Pain occurs when an injury, wound, or disease triggers a response in tissue. Nociceptors are free, peripheral nerve endings that pick up pain stimulus and are present in almost all cell types. These nociceptors transduce stimuli into pain impulses that cause release of chemical mediators. Peripheral nerves conduct pain impulses to the CNS through the spinal cord and up to the brain where they are interpreted as painful. Pain can be activated by an external or internal stimulus such as a dumbbell falling on your foot (external) or bicep tendonitis (internal).
Specific nerve fibers that in regards to pain are C fibers and A Delta fibers.
- C Fibers - Pain is transmitted on these fibers and is usually dull, aching burning or throbbing and lasts a long time
- A Delta - Pain transmitted on these fibers is quick, pricking, stabbing, sharp
Muscle activity may increase, decrease, or remain the same in the presence of pain. Most commonly increases or hypertonicity/spasm with the gol of protecting tissue from further injury.
Types of Pain:
- Acute Pain - Recent onset of tissue damage, tends to be localized, intense with inflammation, responds well to treatment,
- Chronic Pain - Greater than 3 - 6 months in duration, tends to be generalized, decreased activity and socialization, very common among 1/3 population (back)
- Dysfunctional Pain - Pain that does not serve a protective function. It is persistent, spreading, increasing, pain with small movements, unpredictable, and without a known cause. Associated with fatigue, depression and impaired functioning - example is Fibromyalgia
- Referred Pain - transferred to a distant site away from its origin - ex back pain felt in legs
In most medical settings pain must be assessed daily on a 0-10 pain scale. Pain is documented in the subjective section of a SOAP note, since it is what a patient describes.
Physical Therapy Management of Pain:
- Physical Agents (massage, US, heat/ice etc) - May relieve pain by: Moderating release of inflammatory mediators, altering nerve conduction, increasing endorphin levels, decreasing muscle spindle sensitivity, reducing edema, and have fewer less sever side effects that pharmacological interventions.
- NSAIDS - Both analgesic (pain) and anti inflammatory properties, cheap, fast relief, OTC
- Exercise - Studies have shown that exercise decreases pain intensity and increases pain thresholds and tolerance.