Neuropathic pain is caused by damage to or dysfunction of the nerves, spinal cord, or brain.
(See also Overview of Pain.)
Neuropathic pain may result from
Compression of a nerve—for example, by a tumor, a ruptured disk in the spine (causing low back pain and/or pain radiating down the leg), or pressure on a nerve in the wrist (causing carpal tunnel syndrome)
Nerve damage—as occurs in disorders that affect nerves (such as diabetes mellitus or shingles)
Abnormal or disrupted processing of pain signals by the brain and spinal cord
Processing of pain is abnormal in phantom limb pain, postherpetic neuralgia (pain after shingles), and complex regional pain syndrome.
Neuropathic pain may also develop after surgery, such as removal of a breast (mastectomy) or lung surgery (thoracotomy).
Neuropathic pain can contribute to anxiety and/or depression. Anxiety and depression can also worsen pain.
Symptoms of Neuropathic Pain
Neuropathic pain may be felt as burning or tingling or as hypersensitivity to touch or cold. Hypersensitivity to touch is called allodynia. Even a light touch may cause pain.
Sometimes neuropathic pain is deep and aching.
If movement is painful, people may be reluctant to move the painful part of their body. In such cases, muscles that control the painful part may waste away, and movement may become more limited.
People continue to feel pain long after the cause resolves because structures in the nervous system have been changed, making the structures more sensitive to pain.
Diagnosis of Neuropathic Pain
A doctor's evaluation
Doctors base the diagnosis of neuropathic pain mainly on the following:
Symptoms
The likelihood of a nerve injury
Results of the examination
Depending on the symptoms, doctors may do tests to check for disorders that could be causing the pain. Tests may include magnetic resonance imaging (MRI), nerve conduction studies and electromyography (EMG), and blood tests. Nerve conduction studies and EMG help doctors determine whether pain results from a problem with muscle or nerves and help them determine where the injury or dysfunction is located.
Treatment of Neuropathic Pain
Drugs (such as pain relievers, antidepressants, and antiseizure drugs)
Physical and/or occupational therapy
Surgery if needed
Stimulation of the spinal cord or nerves
A nerve block
Understanding what the nature of neuropathic pain is and what to expect often helps people feel more in control and better able to manage their pain.
Treatment of neuropathic pain can vary depending on the specific disorder causing it. For example, if the cause is diabetes, better control of blood sugar levels may help slow the progression of the nerve damage that causes pain.
Often, treatment of neuropathic pain begins with drugs. Drugs can help reduce the pain, making it less debilitating and disruptive, but it is often difficult to completely relieve the pain with drugs.
Other treatments include physical therapy, electrical stimulation of nerves or the spinal cord, nerve blocks, and sometimes surgery.
Psychologic factors that may contribute to the pain, such as anxiety and depression, if present, are also treated from the beginning.
Drugs
Pain relievers (analgesics) may be given to reduce neuropathic pain.
Pain relievers used to treat neuropathic pain include the following:
Adjuvant analgesics are drugs that change the way nerves process pain. These drugs can reduce pain intensity. Many adjuvant analgesics are usually used to treat other problems (such as seizures or depression), but they were found to sometimes relieve pain, including neuropathic pain. These drugs include antidepressantsantiseizure drugs
Opioid analgesics partially relieve neuropathic pain in some people, but the risk of side effects is usually higher than that with adjuvant analgesics.
However, drugs often provide only partial relief and typically only in fewer than half of people with neuropathic pain.
Physical and occupational therapy
Physical therapy and occupational therapy help people do the following:
Continue to move the painful part and thus prevent muscles from wasting away
Increase or maintain the joint’s range of motion
Function better
Decrease sensitivity of the affected area to pain
Other treatments
Surgery may be needed if the pain results from an injury that puts pressure on a nerve.
Electrical stimulation (from electrodes placed over the spine or other areas) may be helpful for certain types of chronic neuropathic pain. In transcutaneous electrical nerve stimulation (TENS), a gentle electric current is applied through electrodes placed on the skin’s surface. TENS units are available over the counter. For this treatment, stimulation pads are placed around the painful area.
Peripheral nerve stimulation involves placing thin wires under the skin to stimulate an individual peripheral nerve. (Peripheral nerves are those outside the brain and spinal cord.) The wires are attached to a small device (stimulator) placed on the skin's surface. This treatment is particularly effective for neuropathic pain, and it targets the painful area better than TENS. Placing the wires under the skin is a minimally invasive outpatient procedure because it requires making small cuts into the skin.
Spinal cord stimulation may be used to relieve neuropathic pain in people with nerve damage after back surgery or with complex regional pain syndrome. This treatment involves implanting a spinal cord stimulator under the skin, usually in a buttock or abdomen. Like a heart pacemaker, this device generates electrical impulses. Small wires (leads) from the device are placed in the space around the spinal cord (epidural space). These leads transmit impulses to the spinal cord. The impulses change the way pain signals are sent to the brain and thus change how unpleasant symptoms are perceived.
Nerve blocks are used to disrupt a nerve pathway that transmits or enhances pain signals. Nerve blocks may be used in people with severe, persistent pain when drugs cannot relieve the pain. Various techniques may be used:
Injecting the area around the nerves with a local anesthetic to prevent the nerves from sending pain signals (doctors commonly use ultrasonography to help them locate the nerves to be treated)
Injecting the area around collections of nerve cells called ganglia to help regulate the transmission of pain signals
Freezing a nerve (cryotherapy)
Burning a nerve with a radiofrequency probe
