patterns observed in the population studied—”normal”
backs. Also, perhaps this finding is a signature of health:
One could argue that because the neuromuscular sys- tem is a fluid and dynamic one, high test–retest correla- tions for days, months, or years would be found only in pathological populations. Patients with chronic back pain, for example, might show higher test–retest scores over time because of their pathology. In this sense, one might want to consider SEMG as a “state” rather than a
“trait” measure, changing in response to the task and the environment. Highly consistent and persistent brac- ing or postural patterns of activation or habitual move- ment patterns might indicate an emerging or expressed pathology.
asked to contract completely for 10 seconds, low am- plitude/poor recruitment is seen, followed by fatigue (indicated by declining amplitude over time). Upon cessation of the recruitment, the release is not crisp, but slow. Finally, postbaseline levels remain elevated and variable.
Table 8–2 lists the criteria for examining attributes of SEMG recordings from the pelvic floor.25 These recordings are based upon Flexiplus SEMG instrumen- tation (see Table 3–1 for benchmark equivalence).
Comparison of the hit rate for 55 “nonmorbid” sub- jects (no pain, no incontinence) to 32 vulvar vestibuli- tis patients is presented in Table 8–2. The percentages of these two cohorts meeting the diagnostic criteria are given as well. Some of the SEMG attributes distin- guish the two groups better than others. The level of variability seems to be the most sensitive indicator, suggesting that the pelvic muscles are quite “noisy” in that population. Inability to cease the contraction, which suggests irritability in the neuromuscular sys- tem, is also a key indicator of a problem. Contractile amplitudes and resting baselines also separate the two groups.
The assessment criteria also suggest potential biofeedback treatment opportunities, which are dis- cussed in Chapter 9.
the middle of the epoch. The practitioner examines these SEMG recordings for latency of recruitment, am- plitude, and fatigue. This phase is followed by a rest period of approximately 15 seconds. Next, a series of ten 10-second periods is studied in which the patient al- ternates between resting and contracting. The patient is asked to make a full contraction and hold it for 10 seconds, and then to stop the contraction and rest for 10 seconds. This recording is examined for the ease of recruitment and derecruitment, the amplitude of con- traction, and the presence of any fatigue. It is followed by a 10-second rest period. Finally, the patient is asked to contract fully and hold for as long as possible over a 60-second period. The practitioner examines this SEMG recording for amplitude and the rate of fa- tigue. This recording is followed by monitoring of a resting baseline, which the practitioner examines for its amplitude and stability.
A normal recruitment pattern for a 10-second hold can be seen in Figure 8–15. Initially, the resting tone is low, and there is a crisp recruitment to a high ampli- tude. At the cessation of the 10-second hold, the SEMG level falls off rapidly and returns to a low resting tone level. In Figure 8–16, an abnormal recruitment pat- tern is evident. Here, the patient exhibits an elevated and unstable resting baseline. When the patient is
Figure 8–15 A normal recruitment pattern recorded from the pelvic floor using an intravaginal recording electrode.
Source:Copyright ©Marek Jantos, PhD.
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Figure 8–16 An abnormal recruitment pattern recorded from a patient with vulvar vestibulitis.
Source:Copyright ©Marek Jantos, PhD.
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CHAPTER QUESTIONS
1. Resting baseline of muscle tone is primarily affected by:
a. posture b. emotional tone c. kinematics d. both a and b
2. When a muscle fails to return to baseline following a movement, it is called:
a. dysfunctional b. irritable c. hypoactive d. hyperactive
3. During a symmetrical movement, one would expect to see:
a. an asymmetrical activation pattern b. a symmetrical activation pattern
c. a symmetrical activation pattern for homologous muscle groups
d. an asymmetrical activation pattern for homologous muscle groups
4. During an asymmetrical movement, one would expect to see:
a. an asymmetrical activation pattern b. a symmetrical activation pattern
c. a symmetrical activation pattern for homologous muscle groups
d. an asymmetrical activation pattern for homologous muscle groups
5. Symmetrical movement is to asymmetrical recruitment as asymmetrical movement is to:
a. irritability b. cocontraction c. flexion–relaxation d. synergy
6. The probability amplitude distribution of SEMG should be:
a. bimodal b. unimodal c. curvilinear d. multiphasic
7. In assessing vulvodynia, which SEMG attribute best separates normal subjects from patient populations?
a. amplitude of contractions b. resting baseline amplitudes c. resting baseline variance d. spectral frequency
8. A “flick” consists of a short, brisk contraction. For which disorder is it commonly used as a diagnostic indicator?
a. upper quarter pain b. incontinence c. vulvodynia d. both b and c
9. In incontinence assessments, fatigue is noted by:
a. an increase in amplitude b. a decrease in amplitude c. an increase in blood flow d. an increase in urine flow
10. How much asymmetry is considered to be within the normal range?
a. 5%
b. 10%
c. 20%
d. 50%
11. The erector spinae muscles are expected to ____________
during full-trunk flexion.
a. cocontract b. turn off c. recruit
d. become hypoactive
12. During abduction of the arms to 90 degrees, what should be the ratio of SEMG activity for the upper and lower trapezius muscles?
a. approximately 1 to 1 b. 2 to 1
c. 1 to 2
d. none of the above
13. Which of the following is not a sign of a trigger point?
a. jump sign b. taut band c. muscle weakness d. referred pain
e. all of the above
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