BackgroundFor patients with psychiatric illnesses remaining refractory to ‘standard’ therapies, neurosurgical procedures may be considered. Guidelines for safe and ethical conduct of such procedures have previously and independently been proposed by various local and regional expert groups.MethodsTo expand on these earlier documents, representative members of continental and international psychiatric and neurosurgical societies, joined efforts to further elaborate and adopt a pragmatic worldwide set of guidelines. These are intended to address a broad range of neuropsychiatric disorders, brain targets and neurosurgical techniques, taking into account cultural and social heterogeneities of healthcare environments.FindingsThe proposed consensus document highlights that, while stereotactic ablative procedures such as cingulotomy and capsulotomy for depression and obsessive-compulsive disorder are considered ‘established’ in some countries, they still lack level I evidence. Further, it is noted that deep brain stimulation in any brain target hitherto tried, and for any psychiatric or behavioural disorder, still remains at an investigational stage. Researchers are encouraged to design randomised controlled trials, based on scientific and data-driven rationales for disease and brain target selection. Experienced multidisciplinary teams are a mandatory requirement for the safe and ethical conduct of any psychiatric neurosurgery, ensuring documented refractoriness of patients, proper consent procedures that respect patient's capacity and autonomy, multifaceted preoperative as well as postoperative long-term follow-up evaluation, and reporting of effects and side effects for all patients.InterpretationThis consensus document on ethical and scientific conduct of psychiatric surgery worldwide is designed to enhance patient safety.

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OBJECTIVESurgical procedures involving deep brain stimulation (DBS) of the globus pallidus internus (GPi) or subthalamic nucleus (STN) are well-established treatments for isolated dystonia. However, selection of the best stimulation target remains a matter of debate. The authors’ objective was to compare the effectiveness of DBS of the GPi and the STN in patients with isolated dystonia.METHODSIn this matched retrospective cohort study, the authors searched an institutional database for data on all patients with isolated dystonia who had undergone bilateral implantation of DBS electrodes in either the GPi or STN in the period from January 30, 2014, to June 30, 2017. Standardized assessments of dystonia and health-related quality of life using the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) and SF-36 were conducted before and at 1, 6, and 12 months after surgery. No patients were lost to the 6-month follow-up; 5 patients were lost to the 12-month follow-up.RESULTSBoth GPi (14 patients) and STN (16 patients) stimulation produced significant improvement in dystonia and quality of life in all 30 patients found in the database search. At the 1-month follow-up, however, the percentage improvement in the BFMDRS total movement score was significantly (p = 0.01) larger after STN DBS (64%) than after GPi DBS (48%). At the 12-month follow-up, the percentage improvement in the axis subscore was significantly (p = 0.03) larger after GPi DBS (93%) than after STN DBS (83%). Also, the total amount of electrical energy delivered was significantly (p = 0.008) lower with STN DBS than with GPi DBS (124 ± 52 vs 192 ± 65 μJ, respectively).CONCLUSIONSThe GPi and STN are both effective targets in alleviating dystonia and improving quality of life. However, GPi stimulation may be better for patients with axial symptoms. Moreover, STN stimulation may produce a larger clinical response within 1 month after surgery and may have a potential economic advantage in terms of lower battery consumption.

Background: Given that anorexia nervosa (AN) is a life-threatening mental disorder and has poor clinical outcomes, novel effective treatments are warranted, especially for severe and persistent cases. Objective: To investigate the safety, feasibility, and clinical outcomes of using deep brain stimulation (DBS) of the nucleus accumbens (NAcc) in treatment-refractory AN patients. Methods: A total of 28 women with refractory AN underwent NAcc-DBS and completed this 2-year follow-up study. The clinical outcomes, including body mass index (BMI) and mood, anxiety, and obsessive symptoms, were assessed using a series of psychiatric scales at 6 and 24 months post operation. Results: While no fatalities were reported during this study, 1 patient showed device rejection. The most common short-term side effect observed was varying degrees of pain at the incision sites (n ¼ 22), which usually disappeared 3e4 days following the operation. No severe surgical adverse events were observed. Compared to presurgical levels, significant increases in BMI and improvement in psychiatric scale scores were noted during the 6-month follow-up and were maintained at the 2-year review. Finally, a post-hoc analysis revealed that the NAcc-DBS was less effective for weight restoration in patients with the bingeeating/purge subtype of AN than in those with the restricting subtype (R-AN). Conclusion: Our long-term follow-up study suggests that NAcc-DBS is safe and effective for improving the BMI and psychiatric symptoms of patients with refractory AN. Although NAcc-DBS appears to be more suitable for patients with RAN , strict inclusion criteria must be applied considering surgeryrelated complications.

Parkinson’s disease (PD) is characterised by the emergence of beta frequency oscillatory synchronisation across the cortico-basal-ganglia circuit. The relationship between the anatomy of this circuit and oscillatory synchronisation within it remains unclear. We address this by combining recordings from human subthalamic nucleus (STN) and internal globus pallidus (GPi) with magnetoencephalography, tractography and computational modelling. Coherence between supplementary motor area and STN within the high (21–30 Hz) but not low (13-21 Hz) beta frequency range correlated with ‘hyperdirect pathway’ fibre densities between these structures. Furthermore, supplementary motor area activity drove STN activity selectively at high beta frequencies suggesting that high beta frequencies propagate from the cortex to the basal ganglia via the hyperdirect pathway. Computational modelling revealed that exaggerated high beta hyperdirect pathway activity can provoke the generation of widespread pathological synchrony at lower beta frequencies. These findings suggest a spectral signature and a pathophysiological role for the hyperdirect pathway in PD.

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Our results demonstrate that the subthalamus is an alternative to the globus pallidus internus as a target for deep brain stimulation to treat primary dystonia.