What is Visceral Pain?
Welcome to this video about visceral pain.
Visceral pain is a component of nociceptive pain, which is the type of pain that results from injury, pressure, or inflammation of body tissues. This differs from neuropathic pain, which is caused by damage to nerves.
With nociceptive pain, stimulation of nociceptors occurs. Nociceptors are the pain-detecting receptors that reside at nerve endings. The pain signal is transmitted by the nociceptors through the cell bodies at the dorsal root ganglia, and through a synapse to a secondary neuron in the dorsal horn of the spinal cord, and finally on to the sensory cortex of the brain.
There are two types of nociceptive pain:
- Somatic pain AND
- Visceral pain
Somatic pain occurs when nociceptive receptors are stimulated in the skin, muscles, ligaments, tendons, bones, or joints. Somatic pain, which is carried by sensory nerves, may result from thermal, chemical, or mechanical stimulation of the nerves.
This type of pain is generally referred to as musculoskeletal pain and tends to be localized to the area of injury.
Pain may range from acute and sharp for surface tissues, to dull and aching for deeper tissues. With somatic pain, when an injury heals, the pain lessens, and somatic pain usually responds to routine analgesia.
Visceral pain, the focus of this video, occurs when nociceptive receptors are stimulated in the internal organs. These receptors, however, respond differently to stimulation than those associated with somatic pain.
The receptors that reside in the internal organs respond more to inflammation, pressure, ischemia, stretching, spasms, and dilation rather than localized injury. Because internal organs and blood vessels have fewer sensory nerves, pain may be less localized and more difficult to pinpoint.
Therefore, visceral pain is often described as dull and aching, or as a vague discomfort, and may become chronic.
Visceral pain also may radiate to surrounding areas or be referred to surface body areas because pain signals from the viscera are transmitted over common nerve pathways with somatic pain signals.
Because signals from multiple skin and visceral neurons come together in the same ascending neuron, the brain is unable to distinguish them. Since there are more receptors in the skin than in the viscera, the sensation of pain is felt in the skin.
A common example of referred pain is that associated with a heart attack. The pain may occur in the chest or be referred to the neck, throat, jaw, ear, left shoulder, and medial aspect of the left arm.
Other examples of referred pain include:
- Pain from the gastrointestinal system (lower esophagus, stomach, small intestines) referred to the epigastric area
- Pain from the pharynx (such as with a sore throat) referred to the ear AND
- Pain from the gallbladder referred to the right shoulder
Pain signals are carried to the brain on A pain fibers or C pain fibers, and the type of fiber influences the pain response.
A fibers are myelinated and carry acute pain signals very rapidly and result in the sensation of sharp localized pain, as in somatic pain.
C fibers, on the other hand, are unmyelinated and carry pain signals slowly, resulting in a dull, aching, and nonlocalized sensation of pain or burning pain. This pain may continue even after the stimulation stops, becoming chronic.
Most visceral pain is carried on these C fibers.
One characteristic that may distinguish visceral pain from other types of pain is that it is often associated with physical symptoms, such as nausea and vomiting, diaphoresis, tachycardia, and other vital sign changes, or psychological symptoms, such as depression and anxiety. These symptoms result from involvement of the autonomic nervous system.
Perception of pain may increase in those with depression or anxiety, especially with disorders such as irritable bowel syndrome, which is aggravated by stress.
Visceral pain is also often associated with functional disorders, which are disorders that impair bodily functioning but for which no abnormality can be detected by the usual diagnostic methods. Visceral pain may be intermittent or constant.
Some common causes of visceral pain include:
- Functional bowel disorders, such as irritable bowel syndrome and functional dyspepsia
- Intestinal blockage
- Chronic pelvic pain, such as with chronic interstitial cystitis, endometriosis, and painful bladder syndromes
- Heart attack
- Inflammation, such as pancreatitis, appendicitis, cholecystitis, and peritonitis
- Urethral blockage, often associated with prostatic hypertrophy
- Tumors, especially involving the pelvis or abdomen
- Impaired blood flow AND
While somatic pain typically responds well to analgesics, visceral pain can be more difficult to control. Treatment approaches vary depending on the cause but may include:
- Analgesics, including adjuvants and topical preparations
- Relaxation, visualization, and mindfulness exercises
- Alternative therapies, such as acupuncture and massage
- Behavioral therapy
- Lifestyle changes, including smoking and drinking cessation, weight loss, and dietary modifications
- Surgical intervention
- Hormone therapy
- Radiation therapy AND
- Physical therapy
About one in five people experience some type of visceral pain, which can be very debilitating and frustrating. Pain may vary in intensity from mild and annoying, to severe and life-limiting. Visceral pain is less understood than somatic pain, and some visceral organs are more sensitive to pain than others. For example, a tumor in one organ may cause little or no pain and in another, severe pain. Diagnosing the cause of the pain is sometimes difficult, particularly because the distribution of pain does not always match the site of origin. People with visceral pain need to feel supported in their attempts to obtain relief.
That’s all for this review of visceral pain! Thanks for watching, and happy studying.