Intraoperative fMRI for Monitoring the Effect of Deep Brain Stimulation in Four Patients with Intractable Obsessive-Compulsive Disorder

Purpose: To investigate the effects of low and high frequency deep brain stimulation (DBS) of the right nucleus accumbens (ACC) and right internal capsule in four patients with intractable obsessive compulsive disorder (OCD) using functional magnetic resonance imaging (fMRI) under intraoperative conditions. Method and Materials: MRI was used to control the stereotactically guided implantation of an electrode for DBS of the right ACC in four patients with intractable obsessive compulsive disorder (OCD). After inserting the electrode, the patients were transferred to the MRI unit. fMRI scans were performed under alternating stimulation conditions using a „block-design“. Stimulation parameters were varied according to stimulation frequency (high/120Hz vs. low/4Hz), voltage (4 V vs. 8 V) and location (nucleus accumbens vs. internal capsule). Results: Notably, we observed a high magnitude of variation across patients: Under high frequency stimulation, the first patient showed activations in the right striatum (globus pallidus, caudate nucleus, claustrum), the right orbitofrontal cortex (Brodmann area 9, 10) and the fusiform gyrus (Brodmann area 19). Under low-frequency stimulation, activation was visualized in the right lateral striatum. The second patient showed a strong left frontal cortical and anterior cingular activation under low frequency stimulation and a deactivation under high frequency stimulation in the same cortical areas. The third patient demonstrated activation under high frequency/high voltage stimulation of the internal capsule in the medial occipital cortex and the left inferior frontal lobe. In the fourth patient, high frequency stimulation led to strong activations with emphasis on bilateral limbic, thalamic and right dorso- and ventrolateral prefrontal cortical structures. Conclusions: Our preliminary findings show the feasibility to perform fMRI under intraoperative conditions. Intraoperative fMRI may provide additional information about the early mechanism of action of DBS of the right nucleus accumbens. Considering the heterogeneity of the results in a small patient population (n=4), further analysis on a broader empirical basis seems advisable and is currently under investigation.