Breaking Down the Barriers of Pain: Part 2
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.
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.
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 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|
|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.
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").
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: