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.

A consensus has yet to emerge whether deep brain stimulation (DBS) for treatment-refractory obsessive-compulsive disorder (OCD) can be considered an established therapy. In 2014, the World Society for Stereotactic and Functional Neurosurgery (WSSFN) published consensus guidelines stating that a therapy becomes established when “at least two blinded randomized controlled clinical trials from two different groups of researchers are published, both reporting an acceptable risk-benefit ratio, at least comparable with other existing therapies. The clinical trials should be on the same brain area for the same psychiatric indication.” The authors have now compiled the available evidence to make a clear statement on whether DBS for OCD is established therapy. Two blinded randomized controlled trials have been published, one with level I evidence (Yale-Brown Obsessive Compulsive Scale (Y-BOCS) score improved 37% during stimulation on), the other with level II evidence (25% improvement). A clinical cohort study (N = 70) showed 40% Y-BOCS score improvement during DBS, and a prospective international multi-center study 42% improvement (N = 30). The WSSFN states that electrical stimulation for otherwise treatment refractory OCD using a multipolar electrode implanted in the ventral anterior capsule region (including bed nucleus of stria terminalis and nucleus accumbens) remains investigational. It represents an emerging, but not yet established therapy. A multidisciplinary team involving psychiatrists and neurosurgeons is a prerequisite for such therapy, and the future of surgical treatment of psychiatric patients remains in the realm of the psychiatrist.

Background: Calcifying pseudoneoplasm of the neuroaxis (CAPNON) is a very rare benign lesion that can be located anywhere in the nervous system, with only 59 intracranial cases described. The general lack of knowledge about this lesion hinders its preoperative diagnosis. Despite the consistent image findings, the final diagnosis is only established based on anatomopathological and immunohistochemical studies. The lesion is more commonly positive for epithelial membrane antigen (EMA) and vimentin, and negative for glial fibrillary acidic protein (GFAP) and S-100, suggesting a leptomeningeal origin. The opposite, however, may also occur, although very rarely (just two cases positive for GFAP and negative for EMA and vimentin reported this far). The treatment consists of total resection of the lesion, which yields a good prognosis. Case Presentation: We report the case of a 23-year-old female who presented with disperceptive focal seizures, sometimes evolving to bilateral tonic-clonic seizures, starting at age 9. She had a nodular calcified lesion in the left precuneus and inferior parietal lobe. The lesion was completely resected, and the immunohistochemical study revealed positivity for EMA, vimentin, GFAP, and S-100. No case hitherto published was positive for all four markers. This atypical immunohistochemical profile of the CAPNON may suggest a dual origin of this lesion, both parenchymal and leptomeningeal. Conclusion: The general lack of knowledge of CAPNON makes this lesion underdiagnosed. Therefore, in the face of a calcified lesion in the nervous system, one should consider the possibility of a CAPNON among the differential diagnoses. The immunohistochemistry is undoubtedly an important tool, but the anatomopathological study, associated with image findings, remain the gold standard for the diagnosis of CAPNON.

Although long known and the most prevalent movement disorder, pathophysiology of essential tremor (ET) remains controversial. The most accepted hypothesis is that it is caused by a dysfunction of the olivocerebellar system. Vilela Filho et al. [2001; Stereotact Funct Neurosurg 77:149-150], however, reported a patient with unilateral hand ET that was completely relieved after a stroke restricted to the contralateral posterior putamen and suggested that ET could be the clinical manifestation of posterior putamen hyperactivity. The present study was designed to evaluate this hypothesis in the most often used model of ET, harmaline-induced tremor in rats. Fifty-four male Wistar rats were randomly distributed into three groups: experimental (EG), surgical control (SCG), and pharmacological control (PCG) groups. EG animals underwent stereotactic unilateral posterior striatotomy. SCG rats underwent sham lesion at the same target. PCG served exclusively as controls for harmaline effects. All animals received, postoperatively, intraperitoneal harmaline, and the induced tremor was video-recorded for later evaluation by a blind observer. Thirteen animals were excluded from the study. Limb tremor was reduced ipsilaterally to the operation in 20 of 21 rats of EG and in two of nine of SCG, being asymmetric in one of 10 of PCG rats. Comparisons between EG × SCG and EG × PCG were statistically significant, but not between SCG × PCG. Limb tremor reduction was greater in anterior than in posterior paws. Lateral lesions yielded better results than medial lesions. These results suggest that the posterior striatum is involved with harmaline-induced tremor in rats and support the hypothesis presented.

Background: Delusions and hallucinations, hallmarks of the psychotic disorders, usually do not respond to surgical intervention. For many years, the surgical technique of choice for the treatment of refractory aggressiveness in psychotic patients in our Service was amygdalotomy in isolation or associated with anterior cingulotomy. No improvement of hallucinations and delusions was noticed in any of these patients. To improve the control of aggression, subcaudate tractotomy was added to the previous surgical protocol. The main goal of the present study was to investigate the impact of this modified surgical approach on delusions and hallucinations. Methods: Retrospective analysis of the medical records of psychotic patients presenting with treatment-resistant aggressiveness, delusions, and hallucinations submitted to bilateral subcaudate tractotomy + bilateral anterior cingulotomy + bilateral amygdalotomy in our institution. Results: Five patients, all males, with ages ranging from 25 to 65 years, followed up by a mean of 45.6 months (17–72 months), fulfilled the inclusion criteria. Delusions and hallucinations were abolished in four of them. Conclusion: These results suggest that the key element for relieving these symptoms was the subcaudate tractotomy and that the orbitofrontal and ventromedial prefrontal cortices play an important role in the genesis of hallucinatory and delusional symptoms of schizophrenia and other psychoses.

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BACKGROUND Resection of the seizure onset zone (SOZ) is considered the gold standard for treating refractory focal aware seizures (FASs). When resective surgery is unadvisable, deep brain stimulation (DBS) of the anterior nucleus of the thalamus (ANT; ANT-DBS) has been the procedure of choice. However, less than half of patients with FASs respond to ANT-DBS. The need for alternative targets to effectively treat FAS is thus evident. OBSERVATIONS The authors report the case of a 39-year-old woman presenting with pharmaco-resistant focal aware motor seizures, with the SOZ located in the primary motor cortical area. She had previously undergone unsuccessful resection of the left temporoparietal operculum elsewhere. Considering the risk of new resective surgery, she was offered combined ventral intermediate nucleus (Vim)/ANT-DBS. Vim-DBS proved to be superior to ANT-DBS for seizure control (88% vs 32%), although the association of both provided the best results (97%). LESSONS This is the first report on the use of the Vim as a target of DBS for the treatment of FAS. The excellent results were presumably obtained by modulation of the SOZ through Vim projections to the motor cortex. This opens a completely new avenue for treating FAS: chronic stimulation of specific thalamic nuclei.