged in the ulcer, as you may not feel them. Next, the doctor will likely remove any dead tissue with a scalpel (débride) from the area, revealing healthy skin. While this will actually make the ulcer larger in size and cause bleeding, it is important to have healthy tissue exposed for faster and cleaner healing. This will likely be done in the operating room, under anesthesia. After the surgery, be sure to follow proper instructions on wound care, making sure to apply any medications and dressings as directed.
Your doctor may send a sample of skin or fluid for bacterial culture and start you on oral antibiotics. It is very important to follow up with your doctor as scheduled: neurogenic ulcers can worsen very quickly and need to be closely monitored. Make sure to call your doctor if you experience any of the following: redness of the area, red streaking up the leg, drainage of the area, pain, foul odor, rising blood glucose, or swelling or redness of the top of the foot.
Your doctor may have you wear a special cast that will allow you to continue to be mobile but take pressure off the area. There are also medications that use growth factors to stimulate wound healing that your doctor may prescribe.
Levin ME: Pathogenesis and general management of foot lesions in the diabetic patient. Levin and O'Neal's The Diabetic Foot.