REGIONAL XENON-133 CEREBRAL BLOOD-FLOW AND CEREBRAL TC-99M-HMPAO UPTAKE IN PATIENTS WITH OBSESSIVE-COMPULSIVE DISORDER BEFORE AND DURING TREATMENT

We previously reported increased regional cerebral cortical uptake and decreased caudate nucleus uptake of Tc-99M-HMPAO in patients with obs essive-compulsive disorder (OCD) before treatment compared to matched normal controls. In the present study, we determined whether or not th ese changes persisted during treatment. Single-photon emission compute d tomography was used to measure regional cerebral blood flow (rCBF) b y Xe-133 inhalation and regional cerebral uptake of Tc-99M-HMPAO in ei ght adult male OCD patients before and during treatment with clomipram ine, and in eight age-matched normal male controls. With Xe-133, there were no significant differences in rCBF between the patients with OCD and their matched controls, and no significant differences in rCBF in the patients before and during treatment. Significantly increased HMP AO uptake in the orbital frontal cortex, posterofrontal cortex, and hi gh dorsal parietal cortex bilaterally occurred in the OCD patients bef ore treatment compared to their matched controls, and there were signi ficant reductions of HMPAO uptake, into the normal range, in all these areas in the patients during treatment. Significantly reduced HMPAO u ptake in the caudate nucleus bilaterally occurred in the patients befo re treatment compared to their matched controls, and these reductions persisted during treatment. This study provides additional support for the involvement of both the orbital frontal cortex and the caudate nu clei in the pathophysiology of OCD.