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The last two decades have seen a re-emergence of surgery for intractable psychiatric disease, in large part due to increased use of deep brain stimulation. The development of more precise, image-guided, less invasive interventions has improved the safety of these procedures, even though the relative merits of modulation at various targets remain under investigation. With an increase in the number and type of interventions for modulating mood/anxiety circuits, the need for biomarkers to guide surgeries and predict treatment response is as critical as ever. Electroencephalography (EEG) has a long history in clinical neurology, cognitive neuroscience, and functional neurosurgery, but has limited prior usage in psychiatric surgery. MEDLINE, Embase, and Psyc-INFO searches on the use of EEG in guiding psychiatric surgery yielded 611 articles, which were screened for relevance and quality. We synthesized three important themes. First, considerable evidence supports EEG as a biomarker for response to various surgical and non-surgical therapies, but large-scale investigations are lacking. Second, intraoperative EEG is likely more valuable than surface EEG for guiding target selection, but comes at the cost of greater invasiveness. Finally, EEG may be a promising tool for objective functional feedback in developing “closed-loop” psychosurgeries, but more systematic investigations are required.

Background: There is an urgent need to develop safe and effective treatments for patients with treatment-resistant depression (TRD). Several neurosurgical procedures have been developed to treat the dysfunctional brain circuits implicated in major depression. Objectives: This review describes the most common ablative procedures used to treat major depressive disorder: anterior cingulotomy, subcaudate tractotomy, limbic leucotomy, and anterior capsulotomy. The efficacy and safety of each are discussed and compared with other current and emerging modalities, including deep brain stimulation (DBS) and MR-guided focused ultrasound (MRgFUS). Methods: The PubMed and MEDLINE electronic databases were used in this study, through July 2016. Keywords, including “treatment resistant depression,” and “ablative neurosurgery,” etc. were used to generate reference hits. Results: Approximately a third to half of patients who underwent ablative procedures achieved a treatment response and/or remission. The efficacy and safety profiles corresponding to both ablative procedures and DBS were very similar. Conclusions: The longitudinal experience with ablative procedures shows that there remains an important role for accurate, discrete lesions in disrupting affective circuitry in the treatment of TRD. New modalities, such as MRgFUS, have the potential to further improve the accuracy of ablative procedures, while enhancing safety by obviating the need for open brain surgery.

Therapy-resistant depression (TRD) is highly prevalent and has major health and economic implications. Although it is associated with psychiatric and medical comorbidity, there does not appear to be any common underlying biological substrate: more likely TRD represents a final pathway for various subpopulations of major depressive disorder patients. Sequential treatment studies indicate that over 40% of patients have not achieved remission after 2 adequate trials. Atypical antipsychotics and neurostimulation therapies are the most recently applied approaches to TRD, each with considerable success. Nevertheless, there is an urgent need to characterize the subtypes of TRD (at neurotransmitter, neural circuitry or neuroanatomical levels) with the aim of providing a personalized medicine approach to treatment.