Proprioceptive reflexes in patients with reflex sympathetic dystrophy.

Reflex sympathetic dystrophy (RSD) is a syndrome that frequently follows an injury and is characterized by sensory, autonomic and motor features of the affected extremities. One of the more common motor features of RSD is tonic dystonia, which is caused by impairment of inhibitory interneuronal spinal circuits. In this study the circuits that modulate the gain of proprioceptive reflexes of the shoulder musculature are quantitatively assessed in 19 RSD patients, 9 of whom presented with dystonia. The proprioceptive reflexes are quantified by applying two types of force disturbances: (1) disturbances with a fixed low frequency and a variable bandwidth and (2) disturbances with a small bandwidth around a prescribed centre frequency. Compared to controls, patients have lower reflex gains for velocity feedback in response to the disturbances around a prescribed centre frequency. Additionally, patients with dystonia lack the ability to generate negative reflex gains for position feedback, for these same disturbances. Proprioceptive reflexes to the disturbances with a fixed low frequency and variable bandwidth present no difference between patients and controls. Although dystonia in the RSD patients was limited to the distal musculature, the results suggest involvement of interneuronal circuits that mediate postsynaptic inhibition of the motoneurons of the proximal musculature.

Diagnostic criteria used in studies of reflex sympathetic dystrophy.

OBJECTIVE: Assessment of the diagnostic criteria of reflex sympathetic dystrophy (RSD) and evaluation of the impact of the introduction of the diagnostic criteria of complex regional pain syndrome (CRPS) on the international application of diagnostic criteria of RSD. METHODS: Randomized controlled trials and clinical investigations, published between January 1980 and June 2000, were evaluated with regard to the applied diagnostic criteria of RSD. RESULTS: One hundred seven studies were identified. Thirty-four of these studies were excluded because of inadequate reporting of diagnostic criteria. The 73 included studies were not homogeneous with regard to the diagnostic criteria because they applied many different aspects of sensory and autonomic features. Only 12% of the studies considered the presence of motor features, mostly vaguely described, as mandatory for the diagnosis RSD. Although 10 of the 23 studies published since the introduction of CRPS have applied this term, only 3 used the exact criteria without additions or other modifications. CONCLUSION: Diagnostic criteria sets of RSD focus on many different aspects of sensory and autonomic features that generally are described vaguely. This has not changed since the introduction of the CPRS criteria. These findings question whether the current criteria adequately define RSD.

Innate cytokine profile in patients with complex regional pain syndrome is normal.

Complex regional pain syndrome (CRPS) is a disabling disease characterized by the classic symptoms and signs of inflammation. In this study we investigated the innate cytokine profile in patients with CRPS to determine a possible role of the immune system in the pathophysiology of CRPS. The cytokine profile before and after lipopolysaccharide and thrombin stimulation was determined in 26 severely affected CRPS patients and 20 healthy controls. No difference in the production of pro- and anti- inflammatory cytokines between patients and controls was found. Hence, our results do not support a role of genetic factors responsible for the cytokine profile in the pathophysiology of CRPS. These findings encourage further investigations of mechanisms responsible for neurogenic-induced inflammation.