PainJournal.net

     Clinical Journal of Pain for

Healthcare Professionals and Patients

Back Pain Assessment with Non-radiographic Methods.

 G.E. Sella, M.D., M.P.H., M.Sc., Ph.D., DAAPM

Back pain is a major symptomatic complaint in the U.S. society, especially in the industrial realm. The annual costs associated with the diagnosis and treatment of acute and especially chronic back pain are by far the largest of all societal costs in the pain field.^1,2  The figures cited more often  are in excess of $80 billion/ year.  Radiologic techniques of back pain assessment comprise a large segment of the diagnostic costs, since CT scans and MRIs are still very expensive procedures. Often, the results of radiologic testing are negative or very non-specific, except in overt cases of fractures, osteophytes with radicular encroachment or acute disc disease.  Most back pain symptoms are associated with soft tissue injury or dysfunctions. Radiologic testing is hardly ever positive or useful in these conditions. Yet, this self-evident truth is hardly ever cited by the radiologists within the context of interpretation of “negative results”. Within the medico-legal realm, physicians feel pressured to order unnecessary back x-rays in cases of back pain in order not to have to face the question “Have you taken an x-ray, doctor?” on the stand, in front of a jury, even if one knows that there is no diagnostic or treatment value for such a procedure.

  The physician dealing with back pain has to perform a careful and detailed physical examination, which includes the musculo-skeletal and neuro-muscular systems.³  The results of the examination may show ‘spasm or rigidity’ of the affected muscles of the back.⁴   They may show sudomotor changes, ‘hot or cold’ as well as differential temperature changes, well localized.⁵ The results may show tender points or trigger points with expected radiation patterns.⁵More rarely, the results may indicate radiculopathy or neuropathy, involving motor, proprioceptive or sensory patterns corresponding to the nerve or radicular level of the injury.⁶

 What other choices do physicians have to evaluate back pain, especially low back pain, in addition to a careful and accurate physical examination? If the pain is attributed to muscular dysfunction, the clinician may add to his/ her armamentarium a gait/ static posture method and two muscular electrophysiological testing methods.^2,7 One interesting fact is that the static posture testing and the muscular testing may be performed simultaneously.

 The static posture method consists of weighing the back pain patient on two identical scales simultaneously four times and then averaging the results obtained from the body-weight placement on each foot. The method has been fully documented in the peer reviewed literature.⁷

  A summary of the results shows the following:

(a) normal, asymptomatic individuals of any body weight place the weight down on each foot within 10%, i.e. 46-54% of the total weight on either foot; when the study was extended to groups in excess of 150 individuals, it was found that the weight placement is 50-50% for any group of any BMI, gender or age group. 

(b) symptomatic individuals place the body weight on the two scales in excess of 10% difference. The statistics show that the difference is >10< 15%. Symptomatic individuals place more weight on the asymptomatic lower limb and less weight on the symptomatic side. This follows the expectation that the asymptomatic lower limb is ‘protectively guarding’ the symptomatic limb. While this fulfils the kinesiological expectation in the acute phase, it may become a chronic, dysfunctional pattern in individuals who are not investigated or rehabilitated adequately in a timely manner.

(c) What about the individuals suspected of symptom simulation, magnification or functional overlay? These individuals place >15-30% of the body weight on the alleged symptomatic lower limb. Placing more weight, and in such a proportion ‘on the wrong foot’, is of course non-physiological and requires further investigations.

 While the double-weighing method has been proven useful in identifying the categories of static gait described above, it is limited in terms of identifying the internal consistency of test performance, especially with regards to identifying the muscular tonus pattern in the lower limb or the para-vertebral area of the individuals with lower limb or back pain.

 The second methodology, surface EMG (SEMG), is the tool of choice in that context.⁸

SEMG is an electro-physiological modality. It is used to assess  skeletal muscular electric behavior in the frequency domain or in the amplitude domain.⁹ The former is a useful technique in terms of identifying and objectivizing the perception of fatigue.

There is a strong, time-related association between the individual perception of muscular fatigue and the decrement of the frequency of action potential discharge (Hz) in the affected muscles.

The latter, the amplitude domain, assesses the amplitude of contraction (summation of multiple units action potentials, µV RMS) of a skeletal muscle during rest or activity.⁹

The technique is fully amenable to statistical treatment and clinical interpretation. It allows for the identification of normal versus pathological (dysfunctional) patterns of muscular behavior, during rest or any given motion.¹⁰

 Dysfunctional muscular behavior can be identified with SEMG in the presence of pain, loss of strength, contra-lateral imbalance or disequilibrium, symptoms of abnormal and sustained contraction (spasm, hypertonus, hypotonus), co-activation & co-contraction, myokimia or fasciculation as well as contracture.⁶

Protocols of dynamic SEMG testing have been devised, tested on all the joints and regions of the body and published.¹⁰

The overall results indicated that SEMG is a reliable, repeatable and valid methodology, with a good level of specificity and sensitivity.^11,12

 Furthermore, it allows for the identification of the internal consistency of motion/rest of a given muscle in the statistical terms of coefficient of variation (C.V). In statistical terms, it is acceptable that a C.V.< 10% is compatible with a good level of internal consistency of any given task or test. A C.V. >10% and especially >15% is considered compatible with a poor level of internal consistency and the task or test performance is considered unreliable or inaccurate.

It is this factor of consistency that allows the SEMG technique to be applicable in conjunction with other soft-tissue injury & pain investigative methods. These may include dynamometry, inclinometry, algometry and the static gait/ posture two-scale method described above.¹⁹

 Only the SEMG method can provide through repetition of testing the documentation that multiple bilateral muscular effort may be consistent or not, differential factor in diagnosis and clinical as well as forensic interpretation. If such SEMG testing is done in conjunction with the tasks inherent in the other methodologies cited, it can provide the co-validation necessary for the correct interpretation of the results of the tests of the different methods described above.

There are two types of SEMG protocols, static and dynamic.^10,18

The static protocol in its present form requires that the testing be conducted on the paravertebral muscles in sequence from the cervical to the sacral region. This implies that the testing is sequential rather than simultaneous and it is limited by the presence of the human postural sway over time.

To circumvent to a possible extent this limitation, the author has devised a protocol that requires that the static testing be repeated at least five times in sequence over the paravertebral area.¹⁰ Statistics are construed to document the average (avg), standard deviation (S.D.) and C.V. of each paraspinal muscle level on each side.

As such, one can document the maintenance of a static posture through a number of tests or changing potential amplitudes values in time, compatible with postural shift, even if the muscular contraction amplitudes are above normal values.

Furthermore, one can compare the right and the left paravertebral sides through the five repetitions and as overall averages. Thus, SEMG static protocol may allow for paravertebral muscular testing with interpretation of results in terms of overall amplitudes of paraspinal muscular tonus, right-left balance/ imbalance and patterns of muscular dysfunction or pathology compatible with postural protective guarding.

Dynamic SEMG testing protocols have been construed to test a joint or region through the primary ROM, or test within the neuro-muscular diagnostic framework.^10,13

In the context of back pain, one may test with SEMG four pairs of pertinent back muscles through the ROM segments which include lumbar flexion, extension, bending and rotation and functional movements such as squatting.¹⁰

  The results may be interpreted within the context of several parameters:

a.  normalcy of  amplitude potentials through rest or activity (comparisons with the results on asymptomatic muscles in the data-base),

b.  bilateral comparisons involving questions of laterality & equilibrium,

c.  regression analysis of the different muscles and segments of motion ( agonism-antagonism relationships comparison of symptomatic muscles to the results of non-symptomatic muscles in the data-base),

d.  presence of abnormal electric potential tonus phenomena such as spasm, hypertonus, hypotonus, fasciculations, co-contractions or co-activation, lack of mirror image in lateral motions such as bending or rotation, etc,

e.  comparisons of the resting electric tonus values with those observed in the static SEMG testing.

 While high electric amplitude potentials of the paraspinal muscles may be noted with static SEMG testing, one may not be able to differentiate those in terms of (electric) spasm, hypertonus or hypotonus. Only dynamic SEMG testing allows for such differential diagnosis.

Pain related secondary loss of strength of the back muscles, especially within the unilateral context can be demonstrated with dynamic SEMG, since weak muscles need to utilize more contractile elements through the ROM segments.⁶

 This differential utilization of energy is evidenced by elevated curves of amplitude through the motion pattern of the painful, weak muscles.

 The description given above on the SEMG static and dynamic testing within the context of back pain is only summary. For more detailed documentation, the reader is referred to specialized texts.

 How can a back pain investigator utilize the three methodologies described within the clinical and forensic aspects of back pain evaluation?

The following general protocol is indicated as follows:

1) Proceed with a thorough physical examination including accurate anthropometric measurements such as the cervical, thoracic and lumbo-sacral ROM, BMI, body composition analysis, circumferences of joints & regions, pertinent dynamometry and pain pattern evaluation, etc. ^2,14,15,17

2) Proceed with the double scale weighing, as per protocol.⁷

3) Proceed with paraspinal static SEMG testing as per protocol.¹⁰

4) Proceed with dynamic SEMG testing of the paraspinal muscles at the levels L1, L5 and other lumbar or back muscles (e.g. quadratus lumborum) as pertinent to the case.¹⁰

 The dynamic SEMG testing statistical output and interpretation allows for the differential diagnosis involving the internal consistency of the test and individual’s overall consistent or inconsistent behavior within the context of ‘back pain’ symptomatology.

The dynamic test may show results compatible with muscular pain phenomena, e.g. electrical spasm, secondarily expressed as loss of motion (functional, related to spasm, hyper- or hypotonus) or loss of strength (increased amplitudes of contraction). Only the dynamic SEMG testing can show the paraspinal muscles electrical amplitudes during motion or rest, while the static SEMG testing shows the resting tonus only.⁶

 The static SEMG testing shows the pattern of paraspinal resting electrical tonus in the standing (or other static positions) from the cervical to the sacral region. As described above, the protocol may help to differentiate right-left differences at any particular vertebral level or as an average of the vertebral column electrical potential tonus as a whole.

This is important in the diagnostic process since it places into evidence the phenomenon of protective guarding, usually seen in the form of increased electrical tonus of the ‘protecting’ side and normal or decreased tonus of the ‘protected’ side.^6,16

It may be observed with SEMG static protocols that the presence of pain in one vertebral region is associated with increased tonus in the affected muscles and more commonly with increase tonus of the contralateral muscles. This high tonus is then spread throughout the column in a zig-zag pattern, compatible kinesiologically with the need to maintain postural equilibrium.¹⁷

The static SEMG testing may show a similar pattern of results through five repetitions of the test, thus demonstrating the consistency of the symptoms and performance.¹⁵

 The example shown below is that of four cases, all patients with low back or other trunk regions pain, all results of MVA or other injuries.

It is meant to be illustrative only of the utilization of the three techniques described above and not as a generalization of the hypothesis, in view of the small numbers described.

All the cases shown have a right-left disequilibrium pattern of paraspinal muscles electrical tonus as shown on the static SEMG, compatible with the clinical presentation of higher level back pain on the right side. As expected , the left paraspinal side shows a higher electric tonus pattern, compatible with protective guarding of the right side.

The dynamic SEMG testing of the various muscles show  abnormal electrical patterns of contraction, uniformly in contralateral disequilibrium and compatible with pain and loss of strength on the right side. (The results of the dynamic testing are not shown on the table for reasons of space. They will be shown in a subsequent article.)

The double scale weighing method showed uniformly a difference of >10% in the average lower limb placement, compatible with the increased effort to ‘protectively guard’ the more symptomatic right side of the back.

 Conclusions

The discussion above illustrated the principles of utilization of three methodologies in the realm of investigation of muscular related back pain.

The three methods are rather autonomous from one another.

The double weighing method utilizes mechanical (or electronic) scales.

The static SEMG method investigates the vertebral column paraspinal muscles electrical activity potentials pattern in the standing or other static positions.

The dynamic SEMG method involves testing the back muscles through the pertinent ROM, activity and resting patterns.

When utilized in the context of back pain assessment, the three methods complement one another and strengthen one another in the clinical and diagnostic context. This observation is illustrated more fully in the clinical and investigative context of the case studies presented.

Return to Articles 

REFERENCES

 1      Sella, G.E., “Back Pain: The Most Common Musculo-Skeletal Pain Syndrome.”, 2002, D. Moss, E.D., Handbook of Mind-Body Medicine for Primary Care, Plenum Publ., in publication.

 2     Sella, G.E., “Neuro-Orthopedic Impairment Rating.”, 2001, R.S. Weiner, Editor, Pain Management: A Practical Guide For Clinicians, 6^th Edition, Section VII, Ch. 44, pgs. 549-562.

 3     Sella, G.E., “Objective Assessment of Soft Tissue Injury.” In: Functional Disorders: Physical Medicine & Rehabilitation, State of the Art Reviews, N.D. Zasler & M.F. Martelli, Eds., Vol. 16, No. 1, pgs. 77-94, Hanley & Belfus, Inc., Philadelphia, Feb. 2002.

 4     AMA Guides to the Evaluation of Permanent Impairment.”, 4^th Ed., 1993, American Medical Association, Chicago.

 5    Sella, G.E.& Finn R.E., Myofascial Pain Syndrome: Manual Trigger Point & SEMG Biofeedback Therapy Methods. Textbook, 2002, Martins Ferry, OH, GENMED Publishing.

 6    Sella, G.E., Neuromuscular Testing with Surface EMG. Textbook, 3^rd Ed., Revised, Vol. I& II, 2002, Martins Ferry, OH, GENMED Publishing.

 7   Sella, G.E., “How Much Do They Weigh? Bilateral Comparisons of Weight Placement Among Symptomatic, Asymptomatic Individuals and Symptom Magnifiers.” Disability: The International Journal of the American Academy of Disability Evaluating Physicians, Vol. 5, No. 2, pgs. 15-25, May 1996.

 8   Sella, G. E., “Considerations on Symptom Magnification and Malingering.” Forensic Examiner, The Official Journal of the American College of Forensic Examiners, Vol. 6, No. 1 & 2, Independent Medical Examiner Column, Jan/Feb 1997.

 9     Basmajian, J.V. & DeLuca, C.J., Muscles Alive, There Function Revealed By Electromyography. 5^th Ed., Williams & Wilkins, Baltimore, 1985.

 10   Sella, G.E., Muscles in Motion: Surface EMG Analysis of the Human Body Range of Motion. Textbook, 3^rd Ed., Revised, Vol. I& II, 2002, Martins Ferry, OH, GENMED Publishing.

 11    Sella, G.E., “Internal Consistency, Reproducibility & Reliability of SEMG Testing.”,  Europa Medico-Physica, Vol. 36, No. 1, pgs. 31-38, Mar. 2000

12    Sella, G.E., “Surface Electromyography Testing: Sensitivity, Specificity, Positive & Negative Predictive Values.”, Europa Medico-Physica, Vol. 36, No. 4, pgs. 183-190, Dec. 2000

 13   Gerhardt, J.J. & Sella, G.E., Inclinometry SEMG & Hand Dynamometry in Clinical  & Disability Medicine. Textbook, 2001, Martins Ferry, OH, GENMED Publishing.

 14    Sella, G. E., “Evaluation of Soft Tissue Injuries.” Disability Analysis in Practice, 2^nd Edition, Handbook: American Board of Disability Analysts, Ch. 15, pgs. 279-314, 1998. Kendall/ Hunt Publishing, Co. Dubuque, Iowa.

 15   Sella, G. E., “SEMG Utilization in the Evaluation of Soft Tissue Injury.” Forensic Examiner, The Official Journal of the American College of Forensic Examiners, Vol. 6, No. 5 & 6, Independent Medical Examiner Column, pgs. 36-37, May/June 1997.

 16    Sella, G.E., “SEMG Utilization in Low Back Pain Investigation & Rehabilitation.”, Kinesitherapie Scientifique, pg. 35, No. 383, Paris, France, Nov. 1998.

 17     Mense, S. & Simons, D.G., Muscle Pain: Understanding Its Nature, Diagnosis & Treatment., Lippincott, Williams & Wilkins, Philadelphia 2001.

 18     Kasman, G.S., Cram, J.R. & Wolf, S.L., Clinical Applications in Surface Electromyography: Chronic Musculo-Skeletal Pain. Aspen Publishers, Inc. Baltimore, MD 1998

 19     Sella, G.E. & Donaldson, C.C.S., Soft Tissue Injury Evaluation: Forensic Criteria. A Practical Manual, 1996, Myosymmetries & GENMED Publishing, Martins Ferry, OH.

Send mail to neuroone@aol.com with questions or comments about this web site.
Copyright © 2001 Preferred Provider Care
Last modified: 11/21/02