Clinical and physiologic evaluation of stellate ganglion blockade for complex regional pain syndrome type I

Objective: The efficacy of peripheral sympathetic interruption after stella te ganglion blockade was assessed by a sympathetic function test. Results w ere compared with clinical signs such as temperature changes, pain reductio n, and the development of Horner syndrome to evaluate the correlation with clinical investigations. Design: Stellate ganglion blockade with local anesthetics was carried out v ia an anterior paratracheal approach in 33 patients suffering from complex regional pain syndrome type I. Patients were examined before and after the procedure. For assessment of sympathetic nervous function, the vasoconstric tor response to sympathetic stimuli was assessed using laser Doppler flowme try. Clinical parameters like surface temperature changes (thermography), p ain relief (visual analogue scale), and Horner syndrome were monitored. Results: Twenty-three (70%) of 33 patients developed an increase in tempera ture difference between the treated hand and the contralateral hand of more than 1.5 degreesC after the procedure, which is a clinical sign of sympath icolysis. In 48% (n = 11) of these patients, the sympathetic function test showed an undisturbed sympathetic nervous function. In 10 patients, no sign ificant increase in temperature difference was observed. Although these pat ients presented with a normal sympathetic vasoconstrictor response, 4 felt pain relief of more than 50%, suggesting a placebo effect. Only 7 patients with pain relief revealed both clinical sympathicolysis and extinguished sy mpathetic nervous function and qualified for sympathetically maintained pai n. Conclusions: Clinical investigation is not reliable in the assessment of st ellate ganglion blockade. Proof of sympathetically maintained pain based on pain relief after stellate ganglion blockade is not conclusive.