Numbness in the foot, called peripheral neuropathy, is caused by a lack of blood supply or some type of damage to the nerves. This numbness can be permanent or transient. Numbness is a lack of feeling in the foot that can be associated with a prickling sensation, pins and needles, or burning feelings in the foot called paresthesias. Permanent numbness in the feet can lead to problems with standing, walking and driving. Take long-term numbness in the foot seriously and report it immediately to a medical professional.
Positional Numbness
The most simple cause of numbness in the foot is positional. We have all experienced numbness in the foot at one time as a result of sitting, standing or lying in the same position for too long. This can block off the blood supply to the foot, causing it to feel numb. This type of numbness is easily alleviated by changing position and as the blood flow returns to the foot, the feeling of numbness disappears.
Diabetic Neuropathy
Diabetes is a serious medical condition that affects many parts of the body. According to The Merck Manuals, the most common form of numbness in the foot due to diabetes, called peripheral neuropathy, is a result of poor control of blood sugar levels. The excess sugar in the blood causes nerve damage that results in numbness in the feet. This type of nerve damage is irreversible. Diabetics need to take special care of their feet because this numbness leads to an impaired ability to feel pain, heat or cold. Diabetics must visually inspect their feet, especially the bottoms, every day to look for cuts or open sores because they cannot feel when they have injured them.
Multiple Sclerosis
Multiple sclerosis, also called MS, is an autoimmune disease that causes the body's immune system to destroy the protective sheath that covers the peripheral nerves, as stated by the Mayo Clinic. This can affect the nerves of the feet, causing numbness. Damage to the nerves as a result of multiple sclerosis is progressive, so at first, even though nerve damage is irreversible, numbness in the feet may come and go. Over time, however, people with MS may eventually lose the ability to walk.
Direct Nerve Injury
Sometimes, numbness is caused by abnormal pressure being put on one or more of the nerves supplying sensation to the feet. According to the National Institutes of Health, a herniated disc in the lower back can bulge out and compress the nerves of the spinal cord. If the pressure is great enough, it can cause an injury to the nerves supplying the foot, leading to numbness in the foot. Wearing shoe gear that's too tight, especially high heels, can lead to a condition called Morton's neuroma in the foot. Morton's neuroma is thought to result from abnormal pressure on the nerves in the ball of the foot, which can result in numbness. Medication, and sometimes surgery, may be necessary to relieve the pressure. In most cases, once the pressure is relieved, the numbness will slowly go away.
Poor Circulation
Some conditions, such as peripheral vascular disease and Raynaud's syndrome, cause a lack of blood flow to feet. This results in numbness. Peripheral vascular disease is caused by a narrowing of the arteries, causing reduced blood flow to extremities. This can cause numbness in the feet while walking. Raynaud's syndrome is a condition that occurs in some people in cold weather, also causing numbness in the feet. Once blood flow is returned to the feet, the numbness can dissipate.
Tarsal Tunnel Syndrome
Tarsal Tunnel syndrome is caused by the pinching of the posterior tibial nerve on the inside part of the ankle as it enters the foot. According to ePodiatry.com, the channel that the nerve passes through to get into the foot is very small and tight, so the nerve is easily compressed if it becomes irritated or inflamed. This can lead to tingling and numbness in the foot. Rest, ice and ant-inflammatory medication are used to treat this, but in extreme cases surgery may be needed to relieve the pressure on the nerve.
Alcoholism
Alcoholism is a chronic disease that causes the body to become dependent on alcohol and affects many parts of the body. Excessive drinking affects the nervous system, which can cause numbness in the hands and feet.
Drug-Induced Neuropathy
Some medications can directly affect the nerves providing sensation to the feet, which can lead to numbness. Nerve damage is caused by certain toxic effects of the medications. Certain heart medications such as hydrolazine and indapamide, some cancer drugs such as vincristine, antibiotics including metronidazole and INH and anti-HIV drugs such as stavudine and zidovudine can all cause numbness in the feet. A more complete list is available at Drugs.com.
Abnormal Levels Of Vitamins And Nutrients
A lack of B12 causes an anemia that results in a low red blood cell count. A longstanding B12 deficiency can cause damage to the myelin sheath covering the peripheral nerves of the extremities, leading to numbness in the feet. Treatment with vitamin B12 may help reverse the condition. According to the National Institutes Of Health, abnormal levels of calcium, sodium or potassium can lead to nerve damage that can cause numbness in the feet.
