[Recent trends in understanding and therapy of complex regional pain syndromes]. / Das komplexe regionale Schmerzsyndrom. Neue Erkenntnisse.

Since the term "complex regional pain syndromes" (CRPS) was introduced based on a revised taxonomy for disorders previously called reflex sympathetic dystrophy and causalgia in 1995, much knowledge grew up on the understanding and therapy of the disease. This review gives an overview on the clinical characteristics, pathophysiology, diagnostic tools and therapeutic options in CRPS. It will especially focus on recent findings on the role of the sympathetic nervous system, the central nervous system and peripheral inflammatory processes as underlying mechanisms. Although there is no diagnostic gold standard, careful clinical evaluation and additional apparative test procedures are very helpful for the diagnosis. An early and interdisciplinary approach is the basis for an optimal and successful treatment.

[The symptom sympathetic maintained pain]. / Das Symptom sympathisch unterhaltener Schmerz.

Sympathetically maintained pain is a symptom which occurs in neuropathic pain syndromes of different etiologies. From animal experiments it is known that nociceptive afferents after partial nerve lesions develop adrenergic sensitivity at the site of the injury. In addition, a sympathetic-afferent coupling takes place in the dorsal root ganglia. It is still controversial if these pathophysiological mechanisms are responsible for the developing of SMP in humans. Clinical studies support the idea that also in humans the application of adrenergic substances in pharmacological doses is capable to influence nociception, but a direct interaction between the sympathetic system and the nociceptive system had not been demonstrated so far. By using a thermal suit for whole body cooling and warming, which produces low and high activity of sympathetic vasoconstrictor neurons, it was possible for the first time to demonstrate an interaction between physiological changes in sympathetic activity and nociception.

[Prophylaxis of postoperative nausea and vomiting (PONV) in children undergoing strabismus surgery. Sevoflurane/N2O plus dimenhydrinate vs.propofol/remifentanil plus dimenhydrinate]. / Prophylaxe von Ubelkeit und Erbrechen bei Kindern nach Strabismuschirurgie. Sevofluran/Lachgas vs.Propofol/Remifentanil unter Gabe von Dimenhydrinat.

UNLABELLED: BACKGROUND AND STUDY GOALS: Strabismus surgery in children is frequently associated with a very high incidence of postoperative nausea and vomiting (PONV). In this study we investigated, whether TIVA is superior to inhalation anaesthesia concerning PONV when a prophylaxis using dimenhydrinate (diphenhydramine chlorotheophyllate) is administered in both groups. METHODS: 110 patients (3-10 years) were prospectively and randomly allocated to one of the following groups: Group TD (TIVA/dimenhydrinate; n= 55): anaesthesia was induced and maintained using remifentanil and propofol in common clinical dosages. Patients were ventilated with 30% O(2) in air. Group VD (Volatile/ dimenhydrinate; n= 55): anaesthesia was induced and maintained with sevoflurane in common clinical concentrations together with N(2)O in 30% O(2). All patients received dimenhydrinate 1 mg.kg(-1) i.v. after induction. PONV was recorded within the first 24 h postoperatively. The chi-square test and a multivariate analysis were used for statistical analysis. RESULTS: 52 patients of group TD and 54 of group VD were analysed. There was a trend in the incidence of postoperative nausea (PN): group TD 17%, 95% CI: 8-30%) compared to group VD 31%, 95% CI: 20-46%), p = 0.09. No difference was seen for PV and PONV: 21% (95% CI: 11-35%) in group TD vs. 35% (95% CI: 23-49%) in group VD, p = 0.109. These non-significant results can be easily attributed to the lack of power about 30%) of this study. According to the results of the multivariate analysis volatile anaesthesia was identified as an independent risk factor for PONV (OR: 2.92, 95% CI: 1.02-8.36). Other variables that were found to be an independent risk factor included history of PONV (OR: 8.19, 95% CI: 1.84-36.43), surgery lasting longer than 30 min (OR: 5.89, 95% CI: 1.82-19.82) and "Faden-operations" (retroequatorial myopexy) (OR: 5.48, 95% CI: 1.74-17.21). CONCLUSIONS: TD only showed a trend to lower PN incidences and no differences as for PV and PONV incidences, most likely due to a lack of power of this study. However, according to the results of the multivariate analysis, inhalation anaesthesia was shown to be an independent risk factor for PONV, as were history of PONV, surgery >30 min and "Faden-operations".

Relation between sympathetic vasoconstrictor activity and pain and hyperalgesia in complex regional pain syndromes: a case-control study.

BACKGROUND: Complex regional pain syndromes can be relieved by sympathetic blockage. The mechanisms of sympathetically maintained pain (SMP) are unclear. We aimed to establish the effect of physiological sympathetic cutaneous vasoconstrictor activity on pain and hyperalgesia in patients with complex regional pain syndromes. METHODS: High and low cutaneous vasoconstrictor activity was produced by whole-body cooling and warming (thermal suit) in 13 patients with type I disease and in ten controls. The degree of cutaneous vasoconstrictor discharge was monitored by measurement of skin blood flow and temperature at the arm and leg. Local skin temperature at the affected region was fixed at 35 degrees C. Pain was quantified during high and low cutaneous vasoconstrictor activity (intensity of spontaneous pain, area of mechanical hyperalgesias, heat-pain thresholds). Furthermore, pain was measured before and after diagnostic sympathetic blockage to identify patients with SMP and sympathetically independent pain. FINDINGS: In patients with SMP, intensity of spontaneous pain significantly increased, by 22%, and spatial distribution of mechanical dynamic and punctate hyperalgesia increased by 42% and 27%, respectively, during high sympathetic activity compared with low activity. Heat-pain thresholds did not differ during high and low cutaneous vasoconstrictor activity (cold and warm state, 43.6 degrees C vs 44.6 degrees C). Pain relief after sympathetic blockage correlated with augmentation of spontaneous pain after experimental stimulation of cutaneous vasoconstrictor activity (r=0.6, p=0.0244). INTERPRETATION: We have shown that in complex regional pain syndromes with SMP, physiological activation of cutaneous vasoconstrictor neurons projecting to the painful arm or leg enhances spontaneous pain and hyperalgesia. We postulate that there is a pathological interaction between sympathetic and afferent neurons within the skin.