Neuropathic pain is a type of pain caused by damage to the nervous system following an injury or illness and affects approximately 1% of the population.
It is often sharper and more intense than other types of pain and does not typically respond well to standard analgesic pharmacotherapy. Instead, management techniques for neuropathic pain frequently involve neurostimulation therapy to address the changes to the nerves directly.
From a clinical perspective, neuropathic pain is a multidimensional condition that can vary considerably concerning intensity, location, and time. Neuropathic pain typically presents as a sharp, intense pain that is sometimes described as shooting through the body. However, other patients describe a pain with different characteristics, such as a burning or heavy sensation, or numbness in a region of the body.
Neuropathic pain is often associated with a chronic pain disorder that will not resolve spontaneously and can significantly impact the quality of life of the patient. The management of the condition can also prove difficult, particularly when it does not respond adequately to standard pharmacological analgesics.
Types: Stimulus-evoked and Stimulus-independent
There are two main types of neuropathic pain, known as stimulus-evoked and stimulus-independent.
Stimulus-evoked pain is aggravated by movement or being touched in certain areas of the body. Stimulus-independent pain is not affected by such movements or touch but may vary in intensity and be constant or intermittent.
Neuropathic pain presents as a result of injury or illness that interferes with the nerves involved in the transmission of pain signals. This damage occurs when the nerves are compressed, entrapped, sectioned, bruised, or stretched.
In a healthy person, the nociceptive pain pathway provides useful information of noxious stimuli in specific parts of the body, such as extreme cold or heat, to allow the body to react and protect itself from harm. This information is carried from the nociceptors at the site of the stimuli to the brain via nerves in the nervous system.
When damage to the nerves involved in the signaling of pain pathways is activated, the signals can be permanently or intermittently activated, even in the absence of noxious stimuli.
Various circumstances may cause damage to the nerves and lead to the presentation of neuropathic pain. These include:
- Back pain
- Exposure to toxins
- Nutritional imbalance
- Post-therapeutic neuralgia
- Trigeminal neuralgia
Unlike nociceptive pain, neuropathic pain does not usually respond well to standard analgesic medication, such as paracetamol, aspirin, or ibuprofen. This is likely due to differences in the mechanism of pain and, instead, neuropathic pain can often be managed more effectively with neurostimulation.
Neurostimulation therapy involves microelectrodes to deliver mild electrical impulses to the epidural space in the body's central nervous system. The treatment aims to restore normal sensation and reduce the impact of neuropathic pain on patients' quality of life.
The results of neurostimulation therapy are highly variable. Still, the success rates are much higher with neuropathic pain than other types, and it is most useful for patients that have pain that is unresponsive to other management techniques.