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6 Articles in Volume 1, Issue #4
Breaking Down the Barriers of Pain: Part 4
Facing Reimbursement Challenges
Getting Back on Track
Taking the Hurt Out of Pain
The Mind-body Connection
The Neural Plasticity Model of Fibromyalgia Theory, Assessment, and Treatment: Part 2

The Neural Plasticity Model of Fibromyalgia Theory, Assessment, and Treatment: Part 2

Part two of this series discusses sEMG and EEG as assessment techniques for fibromyalgia.

Application of the concept of neural plasticity to fibromyalgia suggests that changes should be seen in both the peripheral and central nervous systems. It is through the application of surface electromyographic (sEMG) and electroencephalographic (EEG) assessment techniques that such changes may be seen. It is through the application of biofeedback, specifically multiple channel sEMG biofeedback-assisted neuromuscular therapy and EEG neurotherapy, that we can powerfully impact neuroplasticity.

sEMG Techniques

Before proceeding with the sEMG assessment it is important that a comprehensive medical evaluation of fibromyalgia symptoms be conducted. Various systemic diseases as well as somatoform disorders must be ruled out before considering the diagnosis of fibromyalgia. Moreover, in every case the intensity and frequency of symptoms as well as the presence or absence of various secondary symptoms may differ. A detailed listing of all experienced symptoms is necessary. This includes: a) presence of symptoms; b) length of time each symptom has been present; c) intensity of symptoms; d) frequency of symptoms; e) worsening in either intensity or frequency in the presence or absence of treatment and environmental factors; f) improvement in either intensity or frequency in the presence or absence of treatment and environmental factors; g) listing of different treatments and symptomatic response in time; and h) overall symptom change from the beginning of the appearance of symptoms to the time of the evaluation or re-evaluation.100,101

The essential points of the evaluation, with special focus on fibromyalgia, myofascial pain syndrome, and other muscular painful conditions are as follows:

  1. History of the condition: description of the primary etiology of the condition, e.g. acute post-traumatic, chronic, post-repetitive motion injury, etc. The time span from the original initiation of the pain symptoms to the time of the evaluation has to be described in detail, especially with regard to the investigation, diagnostic process, treatment, and success rate of the rehabilitation102
  2. Review of systems, with special regard to any injury or condition, which may contribute to the maintenance or enhancement of the muscular type pain, fatigue, and concomitant symptoms of depression, anxiety, and especially sleep disorder
  3. Physical examination, with special focus on every system in terms of conditions that may contribute actively to the maintenance of the fibromyalgia or related symptoms. Such examination needs to contain a comprehensive questionnaire, especially involving the pain and emotional symptoms, history thereof, and treatment up to the point of the evaluation
  4. Review of all prescription and OTC medications as well as herbal remedies and nutritional supplements being taken by the patient, with particular attention paid to possible medication effects or adverse interactions that might actively contribute to the patient’s fibromyalgia or related symptoms. Computer software such as The Medical Letter’s Drug Interactions Program® can be very useful in this process
  5. Objective evaluation of the muscular pain components in terms of sEMG of all the affected muscles as well as muscles known to co-activate with the symptomatic muscles, goniometry to assess any changes in the joints range of motion, dynamometry to assess loss of strength, dolorimetry to assess the pain perception pattern, and other tests as necessary90,103-105
  6. Psychological tests related to the emotional component of the pain, including negative cognitions, anxiety, and depression. Some psychometric instruments that are commonly used in the evaluation of chronic pain patients are: Illness Behavior Questionnaire (IBQ), McGill Pain Questionnaire,37 Minnesota Multiphasic Personality Inventory-2 (MMPI-2),107 Survey of Pain Attitudes (SOPA),108 Symptom Check List-90-R (SCL-90-R),109 West Haven-Yale Multidimensional Pain Inventory (WHYMPI)110
  7. Sleep studies where there is sleep disturbance, especially associated with lack of dreaming, early awakening, and sensation of sleepiness during the day. A disproportionate number of persons diagnosed with fibromyalgia also have such physiological sleep disorders as obstructive sleep apnea, restless leg syndrome, buxism, etc. These may be primary or secondary to the fibromyalgia but frequently play a significant role in maintaining the sleep disturbance that appears to lie at the heart of fibromyalgia and therefore, must be addressed.

Once basic medical and psychological investigations are completed then a sEMG evaluation can be conducted.104, 111-113 Surface EMG recordings provide a safe, relatively easy and noninvasive method of reliably and objectively quantifying the electrical activity of muscles both at rest and through their full range of movement. Multiple channel sEMG instruments can provide a method of examining the nervous system’s control of muscle function and may be utilized in differentiating pain due to myofascial causes verses pain due to fibromyalgia, or pain due to a combination thereof. Using sEMG, muscle dysfunction is primarily seen in four phenomena: a) increased electrical activity of the muscle at rest; b) increased electrical activity following movement or failure to return to normal resting baseline activity levels; c) excessive electrical activity during movement; and d) coactivation of muscles during movement that are normally inhibited.88,114

Excessive resting muscle electrical activity may be a direct consequence of improper posture, emotional dysfunction, or learned muscle guarding or bracing114 and is a common finding in myofascial pain patients, particularly in those muscles in body areas that are reported as painful. When muscles retain an elevated level of activity it is believed that fatigue and pain are induced through a disturbance in microcirculation and a subsequent build up of lactic acid.

When muscles retain an elevated level of activity it is believed that fatigue and pain are induced through a disturbance in microcirculation and a subsequent build up of lactic acid.
Table 1. Comparison of Resting Potentials of Asymptomatic Subjects and Myofascial Pain Patients
  Head Neck Trunk Shoulder Elbow Wrist Hand Hip Kne e Ankle Avg
Asympt.i 3.5 3.4 2.2 2.6 1.5 1.6 1.4 1.6 2.2 1.1 2.11
Normaliz % .ii 166 161 104 123 71 76 66 76 104 52 100
MPS .iii 7.4 12.6 6.2 5.2 2.5 1.8 1.8 2.5 2.5 2.6 5.1
Normaliz. %.ii 145 250 118 102 49 35 35 49 49 50 100
Table 2: Average Z-scores by Frequency and Task
Frequency Task
  Eyes Open Eyes Closed Serial 7s
Alpha (7.5-13 Hz) -1.01 .01 -0.1
Beta (13-22 Hz) 1.43 0.34 0.47
Delta (.5-3.5 Hz) 0.13 -.38 -0.22
Theta (3.5-7 Hz) 0.4 0.12 0.05

Using sEMG to examine 173 muscles throughout the body while subjects stood or sat quietly and unsupported in a neutral position, Sella115 found that myofascial pain patients generally show significantly higher and more variable resting electrical activity levels than do asymptomatic subjects. The asymptomatic subjects demonstrated an average resting potential of only 2.0 microvolts across the 173 muscles examined, although these levels varied slightly from muscle to muscle (see Table 1).

Assessment of muscle resting levels shown in Table 1 was done as follows: the ROM protocols for the head, neck, shoulder, elbow, wrist, and hand are all done while standing; the trunk is mixed standing, supine, and prone; the hip, knee, and ankle are mixed supine, prone, sitting, or standing, with each of the specific ROM protocols given in Sella.115 The muscles to be tested are consciously at rest, without any motion or alertness or preparedness for any motion to come. Resting values are tested before the ROM exercise, during the ROM exercise, and after it. The initial resting assessment (pre-exercise) is done for 30 seconds on four bilateral muscles. The final resting assessment (post-exercise) is also done for 30 seconds on the same four bilateral muscles. If muscular discomfort is triggered by the exercise, this will be shown by increased amplitudes of resting potentials at the end of the testing. If the initial resting period is showing increased potentials and the situation improves at the end of the exercise, this could be due to improved muscular function in conditions of de-conditioning. During the ROM exercise, equal time periods of nine seconds of activity and rest are repeated five times during the testing of any given segment of ROM.116 Work by Donaldson84 and Cram116 is consistent with these results, although these authors utilized different positions and protocols. A conversion table for comparing sEMG values between different manufacturers’ instruments at different filter settings has recently been published in an introductory text on sEMG.114

The senior author,117 in examining the resting levels of the muscles associated with the fibromyalgia tender points of the ACR criteria found that, for an average of three samples for each muscle, resting levels are approximately the same as what Sella113 reported for asymptomatic subjects. These results are consistent with what various other authors118 have reported.

A failure of electrical activity to fully return to normal resting levels immediately after the termination of movement is another common sEMG finding in persons with muscle pain and indicates that the muscle for whatever reason is not shutting off or becoming quiet after contraction. A period of rest, sometimes as short as only a few milliseconds, allows for recovery from contractions and improved blood flow that removes lactic acid and other toxic metabolic by-products. Veiersted and his colleagues in Norway119 have shown that a lack of micro-breaks during repetitive muscle activity is an important predictor of the development of chronic upper quadrant pain in light industrial workers. In this regard, Elert et al118 observed that FS patients were less able to relax their muscles in short periods between isometric muscle contractions and had increased muscle fatigueability as compared to healthy controls.118

Muscle imbalances may be documented during both symmetrical movement and at rest by comparing the electrical activity of a muscle on one side of the body (e.g. left SCM) to that of its contralateral homologous partner (e.g. right SCM). Donaldson84,120 determined that differences in peak values greater than 20 percent are abnormal and may be associated with injury and/or pain. Middaugh et al121 have also recommended similar levels of difference (20-35 percent) between contralateral homologous muscles as clinically meaningful.

Legend. Asymp=muscles that were clinically asymptomatic and showed normal resting and activity potentials. iiThe normalization is a process of the ratio of each individual value by the average value and expressed as a percentage comparison to the average value. iiiMPS=muscles which were symptomatic within the clinical picture of myofascial pain syndrome and had abnormal resting and activity potentials. Note: Z-scores are standard scores ranging from -3.00 to +3.00; with a mean of 0 at the 50 percent tile of the distribution of scores. Z-scores of -1.00 and +1.00 lie at approximately the 34 percent tile and 68 percent tile of the distribution respectively. Z-scores of less than -2.00 or greater than +2.00 are significant at approximately the 0.05 level of probability.

Sella112 has published a set of sEMG dynamic ROM assessment protocols for every major joint122 which have been validated in statistical terms (i.e., demonstrating internal consistency, reliability, and reproducibility for each protocol as well as for each segment of ROM) in studies involving 6,400 muscles.111,122 Furthermore, the specificity, sensitivity, and predictive values of these sEMG ROM protocols have been demonstrated clinically in the condition of myofascial pain syndrome.21,84,120

The general protocol involves the following: a) consideration of performance of the full ROM of a particular joint and the muscles involved in the motion done with minimal voluntary effort or muscular contraction; b) motion done with a given, objective resistance (e.g., 4.5 kg ankle weight); and c) motion against isometric contraction. The latter may involve the blocking of the motion at any angular position during a given ROM segment.

Other extremely useful sEMG scanning and ROM assessment protocols have been published by Cram,114,123 Headley,124 and Kasmin125 as well as more recently for a number of specific musculoskeletal dysfunctions by Kasmin and his associates.126

In addition to the classic ROM segments, any investigator is advised to add any necessary clinical or ergonomic motion, as the case may require for the individual being investigated. It has been found empirically that at least five repetitions of any segment of motion are necessary in order to validate statistically the internal consistency of the performance of the person evaluated.127 Since motions which are maintained beyond 10 seconds may produce substitution of muscular activity by nearby muscles, sEMG protocols require the maintenance of motion for no more than seven seconds followed by the command to relax, allowing the muscles to return to rest within two seconds. Intervals of rest between repetitions of at least nine seconds are necessary to attain the minimal resting potential , which is most relevant to the re-energizing of the muscles.100,116

Figure 1. Rotation of the head left, then right. Normal muscle firing patterns. Figure 2. Rotation of the head left, then right. Abnormal muscle firing patterns.

Persons with myofascial pain show differences in various muscle pairs doing the same movement, which Donaldson128 demonstrated, correlated quite strongly (80 percent) with trigger point activity in the upper trapezius and sternomastoid muscles. Sella113 found high specificity (77 percent) and sensitivity (63 percent) values for muscle imbalance measures when comparing painful to non-painful muscles. Figure 1 illustrates normal muscle activity and Figure 2 illustrates muscle imbalances of the sternomastoids and cervical paraspinals.

While the generalized pain as reported in fibromyalgia appears to have a strong connection to the presence of trigger points, other muscle factors are suspected to be involved in the production of tender points. Cocontractions are defined as an increase in electrical activity of a non-synergistic muscle from its resting level when another muscle in another part of the body is contracting while performing a movement. Cocontractions are commonly reported in the literature as phenomena occurring in the newborn that disappears with maturation.129 Ikeda130 demonstrated that cocontractions remain prevalent in such dysfunctions as cerebral palsy, and are thought to reflect an inability to develop the correct inhibitory mechanisms, which incorporate these phenomena into movement patterns. Lenz131 demonstrated during neurosurgery of the thalamus, that cocontractions of the wrist extensors were present in 63 percent of the dystonia patients studied. This phenomenon appeared to be related to the thalamic cerebellar relay nucleus (VIM) and pallidal relay nucleus (VOP).

In exploring this phenomenon, Donaldson132 found that fibromyalgia patients showed increased electrical activity in widely separated parts of the body during movement of the head. They found the wrist extensors (forearm tender point), gluteus minimus (buttocks tender point), and vastus medialis (knee tender point) muscles were active during flexion and rotation of the head while individuals were sitting quietly and fully supported. This phenomenon was seen in 40 out of 40 individuals carefully screened and diagnosed with fibromyalgia. Figure 3 shows sEMG tracings taken from a control subject with no cocontractions using a Physiotech 4000™ sEMG system† with a sampling rate of 240 Hz and a bandpass filter of 40-450 Hz. In all tracings electrodes are placed 2.0 cm apart center-to-center, parallel to the belly of the muscle. The top two tracings (labeled LCPS [left cervical paraspinals] and RCPS [right cervical paraspinals] — note the tracing from the LCPS cannot be seen) show the rotation of the head as occurring in the second segment. Tracings 3 and 4 (labeled LEXT and REXT [left extensors and right extensors]) are recordings taken over the wrist extensors 2.0 cm distal to the epicondyle. Tracings 5 and 6 (labeled LGM [left gluteus maximus] and RGM [right gluteus maximus]) are recorded from electrodes placed over the gluteus medius 2.0 cm apart and parallel to the belly of the muscle. Tracings 7 and 8 (labeled LVM [left vastus medialis] and RVM [right vastus medialis]) are from electrodes placed over the fat pads of the vastus medialis. Note that the change in activity from resting levels for the CPS (cervical paraspinals) is due to the head rotating.

Figure 4 illustrates this phenomenon as occurring in a person with fibromyalgia. It is clearly evident that the left wrist extensors, gluteus medius, and vastus medialis show an increase in EMG activity that is time-linked to the rotation of the head. At this time it is still not known exactly what this phenomenon represents. In order to differentiate this phenomenon from that of cocontraction (which is routinely considered to involve an interaction between agonist and antagonistic muscles) the authors have labeled this generalized phenomenon Diffuse Muscular Coactivation (DMC).

Donaldon117 studied the electrical characteristics of the DMC, in the muscles associated with the 18 tender points. They found that the increased electrical activity represented an increase in RMS (Root Mean Square) activity, which correlates with the amount of force generated.133 The amount of RMS activity varied, from an increase of 800 percent from baseline in muscles about the neck, to 20 percent in the vastus medialis (near the tender points of the knee). This pattern was identical to that found in controls but was found to be on average four times stronger. Examination of the median frequency showed no significant differences between controls and fibromyalgia sufferers, with both groups showing similar patterns of increased activity of approximately 3 Hz.

It is postulated that increased muscle activity, for whatever reason, is the cause of the generalized pain as seen in fibromyalgia sufferers and may possibly represent the cause of the development of tender points and trigger points. It is also postulated that the excessive and inappropriate electrical activity produces fatigue and stiffness as reported in these syndromes. This of course remains to be proven.

Basmajian134 identified four possible neurological mechanisms, which may be involved in the disruption of motor control as seen with sEMG techniques. These are: a) centrally mediated reciprocal inhibition; b) centrally mediated coactivation; c) peripherally mediated reciprocal inhibition; and d) peripherally mediated coactivation. It is presently not known if one, some, or all of these mechanisms are involved in the appearance of the muscle activity seen in persons with fibromyalgia. Regardless of the cause, sEMG techniques remain the only objective way of assessing this phenomenon.

EEG Techniques

Electrical activity in each brain region is homeostatically regulated, resulting in predictable frequency composition of the background EEG.135,136 It has been well established that the EEG power spectrum is independent of ethnic background and displays few deviant values in healthy, normally functioning individuals matched for age and gender.137,138 Significant deviations from normal in the frequency composition of the background EEG have been associated with various biological and functional disorders of the brain.136,137 Although not all researchers fully agree (see Nuwer139), quantitative electroencephalography (qEEG) has demonstrated its utility in the diagnosis and characterization of different pathologies that effect brain functioning.136,138,140

Reliable and practical examination of the cortical electrical activity in persons with fibromyalgia is primarily accomplished through the use of qEEG techniques. Although other relatively inexpensive and clinically accessible procedures, such as single photon emission computed tomography (SPECT),141 can also be used to evaluate brain activity in persons with fibromyalgia, the qEEG procedure is recommended because it allows for the simultaneous evaluation of frequency, amplitude or absolute power, coherence, phase, and relative power, which can then be used to direct EEG biofeedback or neurotherapy treatment.

In qEEG, multiple channel recordings (i.e., usually 19 electrodes at standardized positions) of eyes closed, resting or background EEG are visually edited to remove movement artifact and a sample of artifact-free data (usually one to three minutes) is analyzed by means of a Fast Fourier Transform (FFT) algorithm to create a “power spectrum” by quantifying the power at each frequency of the EEG averaged across the entire sample.135 The test-retest replicability of power spectra computed in this fashion has been shown to be excellent.132,138 The power spectrum of clinical interest is usually considered to extend from about 1 Hz to 30 Hz.

Figure 3. Rotation of the head showing no coactivations. Control subject. Figure 4. Rotation of the head showing coactivations. Fibromyalgia subject.

Although there are a number of good and reliable digital qEEG brain mapping systems presently available, the data referred to was collected using the Lexicor Neurosearch - 24® system.‡ The data was collected at a rate of 128 samples per second with a gain of 32. Electrode impedance in all cases was less than 5k ohms at all 19 active electrodes, with an additional four channels used to monitor movement artifact and one channel used for reference (i.e., linked ears). In this monopolar recording procedure a lycra cap is placed over the individual’s head with electrodes pre-inserted at sites that correspond to those of the International 10/20 locations. Data is collected in the eyes open and eyes closed states and digitized and stored electronically. The data is then visually inspected on the computer monitor by a technician trained in artifact removal producing a level of confidence of 95 percent.

Examination of the background electrical activity of the cortex of persons with fibromyalgia, particularly the brain wave relative power distribution, shows changes in frontal cortical activity.21,67,97,142 These changes are most notable for increases in slow brain wave activity (theta [3.5-7.5 Hz], and the lower frequencies of alpha [7.6-11.9 Hz]) (sometimes referred to as thalpha) throughout the frontal and central cortex of persons with fibromyalgia. This slow wave activity appears in the “eyes-closed” state, significantly increasing in level of activity when compared to the “eyes-open” state. This change is expected when examining the temporal, parietal, and occipital areas, but not in the central and frontal areas. Figure 5 demonstrates a normal pattern of cortical activity and Figure 6 demonstrates the “thalpha” which is often seen in persons with fibromyalgia.

In a carefully controlled study (data as yet unpublished) Donaldson examined brain wave activity during three conditions/tasks: a) in the eyes open condition; b) in the eyes closed condition; and c) while doing serial 7s (silently counting backward from a 1000 by 7s) with eyes closed. Raw EEG was recorded for 10 minutes in each of these conditions, stored electronically to computer, and artifacted by a trained technician. To be included in the study, each set of data had to contain at least two minutes of artifact free data. For each of the three conditions the artifacted data was then converted to Z-scores using the Neurorep Database 3 program.137,143 The results, as outlined in Table 2, show the changes in levels of brain wave activity between the eyes-open, eyes-closed, and serial 7s conditions.

Of interest in the “eyes-open” data is the elevation of beta and decrease in alpha (delta and theta appear unaffected). As both beta and alpha scores should average about zero, it is suspected that the increase in beta activity is related to the decrease in alpha activity. This may explain the reports of a decreased ability to multi-task and sustain concentration. In the eyes closed and serial 7s conditions the alpha level returns to near zero, while beta remains elevated. Theta and delta decrease slightly. Thus the noted spike activity (Figures 5 & 6) appears to be due to significant changes in the higher frequencies (in the eyes open to eyes closed conditions) as opposed to an increase in theta activity. (Authors’ note: beta does not appear to be elevated in Figures 5 & 6 as it is distributed across all the beta frequencies whereas in Table 2 beta is summated producing the elevation). Repeated measures ANOVAs for all frequencies by condition (4X3) was significant (p<.01) for all frequencies over time.

Examination of the individual sites for alpha, eyes-open show a range of -.8065 (FZ) to -1.5811 (O2) with beta showing a range of .34 (FZ) to 2.637 (F7). There was a trend toward decreased alpha posteriorly. No particular pattern for beta was noted except for a decrease in activity along midline (FZ=.34, CZ=.60, PZ=1.2). Eyes-open delta showed a pattern of decreased activity in the front and increased activity in the posterior. Theta activity was elevated primarily at FZ, CZ, and occipitally. Of interest the adjacent areas to FZ (F3, F4) and CZ (C3, C4) were also elevated.

No particular patterns were found for the eyes-closed and serial 7s conditions. Alpha eye-closed and serial 7s showed decreased activity in the parietal and occipital areas, with increased frontally. Beta showed no particular pattern with distribution generally even for either conditions. The midline pattern noted for eyes open was seen again. Delta for both conditions was decreased frontally. Theta showed an elevation across most sites, particularly along the midline as previously noted for both conditions.

In summary, although this data must be treated as preliminary and needing replication, the following is apparent: a) alpha is greatly decreased and beta greatly increased in the eyes-open condition; b) the activity decreases in the eyes-closed and serial 7s conditions except for theta which, relatively speaking, increases; and c) the theta activity primarily increases along the midline affecting FZ, CZ and PZ and their adjacent areas. These changes correspond to a decrease in beta at the same sites.

It is not known what this increased slow wave EEG phenomenon represents. Niedermeyer144 suggests that increased theta activity is abnormal and associated with various forms of pathology. He goes on to suggest that this increased activity may be associated with psychological problems. However, in the Donaldson132 study, psychological testing suggested only 25 percent of the sample had significant psychological problems as measured by the Symptom-Checklist 90-Revised.109

In a similar vein, Westmoreland145 reported that increased slow wave activity is found in individuals suffering from various types of viral infections (i.e., measles), while Van Sweden146 has reported this in individuals exposed to toxic chemicals. Slow wave activity has also been correlated with cholinergic activity and central cholinergic pathways.147

Other clinical researchers in the biofeedback field have recently speculated that the brain is a self-regulatory control system and that most psychopathology can be viewed in terms of a disregulation model,148 that is, in terms of specific failure modes of this control system.81 In this regard, Noton149 suggests that fibromyalgia and chronic fatigue syndromes may be members of a group of disorders — i.e., attention deficit disorder, depression, minor brain injury, premenstrual syndrome, toxic trauma, etc. — that are associated with findings of excessive slow brain wave activity and insufficient cerebral blood flow in certain cortical regions.

In summary, for reasons that need further investigation, the neurological system appears to react to the constant stimulation of the pain signal producing changes and modulation in both the peripheral and central nervous systems. These changes may be used as marker(s) for understanding and treating fibromyalgia with biofeedback techniques.

Read Part 3 of this article series

Last updated on: June 18, 2020
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