Your feet are the instruments of independence that mobilize your life. Marvelously designed, each foot contains 26 bones, 33 joints and more than 100 muscles, tendons and ligaments. Feet function best when their rich network of blood vessels, muscles and nerves are in perfect condition and working harmoniously together. Diseases and injuries that compromise the neurological, vascular, skeletal, tendon and muscular network of the feet can cause foot numbness, weakness and an inability to walk.
The ability of the feet to interact with the environment is largely dependent upon the nervous system. The peripheral nervous system, which receives communication from the central nervous system and the spinal cord, directly innervates the feet. Foot numbness due to peripheral nerve injury is called peripheral neuropathy or peripheral neuritis. The sensation of numbness or tingling in the foot that comes from nerve damage is called paresthesia. Injury to the brain due to stroke, injury to the spinal cord from trauma or disc herniation and injury to the smaller peripheral nerves that directly supply the feet are common causes of paresthesia or numbness of the foot.
According to the American Academy of Orthopaedic Surgeons, diabetes is a leading cause of peripheral neuropathy and foot numbness. It is estimated that 15 percent of the U.S. population or 23 million people have diabetes. Of these, 60 to 70 percent have diabetic neuropathy, the academy reports. Over time, diabetes can cause narrowing of blood vessels and capillaries, which can decrease delivery of oxygen and nutrients to the components of the nervous system. This causes nerve injury, which can result in stroke as well as peripheral neuropathy. Whether the injury is in the brain, the spinal cord or peripheral nervous system, if the areas that pertain to the foot are affected, then numbness, weakness and paralysis can occur.
Other Causes of Foot Numbness
Foot numbness can be present in disorders such as peripheral arterial disease, hypothyroidism and alcoholism. Nerve damage resulting in foot numbness can also be caused by drugs, toxins, prolonged exposure to cold and pressure from a poorly fitted cast, splint, brace or crutches. Chronic kidney disease, autoimmune disorders, low levels of vitamin B-12 or other dietary deficiencies, human immunodeficiency virus and liver infections are also associated with peripheral neuropathy and foot numbness.
Dangers and Precautions
Foot numbness is dangerous because you might injure your foot and not know it. In diabetes this is especially hazardous because slow healing can allow small injuries to develop into gangrene, which can lead to amputation. Foot numbness and tingling should always be brought to the attention of your health care practitioner, who will work with you to find a cause for your foot numbness and develop a treatment plan.