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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

Playing Dual Roles

Gabriel E. Sella, MD, discusses sEMG as the perfect tool for neuromuscular investigation and re-education.

The Expert Series is an on-going series of interviews with leading clinicians in the field of biofeedback lending their insights and techniques they have acquired through their many years of practice.

Gabriel E. Sella, MD, a specialist in family practice and occupational medicine, is the interviewee for the second installment of this series. Dr. Sella has lectured internationally in 15 countries on the subject of soft tissue injury, disability evaluation, sEMG, and biofeedback application in the fields of physical medicine and physiatry. He has six fellowships, three board certifications, and has conducted extensive research on the subject of the sEMG applications for the study of the range of motion. Dr. Sella has published seven textbooks, Muscles in Motion: Surface EMG Analysis of the Human Body Range of Motion; Neuro-muscular Testing with S-EMG; Muscular Dynamics: Electromyography Assessment of Energy and Motion; Graphics of Motion: The Electromyography of Muscular Dynamics; Soft Tissue Injury Evaluation: Forensic Criteria: A Practical Manual; Guidelines for Neuromuscular Re-education with S-EMG /Biofeedback; and S-EMG Muscular Assessment Reference Manual. He has several peer-reviewed publications and more than 80 international meeting presentations on subjects related to sEMG.

Q: Why is bilateral sEMG amplitude important for sEMG investigation and neuromuscular re-education (biofeedback)?

A: sEMG is the only electrophysiological modality that has a dual role and may use two parameters of activity simultaneously. Furthermore, it can be used both in the realm of objective investigation and as an objective outcome treatment measure. The amplitude parameter (microvolt RMS) is a measure of muscular activity electrical effort and to some extent of force. Bilateral measurements of homologous contra-lateral muscles are necessary in order to compare the activity of any given muscle with its counterpart. In any given condition, there should be normally a difference of <25 percent between contra-lateral muscles. A larger difference may have ergonomic or clinical value. Even if the database for most skeletal muscles activity with minimal intent will be shortly available from my work, for any given individual, the amplitude values of the asymptomatic side may represent the better control value as compared to large group values.

Most functional or myotatic units are composed generally of four or more muscles. Thus, bilateral simultaneous sEMG comparisons of four bilateral muscles may allow for a good and functional comparison. Furthermore, I have shown that it may also be indicative of the true effort or consistency of activity over several muscles. This is very important in rehabilitation medicine when it is relevant to focus on a specific muscle that needs to be re-trained. It is paramount in disability medicine when it is relevant to focus on the question of symptom magnification or malingering.

Neuromuscular re-education or sEMG biofeedback needs to have objective documentation in the present era of outcome measurement requirements. Fortunately, sEMG biofeedback can provide such documentation if the rehabilitative treatment is done according to specific and standardized type protocols. Bilateral assessment before the treatment allows for more specific functional diagnoses. The same assessment during and after the treatment period allows for an objective determination of the course of treatment and results within the clinical context of improvement and healing.

Q: Why is it important to assess and train several channels simultaneously?

A: In terms of the assessment protocols, the statistical data of coefficients of variation (CV <10 percent) will be a good determinant of the internal consistency of activity of any given muscle. In assessing simultaneously eight muscles, a CV > 10 percent (or >15 percent) will stand out as inconsistent. If it is found on a symptomatic muscle while it is not found on the seven asymptomatic muscles, it may fit within the clinical picture of abnormal. Furthermore, it will give credence to the fact that the patient or evaluee is not trying to symptom magnify since that is not quite possible to be consistent in motion on seven muscles while being inconsistent on one. The statistical parameter of correlation coefficient (c.c., p) is a good indicator of the reproducibility of any test or study. Thus, results that show good consistency will show also a c.c. > 75 percent (.75). The same reasoning of consistency described above applies. If an outlier is found and is clinically consistent with muscular symptomatology, then, sEMG can be shown to provide more objective evidence to the subjective complaints or clinical findings.

In terms of sEMG biofeedback training, the parameters above allow for the final step of the treatment outcome measurements. Obviously, the clinical results of lack of symptoms are the real outcome. However, from the point of view of objective demonstration, internal consistency of motion of CV <10 percent of the affected muscle and of c.c.>.75 of correlation of activity with the homologous contra-lateral muscle is powerful objective proof of the accuracy of the sEMG biofeedback treatment modality.

Q: What do you mean by describing your approach as clinically objective?

A: My protocols (The Sella protocols) have been described in several books, articles, and presentations. A clinician today needs objective documentation of both the diagnostic and treatment results. In terms of muscles, they can be assessed as subgroups of myotatic units, as subgroups of neuro-innervation or as bilateral homologous contra-lateral data. sEMG allows the development of protocols that corresponds with all of the above. Whether testing is done by myotatic units engaging one or more joints or by neuromuscular innervation that may affect several joints, bilateral testing can be done through the relevant range of motion (ROM) and intervening resting periods. The protocols basically stipulate the repetition times five of any given segment of ROM activity for nine seconds interspersed with nine seconds of rest intervals. The five repetitions allow for more accurate statistical data gathering and for determination of internal consistency and reproducibility along the eight muscles tested. Since the ROM is classically accepted, since the primary movers are classically known and since the neuromuscular innervation is universally accepted, the Sella protocols of sEMG testing are based on clearly accepted data.

These protocols aim for overall standardization of the sEMG procedure, like the standardization that occurred in the 1920s for the EKG procedure. I have published the database on 6,700 individual muscles tested, representing about 173 skeletal muscles investigated through 22 protocols. This database allows any clinician or investigator to compare individual findings on any given patient/evaluee with those of the database.

sEMG can measure a number of muscular electrical activity parameters and by extension, abnormal states of the same parameters.

In terms of the neuromuscular re-education procedure, the same protocols can be applied before, during, or after the treatment to document the results. Since they are objectively described and standardized, they can be repeated and reproduced by any other investigator or clinician.

Q: This sounds like sEMG biofeedback could be useful for a variety of conditions — is that true?

A: Muscle is muscle. It moves or it rests and produces no given movement to the joint or joints that it helps through motion. It can be active as a result of motor stimulation and produce measurable motion and it can also be active without producing motion via ANS stimulation, i.e. states of emotional tension.

sEMG can measure a number of muscular electrical activity parameters and by extension, abnormal states of the same parameters.

Thus, if it is known that a muscle should fatigue symptomatically within a given number of minutes and the median frequency decrements specifically within that period of time, an earlier decrement of the median frequency will indicate clinical pathology. The investigator will have to rule out further the specifics of the pathology, be it of neural, muscular, metabolic, nutritional, endocrine, toxic, or other origins.

In terms of muscular electrical evidence of amplitude dysfunction demonstrated of sEMG, we have shown the appearance of parameters such as electrical spasm, hypertonus, hypotonus, myokimia, fasciculations, etc. during activity or rest. The clinical framework may explain the appearance of those pathological parameters. They have not been shown to exist outside the symptomatologic framework.

Neuromuscular re-education, successful treatment, or improvement in the ergonomic conditions have brought about normalization of the electrical muscular activity and disappearance of the pathological phenomena.

Q: What has limited the application of sEMG biofeedback to these disorders in the past?

A: There were historically a number of problems. These can be divided into several categories and, of course, into overlaps of these categories.

Equipment: A number of manufacturers chose to produce equipment that could be utilized with ease, at affordable prices and gave reproducible results. These manufacturers were far reaching and are bound to survive the competitive market.

Software: Since most clinicians are not computer wizards, software which is accurate, simple to use and affordable is preferable for survival of the technology. Within this context, there is clear need to have software which encompasses a number of protocols such as ones I've written, which can be utilized immediately without any need to re-invent the wheel and/or spending a lot of precious time during working hours to create or modify. Those who produced software that was less than user-friendly found that the market was not interested.

Teaching: Any utilizer of sEMG assessment or treatment protocols needs to have a good background in neuromuscular anatomy, physiology, and kinesiology. Utilizers come from different backgrounds and some do not understand the clear need for knowledge of muscles, muscle activity, and states of tension to the applicability of sEMG. Only when these parameters come together in terms of harmony of knowledge and proper application of this electrophysiological modality that sEMG biofeedback can show its strength and true applicability.

Last updated on: December 22, 2011
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