Neuropathic leg pain is a complex condition that results from nerve damage and usually develops in concert with tissue injury.
Nerves are a critical component to the body’s overall functioning. Collectively referred to as the nervous system, nerves control fundamental body processes such as heart rate and blood pressure. They also relay information from the muscles and skin to the brain and spinal cord.
If you touch a hot stove, it’s the nerves that send information to the brain letting you know that it’s painful to avoid repeating the incident. When the nerves become damaged, as with neuropathy, they send the wrong pain signals, telling the body it’s in pain when no trauma has occurred.
There are different types of neuropathy that can affect the legs. The most common is called peripheral neuropathy, which typically develops in the feet and legs. Sometimes, it progresses into the arms and hands. Symptoms range from numbness and tingling to a sharper pain that occasionally worsens at night. Some people feel pain or weakness when walking or develop sensitivities to touch.
Neuropathic leg pain is a troubling disorder that diminishes quality of life. There are several potential causes.
Injuries leading to nerve damage are the most common cause of neuropathy, according to the National Institute of Neurological Disorders and Stroke (NINDS). Incidents ranging from car accidents to pileups on the football field may result in peripheral neuropathy.
In these cases, the injured nerve may be severed, crushed, or stretched beyond its capacity. Sometimes broken bones can pressure nerves to the point of injury, and lead to the pain and tingling associated with leg neuropathy.
High blood sugar levels characterized by diabetes can, over time, damage the nerves and cause neuropathy. Anywhere from 60-70% of people with diabetes have some form of neuropathy, according to NINDS.
Researchers aren’t sure of the exact reasons why, but believe the excess glucose changes how nerves communicate with the rest of the body. High blood sugar also causes deterioration in the walls of blood vessels that feed nerves with a constant supply of oxygen and nutrients.
People with diabetes may develop a specific type of neuropathy called radiculoplexus neuropathy, also known as diabetic amyotrophy. This variation develops in the nerves in the hips, thighs, or legs.
Symptoms of diabetic amyotrophy usually develop on 1 side of the body, although they sometimes occur on both sides. Signs include severe pain that strikes suddenly, trouble standing up from a seated position, and weakened thigh muscles. Older people with Type 2 diabetes are most at risk.
People who smoke or drink excessive amounts of alcohol have an increased risk of diabetic neuropathy. The physical effects of diabetes wear the body down over time, and people who have had the condition for 25 years or longer are most at risk for developing neuropathic leg pain.
People who drink heavily for a decade or more are at an increased risk for neuropathy. As many as 50% of heavy alcohol users report the condition, according to the National Institutes of Health (NIH).
Researchers aren’t sure why, but believe that alcohol poisons the nerves. People who drink a lot typically don’t eat enough fruits and vegetables, which can also contribute to neuropathic leg pain. High alcohol consumption also affects the kidneys’ health, which can contribute to the development of peripheral neuropathy.
The kidneys are responsible for cleaning the blood and flushing toxins out of the body. When these important organs are not functioning properly, dangerous levels of toxins build up in the blood that can lead to nerve damage and neuropathy.
This progressive autoimmune disease is characterized by damage to myelin, which is the protective coating of nerve fibers. Sometimes the nerves themselves sustain damage. These changes reduce the ability of the brain to communicate with the spinal cord and rest of the body and can lead to neuropathic leg pain.
Cancer or cancer treatment
As tumors grow, they can put undue pressure on nerve fibers, leading to neuropathic pain. Tumors in the leg may result from soft-tissue cancer, known as sarcoma, bone cancer, or they could be a metastasis of a distant, primary cancer. Nerve tissues can also turn cancerous.
While cancerous tumors can lead to leg neuropathy, some lumps are benign. If they grow very large, or develop in the wrong spot, tingling or pain may develop.
1 type of a benign tumor is called a neuroma. These are clumps of overgrown nerve tissue that develop after the nerve is severed from an injury, amputation, or surgery. These nerve tumors can lead to significant pain, sometimes affecting surrounding nerves and worsening the condition.
Another possible cause of neuropathic leg pain is chemotherapy treatment for cancer. Chemotherapy-caused neuropathy is relatively common, affecting 30-40% of patients, according to the National Cancer Institute (NCI).
The drugs that carry neuropathy as a potential side effect aren’t necessarily those used to treat cancers occurring in the leg. For example, the chemotherapy drug Taxol is used to treat cancers including breast, melanoma, and esophageal, among others, but can lead to neuropathy in the foot or higher in the leg.
The severity of neuropathic leg pain from chemotherapy can be mild to severe. The condition is 1 of the most commonly cited reasons for patients stopping their treatment ahead of schedule, according to the NCI. Prognosis varies by patient. Sometimes, lowering a person’s chemotherapy dose alleviates pain. Others develop a mild case that dissipates after completing treatment. Still others experience pain that lasts for months or years later.
In rare cases, inflammation that occurs after surgery may lead to a condition known as post-surgical neuropathy, Mayo Clinic researchers found. This condition is thought to have 2 potential causes. 1 cause is a misguided immune system that attacks nerves as they’re healing, leading to inflammation and neuropathy. Another possibility is that the operation stretches or compresses nerves to the point of damage, leading to neuropathy.
1 of the subjects in the Mayo Clinic study underwent hip surgery and developed severe neuropathic leg pain coupled with muscle weakness shortly after. Patients were treated with immunosuppressive drugs, which helped heal the pain.
What is your experience with neuropathic leg pain?
Photo by Craig Sunter via Flickr