been thought to trigger the release of β-endorphin. 43 It is likely that β-endorphin released from these neurons by stimulation of the hypothalamus is responsible for initiating the same mechanisms in the spinal cord as previously described with other desending mecha-nisms of pain control. Once again, further research is needed to clarify where and how these substances are released and how the release of β-endorphin affects neural acitivity and pain perception.
Dynorphin, a more recently isolated endogenous opioid, is found in the PAG, rostroventral medulla, and the dorsal horn. 22 It has been demonstrated that dynorphin is released during electroacupuncture. 20 Dynorphin may be responsible for suppressing the response to noxious mechanical stimulation. 22 Summary of Pain Control Mechanisms The body’s pain control mechanisms are probably not mutually exclusive. Rather, analgesia is the re-sult of overlapping processes. It is also important to realize that the theories presented are only models.
They are useful in conceptualizing the perception of pain and pain relief. These models will help the ath-letic trainer understand the effects of therapeutic modalities and form a sound rationale for modality application.3 As more research is conducted and as the mysteries of pain and neurophysiology are solved, new models will emerge. The athletic trainer should adapt these models to fit new developments.
CHAPTER 3 Managing Pain with Therapeutic Modalities 49 Other useful pain control strategies include the
following:
1. Encourage cognitive processes that influ-ence pain perception, such as motivation, tension diversion, focusing, relaxation techniques, positive thinking, thought stopping, and self-control.
2. Minimize the tissue damage through the application of proper first aid and immobi-lization.
3. Maintain a line of communication with the patient. Let the patient know what to expect following an injury. Pain, swelling, dysfunction, and atrophy will occur follow-ing injury. The patient’s anxiety over these events will increase his or her perception of pain. Often, a patient who has been told what to expect by someone he or she trusts will be less anxious and suffer less pain.
4. Recognize that all pain, even psychoso-matic pain, is very real to the patient.
5. Encourage supervised exercise to encour-age blood flow, promote nutrition, increase metabolic activity, and reduce stiffness and guarding if the activity will not cause fur-ther harm to the patient.
The physician may choose to prescribe oral or injectable medications in the treatment of the patient. The most commonly used medications are classified as analgesics, anti-inflammatory agents, or both. The athletic trainer should become familiar with these drugs and note if the athlete is taking any
medications. It is also important to work with the referring physician to assure that the patient takes the medications appropriately.
The athletic trainer’s approach to the patient has a great impact on the success of the treatment. The patient will not be convinced of the efficacy and impor-tance of the treatment unless the athletic trainer appears confident about it. The athletic trainer must make the patient a participant rather than a passive spectator in the treatment and rehabilitation process.
The goal of most treatment programs is to encourage early pain-free exercise. The physical agents used to control pain do little to promote tis-sue healing. They should be used to relieve acute pain following injury or surgery or to control pain and other symptoms, such as swelling, to promote progressive exercise. The athletic trainer should not lose sight of the effects of the physical agents or the importance of progressive exercise in restoring the patient’s functional ability.
Reducing the perception of pain is as much an art as a science. Selection of the proper physical agent, proper application, and marketing are all important and will continue to be so even as we increase our understanding of the neurophysiology of pain. There is still the need for a good empirical rationale for the use of a physical agent. The ath-letic trainer is encouraged to keep abreast of the neurophysiology of pain and the physiology of tis-sue healing to maintain a current scientific basis for selecting modalities and managing the pain experi-enced by his or her patients.
Summary
1. Pain is a response to a noxious stimulus that is subjectively modified by past experiences and expectations.
2. Pain is classified as either acute or chronic and can exhibit many different patterns.
3. Early reduction of pain in a treatment program will facilitate therapeutic exercise.
4. Stimulation of sensory receptors via the thera-peutic modalities can modify the patient’s per-ception of pain.
5. Three mechanisms of pain control may explain the analgesic effects of physical agents:
a. Dorsal horn modulation due to the input from large-diameter afferents through a gate control system, the release of enkeph-alins, or both.
b. Descending efferent fiber activation due to the effects of small-fiber afferent input on higher centers including the thalamus, raphe nucleus, and periaqueductal grey region.
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c. The release of endogenous opioids includ-ing β-endorphin through prolonged small- diameter afferent stimulation.
6. Pain perception may be influenced by a variety of cognitive processes mediated by the higher brain centers.
7. The selection of a therapeutic modality for controlling pain should be based on current
knowledge of neurophysiology and the psy-chology of pain.
8. The application of physical agents for the con-trol of pain should not occur until the diagnosis of the injury has been established.
9. The selection of a therapeutic modality for managing pain should be based on establishing the primary cause of pain.
1. What is a basic definition of pain?
2. What are the different types of pain?
3. What are the different assessment scales avail-able to help the athletic trainer determine the extent of pain perception?
4. What are the characteristics of the various sensory receptors?
5. How does the nervous system relay informa-tion about painful stimuli?
6. Describe how the gate control mechanism of pain modulation may be used to modulate pain.
7. How do the descending pain control mecha-nisms function to modulate pain?
8. What are the opiate-like substances and how do they act to modulate pain?
9. How can pain perception be modified by cognitive factors?
10. How can the athletic trainer help modulate pain during a rehabilitation program?
Review Questions
True or False
1. Both sclerotomic and radiating pain may cause pain away from the site of the disorder.
2. Afferent nerve fibers conduct impulses from the brain to peripheral sites.
3. Serotonin and β-endorphin affect synaptic activity.
Multiple Choice
4. Which of the following is NOT a method of pain assessment?
a. McGill pain questionnaire b. Snellen test
c. visual analogue scales d. numeric pain scale
5. Pain receptors in the body are called _______.
a. Meissner’s corpuscles b. Krause’s end bulbs c. Pacinian corpuscles d. nociceptors
6. Which of the following plays a role in trans-mitting sensations of pain?
a. substance P b. enkephalin c. dynorphin d. serotonin
7. Which of the following is/are characteristic(s) of Aδ fibers?
a. large-diameter fibers b. fast conduction velocities c. transmit brief, localized pain d. all of the above
8. Stimulation of the substantia gelatinosa occurs in the __________ theory of pain.
a. space
b. descending c. gate control d. enkephalin release Self-Test Questions
CHAPTER 3 Managing Pain with Therapeutic Modalities 51 9. β-endorphin, an endogenous opioid, is
re-leased from the__________.
a. hypothalamus
b. anterior pituitary gland c. raphe nucleus
d. a and b
10. Which of the following cognitive processes may affect pain perception?
a. depression
b. past pain experiences c. both a and b
d. neither a nor b
Solutions to Clinical Decision-Making Exercises 3–1 After conducting a detailed evaluation, a
number of options are available, including vi-sual analogue scales, pain charts, the McGill Pain Questionnaire, the Activity Pattern Indi-cators Pain Profile, and numeric pain scales.
Numeric pain scales, in which the patient is asked to rate his or her pain on a scale from 1 to 10, are perhaps the most widely used in the athletic training setting.
3–2 The modality selected should provide a signifi-cant amount of cutaneous input that would be transmitted to the spinal cord along Aβ fibers. The modalities of choice may include various types of heat or cold, electrical
stimu-lating currents, counterirritants (analgesic balms), or massage.
3–3 The athletic trainer may choose to use relax–
ation techniques, tension diversion, focusing, positive thinking, thought stopping, and self-control techniques. Certainly the cognitive per-ception of pain and the ability to control that perception is an aspect of rehabilitation that the athletic trainer should take very seviously.
3–4 The athletic trainer should explain that stim–
ulating the trigger point with an electrical stimulating current will trigger the release of a chemical (β-endorphin) in the brain that will act to modulate pain in the shoulder.
References
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12. Cohen, S, Christo, P, Moroz, L: Pain management in trauma patients, Am J Phys Med Rehab 83(2):142–161, 2004.
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Joint Surgery 88(2):58, 2006.
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CASE STUDY 3–1
protect the common peroneal nerve on the posterior lateral aspect of the knee. Following cold application she was encouraged to perform quadriceps setting and heel slides.
Response Her volitional control of the quadriceps improved and she left the clinic able to perform a straight leg raise without a lag. She was also able to move the knee from extension to 50 degrees of flexion.
She was sent home with instructions to use cold three to four times daily followed by the previously described exercises. Stacey demonstrated active range of motion MANAGING ACUTE PAIN
Background Stacey is a 21-year-old college basket-ball player referred for rehabilitation the day after arthroscopic surgery to remove loose bodies and a tear in the medial meniscus of her left knee.
Impression She is typical of patients presenting the day following acute injury and surgery. She is experi-encing considerable discomfort and demonstrates inhi-bition of the quadriceps muscles and an unwillingness to flex and extend the knee.
Treatment Stacey was treated with an ice bag around the knee for 20 minutes, being careful to
CHAPTER 3 Managing Pain with Therapeutic Modalities 53 from terminal extension to 115 degrees of flexion and
good control of the quadriceps on return to the clinic 5 days later. Her rehabilitation progressed well and she returned to playing basketball within 3 weeks in prepa-ration for the upcoming season.
Surgery results in acute pain and the associated guarding, splinting, and neuromuscular inhibition.
When active muscle contractions and range of mo-tion exercises can be performed safely, the use of therapeutic modalities can help the patient regain
function. In this case, cold was selected because of the acute presentation and the ease of use at home. TENS also would have been appropriate, either alone or in combination with cold. It is also important to appreci-ate the effects of pain-free movement on the recovery process. Movement lessens the sensation of stiffness postoperatively and provides large-diameter afferent input into the dorsal horn, which may relieve pain through a gating mechanism or the stimulation of enkephalin interneurons.
CASE STUDY 3–2
MANAGING CHRONIC PAIN
Background Linda is a 31-year-old resident in oral surgery. She was referred for rehabilitation for com-plaints of upper back and neck pain with frequent headaches. She states that she has been experiencing the symptoms off and on for about 2 years. Her symp-toms are worse at the end of the work day, especially on days she is in the operating room. There is no history of trauma to the affected region.
Physical exam reveals a forward head, rounded shoulder posture, spasm of the cervical paraspinal and trapezius muscles, and very sensitive trigger points throughout the region.
Impression Her symptoms were consistent with pain of myofascial origin secondary to posture, job-related stress, and fatigue of the postural muscles.
Treatment She was treated with TENS over the trigger points using a Neuroprobe and soft tissue mobilization, and she was instructed in a routine of postural exercises. She was encouraged to perform
postural exercises and relaxation activities during breaks in her schedule. Linda returned to the clinic indicating she had experienced near complete relief following her first visit for about 6 hours. The stimu-lation of trigger points was repeated and Linda was instructed in the use of a TENS unit with conventional parameters over her most sensitive trigger point. She had access to the TENS unit through the surgical clinic where she worked.
Response Linda was seen for two additional visits.
She indicated her compliance with the exercise pro-gram, which was subsequently expanded into a general conditioning program with an emphasis on upper body endurance. She also indicated that her symptoms were becoming much less severe and less frequent and that the home TENS unit gave her a means of controlling her pain before it became severe enough to affect her activities. Over the subsequent several months, Linda completed her residency without additional care for her neck and upper back.
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