A study carried out by Clark et al [1] used thermographic imaging and a cold provocation test to investigate whether temperature differences between the digits and the dorsum of the hands were different between patients with primary Raynaud's phenomenon and those with underlying systemic sclerosis. Their principal conclusion was that a distal-dorsal temperature difference of >1°C is specific for underlying connective tissue disorder at ambient 30°C.
In order to investigate the possible clinical usefulness of the distal-dorsal temperature difference (DiD) in our laboratory, thermographic images from patients who had attended for routine Raynaud's assessments were analysed retrospectively. Patients were classified (again retrospectively after obtaining ethical approval) according to clear clinical diagnosis: Primary Raynaud's phenomenon (PR, n=26), Connective Tissue Disorders (CTD, n=8), Hand Arm Vibration Syndrome (VWF, n=16), and non-age-matched Normal volunteers (N, n=7).
Patients were acclimatised in a standard environment (23°C) for a minimum of 15 min. (and up to 60 min.) until all digits had vasodilated sufficiently to carry out a cold challenge (15°C for 1 minute). Thermographic images were recorded using a Starsight system (Insight Vision Systems) prior to the cold challenge (baseline, B) and at 6 min. (6) and 12 min. (12) post cooling. These were evaluated for DiD together with thumb-dorsal (ThD) and digit-thumb (DiTh) temperature differences, including left (L) and right (R) differences in the patient groups. No parameters were normally distributed, so the Mann Whitney test was applied. Differences between median values were considered significant for p <0.05. There were significant differences between all patient groups and the normal subjects (not tabulated for reasons of space). The tables below summarise the within group differences for all subjects and between group differences for the patients. Significant positive and negative temperature differences are designated as + and - respectively; 0 signifies no significant difference.
Within Group Differences |
DiD |
ThD |
DiTh |
|---|---|---|---|
| N (B,6,12) | 0+0 | 0++ | 000 |
| PR (B,6,12) | 0-- | 000 | --- |
| CTD (B,6,12 | --- | 0-0 | 000 |
| VWF (B,6,12) | 0-0 | 0-0 | 000 |
Between Patient Group Differences |
DiD |
ThD |
DiTh |
DiTh L |
DiTh R |
|---|---|---|---|---|---|
| CTD vs PR (B,6,12) | -00 | 0-0 | 000 | 000 | 000 |
| VWF vs PR (B,6,12) | 000 | 000 | 000 | ++0 | 000 |
| CTD vs VWF (B,6,12) | 000 | 000 | -00 | -00 | 000 |
In summary, as with the Clark et al [1] study, a significant baseline DiD was found between PR and CTD patients (at ambient 23°C in this study). Additional measurements of ThD and DiTh temperature differences at 6 min. and 12 min. post cold provocation revealed further significant differences between PR, CTD and VWF patients. Differentiation between right and left hand temperature differences provided further significant indicators of PR-CTD, PR-VWF and VWF-CTD differences, which appear to be characteristic for each group.
Further analysis is required to establish potentially diagnostic levels of temperature differences between the groups and determine their sensitivities and specificities before these observations can be applied clinically to Raynaud's assessment reporting. Analysis of results according to dominant hand (rather than simply left and right) may improve differentiation between groups (in particular VWF).
References:
[1] S. Clark, S. Hollis, F. Campbell, T. Moore, M. Jayson & A. Herrick, The distal-dorsal difference as a possible predictor of secondary Raynaud's phenomenon. J. Rheumatol. 26: 1125-1128 (1999).
Harrison DK, Curd C, Mansy S, Hailwood S, Chuck, A. Distal-dorsal temperature measurements reveal characteristic differences between types of Raynaud's phenomena. Thermology Int 15: 153.
Dr. David K. Harrison, Durham Unit, Durham. Tel: +44 (0)191-333-2215.
Regional Medical Physics Department, Freeman Hospital, Newcastle upon Tyne, NE7 7DN, UK.
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