Numbness, or loss of sensation, can occur anywhere in your body. However, it's most often felt in the hands, feet, arms or legs. Numbness can range from harmless (like a leg falling asleep) to permanent, so it's important to determine the cause so that proper treatment can be sought.
Numbness is defined as a loss of sensation or feeling.
Symptoms that are associated with numbness include a "pins and needles" feeling and prickling or burning sensations (parasthesia).
There are dozens of causes of numbness in the feet, including parasthesia, peripheral neuropathy, diabetes, multiple sclerosis, hypocalcaemia, vitamin B-12 deficiency, alcoholism, spinal cord injury, Guillain-Barre syndrome, kidney failure and sarcoidosis---a disease due to inflammation, usually of the lungs or lymph nodes.
Hypocalcaemia is defined as low levels of calcium in the blood.
Symptoms of hypocalcaemia include painful muscle spasms of the hands and feet; facial muscle spasms; facial grimacing; parathesia of the lip, tongue, fingers or foot; and muscle aches.
Wrong Diagnosis lists dozens of causes for hypocalcaemia, including vitamin D deficiency; Barakat syndrome, a rare condition characterised by deafness, kidney disease and low parathyroid hormone production; chronic diarrhoea; and acute pancreatitis.
There are no known causes of Guillain-Barre syndrome, a disorder characterised by immune system attacks on the peripheral nervous system, which connects the brain and spinal cord with the rest of the body. Symptoms for Guillain-Barre syndrome include a loss of reflexes, difficulty breathing, nausea, vomiting, loss of appetite, stomach pain, migraines, low-grade fevers, chills and weakness, usually beginning in the legs.
Peripheral neuropathy is a condition in which the peripheral nerves are damaged. According to Wrong Diagnosis, the "peripheral nerves spread out from the brain and spinal cord and peripheral neuropathy results in unusual or abnormal sensations of the extremities, especially the feet." Common symptoms include pain, numbness, tingling, weakness and atrophy. Among conditions that cause peripheral neuropathy are HIV and AIDS, fractures, atherosclerosis, sarcoidosis, rheumatoid arthritis and Charcot-Marie-Tooth syndrome, an inherited neurological disease characterised by degeneration of the muscles and loss of feeling in extremities.