Chapter 6 - Diagnostic Instrumentation

In clinical practice the case history and physical examination typically supply most of the information necessary to make a diagnosis. Instrumentation may serve to confirm a differential diagnosis or to assess the severity of a condition. For clinical usefulness, instruments must be appropriately applied and results appropriately interpreted by the clinician. This chapter deals with those instruments that measure patient perceptions (e.g., pain severity, activities of daily living), function (e.g., range of motion), and physiology (e.g., muscle strength).

Instruments are designed with various levels of sophistication and make use of underlying assumptions. The meaningful interpretation of a patient's test results depends on the reliability and validity of the instrument. The most effective means to ensure reliability of an instrument is through test standardization. For an instrument to be valid, it must accurately measure the desired function. Besides these two important qualities, clinical utility needs to be considered. The results of the tests should have an impact in diagnosis and/or treatment.

For definitions see the Glossary at the end of this publication.

Accuracy
Anthropometry
Calibration
Diagnosis
Diagnostic
Discriminability
Gold Standard
Instrument
Precision
Reliability
Sensitivity
Specificity
Validity

A. PERCEPTUAL MEASUREMENTS

1.Questionnaires

2.Pressure Algometry

B. FUNCTIONAL MEASUREMENTS

1. Posture/Clinical Anthropometry
a. Plumbline Analysis
b. Scoliometry
c. Moiré Topography
d. Bilateral Weight Scales
e. Automated Measures of Posture
i. Computer digitization
ii. Stabilometry
f. Photogrammetry

2. Measurement of Movement
a. Inclinometry
b. Goniometry
c. Optically Based Systems

3. Measurement of Strength
a. Hand-held Dynamometers
b. Isometric tests
c. Isokinetic tests
d. Isoinertial tests

C. PHYSIOLOGICAL MEASUREMENTS

1. Thermographic recordings
a. Thermocouple Devices
b. Infrared Thermography

2. Galvanic Skin Response (GSR)

3. Plethysmography

4. Electrophysiological Recordings
a. Static EMG
b. Dynamic EMG

A.PERCEPTUAL MEASUREMENTS

1.QUESTIONNAIRES:

It is estimated that approximately 66% of patients who visit a chiropractor suffer from low-back pain (Nyiendo et al. 1989). Traditionally, the perception of pain has been considered too subjective and unreliable a measure as it requires the patient's self-report. However, recent research in the field of pain measurement has given all health care providers instruments that are both valid and reliable.

In assessing pain, the dimensions of severity, duration, and frequency are most often measured. The majority of these instruments are questionnaires that ask the patients to rate their pain on some type of scale. The Visual Analog Scale (VAS) consists of a 10 cm line with a pain descriptor at each end of the line. The patients are asked to mark a point on the line which best represents their perceived level of pain intensity. This scale has been shown to be valid and reliable (Huskisson 1982).

The 101-point Numerical Rating Scale (NRS-101) asks patients to rate their perceived level of pain on a numerical scale of 0 to 100. The 11-point Box Scale (BS-11) asks patients to place an "X" through one of the eleven numbers which are each surrounded by a box; "0" represents one extreme of pain and "10" represents the other (Downie et al. 1978).

Verbal Rating Scales (VRSs) consist of a list of adjectives which describe pain at different levels of intensity. A score of 0 is associated with the least intense pain descriptor; the next, a score of 1, and so on with each adjective having a number score associated with it. A patient's pain intensity score is that number associated with the word he or she chooses as most descriptive of his or her pain level. All of the above scales have been studied and compared to each other. They have few differences. The NRS-101 is perhaps the most practical index (Jensen et al. 1986).

The McGill Pain Questionnaire (MPQ) consists of three major categories of word descriptors (sensory, affected and evaluated) and an intensity scale which allow patients to report their perceived pain experience (Melzack, 1975). While being one of the most well-studied in terms of validity and reliability, it may be somewhat impractical in clinical practice as it should be applied by an interviewer (McDowell and Newell 1987). A short form of the McGill Pain Questionnaire has been developed which correlates highly with the three major pain rating indices of the long form MPQ and can be administered in two to five minutes (Melzack 1987).

Traditionally, chiropractors have relied heavily on physical signs to arrive at a diagnosis. Although physical signs are useful in this capacity, they are rather insensitive measures in determining a patient's disability (Roland and Morris 1983). Usually, a patient's function is verbally discussed between the patient and the chiropractor, but new questionnaire techniques try to objectify this information. These functional questionnaires are designed to measure a patient's anxiety, depression, and limitations in performing activities of daily living.

The questionnaires attempt to quantify function, behaviour, and symptoms directly, rather than to infer them from physical signs elicited from physiological tests. There are a large number of functional questionnaires described in the scientific literature. In general, these questionnaires may be divided into two categories, self-reporting and practitioner-administered. Self-reporting questionnaires are often self-normalizing but suffer from reactivity which may result in unintentional change in the patient's response when exposed to the same questions repeatedly (Barlow et al. 1984). In administering either format, several error sources should be considered including:(i) patient motivation (ii) acquiescence to positively worded items; and (iii) patient's seeking social approval (Topf 1986). Deyo (1988) published an excellent summary review of many functional questionnaires used in back pain research. Some examples from the list are:

-the Pain Disability Index (Tait et al. 1987)

-the Roland Morris Disability Questionnaire (Roland and Morris 1983)

-the Waddell Disability Index (Waddell and Main 1984)

-the Oswestry Disability Questionnaire (Fairbank et al. 1980)

Vernon and Mior (1991) modified the Oswestry Disability Questionnaire and produced a ten-item scaled questionnaire entitled the Neck Disability Index. For depression, the Self-Rating Depression Scale and the Beck Depression Inventory have been shown to be valid and reliable (Zung et al. 1965, Beck et al. 1961). A detailed review of these questionnaires is beyond the scope of this chapter. Overall, these functional questionnaires offer standardization of measurement, comprehensiveness, and good reproducibility and validity (Deyo 1988).

2.PRESSURE ALGOMETRY:

Pressure algometry is a method of measuring pain that has received much attention in the recent literature. It employs a pressure manometer which estimates pain threshold from applied pressure to the myofascial structures (Fischer 1986, 1987). This instrument is most often used in assessing sensitivity of tender points and has been shown to have good inter-rater and test-retest reliability (Simons 1988, Reeves et al. 1986).

B.FUNCTIONAL MEASUREMENTS:

1.POSTURE/CLINICAL ANTHROPOMETRY

(a)Plumbline analysis

The most common method used by chiropractors to evaluate posture is the plumbline analysis. The plumbline provides the clinician a visual frame of reference to evaluate various body landmarks and the alignment in relation to the verticality of the plumbline. The evaluation of the patient is done from the anterior, posterior and lateral stances. There is neither a standard method of plumbline analysis nor studies that examine the issues of validity and reliability.

(b)Scoliometry

There are various forms of instruments that attempt to quantify the physical signs of scoliosis. In 1906, Fipps developed a scoliometer which utilized a grid system that actually plotted spinal deformities and postural changes (Triano et al. 1992). Simple inclinometers and bubble-level scoliometers are used to quantify the deformity of the rib cage, shoulder and pelvic unleveling. Studies have shown that these devices have good reliability (Pearsall et al. 1992, Amendt et al. 1990). The most common clinical test for scoliosis is the Adams forward-bending test where the patient undresses from the waist up and is observed from behind while standing straight (Renshaw 1988). The examiner looks for body asymmetry, especially rib hump, while the patient stands and forward bends at the waist. Reliability studies of scoliosis detection in school-screening programmes demonstrate low specificity and a lack of precision (Daruwalla and Balasubramaniam 1985, Morais et al. 1985, Leaver et al. 1982). The reason for the poor results may not be the method itself but the in-expertise of the examiners. Proper training may significantly improve the precision of the test (Bunnell 1984, Howell et al. 1978). Currently, the gold standard for scoliosis detection remains the standing full-spine radiograph.

(c)Moiré Topography

Moiré topography for scoliosis detection has received mixed reviews in the literature (Daruwalla and Balasubramaniam 1985). It is a static photographic technique modified to highlight body contours for the purpose of quantifying structural deformity; in the same manner as the methods used in map-making to denote elevation (Moreland et al. 1981, Willner 1979). The photographs consist of interference patterns cast onto the body surface by an angled light source passing through a grid. Patient positioning is important as the grid-to-patient distance must be kept constant for accurate follow-up evaluations.

Moiré topography has some usefulness as an investigational procedure, but its clinical utility has not been demonstrated (Triano et al. 1992). Its application is fast and reproducible, but the results are difficult to quantify and the correlation to physical findings is poor.

(d)Bilateral Weight Scales

Asymmetric weight bearing as a result of faulty posture has been considered a contributing factor in the development of degenerative joint disease, sacroiliac instability, chronic lumbar strain and other conditions (Fisk 1977, Hildebrandt 1977, Coggins 1975, Illi 1965). The simplest method to measure whether the loads transmitted throughout the body are asymmetric is by means of bilateral weight scales (Herzog et al. 1989, Vernon and Grice 1984). The patient stands with each foot resting on a separate scale so the clinician can measure unilateral loads on the pelvis. Its usefulness is based on empiricism and its validity has not been determined.

(e)Automated Measures of Posture

(i)Computer digitizers

Computerized electrogoniometers are available for clinical and experimental assessment of posture. These devices locate the position of a point in space with respect to an arbitrary fixed reference point. A marker probe is positioned on the body at key landmarks, and sensors located in the probe's armature determine three-dimensional position (Triano et al. 1992). The patient can assume a second position and the difference between the two positions can be compared. Calculations are then made to deduce the various parameters of posture and flexibility.

The interexaminer reliability of these instruments is questionable. One commercially available electrogoniometric system has been evaluated in a number of studies (Cowherd et al. 1992, Herzenberger et al. 1989, Adams et al. 1988, Gosselin 1987). The accuracy, validity, and reliability of automated measurements can be confounded by four factors (Triano et al, 1992):

(a)interexaminer reliability in landmark identification,

(b)amplitude of postural sway or stability during recording of multiple landmark positions,

(c)magnification of measurement error by the mathematics of automated mathematics, and

(d)use of new methods of analysis before they have been validated as clinically useful and discriminable.

(ii)Stabilometry

Stabilometry is the study of body equilibrium by the use of force plates. There has been a great deal of research on posture in relation to the vestibular system and the geriatric population using stabilometry. Much of this research is published in the European literature (Halvacka et al. 1992, Kollegger et al. 1992, Wolfson et al. 1992, De Benedittis et al. 1991, Nies and Sinnott 1991, Halvacka et al. 1990). This method of measuring postural sway has been shown to valid and reliable.

(f)Photogrammetry

Photogrammetry is used to quantify postures adopted by persons during specific tasks. Methods of measurement include static, video and opto-electronic systems. In clinical practice, photogrammetry may be used in recording postural anomalies as part of the physical examination, quantifying postures adopted by patients during functional performance tests in return-to-work evaluations, and work site ergonomic evaluations (Chaffin and Andersson 1988). To ensure accurate and reliable results, technical concerns such as calibrated alignment of the camera image contrast, standardized postures for repeated measures and distortion effects must be addressed.

2.MEASUREMENT OF MOTION

In the general course of patient care, range of motion is examined using goniometers, inclinometers and optically based systems. Most devices quantify the regional movement of a part and express it as an angular displacement about some centre of rotation.

(a) Inclinometers and (b) Goniometers

Techniques of goniometry are commonly used by chiropractors and provide quantitative data of limitation of joint range of motion. Accurate goniometry requires skill and consistent performance of the examiner. Intrarater measurements are known to vary and should be taken into account when assessing changes in a patient's status (Boone 1978). Goniometry is useful in measuring ROM of the cervical spine and of the peripheral joints. Zachman et al. (1989) compared two cervical goniometers and found the "Rangiometer" by Maker Inc., to be moderately reliable. Accuracy is limited to a range of 10 to 15 degrees (Chaffin and Andersson 1988). Usage for spinal measurements is no longer considered acceptable practice because of the advent of better methods.

Inclinometers use the constant vertical direction of gravity as a reference and require only that a side rests against the body segment surface. The reliability of a number of common clinical methods of measuring ROM of the lumbar spine has been examined (Liebenson and Phillips 1989, Gill et al. 1988). Liebenson found that inclinometers, the modified Schober test, flexible rulers and spondylometers received the most scientific support. In another study, an inclinometer which is secured to the head by a strap showed high interexaminer reliability (Tucci et al. 1986). Loebl et al. (1977) found that a fluid-filled inclinometer was reliable for measuring cervical ROM.

Digital or analog and mechanical or electronic inclinometers are available. Greater accuracy of measurement is available with these, with ranges of 3 to 5 degrees being measurable under typical clinical conditions (Mayer and Gatchel 1988). Inclinometers are particularly suitable for assessing spinal function because they are capable of separating components of motion, e.g., pelvic versus lumbar.

(c)Optically Based Systems

Aside from research applications, the most common clinical use of opto-electronic systems is in conjunction with the use of force plates for assessing gait abnormalities (Herzog et al. 1988, Herzog et al. 1989, Prodromas et al. 1985). Video-monitoring is often used in industrial practice to capture the salient features and at least semi-quantify motions and postures at the work station. Work-related spine injuries, carpal tunnel syndrome and other cumulative trauma disorders are frequent areas of concern where these methods are used. The primary parameters of importance are joint angle, angular velocity, and angular acceleration. Coupled with appropriate software and external load measurements, joint loads and patterns of behaviour can provide information on relative risk of work-related tasks.

3.MEASUREMENT OF STRENGTH

There is a wide array of testing instruments for the measurement of muscle performance. Four basic categories are manual muscle testing, isometric, isokinetic and isoinertial testing. It has been suggested that there is no single form of testing that is decidedly superior or more valid for measuring muscle strength (Sapega, 1990). Evaluation of the various strength mensuration devices, that attempt to measure that different characteristics of strength, must consider whether the device is safe, practical, reliable and reproducible. Also whether the device is predictive of capability, specific to the requirement being tested (i.e., job demands) and ethically and/or legally defensible (Chaffin, 1975). The individual characteristics of each testing instrument must be considered in order to be able to interpret the results with any degree of validity.

(a)Hand Held Dynamometers

Manual strength testing has been shown to provide only a rough approximation of capability (Saraniti et al, 1980; Frese et al, 1987). It has been shown that 35% difference in strength is required in order for manual testing to demonstrate any accuracy (Sapaga, 1990). Because of the wide variation that is seen with manual assessment, a number of hand held devices have been developed to better quantify strength variation. The most noted is the hand dynamometer, which has been shown to have a greater degree of accuracy and reliability than other instruments (Bohannan, 1986; Byl et al, 1988; Silverman et al, 1989).

(b)Isometric Strength Testing

Isometric muscle testing is the method for determining the force of a muscle contraction without a change in muscle length. There are several technical concerns in the performance of isometric tests: 1) the inertial effects at the onset of the test; 2) patient fatigue; 3) patient posture; and 4) patient motivation. The objective of the test is to identify and record the maximum voluntary contraction force that can be sustained (Chaffin et al. 1988). At this time, the tasks that can be adequately represented with isometric tests are sagitally symmetric. Normative data for both lifting tasks in different occupational classifications (Chaffin, 1975) and reciprocal trunk strength ratios (Triano and Schultz, 1987; Kibler et al, 1989) are available.

(c)Isokinetic Strength Testing

Isokinetic strength testing is used as a means of measuring the torque generated with a maximal muscle contraction with a constant velocity and arc of movement. The measure of the torque generated only has validity during the controlled part of the motion. The maximum voluntary effort will coincide with the greatest mechanical advantage of the joint for the motion that is being attempted (Baltzopoulos et al. 1989). There are two technical concerns with isokinetic measurements. They are: 1) gravitational effects; and 2) torque overshoot. These can be corrected with technical adjustments to the machine. Standard isokinetic measurements are commonly taken at increments of 30 degrees per second using 2-6 repetitions with a maximal single torque value used as the measure of performance.

(d)Isoinertial Strength Testing

While no testing method yet devised allows an assessment of free dynamic motion such as would occur at a work site or in sports, isoinertial equipment may come closer than others. Several authors have examined the ability to predict performance by controlling torque during movement (Jacobs et al. 1988, Jiang et al. 1986, Kroemer 1983, Kroemer 1985, Parnianpour et al. 1989, Stevenson et al. 1989). Isoinertial systems can be made capable of monitoring position, velocity and torque simultaneously. Normative data are available for certain occupational subgroups (Gomez et al, 1991).

C.PHYSIOLOGICAL MEASUREMENT

1.THERMOGRAPHIC RECORDINGS

(a)Thermocouple Devices

Thermocouple devices are purported to measure variations in localized paraspinal skin temperatures. These devices have been prominent in the history of the profession and are still used presently (Trott et al, 1972). This type of paraspinal measure has not been shown to have good discriminability, and both their validity and reliability of measurement are highly doubtful (Trott et al, 1972; Chang et al, 1985).

(b)Infrared Thermography

Body heat loss to the environment takes place passively by convection, conduction, and radiation. Regional body temperature is regulated by the interaction of central autonomic control mechanisms and multisegmental spinal vasomotor reflexes (Fuhrer 1975, Ruch et al. 1965). Thermography is a technique where an infrared camera is used to portray photographically the surface temperatures of the body, based on self-emanating infrared radiation. It is important to realize that thermography is not an anatomical test and is more of a physiological test of the vascularization of the skin.

Thermographic devices vary from hand-held instruments to sophisticated computer-assisted infrared imaging systems. As a diagnostic procedure, thermography is highly controversial. There are a few studies on the reliability of certain thermographic devices which show nonexistent to moderate agreement (Plaugher et al. 1991, Keating et al. 1990). There are no randomized clinical trials of treatment that used thermography as an outcome measure and therefore its clinical utility remains uncertain. A few published case reports have shown thermographic changes while under conservative treatment (Diakow 1988, Brand and Gizoni 1982). In one study which involved a meta-analysis of the procedure for lumbar spine disorders, the research data base was severely criticized (Hoffman et al. 1991).

Standardized examination protocols are being established for infrared and liquid crystal procedures (Vlasuk 1992). The main criticism of thermography is that its diagnostic specificity is unproven to the extent that, given the available evidence in the literature, it cannot replace other types of proven examination procedures.

2.GALVANIC SKIN RESPONSE (GSR)

Devices to detect differences in paraspinal regional electrical skin resistance have been employed by the chiropractic profession for many decades. Loci of lowered skin resistance were thought to be related to areas of cutaneous hyper or hyposympathetic activity which, themselves, would be due to a putative joint dysfunction. Other devices have been employed to detect punctate areas to lowered skin resistance putatively corresponding to acupuncture points. A final category of device consists of an apparatus designed to measure digital (hand) GSR, thought to reflect global levels of sympathetic nervous system activity and, by influence, general level of arousal.

These devices are subject to a high degree of intra- and inter-subject variability, which call into question their reliability. Older Class II studies are seriously in need of update and replication with modern instrumentation and more rigorous research methodology. Recent Class II studies have cast serious doubt on the reliability and validity of GSR in assessment of spinal dysfunction (Giesen et al. 1989, Nansel and Jansen 1988).

3.PLETHYSMOGRAPH

The plethysmograph quantifies the relative tissue volume of the distal extremities. It is a safe and effective when tissue volume changes and a symptom or peripheral vascular differential diagnosis is required (Ris et al. 1991). Special training is necessary and results should be interpreted by a trained health care practitioner. The role of plethysmography in monitoring spinal disorders is questionable. Figar et al. (1967) and Figar and Krausova (1965) showed improvement after manipulation in 32 of 44 previously determined abnormal finger plethysmograms of patients with radicular syndromes involving the sixth to eighth cervical segments. Vernon (1982) showed improvement in the costoclavicular neurovascular signs after a course of costal manipulations in a case study where the plethysmograph was utilized.

4.ELECTROPHYSIOLOGICAL RECORDINGS

Electromyography: (a) Static EMG and (b) Dynamic EMG

A surface measurement that monitors myoelectric volitional responses can be used to examine superficial layer muscle recruitment and fatigue. When calibrated against known exertional efforts, biomechanical estimates of muscle tensions for simple isometric tasks can be made (Bean et al. 1988). Clinical applications to the evaluation of spine-related disorders have been proposed under the heading of surface paraspinal scanning EMG (Gientempo et al. 1990) using either post-style or adhesive tape-on electrodes. With the exception of flexion-relaxation (Ahern et al. 1988, Sihoven et al. 1991, Triano et al. 1987) and spectral density parameters like mean/median frequency shifts (Bolecek et al. 1990, Emley et al. 1990, Roy et al. 1988) during isometric contraction using tape-on electrodes, clinical usefulness is limited because the discriminability of these procedures has not been fully evaluated. Myoelectric monitoring during simple postural tasks shows common patterns of behaviour but these are easily influenced by subtle changes in posture and other sources of error (Iacono 1991). Triano and Luttges (Triano et al. 1985) found that an ensemble of flexion and postural tasks might discriminate healthy subjects from unhealthy patients, whereas single postures alone were insufficient. Lumbar disc and nonspecific backache tend to have overall higher electrical activity but are confounded by a high sensitivity to positional variation (Arena et al. 1989).

Comparison of right/left myoelectric amplitudes during static postures remains to be validated as being discriminable. Acute spinal symptoms may be associated with alterations in muscular tone (e.g., hypotonus, hypertonus, spasm). However, the meaning of measurements associated with them is uncertain and does not contribute significantly to therapeutic decision making (Deyo 1990). It has not yet been established whether changes in paraspinal muscle tone can be found in patients with chronic back pain.

A.PERCEPTUAL MEASUREMENTS

1.Questionnaires:

6.1Patient questionnaires which have been shown to be reliable and valid are effective methods of assessment.

Rating: Established
Evidence: Class I
Consensus level: 1

2.Pressure Algometry:

6.2Pressure algometry is a reliable and safe method of quantifying the patient's perception of pain.

Rating: Established
Evidence: Class I, II, III
Consensus level: 1

B.FUNCTIONAL MEASUREMENTS

1.Posture/Clinical Anthropometry

6.3(a)Plumbline Analysis is a safe observational measure of static vertically oriented body alignment.

Rating: Promising
Evidence: Class III
Consensus level: 1

6.4(b)Scoliometry may be a useful physical measure to quantify scoliotic variation.

Rating: Established
Evidence: Class I, II, III
Consensus level: 2

6.5(c)Moire Topography is a means of quantifying postural deformity.

Rating: Equivocal
Evidence: Class II, III
Consensus level: 1

6.6(d)Bilateral weight scales may be used as a means of measuring weight bearing asymmetry.

Rating: Equivocal
Evidence: Class II, III
Consensus level: 1

(e)Automated measures of posture

6.7(i)Computer digitizers may be used for postural evaluation. Its degree of usefulness is undetermined due to operational and technical limitations.

Rating: Equivocal
Evidence: Class II, III
Consensus level: 1

6.8(ii)Stabilometry is a reliable and valid tool for measuring postural sway.

Rating: Established
Evidence: Class I, II
Consensus level: 1

6.9(iii)Photogrammetry methods is a valid and reliable means of assessing those postures assumed by persons engaging in specific dynamic tasks.

Rating: Established
Evidence: Class I, II, III
Consensus level: 1

2.Measurement of movement

(a)Inclinometers are valid and reliable instruments for measuring spinal motion.

Rating: Established
Evidence: Class I, II, III
Consensus level: 1

6.11(b)Goniometers are considered valid and reliable instruments for measuring joint range of motion.

Rating: Established
Evidence: Class I, II, III
Consensus level: 1

6.12(c)Optically-based systems are valid and reliable methods for evaluating specific gait abnormalities and a wide variety of skeletal movements.

Rating: Established
Evidence: Class I, II, III
Consensus level: 1

3.Measurement of strength

6.13(a)Hand-held dynamometers are effective instruments to measure grip strength where differences of 35% or greater exist.

Rating: Established
Evidence: Class I, II, III
Consensus level: 1

6.14(b)Isometric strength testing instruments are valid and reliable methods of determining the force of muscle contraction without change in muscle length.

Rating: Established
Evidence: Class I, II, III
Consensus level: 1

6.15(c)Isokinetic strength testing instruments are used as a means of measuring the torque generated with a maximal muscle contraction with a constant velocity and arc of movement.

(a)(i)For use in sports injury assessment and rehabilitation

Rating: Established
Evidence: Class II, III
Consensus level: 1

(b)(ii)For use in spinal assessment and rehabilitation

Rating: Promising
Evidence: Class II, III
Consensus level: 1

6.16(d)Isoinertial strength testing instruments may be used to measure muscle strength in correlation with coupled anatomical motion, velocity and torque generated.

Rating: Promising
Evidence: Class II, III
Consensus level: 1

C.Physiological measurements

1.Thermographic Recordings

6.17(a)Thermocouple devices are safe, but there is no evidence to support a claim of effectiveness.

Rating: Doubtful
Evidence: Class II, III
Consensus level: 1

6.18(b)Infrared thermography may be used to determine variations of body surface temperatures.

Rating: Equivocal to Promising
Evidence: Class II, III
Consensus level: 1

6.192.Galvanic skin response is not considered to be useful as a measure of spinal dysfunction due to the lack of reliability and validity.

Rating: Doubtful
Evidence: Class II, III
Consensus level: 1

6.203.Plethysmograph are safe and effective measures of tissue vascularity.

(i)for the purpose of peripheral vascular differential diagnosis.

Rating: Established
Evidence: Class I, II, III
Consensus level: 1

(b)(i)for the purpose of monitoring spinal disorders.

Rating: Equivocal
Evidence: Class II, III
Consensus level: 1

4.Electrophysiological recordings

6.21(a)Static EMG (surface scanning) is a surface application of myoelectric sensors that is used to measure myoelectric volitional responses in a static state.

Rating: Investigational
Evidence: Class II, III
Consensus level: 1

6.22(b)Dynamic EMGs, such as flexion relaxation and mean/median frequency shift measures, are surface applications of myoelectric sensors used to measure myoelectric volitional responses during muscles contraction.

Rating: Promising
Evidence: Class II, III
Consensus level: 1

Measurement instruments used in chiropractic practice are important not only in the initial assessment of the patient but also in the ongoing evaluation of their response to a particular intervention. The instrument used, therefore, must be applicable, appropriate, reliable, and valid. This means that the clinician utilizing a particular instrument must clearly understand its intended use, properties and the limitations.

This chapter attempts to outline the instruments available to the practitioner and to rate them according to the results of studies reported in the scientific literature. It is expected that some of the aforementioned recommendations may in fact change as a result of ongoing research.

In order for the interpretation of changes in a subject's test results to be meaningful, the reliability and validity of the procedures must be high. The test should be relevant to the individual's activities that have been impaired, to normative data, or both, and should be able to discriminate healthy and unhealthy people. Careful attention to standardized test protocols is essential if replication of meaningful results is to occur.

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