Parkinson's disease (PD) is among the disorders in which the placebo effect can play a significant role. [1][2][3][4] Functional imaging studies have demonstrated that this effect is related to dopamine release in the striatum. 5 This dopamine release appears to be linked to expectation of reward (i.e., clinical benefit), which is in turn mediated by dopamine release in the ventral striatum.Since the initial description of high-frequency deep brain stimulation (DBS) of the subthalamic nucleus (STN) for the treatment of severe PD in 1995, 6 many centers have reported efficacy and the safety of this procedure. 7-10 Despite its clinical success, the mechanism underlying the effects of STN DBS in PD remains unknown. 11 Only two previous studies have been published describing the role played by expectation in the outcome of movement velocity in parkinsonian patients treated with effective STN DBS. 12,13 The objective of this study is to determine whether the degree to which patients with Parkinson's disease expect therapeutic benefit from STN DBS influences the magnitude of their improved motor response. PATIENTS AND METHODS This study was approved by the University of British Columbia Clinical Research Ethics Board (C98-0404).Ten patients with idiopathic Parkinson's disease who had received bilateral STN DBS were enrolled in the study. Disabling motor fluctuations with severe bradykinesia and dyskinesias secondary to the chronic use of antiparkinsonian medication were the main indications for surgery. There were two women and eight men whose mean age was 61 years (range, 42-78 years). The mean duration of the symptoms before surgery was 14 years (range, 6 -23 years). All underwent microelectrode-guided placement of bilateral deep brain stimulation electrodes (model 3389; Medtronic, Minneapolis, MN) in the subthalamic nuclei, connected to an implantable pulse generator below the left clavicle (Kinetra, model 7428; Medtronic). The stimulation parameters and reduced level of medications were then optimized over several months. At the moment of the study, the mean dose of L-dopa and dopamine agonist in the form of L-dopa equivalents that the patients were receiving was 690 mg (range, 200 -1,300 mg). Patients were then tested for this study after a 12-hour period of no antiparkinsonian medications and no stimulation. Four consecutive Unified Parkinson's Disease Rating Scale (UPDRS) scores were performed in the following conditions: stimulator OFF and patient aware that the stimulation was OFF; stimulator OFF and patient unaware whether the stimulation was ON or OFF; stimulator ON, patient aware; stimulator ON, patient blind. The four conditions were randomly assigned. The stimulator remained OFF or was switched OFF for 10 minutes after each evaluation. The patients were evalu-

Intracranial aneurysms (IAs) are found more often in patients with aortic coarctation (AC) than in the general population and aneurysm rupture occurs much earlier in the lives of these patients when there is coexistent AC. The diagnosis of AC is frequently made only after a serious cerebrovascular complication has developed. The aim of this paper is to call attention to AC in patients presenting with aneurysmal subarachnoid hemorrhage. The literature is reviewed, the key clinical features are highlighted, and the proposed pathogenesis of this association is discussed. The authors present clinical information and imaging data obtained in three young patients with ruptured IAs that were associated with initially unnoticed AC. Abnormal results of cardiovascular examinations led the authors to consider an underlying AC, which was later confirmed by aortography. These aneurysms were successfully treated prior to correction of the ACs. The diagnosis of AC should be considered in adolescent and young adult patients presenting with IAs.

The anatomy of the nuclei and fiber projections within the ventrolateral thalamus in humans can be described using 3T MR imaging. The findings were reproducible in vivo with 3T but not 1.5T MR imaging. Additional studies are needed to confirm the accuracy of this observation for clinical purposes.