Characteristics of patients with myofascial pain syndrome of the low back

Abstract

The objective of this study is to determine characteristics of patients with myofascial pain syndrome (MPS) of the low back and the degree to which the low back pain in the patients examined can be attributed to MPS. Twenty-five subjects with myofascial trigger point(s) [MTrP(s)] on the low back participated in this cross-sectional study. The location, number, and type of selected MTrPs were identified by palpation and verified by ultrasound. Pain pressure threshold, physical function, and other self-reported outcomes were measured. Significant differences were found in Group 1 (Active), 2 (Latent), 3 (Atypical, no twitching but with spontaneous pain), and 4 (Atypical, no twitching and no spontaneous pain) of participants in the number of MTrPs, current pain, and worst pain in the past 24 h (p = .001-.01). There were interaction effects between spontaneous pain and twitching response on reports of physical function, current pain, and worst pain (p = .002-.04). Participants in Group 3 reported lower levels of physical function, and higher levels of current pain and worst pain compared to those in Group 4. Participants in Group 1 and 2 had similar levels of physical function, current pain, and worst pain. The number of MTrPs is most closely associated with the level of pain. Spontaneous pain report seems to be a decisive factor associated with poor physical function; however, twitching response is not.

Keywords: Chronic low back pain; Myofascial pain syndrome; Trigger point.

Figure 1

The interaction effect in the SF-20 physical function subscale between pain and twitching. For participants who reported pain, their SF-20 Physical Function response was lower if they did not have twitching responses (64.15 ± 11.35), while it was higher if they had twitching response (84.20 ± 4.41). On the other hand, for those who did not report pain, their response in SF-20 Physical Function was higher if they did not have twitching responses (94.78 ± 7.27) and lower if they had twitching responses (77.34 ± 7.40). There was a significant difference in the SF-20 Physical Function percentage between Pain and No Pain participants when they had no twitching responses, p = .04.

Figure 2

The interaction effect in the reported current pain level on the numeric pain rating scale between pain and twitching. For participants who reported pain, their reported Current Pain Level was higher if they did not have twitching responses (5.41 ± 0.87), while it was lower if they had twitching response (0.38 ± 0.34). However, for those who did not report pain, their Current Pain Level was lower if they did not have twitching responses (0.65 ± 0.54) and higher if they had twitching responses (3.19 ± 0.56). There was a significant difference in the Current Pain Level between pain and no pain participants when they had no twitching responses, p < .001.

Figure 3

The interaction effect in the reported worst pain level in the past 24 h on the numeric pain rating scale between pain and twitching. For participants who reported pain, their Worst Pain Level in the past 24 h was higher if they did not have twitching responses (7.29 ± 1.19), while it was lower if they had twitching responses (5.97 ± 0.46). Conversely, for those who did not report pain, their Worst Pain Level in the past 24 h was lower if they did not have twitching responses (2.03 ± 0.77) and higher if they had twitching responses (4.54 ± 0.78). There was a significant difference in the current pain level between pain and no pain participants when they had no twitching responses, p = .04.