This pilot study was designed to assess the efficacy of low-frequency repetitive transcranial magnetic stimulation (rTMS) over the right orbitofrontal cortex (OFC) by means of a double-cone coil in patients suffering from obsessive-compulsive disorder. We hypothesized that low-frequency stimulation of the OFC would lead to a reduction in clinical symptoms, as measured on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). A randomized, double-blind, crossover design was implemented with two 1-week treatment periods (active stimulation versus sham stimulation) separated by a 1-month washout period. Concomitantly, a subgroup of patients underwent a positron emission tomography (PET) scan after each stimulation sequence. Statistical analyses compared the Y-BOCS scores at the end of each period. At day 7, we observed a significant decrease from baseline in the Y-BOCS scores, after both active (P<0.01) and sham stimulation (P=0.02). This decrease tended to be larger after active stimulation than after sham stimulation: −6 (−29, 0) points versus −2 (−20, 4) points (P=0.07). Active versus sham PET scan contrasts showed that stimulation was related to a bilateral decrease in the metabolism of the OFC. The OFC should definitely be regarded as a key neuroanatomical target for rTMS, as it is easier to reach than either the striatum or the subthalamic nucleus, structures favored in neurosurgical approaches.
ObjectiveThis review aimed to investigate the therapeutic potential of Deep Brain Stimulation (DBS) for treating resistant Major Depressive Disorder (MDD). We explored the role of Nucleus accumbens (Nac) as a target for treatment.MethodWe made a systematic review of all studies examining the mechanisms of action of high frequency brain stimulation and the pathophysiology of MDD. We also reported all the studies exploring the therapeutic potential of DBS in MDD.ResultsAs a central relay-structure, the Nac seems to play a central role in MDD symptomatology. We investigated its role as a primary target for DBS in depressed patients. Anatomically the Nac is at the centre of the interactions between dopaminergic, serotoninergic and glutamatergic systems. Functionally, the Nac is involved in both normal and abnormal reward processes and in anhedonia and loss of motivation. Due to its central location between the emotional system, the cognitive system and motor control system, the Nac seems to have a central role in mood and feeling regulation.ConclusionAccording to encouraging recent studies, DBS seems to be a promising technique in resistant MDD treatment.
This controlled study reports negative results on the primary outcome but demonstrates a transient effect of 20 Hz rTMS guided by neuronavigation and targeted on an accurate anatomical site for the treatment of AVHs in schizophrenia patients.
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