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


OBJECTIVE
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.


BACKGROUND
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.
Carlson
C R
CR
Department of Psychology, University of Kentucky, Lexington, USA.
Wynn
K T
KT
Edwards
J
J
Okeson
J P
JP
Nitz
A J
AJ
Workman
D E
DE
Cassisi
J
J
D000328:Adult; D004576:Electromyography; D005260:Female; D006801:Humans; D018670:Monitoring, Ambulatory; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009333:Neck; D010146:Pain / Q000503:physiopathology* / Q000523:psychology; D010147:Pain Measurement; D012782:Shoulder / Q000503:physiopathology*; D011795:Surveys and Questionnaires