Nerves function like electric cables transmitting signals, including pain signals, to and from the brain. Damage to nerves can interfere with the way those signals are transmitted and cause pain signals that are abnormal. For instance, you may feel a burning sensation even though no heat is being applied to the area that burns.
Nerves can be damaged by diseases such as diabetes, or they can be damaged by trauma. Certain chemotherapy drugs may cause nerve damage. Nerves can also be damaged as a result of stroke or an HIV infection, among other causes. The pain that comes from nerve damage could be the result of damage to the central nervous system (CNS), which includes the brain and spinal cord. It could also result from damage to peripheral nerves, those nerves in the rest of the body that send signals to the CNS.
The pain caused by nerve damage, neuropathic pain, is often described as burning or prickling. Some people describe it as an electrical shock. Others describe it as pins and needles or as a stabbing sensation. Some people with nerve damage are often hypersensitive to temperature and to touch. Just a light touch, such as the touch of a bed sheet, can set off the pain.