Definition & Overview

Neuropathic pain, also commonly known as nerve pain, is a kind of pain that results from damaged, injured or dysfunctional nerve fibers. It is complex and usually chronic, with mild to severe symptoms. More than an actual condition, neuropathic pain is defined to be a consequence of a disease affecting the somatosensory system. It affects about 7 out of 100 people and is more common in older individuals.

Symptoms of Neuropathic Pain

Neuropathic pain does not necessarily involve severe pain. However, it almost always involves abnormal levels of pain sensitivity. It can range from a persistent, mild discomfort to a sharp, shooting, unbearable pain. The discomfort may be described as numbness, burning sensation, a tingling feeling, a sharp, stabbing pain, or similar to an electrical shock. Certain terms that are often used to describe nerve discomfort include the following:

  • Allodynia: a harmless stimulus such as light touch that can provoke pain or discomfort
  • Hyperpathia: a brief period of discomfort that causes prolonged, unbearable pain
  • Hyperalgesia: a usually mild discomfort that the nerves interpret as severe pain
  • Paraesthesia: a discomfort or pain felt even if there are no direct physical stimuli

Causes of Neuropathic Pain

There seems to be no single, obvious cause for this condition. Although neuropathic pain is thought to be related to the damage to the peripheral nerves. Damage and injuries to the brain or spinal cord are also known to cause nerve pain. Other causes include the following:

  • Trigeminal neuralgia or infection of the cranial nerves
  • Shingles (herpes zoster infection) or viral infection in the nerves
  • Diabetic neuropathy, which is a nerve disorder that develops in diabetic individuals (over 25% of neuropathies are a result of diabetes)
  • Motor neuron diseases such as multiple sclerosis
  • HIV-related neuropathy
  • Cancer and cancer treatment
  • Alcoholism or drug side effects
  • Toxic substance accumulation
  • Physical trauma to the nerves
  • Connective tissue disease
  • Consequence of stroke

Types of Pain in Neuropathy

The seven categories of neuropathic pain that are based on underlying causes are the following:

  • Toxic: Pain caused by nerve damage due to exposure to toxic chemicals such as during chemo-radiation treatment for cancer

  • Metabolic: Neuropathy linked to nutritional deficiencies that cause metabolic dysfunction such as in the case of diabetes and vitamin B1 deficiency

  • Trauma: nerve pain caused by physical trauma to the nerves, such as in the same of phantom limb syndrome

  • Compressive: Excessive external pressure on the nerve ends can cause prolonged injury and degeneration of the nerves, which can cause neuropathic pain

  • Autoimmune: Natural antibodies may be responsible for the damage of nerves, causing pain and discomfort

  • Infectious: Viral conditions that result in neurological pain including Varicella Zoster virus (trigeminal neuralgia), HIV, Guillain- Barre, and Chagas Disease

  • Congenital: Neuropathic diseases may be linked to congenital abnormalities and hereditary conditions

When to See a Doctor

Neuropathic pain almost always involves a good deal of pain or discomfort, such that a visit to the doctor is often necessary. During your first visit, the doctor will first diagnose the pain by assessing your history and asking about your symptoms. The doctor will then refer you to a neurologist or nerve specialist if nerve damage is suspected or a more complicated solution is necessary.

A physical examination and various tests will be performed to reveal the underlying cause of the nerve pain. Your ability to sense stimuli such as light touch, body position, temperature, and pain will be determined in order to find out whether nerve fibers are significantly affected. Blood tests to rule out diabetes, liver or kidney dysfunction, vitamin deficiencies and other metabolic disorders may also be performed. Depending on the results of the medical examination, other more sophisticated tests such as electromyelogram (EMG), nerve conduction velocity (NCV), magnetic resonance imaging (MRI) or nerve biopsy may be suggested to further elucidate the condition.

Treatment for Neuropathic Pain

Treatment for neuropathy is centered on two main goals: the treatment of the underlying causative condition and the proper management of pain symptoms. This goes without saying that diagnosing the cause of the pain is important in determining the right treatment plan for a patient. For instance, if the neuropathy is caused by mechanical pressure on the nerve fibers, surgical or interventional procedures may be required. If the root cause is a vitamin deficiency, then supplementation will be suggested. Correcting the underlying condition can often result in the neuropathic pain resolving on its own as the damaged nerves start to regenerate or heal.

To treat the discomfort and disconcerting symptoms of neuropathy, certain medications are recommended and these include the following:

  • Pain Medications - Over-the-counter medications rarely work for neuropathic conditions; stronger opiate-based painkillers such as morphine or codeine are usually suggested, but only for short-term use due to unwanted side effects.

  • Anti-depressants - Anti-depressants such as duloxetine has been found to work in alleviating neuropathy by interfering the transmission of nerve impulses. Results usually set in after a few weeks of regular use.

  • Anti-convulsants or anti-seizure medications - Anti-epileptic medicines are often prescribed as a faster alternative to anti-depressants. Just like anti-depressant medications, these are known to effectively ease nerve pain by stopping nerve impulses but with fewer side effects.

  • Local anesthetics - Topical application of anesthetics such as lidocaine can provide temporary relief in some forms of pain such as post-herpetic or trinomial neuralgia.

  • Nerve block injections - Nerve block treatment involves the injection of an anesthetic directly to the affected nerve to interrupt the pain signal and offer immediate comfort.

Because of the complex nature of this condition, treatment for pain symptoms often involves a multi-disciplinary, integrated approach that consists of pain management medications and a well-planned rehabilitation program. Aside from medications, physical treatments through physiotherapy, percutaneous electrical nerve stimulation (PENS) and physical therapy may be advised for serious cases of neuropathy. Moreover, non-medical treatments to relieve stress, anxiety and depression such as psychological counseling, stress management, relaxation or massage therapy, and behavioral therapy are also known to help patients with persistent neuropathic pain.

References:

  • American Chronic Pain Association: "Neuropathic Pain.” Available: http://www.theacpa.org/condition/neuropathic-pain
  • Loeser, J. D. (Ed), Bonica’s Management of Pain, 3rd Edition, Lippincott, Williams & Wilkins, Philadelphia, 2001.
  • National Institute of Neurological Disorders and Stroke. “Neurological Diagnostic Tests and Procedures” Available: http://www.ninds.nih.gov/disorders/misc/diagnostic_tests.htm#diagnostic
  • The Neuropathy Association Website “About Peripheral Neuropathy” Available: http://www.neuropathy.org/site/PageServer?pagename=About_Facts1
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