Background and Objectives The aim of the present case series was to examine whether changes in regional cerebral blood flow (rCBF) induced by electroconvulsive therapy (ECT) in the thalamus are related to the efficacy of ECT. Four chronic pain patients with complex regional pain syndrome (CRPS) type-1 (age, 33 to 58 years) who had failed to respond to standard pain treatments received a course of ECT. To investigate the possible mechanisms of the analgesic effect of ECT on chronic CRPS type-1, we measured significant changes in the rCBF of the thalamus using technetium-99m ethyl cysteinate dimer single photon emission computed tomography (99mTc ECD SPECT), before and after ECT and compared these values between responders and nonresponders.

Results Two of 4 (50.0%) patients responded to ECT treatment (response defined as a reduction of at least 60% on the visual analog scale [VAS]). 99mTc ECD SPECT showed that the mean contralateral thalamus-to-cerebellum ratio increased 11.5% after ECT compared with the ratio before ECT in the 2 responders, but remained unchanged in nonresponders.

Conclusions The results from the SPECT suggest that normalization of the balance of rCBF in the thalamus may be related to the analgesic efficacy of the ECT on CRPS Type-1.