Sources of Pain | Pain Physiology | Types of Pain

Sources of Pain:

 In this approach the major goal of assessment is to identify the pathophysiological mechanism of the pain. Use this information to plan appropriate intervention.

Physical therapy diagnosis:

The most effective physical therapy diagnosis will define the syndrome and address the causes of pain. Rather than just identifying the sources of  pain. Usually, a careful assessment of pain behavior is invaluable in determining the nature and extent of the underlying pathology.


Clinical Evaluation of Pain:

The clinical evaluation usually involves identification of the primary disease/etiological factor(s) considered responsible for producing or initiating the pain. The client is placed within a broad pain category. Usually labeled as nociceptive (e.g., pinprick), inflammatory (e.g., tissue injury), or neuropathic.
Pain is categorized on the basis of intensity and quality. Such an approach allows for physical therapy interventions for each identified mechanism involved.
From a screening perspective we look at the possible sources of pain and its types. When listening to the client’s description, consider these possible sources of pain :

  • Cutaneous
  • Somatic
  • Visceral
  • Neuropathic
  • Referred   

Cutaneous Sources of Pain:

Cutaneous pain (related to the skin) includes superficial somatic structures located in the skin and subcutaneous tissue. It is well localized as the client can point directly to the area that “hurts. Skin pain or tenderness can be associated with referred pain from the viscera or referred from deep somatic structures.

Characteristics of Cutaneous:

The difficulty is that biomechanical dysfunction can also result in these same changes. Which is why a careful evaluation of soft tissue structures along with a screening exam for systemic disease is required. 

Somatic Sources of Pain:

This pain can be superficial or deep. Somatic is labeled according to its source as deep somatic, somatovisceralsomatoemotional (also referred to as psychosomatic), or viscerosomatic. Psychophysiologic disorders, including somatoform disorders are discussed in detail elsewhere. Superficial somatic structures involve the skin, superficial fasciae, tendons sheaths, and periosteum. Deep somatic pain comes from pathologic conditions of the periosteum and cancellous (spongy) bone, nerves, muscles, tendons, ligaments, and blood vessels. When we talk about the “psycho-somatic” response, we refer to the mind-Body connection. 

Characteristics of Somatic Pain:

 It can be associated with an autonomic phenomenon. Such as sweating, pallor, or changes in pulse and blood pressure. Commonly accompanied by a subjective feeling of nausea and faintness. Pain associated with deep somatic lesions follows patterns that relate to the embryologic development of the musculoskeletal system. This explains why such pain may not be perceived directly over the involved organ. Parietal pain (related to the wall of the chest or abdominal cavity) is also considered deep somatic. 

Psychosomatic sources of Pain:

Somatoemotional or psychosomatic sources of pain occur when emotional or psychologic distress produces physical symptoms. Either for a relatively brief period or with recurrent and multiple physical manifestations spanning many months or years. Two different approaches to somatization have been proposed. 15 Alternately, there are viscerosomatic sources of pain. When visceral structures affect the somatic musculature, such as the reflex spasm and rigidity of the abdominal muscles. In response to the inflammation of acute appendicitis or the pectoral trigger point associated with an acute myocardial infarction. 

Visceral Sources of Pain:

This source of pain includes all body organs located in the trunk or abdomen. Such as those of the respiratory, digestive, urogenital, and endocrine systems, as well as the spleen, the heart, and the great vessels. It is not well localized for two reasons: 1. Innervation of the viscera is multisegmental 2. There are few nerve receptors in these structures .It is well known for its ability to produce referred pain. Referred pain occurs because visceral fibers synapse. At the level of the spinal cord close to fibers supplying specific somatic structures. 
Pain of a cardiac source can affect any part of the soma (body) also innervated by these levels. 

Neuropathic Pain:

Neuropathic or neurogenic pain results from damage to or pathophysiologic changes of the peripheral or central nervous system. Pain can occur as a result of injury or destruction to the peripheral nerves. Pathways in the spinal cord, or neurons located in the brain. Neuropathic can be acute or chronic depending on the time frame. Disruptions in the transmission of afferent and efferent impulses. In the periphery, spinal cord, and brain can give rise to alterations in sensory modalities. (e.g., touch, pressure, temperature), Sometimes motor dysfunction. 

Characteristics of Neuropathic:

It can be drug-induced, metabolic based, or brought on by trauma to the sensory neurons or pathways in either the peripheral or central nervous system.It is steady or evoked by some stimulus that is not normally considered noxious (e.g., light touch, cold). Some affected individuals report aching pain. Neuropathic is not alleviated by opiates or narcotics, although local anesthesia can provide temporary relief. Medications used to treat neuropathic include antidepressants, anticonvulsants, antispasmodics, adrenergics, and anesthetics.

Referred Pain:

By definition, referred pain is felt in an area far from the site of the lesion, but supplied by the same or adjacent neural segments.It occurs by way of shared central pathways for afferent neurons and can originate from any cutaneous, somatic, or visceral source. It can occur alone or with accompanying deep somatic or visceral pain. When caused by an underlying visceral or systemic disease, visceral  usually precedes the development of referred musculoskeletal pain.

Characteristics of Reffered:

Referred is usually well localized. Local tenderness is present in the tissue of the referred area, but there is no objective sensory deficit. It is often accompanied by muscle hypertonus over the referred area of pain. Finding the original source of referred pain can be quite a challenge . 

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