[New viewpoints on the clinical picture, diagnosis and pathophysiology of reflex sympathetic dystrophy (Sudeck's disease)].

Reflex sympathetic dystrophy can be elicited by various factors (e. g. trauma, herpes zoster, myocardial infarction). Independent of kind and site of a lesion, symptoms occur most often in the whole distal part of the affected extremity. There in most cases, a triad of autonomic, motor and sensory disturbances can be found clinically. For early diagnosis--beside clinical investigation--a comparative measurement of skin temperatures on both sides of finger or toe tips, respectively, is recommended. Hereby the clinical finding of a warmer or colder extremity can be proved, which supplies evidence of a disturbed skin blood flow. In case, the above mentioned triad and a disturbance of skin circulation is found, diagnosis of sympathetic reflex dystrophy can be made with great certainty. With regard to the underlying pathophysiology, symptoms can be explained at this time satisfactory only by the assumption of a vicious circle. Starting from a painful event (e.g. trauma, mark in a plaster cast, nerve lesion or myocardial infarction) a functional disturbance of the sympathetic nervous system is initiated. This results in a disturbance of the circulation in all of the affected tissues (skin, muscle, bone and joint), which finally gives rise to an abnormal excitation of afferent receptors, particularly of nociceptors. This excitation maintains the disturbance of the sympathetic nervous system at central nervous level (vicious circle). The most relevant pathomechanism in this process seems to be the occurrence of an imbalance between the activity of sympathetic vasoconstrictor neurons supplying arteries and those, supplying veins. A sympatholytic therapy, if applied in time, is able to cut off the vicious circle, which may lead to a restitutio ad integrum. Further investigations will show to what extent psychological factors are involved in developing the central nervous disturbance of the sympathetic nervous system and may also show if in addition the motor system is affected.