Oxidative stress in Complex Regional Pain Syndrome (CRPS): no systemically elevated levels of malondialdehyde, F2-isoprostanes and 8OHdG in a selected sample of patients.

Exaggerated inflammation and oxidative stress are involved in the pathogenesis of Complex Regional Pain Syndrome (CRPS). However, studies assessing markers for oxidative stress in CRPS patients are limited. In this study, markers for lipid peroxidation (malondialdehyde and F2-isoprostanes) and DNA damage (8-hydroxy-2-deoxyguanosine) were measured in nine patients (mean age 50.1 ± 17.1 years) with short term CRPS-1 (median 3 months) and nine age and sex matched healthy volunteers (mean age 49.3 ± 16.8 years) to assess and compare the level of oxidative stress. No differences were found in plasma between CRPS patients and healthy volunteers for malondialdehyde (5.2 ± 0.9 µmol/L vs. 5.4 ± 0.5 µmol/L) F2-isoprostanes (83.9 ± 18.7 pg/mL vs. 80.5 ± 12.3 pg/mL) and 8-hydroxy-2-deoxyguanosine (92.6 ± 25.5 pmol/L vs. 86.9 ± 19.0 pmol/L). Likewise, in urine, no differences were observed between CRPS patients and healthy volunteers for F2-isoprostanes (117 ng/mmol, IQR 54.5-124.3 vs. 85 ng/mmol, IQR 55.5-110) and 8-hydroxy-2-deoxyguanosine (1.4 ± 0.7 nmol/mmol vs. 1.4 ± 0.5 nmol/mmol). Our data show no elevation of systemic markers of oxidative stress in CRPS patients compared to matched healthy volunteers. Future research should focus on local sampling methods of oxidative stress with adequate patient selection based on CRPS phenotype and lifestyle.

Intravenous clodronate in the treatment of reflex sympathetic dystrophy syndrome. A randomized, double blind, placebo controlled study.

OBJECTIVE: To evaluate the efficacy of intravenous (i.v.) clodronate in patients with reflex sympathetic dystrophy syndrome (RSDS) and to assess the urinary excretion of type I collagen crosslinked N-telopeptide (NTx) before and after the treatment. METHODS: Thirty-two patients with RSDS were randomized to receive either i.v. clodronate 300 mg daily for 10 consecutive days or placebo. Forty days later, the placebo treated patients received the clodronate treatment. Outcome measures included as a primary endpoint the visual analog scale of pain (VAS, range 0-100); secondary endpoints were a clinical global assessment (CGA, range 0-3) and an efficacy verbal score (EVS, range 0-3). Clinical and biochemical assessments were performed before the treatment, 40 (T40), 90 (T90), and 180 (T180) days later. RESULTS: At T40 the 15 patients randomized to clodronate treatment showed significant decreases of VAS and CGA (p = 0.002, p = 0.001, respectively). Compared with the placebo group (17 patients), significant differences were found in all clinical variables (VAS: p = 0.001; CGA: p = 0.001; EVS: p<0.0001). A further clinical improvement was observed throughout the study. Pooling the results of all 32 patients after clodronate treatment, at T180 the overall percentage decrease of VAS was 93.2+/-15.6%, with 30 patients significantly improved or asymptomatic. Significant inverse correlations between baseline NTx values and decreases of VAS were found at T90 (p = 0.03) and T180 (p = 0.01). No adverse events related to treatment occurred. CONCLUSION: A 10 day i.v. clodronate course is better than placebo and effective in the treatment of RSDS. NTx seems to be a predictive factor for clodronate efficacy.

Phosphate excretion in reflex sympathetic dystrophy syndrome before and after a single infusion of pamidronate.

To clarify the relations between reflex sympathetic dystrophy syndrome and moderate phosphate diabetes, we prospectively determined urinary phosphate excretion parameters (clearance, renal tubular reabsorption of phosphate and threshold of tubular reabsorption of phosphate) in 37 patients with reflex sympathetic dystrophy syndrome before and after treatment with 60 mg of pamidronate (n = 23) and in 35 age- and sex-matched controls. Urinary phosphate excretion parameters were identical in cases and in controls. Fourteen of the 23 cases treated by pamidronate were improved after one to two months. Pamidronate had no effect on phosphate excretion. Four cases versus only one control had phosphate diabetes (X2 = 0.18). Three of the four cases with phosphate diabetes failed to respond to pamidronate therapy but improved under phosphate and 1,25-diOH vitamin D3 therapy.