Ambulatory electromyogram activity in the upper trapezius region: patients with muscle pain vs. pain-free control subjects.

STUDY DESIGN: This study compared the ambulatory electromyogram activity of persons reporting pain in the shoulder and cervical regions with an equal group of persons not reporting such pain. Ambulatory electromyogram data were obtained over 3-day periods. In addition, all participants completed several standard psychological questionnaires. OBJECTIVES: The results were analyzed with inferential statistics to determine whether subjects reporting significant pain in the shoulder and cervical regions had greater ambulatory electromyogram activity than an equal number of subjects not reporting pain. SUMMARY OF BACKGROUND DATA: Considerable controversy exists regarding the role of muscle activity in the etiology and maintenance of muscle pain disorders. Given the availability of ambulatory recording devices that can provide a detailed record of muscle activity over an extended period of time, the present research was conducted to determine whether persons reporting shoulder and cervical pain could be differentiated from a group of normal subjects. METHODS: All subjects (N = 20) completed a battery of tests with standardized psychometric instruments and then were fitted with ambulatory electromyogram monitors to record electromyographic activity of the upper trapezius region of the dominant side; the time, duration, and amplitude of electromyogram activity greater than 2 microV was recorded. The monitors were worn during normal working hours (mean, 6.2 hours per day) over 3 consecutive days. In addition to wearing the monitors, all subjects completed hourly self-ratings of perceived muscle tension during the recording periods. RESULTS: As expected, subjects with muscle pain reported significantly more pain (mean, 4.9) than did the normal control subjects (mean, 0.9), t(15) = 3.29, P < 0.01. However, patients with muscle pain did not have greater average electromyogram activity (mean, 6.4 microV) over the 3-day period as compared to the normal controls (mean, 7.1 microV), t(18) = -0.25, P < 0.80. Self-monitoring of perceived muscle tension also did not reveal differences between pain subjects and the normal control subjects (P < 0.75). CONCLUSIONS: Ambulatory measurements of electromyogram activity did not differentiate persons reporting upper trapezius or cervical pain from those that did not report such pain. Persons reporting pain are also not distinguishable from normal control subjects on a variety of self-report measures. These results raise questions regarding the role of ambulatory electromyogram recordings in the evaluation and treatment of muscle pain disorders.

The Children's Headache Assessment Scale (CHAS): factor structure and psychometric properties.

This study investigated the content validity, factor structure, and psychometric properties of the Children's Headache Assessment Scale (CHAS), a parent rating scale for identifying environmental variables associated with pediatric headache. In Study 1, input from physicians and psychologists was obtained to develop a revised set of 44 items receiving high endorsement. In Study 2, the questionnaire was administered to parents of 92 child headache sufferers, ages 6-16, and readministered 2 weeks later. An exploratory factor analysis revealed five factors (Disruptive Impact, Social Consequences, Stress Antecedents, Physical Antecedents and Quiet Coping, and Prescription Medication Use) that reflect distinct environmental concomitants of childhood headache. Scale reliabilities (alpha, .64-.82) indicate acceptable internal consistency, and test-retest reliabilities indicate relatively stable factors and items. High scores on the Disruptive Impact factor were associated with more severe, lengthy, and infrequent headache occurrence, lending initial support for the validity of this factor. Overall, the findings support the clinical and research utility of the CHAS in behavioral treatment of childhood headache.

Validation of surface EMG as a measure of intravaginal and intra-abdominal activity: implications for biofeedback-assisted Kegel exercises.

This study validates surface EMG as a measure of pelvic muscle and abdominal activity by showing its high correlation to internal pressure data. Using standardized scores, between-subjects correlation of perineal EMG and intravaginal pressure was r = .75, and the correlation of abdominal EMG and intra-abdominal pressure was r = .72. Discriminant validity was also demonstrated by showing low correlation between standardized abdominal and perineal EMG measurements (r = .10). A repeated measures multivariate analysis of variance demonstrated that visual and auditory biofeedback of EMG during pelvic floor contractions increases intravaginal pressure when compared with trials without biofeedback. Potential benefits of fabric electrodes include reduced invasiveness and risk and the ease with which patients can utilize this technology for home practice.

The detection of malingering and deception with a short form of the MMPI-2 based on the L, F, and K scales.

This project examined the use of a short inventory based on the validity subscales from the MMPI-2. In Study 1, 69 subjects responded to the extracted L, F, and K items and to those items when embedded in the complete MMPI-2. Correlations between administrations were equivalent to the original test-retest reliabilities for these scales. In Study 2, 60 subjects responded to the short-form with instructions to be honest, fake good, or fake bad. The correct classification rate was 77% using the standard MMPI-2 rules of L greater than 7OT for faking good and F greater than 7OT for faking bad. Taken together, these findings suggest that the short-form may be useful alone or when combined with other questionnaires to identify potential problems in self-report.