This is Polyneuropathy or otherwise known as damage to a number of neurones and their myelin sheath, this can be caused by a number of things, such as:
1) A nutritional deficiency, for example, Folic acid and vitamins B1,B2,B6 and B12.
2) Metabolic disorders such as Diabetes Mellitus.
3) Chronic Diseases such as renal failure, hepatic failure and carcinoma.
4) Toxic reactions caused by lead, arsenic, mercury, carbon tetrachloride, aniline dyes and certain drugs such as phenytoin and chloroquine.
5) Infections such as influenza, measles, typhoid fever, diphtheria and leprosy can cause polyneuropathy.

The long neurones associated with the legs and feet are usually affected first.
The outcome of this type of neuropathy depends upon the cause of the neuropathy and the extent of the damage.