Muscle injections with lidocaine improve resting fatigue and pain in patients with chronic fatigue syndrome

Figures & data

Table 1 Demographics

	Lidocaine injections	Saline injections	p-value
Females/males	28/2	26/2
Age (SD), years	50.8 (12.4)	50.3 (11.1)	ns
Illness duration (SD), years	13.9 (7.1)	15.4 (9.2)	ns

Abbreviations: ns, not significant; SD, standard deviation.

Figure 1 Mean (SD) ratings of overall fatigue of participants with CFS before (black bars) and after (hatched bars) injections with 1% lidocaine or normal saline.

Notes: All subjects received concomitant injections into both shoulders and buttocks. Fatigue ratings were obtained before and 30 min after the muscle injections. Fatigue ratings of CFS participants decreased significantly more after lidocaine compared to normal saline injections (p = 0.03).
Abbreviations: CFS, chronic fatigue syndrome; SD, standard deviation; VAS, visual analog scale.

Figure 2 Mean (SD) pain ratings of participants with CFS before (black bars) and after (hatched bars) muscle injections with 1% lidocaine or normal saline.

Notes: All subjects received injections into both shoulders and buttocks in counterbalanced order. Pain ratings were obtained directly before and 30 min after the muscle injections. Pain ratings of CFS participants decreased significantly over time (p < 0.001) but not significantly more after lidocaine compared to normal saline injections (p > 0.05).
Abbreviations: CFS, chronic fatigue syndrome; SD, standard deviation; VAS, visual analog scale.

Table 2 Ratings of fatigue, pain, depression, and anxiety

	Lidocaine injections		Saline injections
	Before	After	Before	After
Fatigue VAS (SD)	6.3 (1.6)	4.1 (2.3)***	5.5 (1.4)	4.7 (2.1)***
Pain VAS (SD)	4.7 (2.1)	3.1 (2.0)***	4.3 (2.0)	3.0 (1.9)***
Depression VAS (SD)	1.6 (2.0)	1.2 (1.6)**	1.4 (1.9)	0.4 (0.1)**
Anxiety VAS (SD)	2.4 (2.2)	2.0 (2.2)*	2.5 (2.5)	1.6 (2.2)*

Notes:

*** p < 0.001;

** p = 0.003;

* p < 0.05.

Abbreviations: SD, standard deviation; VAS, visual analog scale.

Figure 3 Average pressure pain thresholds (SD) of patients with CFS before (black bar) and 30 min after (hatched bar) muscle injections with 1% lidocaine or normal saline into both shoulder and gluteal areas.

Notes: Pressure pain thresholds were tested at (A) trapezius muscles and (B) gluteal muscles. Pressure pain thresholds significantly increased 30 min after the injections (p < 0.05) at all sites, but this effect was only significantly different between lidocaine and normal saline at the shoulders (p = 0.03).
Abbreviations: CFS, chronic fatigue syndrome; SD, standard deviation.

Table 3 Time × condition interaction effects of muscle injections on mechanical pain thresholds

	Mechanical pain threshold (F(1,46))	${\eta }_p^2$	p-value	Time × condition (F(1,46))	${\eta }_p^2$	p-value
Shoulders	31.25	0.38	<0.001	5.01	0.09	0.03
Buttocks	29.52	0.38	<0.001	1.54	0.03	>0.05

Notes: Bold figures indicate the statistically significant results.

Figure 4 Average heat pain ratings (SD) of 10 s heat stimuli in patients with CFS at 45°C before (black bars) and 30 min after (hatched bars) muscle injections with 1% lidocaine or normal saline into both shoulder and gluteal areas.

Notes: Supra-threshold heat pain stimuli were applied to the (A) forearms and (B) lower legs (over the anterior tibialis muscles). Heat pain ratings at both sites were not significantly different after injections with lidocaine or normal saline (p > 0.05).
Abbreviations: CFS, chronic fatigue syndrome; SD, standard deviation.

Table 4 Time × condition interaction effects of muscle injections on heat pain ratings

	Heat pain ratings (F(1,56))	${\eta }_p^2$	p-value	Ratings × condition (F(1,56))	${\eta }_p^2$	p-value
Arm 45°C	0.995	0.017	>0.05	0.267	0.005	>0.05
Leg 45°C	7.63	0.12	0.008	0.0	0.0	>0.05

Notes: Bold figure indicates the statistically significant result.