Deep Brain Stimulation for the Treatment of Resistant Depression: Systematic Review of the Literature

Depression is the leading cause of disability worldwide, and it is related to high suicide rates. Furthermore, a great number of patients do not respond to any of the available treatments. Deep brain stimulation (DBS), a versatile technology with expanding indications, is considered a potential treatment for resistant depression. However, in over 10 years of clinical research, its efficacy has not been completely proven. Although new trials using DBS for treatment-resistant depression keep emerging, two of the three Level I evidence-based studies recently conducted have not provided conclusive data. Methodological limitations andmajor biases have compromised the obtention of clearer results. In this systematic review of the literature, we intend to critically assess the clinical trials performed in this field.

Safety of transcranial direct current stimulation in a patient with deep brain stimulation electrodes / Segurança da estimulação transcraniana por corrente contínua em uma paciente com implante de eletrodos de estimulação cerebral profunda

ABSTRACT Background: Transcranial direct current stimulation (tDCS) has been investigated in movement disorders, making it a therapeutic alternative in clinical settings. However, there is still no consensus on the most appropriate treatment protocols in most cases, and the presence of deep brain stimulation (DBS) electrodes has been regarded as a contraindication to the procedure. We recently studied the effects of cerebellar tDCS on a female patient already undergoing subthalamic nucleus deep brain stimulation (STN-DBS) for generalized dystonia. She also presented with chronic pain and depression. With STN-DBS, there was improvement of dystonia, and botulinum toxin significantly reduced pain. However, depressive symptoms were worse after STN-DBS surgery. Methods: Neuromodulation with 2 mA anodal cerebellar tDCS was initiated, targeting both hemispheres in each daily 30 minute session: 15 minutes of left cerebellar stimulation followed by 15 minutes of right cerebellar stimulation. The DBS electrodes were in place and functional, but the current was turned off during tDCS. Results: Although our goal was to improve dystonic movements, after 10 tDCS sessions there was also improvement in mood with normalization of Beck Depression Inventory scores. There were no complications in spite of the implanted STN-DBS leads. Conclusion: Our results indicate that tDCS is safe in patients with DBS electrodes and may be an effective add-on neuromodulatory tool in the treatment of potential DBS partial efficacy in patients with movement disorders.

RESUMO Descrição: A estimulação transcraniana por corrente contínua (ETCC) tem sido investigada nos distúrbios de movimento, tornando-a uma alternativa terapêutica no contexto clínico. Contudo, não há consenso quanto aos protocolos mais apropriados na maioria dos casos e a presença de eletrodos de estimulação cerebral profunda (ECP) é geralmente considerada uma contraindicação. Recentemente, estudamos os efeitos da ETCC cerebelar em uma paciente do sexo feminino com implante de eletrodos de estimulação cerebral profunda (ECP) para distonia generalizada. Ela também apresentava dor crônica e depressão. A ETCC foi realizada dois anos após o implante de eletrodos de ECP. Com a ECP houve melhora da distonia e a toxina botulínica reduziu a dor. Contudo, os sintomas depressivos pioraram após a cirurgia de ECP. Métodos: Foi proposta ETCC cerebelar anódica de 2mA, sobre os dois hemisférios em cada sessão de 30min: 15 min de ETCC cerebelar esquerda seguida de 15min de ETCC cerebelar direita. Resultados: Embora o nosso objetivo tenha sido melhorar os movimentos distônicos, após 10 sessões de ETCC houve melhora também do humor da paciente. Não houve nenhuma complicação, apesar da presença de eletrodos de ECP. Conclusão: Nossos resultados apontam para a segurança da tDCS e sua aplicação potencial e efetiva como ferramenta neuromodulatória adicional no tratamento de possíveis sintomas persistentes após a ECP em pacientes com distúrbios de movimento.

Frameless stereotactic for deep brain stimulation placement: operative technique.

Deep brain stimulation (DBS) has been shown to be a safe and effective method for the treatment of refractory Parkinson's disease and other movement disorders. Traditionally, frame-based stereotactic have been the standard technique commonly used for DBS surgery. With the development of image-guided neurosurgical systems, frameless stereotactic has been increasingly used for tumor resection or biopsy without the use of stereotactic frame. Frameless stereotactic for functional surgery has been recently developed with the accuracy comparable to frame-based stereotactic surgery. The authors report the surgical technique of frameless functional stereotactic for the treatment of movement disorders.

State of the art: deep brain stimulation in Parkinson's disease.

Surgical therapy for Parkinson's disease has a long history beginning in the 1930s with empirical exploration of different brain targets, such as resection of the primary motor cortex or extirpation of the caudate. Recently, there has been a renaissance of functional neurosurgery for the treatment of advanced Parkinson's disease, particularly deep brain stimulation (DBS). To date, DBS of the globus pallidus interna and subthalamic nucleus has been reported to relieve motor symptoms and levodopa-induced dyskinesia in patients with advanced Parkinson's disease. DBS also has different advantages over pallidotomy and subthalamotomy, including reversibility, decreased risk of reoperation and decreased morbidity. In addition to well-experienced neurologists and neurosurgeons, a multidisciplinary team approach is fundamental and critical to ensure success in the DBS procedure in individual patients. With the advances in neuroimaging, neurophysiology and localization techniques, it is increasingly likely that there will be more surgical targets in the future that can also improve cardinal features of Parkinson's disease, or even nonmotor manifestations of this condition.