Influence of active scars in abdominal wall on abdominal and back muscles activity in chronic low back pain – surface electromyography pilot study

Abstract

Introduction: An active scar has been defined as one which is tender and around which the tissues show various abnormalities. Clinically, we have felt that active scars in the abdomen cause the underlying muscles to be less active. In addition, an active scar on the abdomen may increase resistance to stretch, thus restricting flexibility of the back. Such scars may, therefore, be a cause of back pain. The aim of this study was to compare electromyography activity of right- and left-sided abdominal muscles underlying unilateral abdominal active scars.

Patients and methods: Thirteen patients and 13 healthy controls were examined by surface electromyography (SEMG). We proceeded with SEMG of the straight abdominal muscles on both sides on lifting the head and the shoulders with the subject supine, and of the erector spinae with the patient prone. The patients with active scars were examined before and immediately after soft tissue treatment.

Results: SEMG examination showed increased muscle activity of the rectus abdominis in 6 cases on the side of the active scar and in 7 cases on the opposite side. This asymmetry decreased after treatment in 7 cases (P = 0.045). Asymmetry was also found in the controls: this asymmetry was, however, significantly less than in the patients with an active scar (P = 0.029). The reason for the discrepancy between palpatory and EMG findings is discussed.

Keywords:

• ACTIVE SCARS
• SURFACE ELECTROMYOGRAPHY
• MUSCLE TONE
• PALPATORY ILLUSION
• SOFT TISSUE MANIPULATION