Objectives: To test possible human lymphocyte antigen (HLA) associations in subjects with reflex sympathetic dystrophy (RSD), and to determine correlation of HLA associations to treatment outcomes.
Design: Identification of class I (HLA-A, B, C) and class II (HLA-DR and DQ) (MHC) antigens by well-defined reagents in patients with RSD.
Setting and patients: The HLA analysis was performed on 15 Caucasian women attending a university pain clinic and diagnosed with RSD on the basis of strict inclusion and exclusion criteria.
Outcome measures: Resistance to treatment was defined on the basis of lack of response to conservative management, failure to experience long-term symptom relief after sympathetic blocks, recurrence of pain after sympathectomy, need for palliative treatment, and degree of residual disability at the end of all treatments.
Results: A twofold increase of A3, B7, and DR2(15) MHC antigens was observed in the study population compared to control frequencies. Eighty (five of six) of DR2(15)-positive patients proved to be resistant to treatment.
Conclusions: The results of this pilot study are the first to suggest a possible genetic diathesis in RSD patients with poor treatment outcome. If this finding can be confirmed in larger studies, strictly defined RSD could constitute the third neuroimmune disorder (besides multiple sclerosis and narcolepsy) associated with DR2(15). Gene(s) conferring susceptibility to RSD may be present within or near the MHC region of the short arm of chromosome 6. Due to the small size of our study group it is imperative that larger studies be done in RSD patients employing strict diagnostic criteria to confirm or refute our original observations.