BONE ATROPHY IN COMPLEX REGIONAL PAIN SYNDROME PATIENTS MEASURED BY MICRODENSITOMETRY

Purpose: To determine the usefulness of quantitative measurement of bo ne atrophy in the diagnosis and the long-term follow-up of patients wi th complex regional pain syndrome (CRPS), The bone-sparing effect of a 5-hydroxytriptamine (5-HT2) antagonist was also studied. Methods: Bon e mass was measured by computerized micro-densitometry at the middle p osition of the second metacarpal, The effect of repeated stellate gang lion blocks (SGBs) three times per week with mepivacaine (n = 11), adm inistration of a 5-HT2 antagonist (sarpogrelate hydrochloride, 300 mg a day po) (n = 12), and combined therapy (n = 10) were compared by mic ro-densitometry and conventional visual analogue scale (VAS) for analg esia after three months of treatment. Results: In CRPS patients, metac arpal index (cortical bone thickness), maximum bone density (cortical bone density), minimum bone density (trabecular bone density), and ave rage bone density were reduced on the affected side (14.1%, 12.1%, 25. 0% and 19.3% respectively). The rate of reduction in bone mass correla ted with the duration of the disease (P < 0.05). Therapy with the 5-HT 2 receptor antagonist (with or without repeated SGBs) decreased pain i ntensity (from 6.10 to 3.81 with SGB, from 6.30 to 2.91 without SGB, r espectively; P < 0.01) and bone atrophy evaluated by micro-densitometr y (P < 0.05). In contrast, repeated SGBs alone reduced pain intensity (from 6.30 to 2.91; P < 0.01) but did not ameliorate bone atrophy, Con clusion: Bone micro-densitometry is useful in the assessment and follo w-up of CRPS and for evaluation oi treatment. The 5-HT2 antagonist, sa rpogrelate hydrochloride, is a promising treatment for CRPS patients.