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7 Articles in Volume 1, Issue #2
A Good Night’s Rest
Breaking Down the Barriers of Pain: Part 2
MET Treatment Protocols
MPS Treatment Methods
Playing Dual Roles
Providing Valuable Input
Treating Back Pain Lumbar

Breaking Down the Barriers of Pain: Part 2

Source-of-pain physical examinations,diagnoses, and treatment options are reviewed in part two of this series.

Source-of-Pain Physical Examination

Physicians are trained to detect the unusual sign, the Babinski, the tongue fasciculation, but often overlook common findings. The most common pain conditions are those arising in the musculoskeletal system and diagnosing them requires additions to the traditional exam.

Manual Palpation

Medical physicians are not typically trained in manual palpation techniques. Direct palpation for localized or generalized tenderness should be part of any examination of a musculoskeletal pain complaint. The technique at its most elemental is to palpate where the patient states it hurts. The clinician uses the index finger or thumb and presses firmly inward for one or two seconds in the painful areas and inquires if the patient experiences painful tenderness. It is especially helpful to watch the patient's face for grimacing. One of five responses can be expected:

The palpated area is non-tender. This is found when the source of pain arises in proximal nerve or root, or less commonly, with pain arising from internal organs.

  • There are spots of discrete, localized tenderness to firm palpation, typically the size of small almonds or large pine nuts. This is the hallmark of true muscle pain, "trigger points."
  • There is tenderness over the tendon insertion or joint consistent with localized pathology such as lateral epicondylitis.
  • There is diffuse tenderness to palpation of any and all areas, characteristic of fibromyalgia.
  • There is localized painful sensitivity to light touch — allodynia — typically of the hand or foot, characteristic of "RSD."

Passive Range of Motion

Passive Range of Motion (PROM) is an assessment tool used routinely by physical and occupational therapists, but is not typically taught to physicians. Therapists use it to measure the degree of joint motion as an assessment of function, but this maneuver also has diagnostic value in determining if the painful condition is arising in the joint. Begin by asking the patient to move the involved body part in a direction or posture that elicits pain. For instance, if the patient reports shoulder pain, ask the patient what movements of the arm will elicit pain. Then take the extremity in your hands, ask the patient to relax his or her muscles as much as possible, and move the extremity slowly and gently in the indicated direction. If pain arises in the joint itself, whether the synovium, tendon insertions, or ligament, this maneuver will elicit pain at some point during the arc of passive motion. This is then contrasted with isometric contraction. In addition, there are specific maneuvers that are used to diagnose sacro-iliac joint dysfunction. These are the Gaenslen's, Patrick's, and Yeoman's tests.

Isometric Contraction

After testing PROM, isometric contraction should be tested by locking the joint so that there is no movement proximal or distal to the joint. Ask the patient to forcefully try to move and contract against the resistance. This maneuver will increase the patient's pain if it arises in muscle, but not if it arises in joint. By comparing PROM to isometric contraction it is possible to isolate joint from muscular involvement.

Source-of-Pain Examination Summary Table
Source-of-Pain Contraction   Pain Drawing Passive Range Tenderness Isometric to Palpation of Motion  
Muscle Myofascial referral patterns Discrete localized tenderness which reproduce predominant pain Non-painful Painful
Root Dermatomal None Non-painful Non-painful
Peripheral Nerve Stocking-glove or peripheral n. distribution None, or mild hyperpathia of nerve distribution Non-painful Non-painful
Joint/tendon Localized over affected joint   Tenderness over joint Painful Non-painful
Fibromyalgia Diffuse Diffuse tenderness to moderate pressure   Non-painful Poor effort due to fear of pain
Somatoform pain disorders Diffuse Diffuse to light touch Non-painful Non-painful
RSD Distal extremity Distal sensitivity to light touch Non-painful Non-painful

Nerve Signs Asymmetrical Reflexes

Reflexes are of course extremely valuable in diagnosing brain or spinal cord pathologies but are less useful in diagnosing musculoskeletal pain conditions. The knee reflex responds to an overlap of roots centered on L4, which is uncommonly involved in disc herniations and thus is rarely diagnostic. Ankle reflexes are more useful; they are typically absent bilaterally with peripheral neuropathies such as diabetic neuropathy and can be asymmetrically reduced with an S1 radiculopathy.

Tinel's Sign

Tapping over a nerve elicits painful paresthesias in the distribution of an irritated peripheral nerve. The most common use is tapping over the median nerve at the wrist. One can also tap over the ulnar nerve at the elbow (the "funny bone").

Myalgias

Approximately 80 percent of us will have muscle pain during our lifetimes, and 20 percent will have muscle pain for more than 30 days in a given year. Muscle pain is the most common work-related injury, and the most common cause of chronic pain. While many muscle injuries recover quickly, many do not, and become chronic. The reasons include:

  • There is no routine diagnostic test for muscle pain. EMG-NCV, imaging studies and blood tests are all negative in these conditions. Thus the diagnosis depends on the description of symptoms and the physical examination.
  • There is no surgery or medication that is curative of muscle pain. Muscle relaxants such as Soma, Robaxin, Parafon-forte are actually sedatives and provide only temporary relief.
  • The traditional treatment for muscle pain conditions has been physical therapy and various chiropractic and osteopathic techniques. Traditional spinal manipulation, while appropriate for facet pathology, often aggravates muscle pain conditions, or yields very temporary relief. Traditional physical therapy is based on the incorrect assumption that musculoskeletal pain conditions are caused by poor conditioning or weakness and the strengthening programs provided often aggravate the pain.
  • The medical profession poorly understands the underlying cause of muscle pain. Although John F. Kennedy's White House physician, Janet Travell, MD, popularized the term trigger point, she believed that a trigger point was an area of poor blood flow in the muscle. This could never be established and turned out to be incorrect.
  • Muscle pain is aggravated by muscle tension. Muscle pain conditions have a psychophysiological component, which must be treated together with the physical component.

Clinical Presentation

Muscle pain is most common in the head, neck, shoulders, mid and low back, and the forearms. The pain has an aching or tight quality and is poorly localized. The pain is continuous, fluctuating from a sense of tightness only, to such severe pain that the sufferer is unable to carry on normal activities. The pain is typically worse on awakening in the morning, subsides somewhat with arising and becoming active, and then increasing again with the day's activities and with over-exertion and stress. The specific location of pain varies with which muscles are involved; the most commonly involved muscle patterns are shown in the figures in the Jan/Feb 2001 issue of Practical Pain Management.

Source-of-Pain Diagnoses
Source of Pain Diagnoses
Myalgias Myofascial pain, cervical strain (whiplash), lumbar strain, repetitive strain, tension headache, "mechanical" back syndrome, piriformis syndrome, thoracic outlet syndrome
Nerve Compression, Nerve Root Disc herniation with root compression
Nerve Compression, Peripheral Nerve Carpal tunnel syndrome, ulnar nerve compression
Nerve Damage, Nerve Root Residual radiculopathy, peripheral neuropathy, metabolic (e.g. diabetes), toxic and Peripheral Nerve (e.g. chemotherapy-related)
Joint/Tendon Inflammation Epicondylitis, DeQuervain's, shoulder impingement syndromes, vertebral facet arthropathy, osteoarthritis
Migraine Migraine
"RSD" Complex regional pain syndrome, reflex sympathetic dystrophy, causalgia, Sudek's dystrophy
Somatization Somatoform pain disorder
Fibromyalgia Fibromyalgia, chronic fatigue syndrome
Drug Dependence Opiates, benzodiazepines
Drug Addiction Opiates, benzodiazepines

Examination

The hallmark of muscle pain is trigger points, discrete localized spots of tenderness to firm palpation that are present in characteristic locations within the affected muscle. In addition, pain is reproduced by isometric contraction.

Pathophysiology

In their first text, published in 1983, Janet Travell, MD, and David Simons, MD, proposed that the trigger point was an area of hypoxia and/or metabolic distress in muscle tissue, precipitated by injury and sustained by metabolic factors.1 Biopsy studies failed to find any objective pathology and for many years the concept of trigger points was rejected by academic medicine.

In 1993 it was discovered that the central nidus of trigger points contained abnormal electromyographic activity, localized muscle spasm, while adjacent fibers of the same muscle remained electrically silent. The EMG abnormality was significantly greater in patients with muscle pain than in normal subjects.2

Subsequent research has shown that the abnormal EMG activity is not affected by curare — the traditional muscle paralytic agent — but is blocked by the alpha-1 adrenergic antagonists, phentolamine, and phenoxybenzamine. A biopsy of the trigger point, obtained by needle-EMG-guided injection of methylene blue, identified a muscle spindle.3

A sympathetically mediated spindle contraction model has been proposed. In this model, a traumatic or repetitive over-stretch of the muscle and its stretch receptors, such as occurs with a whiplash or strain injury, initiates contractions of the intrafusal muscle fibers. Co-existing emotional tension produces excessive sympathetic activation of the intrafusal fibers so that the contractions become self-sustaining. This in turn leads to increased pressure within the spindle capsule and pain.4

Figure 5 shows an anatomical drawing of a muscle spindle viewed longitudinally. The spindle is approximately the size of a swollen grain of rice and has been called the "eye" of the muscle, providing information on the degree of stretch, tension, and pressure within the muscle. The trapezius, for example, has a hundred or more spindles, scattered throughout the belly of the muscle. The spindle capsule is shown in blue. The capsule is filled with hyaluronic acid and is a pressure and pain-sensitive structure. Inside the capsule are eight to 12 intrafusal muscle fibers that are dual-innervated by the gamma efferent system and the sympathetic system.

Simons and Hong have proposed an alternative model in which the abnormal EMG activity is caused by excessive acetylcholine release from dysfunctional neuromuscular junctions.5 Dr. Hong and his colleagues have conducted a series of animal electrophysiological studies that so far have not confirmed this hypothesis,6 but have confirmed the blockade of trigger point EMG activity by the adrenergic antagonist, phentolamine.7 The Simons and Hong hypothesis does not explain why the presenting symptom is pain, not weakness, as with other neuromuscular junction disorders such as myasthenia gravis; nor does it explain why the EMG activity is modulated by the sympathetic nervous system. Nevertheless, to date neither the spindle nor the neuromuscular junction theories have been proven.

Treatment Medications

Muscle relaxants such as Soma, Robaxin and Parafon-forte are sedatives and short acting, but can be useful to manage flair-ups. Flexeril (cyclobenzaprine) is closely related structurally to Elavil (amitriptyline). Although the pharmaceutical company recommends 10 mg t.i.d, this is too sedating for most patients and hs dosing is better tolerated. In contrast to the other muscle relaxants, Flexeril requires several days to become effective.

Patient Education

The most important and perhaps most challenging component of treatment is helping the patient understand and accept that it is in fact muscle that is causing his or her pain.

Gentle Muscle Stretch

As discussed in the pathophysiology section, the best evidence available is that muscle pain arises from the muscle spindles, the stretch receptors of the muscle. The affected spindles are under pressure, shortened, and in spasm and must be restored to the normal lengthened state. This cannot be accomplished by traditional physical therapy techniques, which emphasize muscle strengthening. The affected muscle must be placed in a relaxed state and then very slowly stretched. If the stretch is too quick or too extended, the stretch receptor will reflexively increase its tone aggravating the condition. The stretch must be very slow and gentle, typically only a few millimeters of movement over several minutes. Ideally this is done using specialized gym equipment that permits isolating the affected muscle, placing it in a relaxed state and providing the slow stretch mechanically. Nevertheless the stretches can be taught for use with traditional equipment as well as for home practice.

Muscle Tension Reduction

As discussed, muscle pain is sustained and aggravated by tension, via sympathetic activation of the muscle spindles. The tension must be addressed and reduced or it will override the stretching program. Surface EMG biofeedback is the most direct method of teaching this skill. A patient uses the EMG signal to recognize the sensation of tension, which is experienced as a tightening between the shoulder blades and to take steps to reduce it before it progresses to increased pain. Biofeedback is most often practiced by psychologists, but is also used by therapists and other clinicians. Occupational therapists are ideally suited to this method because they are trained to combine physical techniques with functional and psychological ones. n

Last updated on: July 24, 2014
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