Deep Brain Stimulation (DBS) is a technique that consists of a surgically implanted lead that provides focal electrical neural-network modulation within a brain circuit or circuits of interest. Initially, modern DBS systems were developed to address dysfunctional circuits in patients diagnosed with Parkinson’s disease, treatment-resistant tremor or other movement disorders. Recently, DBS’s therapeutic role has expanded to several psychiatric disorders.
What are the pathologies that can be treated with DBS and what has your research with DBS suggested?
The definitions for “treatment resistance” have been clearly defined for the use of DBS in patients suffering from severe psychiatric diseases.
In the case of MDD, treatment resistance has been defined as the failure of standard of care interventions such as antidepressants and adjunctive medications, and psychotherapy (typically cognitive behavioral therapy [CBT]) as well as electroconvulsive therapy and/or transcranial magnetic stimulation. The medical histories of these patients are marked by multiple hospitalizations, and by multiple trials of ultimately ineffectual and therefore discouraging treatments. This so-called chronic, treatment-resistant depression (TRD) is a major public-health issue, as well as a pathophysiological conundrum. Several data suggest that dysfunctional brain circuits are implicated, and that high-frequency deep brain stimulation (DBS) could represent an adjustable and reversible method of modulating these brain areas.
In TRD, a number of case reports have been published, describing a range of different targets, including the lateral habenula (Sartorius et al., 2010), inferior thalamic pedoncle (Jimenez et al., 2005), and the medial forebrain bundle (Coenen et al., 2011). Using larger samples, Mayberg and Lozano reported striking results over the short (Lozano et al., 2012, Lozano et al., 2008) and longer-term (Holtzheimer et al., 2012) effects of DBS targeting the subgenual cingulate cortex. Their results have been confirmed by Puigdemont et al., 2012. Other teams (Bewernick et al., 2010, Bewernick et al., 2012, Malone et al., 2009, Schlaepfer et al., 2008) have also obtained promising results with brain targets corresponding to the ventral part of the striatum, including the ventral caudate and nucleus accumbens (Acb).
For patients suffering from OCD, the level of maximum resistance is highly likely to be attained. Considering that a failure of at least 2 SSRIs occur, then clomipramine, then additional antipsychotics at low doses may be applied as well as the inability to cope with the symptoms using intensive Cognitive Behavioral Therapy (Exposure and Response Prevention).