SPECIAL ISSUE. Static Surface Electromyography and Neuromuscular Reeducation. Gabriel E. Sella, MD, MPH, MSc, PhD (HC), BCB

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1 Biofeedback Volume 38, Issue 2, pp SPECIAL ISSUE Static Surface Electromyography and Neuromuscular Reeducation Gabriel E. Sella, MD, MPH, MSc, PhD (HC), BCB Martins Ferry, OH Keywords: static surface electromyography, postural sway, splinting, guarding, laterality EAssociation for Applied Psychophysiology & Biofeedback 64 Static surface electromyography can provide an objective test of the cervical, thoracic, and lumbar posterior areas that needs to be performed within a clear clinical or ergonomic context. It is of great help in postural assessment in the standing position in people with healthy backs or postural dysfunctions. The author has devised a protocol that allows statistically based treatment and more valid clinical interpretation. Most often, static surface electromyography is a necessary precursor to dynamic surface electromyography of any area of clinical concern. When appropriate, neuromuscular reeducation with surface electromyography biofeedback can be performed to improve resting tonus dysfunctions observed on the static surface electromyography testing. Definition of Static Surface Electromyography Static surface electromyography (SEMG) is a widely used, physiologically based investigative procedure. It aims to assess the electric potentials of the paraspinal muscles from the cervical to the sacral area while the client is not consciously moving. The procedure is performed most often in the standing position. It also may be executed in the sitting position or in the prone position (Cram & Holtz, 1998). Static SEMG: The Classic Procedure and the Sella Protocol The Classic Procedure In the following procedure, the client is standing on a firm floor, at ease with the shoes off. The examiner first wipes thoroughly with alcohol pads the paraspinal area from the neck down to the sacral area. The client with long hair may have to wear a shower cap, such that the hair will not interfere with the testing. Then, the examiner marks bilaterally the intervertebral spaces (with water markers) where the electrodes are to be placed. Next, the examiner places the static surface electrodes bilaterally in the vertical line of muscular action starting from the highest feasible cervical paraspinal area and, segment by segment, going down to the first sacral area (Cram & Holtz, 1998; Sella, 2001a). Should the participant inadvertently move, sneeze, or cough, the testing will need to be repeated. This is the classic procedure, and it is still followed by a number of practitioners. In the Sella protocol, described later in this article, the measurements need to be repeated in sequence in the same position five times. Commonly used SEMG computer programs produce graphics and numerical values of the action potentials, commonly in microvolts (mv) root mean squared (RMS), of the paraspinal muscles tested. Strengths and Limitations of the Technique Static SEMG is a useful initial SEMG test of the paraspinal muscles. It is followed usually by dynamic testing, and it gives the examiner a good general idea of the findings to come. A number of parameters of static function and dysfunction can be unveiled with this test. The test is rather rapid in the hands of an experienced examiner, even if repeated five times, according to my protocol. The results are handy and can be treated statistically. The test in the classic format has several limitations: 1. Although it assesses the contralateral paraspinal muscles simultaneously, the classic technique does not allow for simultaneous testing of all the paraspinal levels. Thus, the time sequence is a limitation because muscles can contract or relax differently during the time span of the test. Even with experience, the test takes 2 to 4 minutes, depending on the speed of the computer program and the collaboration of the client. 2. The test is called static, but in reality it is dynamic as a function of the time factor. Apparently there are technical developments of meshes with electrodes that may assess simultaneously several levels of muscles. Until the test can be performed bilaterally and simultaneously on all the paraspinal muscles cited,

2 Sella the sequential nature will be a limitation to the static interpretation component of the test. 3. The test cannot be performed validly on very obese individuals whose subcutaneous adipose layer exceeds 15 mm. It is unlikely that SEMG electrodes can validly assess paraspinal muscular activity at a depth of.15 mm from the skin, considering the high electrical resistance of fat tissue. Static SEMG, like any other objective test, should be performed in the health field only within a clinical or ergonomic (including research) context and after the clinician performs a thorough physical examination. The exam needs to include especially neuromotor and musculo-skeletal testing of the axial and appendicular skeletons (Sella, 2002a, 2002b). The testing may also include objective procedures such as simultaneous weighing of the person as he or she stands with each foot on a separate identical scale in order to determine the bilateral postural positioning of the trunk on the lower limbs (Sella, 1996). The Issue of Postural Sway What is postural sway? It is a natural, minimal motion of the standing person. Although the motion is mainly lateral and is similar on the right and left sides of the body, it also may be found in anterior-posterior and diagonal dimensions. The bipedal body in the standing position needs to sway slightly in order not to let positional or even ballistic muscles fatigue (Sella, 2002b). Most often the sway is more clearly visible with special video cameras than with the naked eye. The dynamic extension of the postural sway is that of the upper limb swing during walking. The right upper limb tends to move in tandem with the left lower limb and vice versa. This is an evolutionary phenomenon related to the similar quadruped walking motion of the primate ancestors (Sella, 2006). The postural sway is not constant in frequency or amplitude. Thus, it is expected that if static EMG testing is performed in a repeated fashion, the paraspinal muscles potential amplitude activity would be slightly different, in relation to the swing phase of the postural sway. The expectation in asymptomatic individuals is that the paraspinal muscular activity should vary within normal (i.e., according to the Sella database) restingstanding postural limits. The database is reported in Sella (2001b). A number of spinal muscular and other dysfunctions may affect the performance of the postural sway. The Issues of Acute Splinting and Chronic Protective Guarding Splinting represents the acute phase of a muscular injury. Whether its location is a limb or part of the neck and trunk, a reflex-like action protects the injured body part from motion. Thus, the anatomic part in question is kept away from voluntary motion as much as possible. More often than not, the contralateral muscles become very active to counter the splinting effect of the injured part. This is called protective guarding. Whereas in the case of an injured limb the contralateral limb takes over most movements and actions formerly expected of the splinted limb, the same cannot be said for the axial muscles. Dynamic SEMG testing of paraspinal muscles that includes acutely injured ones will find the muscles in acute pain to be in spasm (i.e., to show variable amplitudes of electric potentials that do not differ between the resting and the active phase of the dynamic testing). The contralateral muscles are usually found to act normally or may show hyperactivity (i.e., normal resting values of amplitude potentials in the presence of active potentials of high amplitude). Static EMG testing presents an interesting picture of splinting. The splinted area shows spasm, whereas the aspect of the whole paraspinal area of the neck and trunk often shows a zigzag formation, as if the whole trunk is trying to protectively guard the injured component. If splinting is not resolved in a timely fashion by treating the muscular injury early, a condition of chronic protective guarding may ensue. This guarding, splinting, and zigzag pattern of paraspinal muscle activity can become habitual. The individual affected may not be completely aware of its presence, save for some pain and early muscular fatigue. The Issue of Laterality and Expectations of Right/Left Torso Muscles Tonus Differences The Sella database shows that normal contralateral, homologous paraspinal and other muscles differ in amplitude of contraction, whether in the resting or the active state, within 20% or less of one another (Sella, 2000b, 2001b). In unilateral or bilateral dysfunction, the contralateral differences may vary up to 50% between left and right. During static SEMG assessment of the paraspinal muscles, in standing or other positions, action potential values exceeding the average minimal resting value 6 a confidence interval of 20% could be considered abnormal (Sella, 2000b, 2001b). Those differences, whether in the asymptomatic or symptomatic case, show equally well in dynamic and in static SEMG testing. Postural sway in asymptomatic individuals does not affect the resting action Biofeedback Summer

3 Static SEMG and Neuromuscular Reeducation 66 potentials of the paraspinal muscles over time. This is better observed when the testing with static SEMG testing is performed over five or more sequential repetitions. The Issue of Disk Herniation If a cervical, thoracic, or lumbosacral disk is herniated bilaterally, there may be bilateral pain and dysfunction related to the proximal root nerves suffering and their effect on the adjacent paravertebral muscles. Unilateral disk herniation at any of these levels may affect the pertinent homolateral paravertebral muscles with expected elevation of the action potential amplitudes, as seen on static or dynamic SEMG (Sella, 2002a, 2006). Herniation at the cervical level also may affect the brachial plexus and the upper limbs, but that will not be noted on a static SEMG assessment. Herniation at the lumbosacral level may also affect the lumbosacral plexus and the lower limbs, but that will not be noted on the static SEMG. In the case of disk herniation at any level, repeated static SEMG will not show great differences in action potential amplitudes among repeated trials of testing. The muscular dysfunction is found to be on a structural basis, and the effects should not differ much within the time frame of the examination. The Issue of Scoliosis Adult individuals with scoliosis are known to suffer from moderate to severe back pain. Even though their overall musculature has adjusted to the abnormal torso posture, muscular imbalance is very often seen with static SEMG. The pictures below illustrate the phenomenon in two men of different ages. Both suffer from severe scoliosis and trunk deformity. The increased muscular activity in the areas noted on the static SEMG testing parallel the painful response to pressure in the same areas (see Figures 1 through 4). The Issue of a One-Time Static SEMG Test versus the Procedure of Five Repetitions of the Test (The Sella Protocol) Many chiropractors and other SEMG practitioners usually perform one test per visit. The protocol does not make use of statistical data. They discuss the observations with the patient/client and then proceed with the treatment, whether that may be chiropractic practice, biofeedback, or some other discipline. Obviously, that protocol serves fully the needs of their practice. It is attractive and time effective to show a nice graph of the back to a patient and to direct the patient toward treatment based on that graph. However, is that all there is to static SEMG testing? There is an old saying: One swallow does not make a summer. The same may hold true for a one-trial static SEMG test. The author has found empirically that only repeated sequential testing can enable the clinician to proceed with statistical analysis and clinical decisions. A minimum of five test trials is needed to validly perform statistics such as standard deviation and coefficient of variation. The statistics evaluate laterality, consistency of performance, and postural sway effects and help rule out the consistency or inconsistency of performance of the individual over time in the presence of muscular dysfunction (Sella, 1997a, 1997b). The only disadvantage of the Sella protocol of static SEMG is the time it takes to repeat the test five times in sequence rather than limit it to onetime testing. On the other hand, there are several advantages to the repeated procedure: 1. If the results of the five tests are quite similar in the cervical, thoracic, and lumbosacral areas contralaterally, there is little to be questioned, whether the results are within normal limits or represent unilateral dysfunctions. 2. If the results vary within small limits, equivalent to small overall standard deviations, these differences could be attributed to postural sway and reported as such. 3. If the results vary considerably, especially in terms of normal findings in one test and hypertonus/spasm in another, all without patient complaints of pain in the salient area, it is likely that there could be dysponesis and the issue could be resolved only by proceeding with appropriate dynamic SEMG studies of the pertinent muscles (Sella, 1997a, 1997b, 2000b). Dysponesis refers to maladaptive or misplaced effort, in this case muscle activation not serving functional activity. 4. Retesting with static SEMG at subsequent encounters, especially during the SEMG/biofeedback rehabilitation period, may throw further light on the muscular behavior of the paraspinal muscles in similar positions. 5. Retesting enables one to proceed with statistical analysis. Statistical Analysis of the Sella Static SEMG Protocol Tables 1 and 2 are quite large and, at first sight, cumbersome to view. However, considering the fact that they encompass five cervical paraspinal areas, 12 thoracic

4 Sella Figure 1. Patient 1: 52-year-old man with unoperated scoliosis. areas, and five lumbar areas bilaterally, they cannot be made smaller. The statistics are computed bilaterally and comparisons are made across the same intervertebral area and also for the paraspinal region as a whole. The following discussion of the tables and overall statistics is meant to confer a better understanding of the regional results, considering the muscular-anatomic differences and the weight-bearing differences among the three main regions of the neck and trunk. The Cervical Region The posterior cervical muscles are involved in maintaining the vertical posture of the (heavy) head on the neck and in facilitating the cervical motions of flexion, extension, rotation, lateral bending, and head/neck translation. Static SEMG testing at the different paracervical locations evaluates the amplitude potentials of the following (nonmoving) muscles in superimposed layers: longissimus capitis, splenius capitis, semispinalis capitis, rectus capitis, obliquus capitis, splenius cervicis, cervical multifidi, and rotatores. All these muscles are covered by a thin layer of the upper trapezius muscle. The technique cannot distinguish one muscle lying over another due to the size and depth of the muscles. The technique is further limited by the variable presence of occipital hair (i.e., the variable extent of the hairline over the posterior cervical vertebrae). The presence of hair may not allow testing over the C1, C2, or even C3 levels in some individuals. The Thoracic Region The posterior thoracic muscles are involved in maintaining the vertical posture of the upper trunk and in facilitating the thoracic motions of rotation. The thoracic spine muscles facilitate the ribs function in inspiration and expiration. Static SEMG testing at the 12 parathoracic locations evaluates the amplitude potentials of the following (nonmoving) muscles in superimposed layers: semispinalis dorsi, spinalis dorsi, longissimus dorsi multifidi, and rotatores. The technique cannot distinguish one muscle lying over another due to the size and depth of these muscles. The Lumbar Region The posterior lumbar muscles are involved in maintaining the vertical posture of the upper trunk as a whole and in facilitating the lumbar motions of flexion and extension as well as lateral bending. The lumbar spine muscles facilitate abdominal and pelvic activities as well as hip activities. Static SEMG testing at the five lumbar paravertebral locations evaluates the amplitude potentials of the following (nonmoving) muscles in superimposed layers: iliocostalis lumborum, longissimus thoracis, multifidi spinae, and rotatores. The technique cannot distinguish one muscle lying over another due to the size and depth of the muscles. Bilateral testing of the paraspinal muscles with static SEMG is expected to render results of similar amplitude and values bilaterally, provided that the client is not moving during the test. If any unilateral muscular dysfunction is present, it is expected to last over the time period of the testing (five repetitions over minutes), unless the client indicates the presence of pain or other symptoms. The statistics performed across each paraspinal area are expected to show rather similar standard deviations and coefficients of variation. The statistics performed longitudinally over the whole lumbar column tested five times are expected to show similar overall average potential amplitude (mv RMS) results of the right and left sides, including the standard deviations and coefficients of variation, as well as contralateral differences of,20%, either at each lumbar vertebral level or over the lumbar column as a whole. Biofeedback Summer

5 Static SEMG and Neuromuscular Reeducation Figure 3. Static SEMG display from Patient Figure 2. Patient 2: 32-year-old man with postsurgical rods from scoliosis repair. Clinical Correlates of the Statistical Analysis Results The statistical data provide a guide to the clinical interpretation of the findings. The following description pertains first to the distinct separation of the cervical, thoracic, and lumbar regions. Comparison of the averages of action potentials (mv RMS), standard deviations, and coefficients of variation across the five trials of testing on a unilateral and bilateral basis: 1. Note any trends of magnitude of the action potential averages. Is the amplitude showing an increasing or decreasing trend over the five trials? If there are no particular trends, the differences may be due to postural sway. If there are trends, note whether they occur unilaterally or bilaterally. If there is an increasing trend on one side and a decreasing trend on the other side, there may be clinical reasons for the shifting, related usually to low back pain. 2. Note whether the standard deviations (SD) of the right and left sides are within 20% of each other. This is expected in terms of postural sway. If the SD is.20% on either side (but not on both), there are clinical reasons to search for muscular dysfunction on the affected side. 3. Note whether the coefficients of variation (CV) of the right and left sides are within 20% of each other. This is expected in terms of postural sway. Although the CVs should ideally be #.10, this rarely happens due to postural sway. 4. Note the percentage difference between the two sides as a whole for the cervical, thoracic, or lumbar component. If the difference exceeds 20%, the side with the larger action potential amplitude is the one to search further for muscular dysfunction. The comparisons for the testing as a whole are to be made if the criteria of less than or equal to 20% hold for each component and if the difference holds in the same direction. The Dynamic SEMG of the Cervical, Thoracic, and Lumbar Paraspinal Muscles and its Correlates to the Static SEMG Testing As discussed previously, static SEMG is a rather complete test of its own and may show a number of unique findings. It serves as an excellent pointer to the dynamic SEMG test in that the clinician may be able to place the electrodes on the areas of abnormal muscular tonus for the dynamic testing in addition to the classic placements. Furthermore, the dynamic testing may clarify whether the abnormally high electric tonus pertains to findings such as spasm or hypertonus (Sella, 2000b, 2001a).

6 Sella Figure 4. Static SEMG display from Patient 2. The dynamic SEMG of the cervical area is performed using the typical cervical range-of-motion format. The same applies to the dynamic thoracic and lumbar testing. Because there is an obvious myofascial connection among all the muscles described previously, if the clinician is aware of the static SEMG results of the whole cervicalthoracic-lumbar region, one may better interpret the dynamic testing results, especially with regard to the resting tonus. This holds equally well for the resting tonus before and at the end of the testing and for the resting tonus during the performance of different segments of motion. Neck and Back Muscular Dysfunctions and SEMG Biofeedback Muscular Reeducation The most common purpose of the static SEMG testing is to help the clinician devise a program of neuromuscular reeducation of the neck and back muscles (Sella, 2000a, 2001a). The most common question is whether any resting tonus dysfunction seen on the static SEMG graph or from statistical analysis is only a resting tonus dysfunction or is related to segmental motion activity. The question can only be answered by performance of the dynamic SEMG according to an established protocol (Sella, 2000b). The resting tonus action potential amplitude is paramount to recognizing muscular electric dysfunction and treating it properly. The resting tonus depends on intact vascular supply, nerve function, and motor engram memory. If the resting tonus is not normalized, it is unlikely that the muscular activity performance is optimal. The muscle in question will tend to fatigue easily, and symptoms such as pain may ensue (Sella, 2000a, 2000b, 2001a, 2006). The first step in the biofeedback process is to enable the patient to better control the size of the static resting action potential in an area with normal bilateral findings (Sella, 2000a). The clinician needs to place the electrodes along the vertical axis in the paravertebral area, 2 cm away from the respective dorsal spines. The patient is directed to tense the whole area voluntarily and try to maintain the tonus for 10 seconds at about 10 mv RMS bilaterally. Then the patient is instructed to slowly reduce the tension to below 3 mv RMS. The process may be repeated about five to six times or until the patient reports familiarity with the process. If the biofeedback equipment has the availability of software with games or animation, the playing of the games is preferable in most cases, because this type of learning is more right brain and easier to retain in memory. When the blank training is completed, the patient is directed to proceed in like fashion with the salient paravertebral area of clinical interest. The second step is the use of the new learned biofeedback lessons and the asymptomatic region and application of the lessons to reduce and normalize the tonus in the salient, symptomatic regions demonstrated to be abnormal on the SEMG testing (Sella, 2000a). Success of the neuromuscular reeducation procedure is ensured when the person becomes asymptomatic and when new static SEMG testing is performed and the previously abnormal (elevated) action potential amplitudes are found to be normal. Furthermore, the final proof consists of performing dynamic SEMG testing in the salient area, with findings of normal resting and activity results (Sella, 2000a, 2000b, 2001b). Static SEMG: A Glimpse at the Future As stated previously, one important limitation of the SEMG static testing is that the test is performed sequentially on the paravertebral areas rather than simultaneously. Simultaneous testing of different muscles is theoretically feasible with many SEMG software platforms. Future software versions should be adapted to test bilaterally and simultaneously the five lumbar, 12 thoracic, and up to seven cervical paravertebral muscles. One can foresee a chain of electrodes adaptable to the different human torso lengths to be placed on the appropriate locations so that the test could be done simultaneously. The test could be repeated any number of times necessary. Future software programs should include the aforementioned statistical treatment protocol for the different regions and the torso as a whole. Biofeedback Summer

7 Static SEMG and Neuromuscular Reeducation 70 Table 1. Static SEMG statistics from test on Patient 1 RT LT Average SD CV % Difference RT & LT 5 RT LT RT LT RT LT Vertebral Column C C C C C C C T T T T T T T T T T T T L L L L L S Total Note. RT 5 right; LT 5 left; CV 5 coefficient of variation.

8 Sella Table 2. Static SEMG statistics from test on Patient 2 RT LT Average SD CV % Difference RT & LT 5 RT LT RT LT RT LT Vertebral Column C C C C C C C T T T T T T T T T T T T L L L L L S Total Note. RT 5 right; LT 5 left; CV 5 coefficient of variation. Biofeedback Summer

9 Static SEMG and Neuromuscular Reeducation This way, the exam time and statistical analysis time would be most effective and efficient. The reporting software should be appropriate for sending the reports, including the interpretation, to insurance companies and other administrative bodies for assessment and reimbursement. References Cram, J. R., & Holtz, J. (1998). Introduction to surface electromyography. Gaithersburg, MD: Aspen Publishers. Sella, G. E. (1996). How much do they weigh? Bilateral comparisons of weight placement among symptomatic/asymptomatic individuals and symptom magnifiers. Disability, 5(2), Sella, G. E. (1997a). Considerations on symptom magnification and malingering. Forensic Examiner, 6(1 2), 6 7. Sella, G. E. (1997b). S-EMG utilization in the evaluation of soft tissue injury. Forensic Examiner, 6(5 6), Sella, G. E. (2000a). Guidelines for neuro-muscular re-education with S-EMG biofeedback. Martins Ferry, OH: GENMED Publishing. Sella, G. E. (2000b). Muscular dynamics: Electromyography assessment of energy and motion. Martins Ferry, OH: GENMED Publishing. Sella, G. E. (2001a). Playing dual roles: S-EMG utilization in neuromuscular investigation and re-education. Practical Pain Management, March/April, Sella, G. E. (2001b). S-EMG muscular assessment reference manual. Martins Ferry, OH: GENMED Publishing. Sella, G. E. (2002a). Neuro-orthopedic impairment rating. In M. V. Boswell & B. E. Cole (Eds.), Weiner s pain management: A practical guide for clinicians (6th ed., pp ). Boca Raton, FL: CRC Press. Sella, G. E. (2002b). Objective assessment of soft tissue injury. In N. D. Zasler & M. F. Martelli (Eds.), Functional disorders: Physical medicine & rehabilitation, State of the art reviews (Vol. 16, no. 1, pp ). Philadelphia: Hanley & Belfus. Sella, G. E. (2006). SEMG: Objective methodology in muscular dysfunction investigation and rehabilitation. In M. V. Boswell & B. E. Cole (Eds.), Weiner s pain management: A practical guide for clinicians (7th ed., pp ). Boca Raton: CRC Press. 72 Gabriel E. Sella Correspondence: Gabriel E. Sella, MD, 92 N 4th Street, Martins Ferry, OH 43935, Paris10@aol.com.