Nociceptive Pain

Definition

The Nociceptive pain can be defined as the pain that occurs in response to a harmful stimulus. Among the most common stimuli, there are: extreme temperatures, intense pressure or irritating substances. What happens is that the pain receptors (nociceptors) are activated by the above-mentioned stimuli and send the pain signals to the cells of the central nervous system. The brain recognizes the threat and takes action, withdrawing the respective part of the body from the different stimuli.

Nociceptive Pain and Neuropathic pain

The nociceptive pain occurs when there is damage done to the tissues of the body or when the body comes into contact with stimuli that have the potential for damage. There are different words that could be used in order to describe nociceptive pain – depending on each person experiencing it, you may hear it being described as ‘sharp’, ‘throbbing’ or ‘aching’. In general, both benign and malignant pathologies are capable of causing this kind of pain; in case of cancer, the nociceptive pain can be caused by the spreading of the tumor to different parts of the body (metastases). In certain patients, the nociceptive pain is caused by a blockage that occurs at the level of an organ or as there is a blockage in one of the major blood vessels.

It is important to understand that the nociceptors are the ones identifying pain at any part of the body, sending the signals to the brain. The pain signals are transmitted through the peripheral nerves to the spinal cord and further to the brain. The pain can be present at the level of the skin or it can be visceral (involving the internal organs). As it was already mentioned, blocked blood vessels can also lead to the appearance of nociceptive pain. When the nociceptive pain is present at the level of the skin, it has a specific localization and it is constant. The visceral nociceptive pain, on the other hand, comes and goes, having an indefinite localization. Nociceptive pain responds quite well to the pain medication, including to opioids (even though these can only be administered only for short periods of time, due to the high risk for addiction).

In the situation of neuropathic pain, it means that somewhere in the body a nerve or a bundle of nerve fibers is subjected to physical stress. The actual damage comes from the compression of the respective nerves. Apart from the neuropathic pain, patients described a wide range of other symptoms, including: numbness, paresthesia, burning sensation and muscular weakness. Among the major causes of neuropathic pain, there are: neuro-degenerative disc disease, disc hernia, infection or inflammation causing the compression of spinal nerves. The neuropathic pain generally appears on the territory that corresponds to the compressed nerve root. Cervical and lumbar radiculopathies are known to lead to the appearance of neuropathic pain, more frequently than the rare thoracic radiculopathy.

The neuropathic pain appears in response to an injury or due to the poor functioning of the central or peripheral nervous system. Tumors, excessive scar tissue from previous spinal surgical interventions and viral infections can cause the neuropathic pain to appear as well. In more severe cases, the pain can be elicited just by simply touching the patient. As opposed to the nociceptive pain (acute), the neuropathic pain is chronic, persisting for months or even years. The treatment response to medication can be reduced, this being the reason why surgical intervention is commonly recommended for the improvement of the symptoms. Depending on the cause that has led to the appearance of the neuropathic pain, the surgeon might choose either the open approach or the minimally invasive procedure. Physical therapy can also be useful in bringing relief from the neuropathic pain.

Examples of Nociceptive pain

These are several examples of nociceptive pain:

• Cut on the skin
• Broken bone (fracture)
• Ligament sprains
• Chemical or thermal burns
• Bruises on the skin
• Inflammation – infectious causes or inflammation from autoimmune disorders
• Different blockages inside the body (at the level of internal organs or major blood vessels)
• Myofascial pain – suggestive of an abnormal physical stress on the muscles
• Jamming your finger in the car door
• Touching something extremely hot (immediate withdrawal reaction of the affected limb)
• Putting your feet or other part of the body in hot water
• Nociceptive pain that results from intense physical effort (pulled muscles)

Treatment

These are the most common treatment solutions for nociceptive pain:

• Non-steroidal anti-inflammatory medication
  • Most common – acetaminophen, ibuprofen, naproxen
• Opioid medication
  • Most common – morphine, diamorphine, pethidine, oxycodone, tramadol
  • Other opioids – codeine, methadone, dihydrocodeine
  • Best way of administration – intravenous route
  • Cannot be used for prolonged periods of time, due to the increased risk for addiction
  • Can be used in combination with the non-steroidal anti-inflammatory medication in patients who suffer from renal colic or pain in the joints/bones.