Peripheral neuropathy is a broad term describing disease of the nervous system outside the brain and spinal cord. It typically refers to abnormal nerve function in the legs, although it can be present in the arms as well. The disease can have many different causes, but nearly always at results in decreased sensation to the feet and lower legs. This decreased sensation is sometimes imperceptible and noticeable only on a medical exam, and sometimes outright numbness is felt. More advanced cases actually have painful sensations as part of the symptoms, including burning, tingling, pins and needle sensation, and sharp, shooting, electrical pains. The most advanced cases involve muscle control, in which the nervous system directly participates in. Cramping, weakness, and balance loss can be seen in severe cases of peripheral neuropathy. Other aspects of the nervous system directing involuntary responses like sweating can be affected by neuropathy, leading to symptoms such as dry or cracked skin.
The conditions that cause peripheral neuropathy are varied, and include diabetes (the most common cause), spinal disease, strokes, polio, vitamin B deficiencies, folate abnormalities, syphilis, certain medications, chemotherapy, surgical or radiological nerve damage, neuromuscular disorders, as well as unknown genetic causes (idiopathic peripheral neuropathy). Each disease can have slightly different symptoms, and affect the nerve function in different ways. However, the end result for the foot is generally the same for most all causes, with the exception of polio or neuromuscular disorders which are nearly always accompanied by foot deformities.
Treatment of peripheral neuropathy can be likewise varied. In certain conditions, like diabetes or nutrient deficiency, controlling the disease will control the neuropathy symptoms. In other cases, the symptoms can only be controlled medically. Traditional pain medications such as anti-inflammatories, Tylenol or narcotics do not usually work well on neuropathic pain. Some topical medications containing hot pepper extract or menthol bases can help ease mild pain. Most cases require medication that modifies the abnormal nerve signal. This includes anti-seizure or anti-depressant medications that are also FDA approved to treat neuropathy. Unfortunately, side effects in some individuals can limit their use, including sedation, leg swelling, and blurry vision. There are some prescription nutritional supplements that can be used for multiple causes of peripheral neuropathy, although their overall effectiveness in the larger population is still being debated.
Proper care of the foot with peripheral neuropathy is important, as poor sensation can lead to a number of problems, especially in diabetics. Shoes must be worn at all times, including in the home, as objects puncturing bare skin or feet in socks can be unfelt, leading to tissue damage and infection. The feet must be inspected regularly to ensure that there are no skin wounds, infection, or inflammation that may otherwise go unfelt. All foot or ankle sprains and strains need to be evaluated by a podiatrist to ensure the injury is not worse than assumed, as neuropathy can limit the pain of serious sprains and even fractures. Bathing or soaking needs to be performed with some caution, as the temperature of the water can be incorrectly judged by a foot or even hand with poor sensation: the forearm should be used to test water temperature before the foot enters the water to prevent scalding. The skin also needs to be hydrated regularly with moisturizers due to the drier skin, and regular soaking should be avoided due to the drying effect soaking has on skin as it leaches essential oils from the skin surface.