The pain arrives mainly at night: burning, tingling, or electric-shock stabbing that stymies sleep. Just covering your feet with a blanket can feel unbearable. If you get up in the dark, you may find yourself tripping or bumping into things, not because you can’t see, but because you can’t fully feel your feet. Creeping slowly from your toes upward over months or years, this pain and numbness, which can also affect your hands and arms, is perplexing and alarming.
The likely culprit? Peripheral neuropathy, which is damage to the peripheral nerves that reach throughout your body. While diabetes is the leading cause of this condition, peripheral neuropathy is surprising in both its origins and scope, with an extensive list of possible causes.
The root of the problem
Peripheral nerves, which carry messages to and from the brain, contain large fibers that are covered with a type of fatty insulation and small, skinny, uninsulated fibers. The small fibers report sensory information such as pain, heat, or cold, while also controlling involuntary vital functions, such as heart rate and blood pressure. The most common form of peripheral neuropathy strikes the longest nerves in the body, those leading to the skin of the hands and feet, where it can cause pain or numbness. Small-fiber nerve damage can also trigger problems in other parts of the body:
- Low blood pressure can lead to symptoms that include fainting, dizziness, or lingering fatigue.
- Bloating, nausea, indigestion, constipation, or diarrhea are often misdiagnosed as irritable bowel syndrome.
- Incontinence or sexual problems, while rare, are unquestionably distressing when they occur.
- Heat intolerance may lead to excessive sweating, or sufferers may lose the ability to sweat.
As with many conditions, early diagnosis and treatment offer the best chance for effective symptom and damage control. But by the time many people with peripheral neuropathy seek a diagnosis, doctors find that the condition is actually worse than a patient’s symptoms may suggest, so don’t delay. Even if your symptoms seem vague, see your primary care doctor as soon as possible.
Your physician will review your medications and supplements, screen you for diabetes, thyroid issues and vitamin levels, and may perform a variety of tests to pinpoint peripheral neuropathy and its causes. These may include nerve conduction and electromyography to measure large-fiber damage, a skin biopsy to count small-nerve fiber endings in the skin, or a sweat test to gauge the body’s ability to regulate temperature. A spinal tap may be used to examine spinal fluid for signs of infection or other dangerous conditions, while a tilt-table test may be used to monitor heart rate and blood pressure.
If your doctor can pinpoint the cause of your neuropathy, your treatment options can be tailored to address the underlying issue. For example, patients with autoimmune disease will be referred to a rheumatologist, who may prescribe immune-modifying treatments that can actually reverse nerve damage and symptoms. Diabetes patients should work with an endocrinologist to improve blood sugar control and monitor medications.
Recovery can be more challenging when peripheral neuropathy has no traceable cause, which is true in up to half of all cases. Even then, a variety of approaches can provide meaningful relief, though full nerve repair is typically elusive.
Medication. Over-the-counter pain medications, such as nonsteroidal anti-inflammatory drugs, can relieve mild symptoms, as can topical treatments such as capsaicin cream.
When these aren’t sufficient, there are several types of drugs to try. Some patients find relief with anti-epilepsy drugs like gabapentin (Gralise, Neurontin, Horizant) and pregabalin (Lyrica) or antidepressants like duloxetine (Cymbalta) and venlafaxine (Effexor XR). The antidepressants amitriptyline (Elavil), doxepin (Silenor, Zonalon) and nortriptyline (Pamelor) may also help, as they interfere with the chemical processes in your brain and spinal cord that cause you to feel pain.
Physical and occupational therapy can help you cope with limitations in how you walk or use your hands.
Some simple lifestyle changes can also improve your symptoms:
- Exercise regularly to improve blood flow to nerves.
- If you have diabetes, limit your sugar intake.
- Vitamin B12 protect nerves and may even enhance nerve regeneration. Ensure that you get enough by eating foods like dairy, lean meat, poultry, and eggs. If you are vegetarian or vegan, talk to your doctor about taking a supplement.
- Avoid eating fish that are high in mercury, a toxin that can worsen neuropathy. The worst offenders are king mackerel, orange roughy, swordfish, tuna, and grouper.
- Limit alcohol, which is toxic to nerves and can make neuropathy symptoms worse.
- Don’t smoke. Smoking narrows and damages peripheral blood vessels.
- Review your medications regularly with your primary care doctor. A variety of medications can cause reversible peripheral neuropathy— even long after you’ve been taking them with no problems.