Presentation: Sparing of the Thumb in Raynaud’s Phenomenon (2007)

24 Sparing of the Thumb in Raynaud’s Phenomenon

Purpose
When specifically asked, many patients with Raynaud's phenomenon (RP) report that their thumbs are spared, yet to our knowledge the degree of thumb involvement in patients with RP has not been previously researched. Our objectives were to test the hypothesis that RP spares the thumbs and to determine whether thumb involvement (as assessed by symptoms and thermography) differs between primary RP (PRP) and secondary RP (SRP).
Methods
This was a cross-sectional study of 44 patients with RP. The following were documented to allow comparisons between fingers:
1. Symptoms of RP (biphasic colour change) in each digit, graded as 'never', 'sometimes' and 'always' affected during an attack of Raynaud's, as noted by the patient.
2. Thermography at 230C. A distal-dorsal difference (DDD) in temperature, finger tips minus dorsum of the hand, at 23 0C of -1 0C or less was considered to be clinically relevant.
3. The ‘worse’ of the left and right scores for each digit was considered for analysis. The results were analysed using McNemar’s tests and repeated measures analyses of variance.
Results
Fourteen patients (2 M, 12 F) had PRP and 30 (4 M, 26 F) had SRP, of whom 12 had systemic sclerosis. Mean age was 45 years (SD 15.7). Results are shown in Table 1.
Symptom scores in the thumb were significantly better than those in the fingers (p≤0.001 for each comparison). As only three participants had any finger scores better than the thumb, there was no power to compare PRP and SRP. Mean DDD was significantly better in the thumb (p<0.001 for each comparison). Although DDD scores were higher (better) in PRP (p=0.01), there was no evidence that the relative effect of the thumb differed between the two groups (p=0.26).
Conclusion
1. Our findings confirm that the thumbs are spared in RP, both primary and secondary, as demonstrated by both symptoms and thermography
2. The reasons for sparing of the thumb were not addressed in this study but raise questions regarding pathophysiology.
3. Thumb involvement could be of prognostic value, and should be the subject of prospective studies.
Table 1.Summary of symptoms and thermography(n=44)
Table 1.Summary of symptoms and thermography(n=44)
AlwaysNeverDDD<-10C at 23 0C
Thumb4 (9%)18 (41%)8 (18%)
Index finger30 (68%)2 (5%)28 (64%)
middle finger29 (66%)1 (2%)24 (55%)
ring fnger24 (54%)2 (5%)25 (57%)
little finger17 (39%)4 (9%)23 (52%)

 B.G. Chikura, None; T.L. Moore, None; J.B. Manning, None; A. Vail, None; A.L. Herrick, None.