In this review, the available evidence to guide clinicians regarding eligibility for deep brain stimulation (DBS) in the main conditions in which these forms of therapy are generally indicated-Parkinson's disease (PD), tremor, and dystonia-is presented.In general, the literature shows that DBS is effective for PD, essential tremor, and idiopathic dystonia. In these cases, key points in patient selection must include the level of disability and inability to manage symptoms using the best available medical therapy. Results are, however, still not optimal when dealing with other aetiologies, such as secondary tremors and symptomatic dystonia. Also, in PD, issues such as age and neuropsychiatric profile are still debatable parameters. Overall, currently available literature is able to guide physicians on basic aspects of patient selection and indications for DBS; however, a few points are still debatable and controversial. These issues should be refined and clarified in future studies.RÉSUMÉ: Les critères de recevabilité de la stimulation cérébrale profonde dans des cas de maladie de Parkinson, de tremblements et de dystonie. On le sait, la maladie de Parkinson (MP), des tremblements et la dystonie demeurent les principales conditions pour lesquelles la stimulation cérébrale profonde (SCP) est habituellement indiquée. Dans cette étude, nous voulons donc mettre en évidence les preuves scientifiques pouvant orienter les cliniciens dans le choix d'un traitement de SCP. En général, les ouvrages scientifiques montrent que la SCP est efficace pour traiter la MP, les tremblements essentiels et la dystonie idiopathique. Dans ces cas, le degré d'invalidité des patients ainsi que leur incapacité à contrôler ou à agir sur leurs symptômes à l'aide du meilleur traitement médical disponible constituent deux aspects clés dans un processus de sélection. Cela dit, les résultats ne sont pas encore concluants lorsqu'on traite d'autres étiologies telles que les tremblements secondaires et la dystonie symptomatique. De plus, l'âge et le profil neuropsychiatrique des patients continuent à représenter des paramètres discutables. En somme, si la littérature scientifique existante peut orienter les médecins quant aux principaux aspects présidant à la sélection des patients et fournir des précisions en matière de SCP, certains aspects demeurent néanmoins discutables et controversés. Voilà pourquoi ces derniers devraient être davantage examinés et clarifiés dans le cadre de travaux subséquents.

Background Deep brain stimulation (DBS) of the subthalamic nucleus (STN) or internal globus pallidus (GPi) represents an effective and universally applied therapy for Parkinson's disease (PD) motor complications. However, certain procedure‐related problems and unrealistic patient expectations may detract specialists from indicating DBS more widely despite significant clinical effects. Methods This review provides a pragmatic educational summary of the most conflicting postoperative management issues in patients undergoing DBS for PD. Results DBS in PD has been associated with certain complications and post‐procedural management issues, which can complicate surgical outcome interpretation. Many PD patients consider DBS outcomes negative due to unfulfilled expectations, even when significant motor symptom improvement is achieved. Speech, gait, postural stability, and cognition may worsen after DBS and body weight may increase. Although DBS may induce impulse control disorders in some cases, in others, it may actually improve them when dopamine agonist dosage is reduced after surgery. However, apathy may also arise, especially when dopaminergic medication tapering is rapid. Gradual loss of response with time suggests disease progression, rather than the wearing off of DBS effects. Furthermore, implantable pulse generator expiration is considered a movement disorder emergency, as it may worsen parkinsonian symptoms or cause life‐threatening akinetic crises due to malignant DBS withdrawal syndrome. Conclusion Major unsolved issues occurring after DBS therapy preclude complete patient satisfaction. Multidisciplinary management at experienced centers, as well as careful and comprehensive delivery of information to patients, should contribute to make DBS outcome expectations more realistic and allow post procedural complications to be better accepted.

It has been suggested that potential risk of hemiballismus after subthalamotomy makes DBS preferable to ablation for IPD treatment; however, cost and the need for regular electrode control have also been observed as disadvantages to stimulation. The objective was to compare efficacy and safety of different surgical approaches to STN, in a prospective randomized pilot study. Sixteen consecutive IPD patients randomized to receive either: bilateral STN-DBS, bilateral subthalamotomy or unilateral subthalamotomy plus contralateral STN-DBS implantation, and followed for 12 months after surgery. One patient died and was excluded from the analysis. Total and motor UPDRS scores, as well as drug-induced dyskinesias improved significantly at 1 year follow-up, regardless of the procedure administered and without statistically significant differences between treatment modalities. Discrete changes were observed on ACE and MMSE scores. Psychiatric examination of patients subjected to bilateral stimulation and lesion, revealed slight increment in apathy and irritability scores, coinciding with significant deterioration of mentation, behaviour and mood as measured using the UPDRS. One patient presented persistent hemiballismus and required ulterior posteroventral pallidotomy. In this small group of patients, overall motor performance significantly improved after all three procedures, without major differences in outcome. Adverse events were, nevertheless, observed after both ablation and stimulation. The role of bilateral subthalamotomy in patients unable to receive a DBS electrode-implant merits further exploration in a larger series of patients with longer follow-up.