Neuropathic pain is caused by a physical or functional injury in the pain transmission pathways (nerves) at any site in the nervous system.
The exact prevalence of neuropathic pain is not known. In Europe, around 20% of the population suffers from chronic pain, and 7-8% suffers from predominantly neuropathic pain, with an annual prevalence of almost 1% of the population.
Depression, anxiety, and sleep disorders are also significantly more prevalent in patients with neuropathic pain when compared to other types of pain.
Neuropathic pain: characteristics
Neuropathic pain has some differential characteristics in comparison with somatic pain:
- It does not appear in response to stimulation of the peripheral nociceptors.
- It is a pain that is perceived in the form of hyperalgesia (a perception of a
- stimulation as more intense than it normally is), hyperesthesia (an abnormal and painful increase in touch sensitivity), dysesthesia (an abnormal unpleasant sensation) and allodynia (an abnormal perception of pain).
- In a high percentage of cases, the pain does not coincide with the neurological injury; a delay in time between neurological damage and onset of pain is frequent (weeks, months, and even years).
- In most cases it is poorly identified.
- Relief using opioid analgesics is only partial and is poor, even null, although it can be alleviated with psychotropic drugs.
Diagnosis of neuropathic pain
The diagnosis of neuropathic pain is essentially clinical and is made using the medical history and a neurological examination.
Since pain is, by definition, a subjective symptom, the application of pain assessment scales, such as the Visual Analogue Scale (VAS), is very useful. A detailed neurological examination, including a careful assessment of sensitivity, is also necessary. Further examinations will be aimed at detecting the underlying lesion of the neuropathic pain, if possible.
Causes of neuropathic pain
Some of the most common causes of neuropathic pain are: diabetic neuropathy, herpes Zoster (postherpetic neuralgia) and direct trauma to the nerves, such as possible post-surgical sequelae.
Neuropathic pain can also coexist with other types of pain, such as lower back pain associated with radiculopathies or musculoskeletal diseases.
Diabetic neuropathy is a type of nerve damage that can occur as a consequence of diabetes. High blood glucose levels can damage nerves throughout the body. Diabetic neuropathy largely affects the nerves in the legs and feet.
Diabetic neuropathy is a frequent and serious complication of diabetes. It affects more than 50% of diabetic patients after twenty years of evolution of the disease.
However, development can generally be prevented or delayed by strict controls on blood sugar levels and a healthy lifestyle.
Peripheral neuropathy is the most common type of diabetic neuropathy. It first affects the feet and legs, followed by the hands and arms. In general, the signs and symptoms of peripheral neuropathy worsen at night. The main symptoms are the following:
- Numbness and reduced ability to feel pain or perceive temperature changes.
- A tingling or burning sensation.
- Acute pain or cramps.
- Greater touch sensitivity.
- Muscular weakness.
- Loss of reflexes, especially in the ankle.
- Loss of balance and coordination.
- Ulcers and infections in the feet, and pain in the bones and joints.
Neuropathic pain treatment
Adequate pain assessment and diagnosis are critical to successfully treating neuropathic pain. Furthermore, identifying and simultaneously managing depression, anxiety and sleep disorders, which affect the quality of life of the patient, is also important.
The groups of drugs with the clearest evidence for managing neuropathic pain include neuroanalgesics, such as capsaicin, antidepressants, neuromodulators or gabapentinoids, opioids, and anticonvulsants.
On the other hand, non-pharmacological measures such as stress reduction, good sleep or physical therapy should also be considered.