Identification of complex regional pain syndrome in the upper limb: Skin temperature asymmetry after cold pressor test

Figures & data

Figure 1. Testing areas for each of the major peripheral nerve distributions in the hand.

Table 1. Patient demographics and baseline characteristics (N = 33).

Characteristics		Mean	SD	Range
Age		46.2	13.7	15–76
Duration of injury or pain (months)		22.4	38.5	1–184
SkTA pre CPT (°C)	Median	0.99	1.22	0.1–6.4
	Ulnar	1.09	0.85	0–3.6
	Radial	0.81	0.68	0–2.7
SkTA post CPT (°C)	Median	1.43	1.31	0.1–5.3
	Ulnar	1.13	1.00	0–4.9
	Radial	1.01	0.95	0–3.4
Characteristic		Frequency	Percentage
Gender		M = 16 F = 17	M = 48.5% F = 51.5%
Diagnosis		CRPS = 17 PNI = 10 Fracture = 6	51.5% 30.3% 18.2%
Dominance		R = 21 L = 12	R = 63.6% L = 36.4%
Side of injury		R = 17 L = 16	R = 51.5% L = 48.5%

SkTA = skin temperature asymmetry; CPT = cold pressor test; M = male; F = female; R = right; L = left; CRPS = complex regional pain syndrome; PNI = peripheral nerve injury.

Table 2. Healthy volunteers (n = 32).

Characteristics		Mean	SD	Range
Age		39.3	12.1	20– 59
SkTA pre CPT (°C)	Median	0.40	0.39	0– 1.4
	Ulnar	0.62	0.46	0–2.1
	Radial	1.67	1.38	0–5.0
SkTA post CPT (°C)	Median	0.37	0.36	0–1.4
	Ulnar	0.63	0.50	0–2.0
	Radial	0.26	0.21	0– 0.9
Characteristic		Frequency	Percentage
Gender		M = 9 F = 23	M = 32.1% F = 71.9%
Dominance		R = 29 L = 3	R = 90.6% L = 9.3%

SkTA = skin temperature asymmetry; CPT = cold pressor test; M = male; F = female; R = right; L = left.

Table 3. Temperature values by nerve distribution.

Patient characteristics		Mean	SD	Range
Median	Pre CPT	A = 31.9	1.7	27.0–34.4
		U = 31.6	1.7	27.1–34.1
	Post CPT	A = 31.8	1.7	27.0–34.1
		U = 31.5	1.7	27.0–33.7
Ulnar	Pre CPT	A = 31.9	1.8	28.5–34.9
		U = 31.8	1.8	27.3–34.7
	Post CPT	A = 31.5	1.8	28.0–34.8
		U = 31.5	2.1	27.1–34.9
Radial	Pre CPT	A = 31.8	2.7	25.2–36.1
		U = 32.0	2.2	27.5–36.0
	Post CPT	A = 31.2	2.8	24.7–35.6
		U = 31.5	2.3	26.3–35.2
Healthy volunteer characteristics		Mean	SD	Range
Median	Pre CPT	R = 28.8	3.8	21.8–35.0
		L = 29.0	3.6	23.2–34.9
	Post CPT	R = 28.5	3.8	22.7–34.8
		L = 28.7	3.6	23.2–35.0
Ulnar	Pre CPT	R = 30.4	2.5	24.5–34.4
		L = 30.8	2.3	26.2–34.5
	Post CPT	R = 30.5	2.2	27.0–34.3
		L = 30.9	2.0	27.2–34.4
Radial	Pre CPT	R = 31.0	1.5	28.2–33.4
		L = 31.0	1.4	28.1–33.7
	Post CPT	R = 31.0	1.6	27.7–33.4
		L = 31.0	1.5	28.6–33.5

CPT = cold pressor test; A = affected hand; U = unaffected hand; R = right hand; L = left hand.

Table 4. Sensitivity and specificity estimates.

Diagnostic value	Cut-point	Pre CPT (95% CI)	Post CPT (95% CI)
Sensitivity	>1.0°C SkTA	88.2 (63.6–98.5)	88.2 (63.6–98.5)
Specificity		37.5 (15.2–64.6)	18.8 (4.1–47.5)
Sensitivity	>1.5°C SkTA	58.8 (32.9–81.6)	82.4 (56.6–96.2)
Specificity		56.3 (29.9–80.3)	43.8 (19.8–70.1)
Sensitivity	>2.0°C SkTA	29.4 (10.3–56.0)	52.9 (27.8–77.0)
Specificity		81.3 (54.4–96.0)	56.3 (29.9–80.3)

CPT = cold pressor test; SkTA = skin temperature asymmetry.

Figure 2. ROC curve plotted using the largest asymmetry value from each subject pre and post CPT.