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Pain Problems » Body Ache » Neuropathic Pain

Neuropathic pain occurs as a result of damage to the nervous system, be it the peripheral nerves, or the central nervous system (CNS). The International Association for the Study of Pain describes neuropathic pain as: " pain initiated or caused by a primary lesion or dysfunction of the nervous system". However many experts now consider the term 'dysfunction' too broad and have instead proposed an alternative definition: "pain caused by a lesion of the peripheral or central nervous system (or both) manifesting with sensory symptoms and signs". However the neuropathic pain is caused by damage to central or peripheral nervous system or both, results in abnormal processing of sensory input, it serves no useful purpose, pain occurs spontaneously or in response to environment; it is usually sustained or chronic in nature. World over neuropathic pain incidence is underreported and hence underestimated. People with diabetes mellitus, herpes zoster or spinal cord injury are more likely to be affected by neuropathic pain. It is estimated that at least 20% of adults with diabetes experience at least one manifestation of painful diabetic peripheral neuropathy. In addition, neuropathic pain constitutes 25-50% of all visits to pain clinics amongst patients infected with the human immunodeficiency virus (HIV). 

The common varieties of neuropathic pain are diabetic neuropathy, postherpetic neuralgia, Trigeminal neuralgia, complex regional pain syndrome and others. The neuropathy can affect single nerve (a mononeuropathy) or many nerves (a polyneuropathy). It may or may not be painful. A bilateral symmetrical neuropathy is usually of systemic cause. A painful mononeuropathy is often referred to as neuralgia. Some details about each disorder are already mentioned and some are described below. 

Table. VARIOUS NEUROPATHIC PAIN STATES5
 
PERIPHERAL CENTRAL
  1. Alcoholic polyneuropathy
  2. Chemotherapy induced neuropathy
  3. Complex regional pain syndrome
  4. Diabetic peripheral neuropathy
  5. Carpal tunnel syndrome
  6. HIV sensory neuropathy
  7. Phantom limb pain
  8. Post herpetic neuralgia
  9. Post mastectomy pain
  10. Trigeminal neuralgia
  11. Glossopharyngeal neuralgia
  12. Radiculopathy (cervical, thoracic, lumbosacral)
  13. Neuropathy secondary to tumour infiltration
  1. Compressive myelopathy from spinal stenosis
  2. HIV myelopathy
  3. Multiple sclerosis pain
  4. Parkinson's disease pain
  5. Post stroke pain
  6. Spinal cord injury pain
  7. Syringomyelia
  8. Post radiation myelopathy
 
Treatment 
- Medical Management
- Interventions
  1. Alcoholic neuropathy - The incidence of neuropathy in chronic alcoholism is in the region of 10%, including asymptomatic patients. Of the symptomatic patients, approximately one quarter complain of pain or paraesthesia as the first symptom. This is compounded by concurrent dietary deficiencies. Non-selective damage occurs, causing a sensory and motor deficit. Pain is burning, with tenderness of the feet and legs with upper limbs rarely involved.
  2. Nutritional deficiency neuropathy - Vitamin B1 and niacin deficiencies cause peripheral neuropathy. An associated condition, burning feet syndrome, does not necessarily have the clinical signs of peripheral neuropathy but responds to dietary enhancement of the B vitamins.
  3. Other neuropathic pain conditions - Approximately 8% of patients who have had a stroke subsequently develop a painful syndrome that is characterized by abnormal temperature and pain sensibility in the area of the body affected by the stroke. Spinal cord injuries and cancer related pathologies, including tumour related nerve compression and radiation induced neural injuries, may all predispose to neuropathic pain. It is estimated that 55% of people with spinal cord injuries experience neuropathic pain in the 6 months following the injury; 75% have symptoms of neuropathic pain 5 years after injury. In patients infected with HIV, concomitant infection with hepatitis C or human T lymphocyte virus 1 (HTLV -1) can lead to painful peripheral neuropathy11.