(See also Overview of Pain.)
Neuropathic pain may result from
Neuropathic pain can contribute to anxiety and/or depression. Anxiety and depression can also worsen pain.
Neuropathic pain may also develop after surgery, such as removal of a breast (mastectomy) or lung surgery (thoracotomy).
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.
Doctors base the diagnosis of neuropathic pain mainly on the following:
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 result from a problem with muscle or nerves.
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.
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 the nerves process pain and that thus affect pain intensity. Many of these drugs 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 antidepressants and antiseizure drugs, which are commonly used to treat neuropathic pain.
Opioid analgesics partially relieve neuropathic pain in some people, but the risk of side effects is usually higher than that with adjuvant analgesics.
Drugs applied to the skin (topical drugs), such as a capsaicin cream or a patch that contains lidocaine (a local anesthetic), may be effective.
However, drugs often provide only partial relief and typically only in fewer than half of people with neuropathic pain.
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) is 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. Often, people are taught to use the TENS device, so that they can use it as needed.
Peripheral nerve stimulation involves placing electrodes under the skin to stimulate an individual peripheral nerve. (Peripheral nerves are those outside the brain and spinal cord.) The electrodes are often more effective than TENS for neuropathic pain, but placing them under the skin is an invasive procedure because it requires making small cuts into the skin.
Spinal cord stimulation is commonly 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
Injecting a caustic substance (such as phenol) into a nerve to destroy it
Freezing a nerve (called cryotherapy)
Burning a nerve with a radiofrequency probe
Phantom limb pain cannot be caused by a problem in the limb. Rather, it must be caused by a change in the nervous system above the site where the limb was amputated. But the brain misinterprets the nerve signals as coming from the amputated limb. Usually, the pain seems to be in the toes, ankle, and foot of an amputated leg or in the fingers and hand of an amputated arm. The pain may resemble squeezing, burning, or crushing sensations, but it often differs from any sensation previously experienced. For some people, phantom limb pain occurs less frequently as time passes, but for others, it persists.
Massaging the remaining (residual) part of the limb sometimes relieves phantom limb pain. If massaging is ineffective, pain relievers (analgesics) can be taken.
Typically, nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen, or adjuvant analgesics, such as nortriptyline or duloxetine (antidepressants) or gabapentin or pregabalin (antiseizure drugs), are used. But sometimes opioid pain relievers are required. If opioid pain relievers do not relieve the pain or if a person needs to take opioids for a long time, a pain management specialist may be asked to supervise treatment.
Treatment may include using mechanical devices (such as a vibrator), ultrasound, and spinal cord stimulation. Spinal cord stimulation involves surgically placing a spinal cord stimulator (a device that generates electrical impulses) under the skin, usually in a buttock or abdomen. Small wires (leads) from the device are placed in the space around the spinal cord (epidural space). These impulses change the way pain signals are sent to the brain and thus change how unpleasant symptoms are perceived.
Mirror therapy may be helpful. A health care practitioner teaches people how to use this therapy. People sit with a large mirror facing their unaffected limb and hiding their missing limb. The mirror reflects the image of the unaffected limb, giving people the impression that they have two normal limbs. People are then instructed to move the unaffected limb while watching its reflected image. Thus, people feel as if they are moving two normal limbs. If people do this exercise for 30 minutes a day for 4 weeks, pain may be substantially reduced. This therapy changes the pathways in the brain that interpret pain signals in the body.
Shingles is caused by reactivation of the varicella-zoster virus, the virus that causes chickenpox. Some people who have had shingles continue to have pain (postherpetic neuralgia) long after the rash has gone away.
What causes postherpetic neuralgia is unknown. But it is more likely to develop if the shingles rash is severe, if people are older when shingles develops, and if shingles affects certain areas of the body. For example, if shingles affects the face, postherpetic neuralgia is more likely to develop than if shingles affects the torso.
The pain may be felt as any combination of the following:
The area where the rash first occurred becomes painful and tender to the touch.
The pain may be debilitating. The pain may subside within several months or last for years.
Vaccination with the shingles (herpes zoster) vaccine can help reduce the risk of getting shingles. A new shingles vaccine has replaced an older one and provides protection longer, even in people whose immune system is weakened. It can also help reduce the risk of developing postherpetic neuralgia in people who get shingles despite being vaccinated.
No treatment is routinely effective. Treatment of postherpetic neuralgia may include
Pain relievers (analgesics)
Adjuvant analgesics, including certain antiseizure drugs (such as gabapentin and pregabalin) and antidepressants (such as amitriptyline)
Lidocaine ointment or patch applied to the affected area
Capsaicin cream applied to the affected area after the area is numbed with lidocaine
Botulinum toxin A injected into the affected area
Sometimes opioid analgesics are needed.