[Artificial intelligence in neurosurgery]. / Künstliche Intelligenz in der Neurochirurgie.

BACKGROUND: Artificial intelligence (AI) in neurosurgery is becoming increasingly more important as the technology advances. This development can be measured by the increase of publications on AI in neurosurgery over the last years. OBJECTIVE: This article provides insights into the current possibilities of using AI in neurosurgery. MATERIAL AND METHODS: A review of the literature was carried out with a focus on exemplary work on the use of AI in neurosurgery. RESULTS: The current neurosurgical publications on the use of AI show the diversity of the topic in this field. The main areas of application are diagnostics, outcome and treatment models. CONCLUSION: The various areas of application of AI in the field of neurosurgery with a refined preoperative diagnostics and outcome predictions will significantly influence the future of neurosurgery. Neurosurgeons will continue to make the decisions on the indications for surgery but an optimized statement on diagnosis, treatment options and on the risk of surgery will be made by neurosurgeons with the help of AI in the future.

Prospective evaluation of Globus pallidus internus deep brain stimulation in Huntington's disease.

INTRODUCTION: Pharmacological treatment of chorea in Huntington's disease (HD) is often limited by poor efficacy or side effects. Pallidal deep brain stimulation (DBS) has been considered in these patients but experience is so far limited. METHODS: We prospectively evaluated the effects of bilateral DBS of the Globus pallidus internus (GPi) over one year in six severely affected HD patients with treatment refractory chorea in an advanced stage of the disease. Primary endpoint of the study was improvement in chorea. Additionally, we evaluated the effects of GPi DBS on the motor part of the Unified Huntington's Disease Rating Scale (UHDRS), bradykinesia, dystonia, functional impairment, psychiatric and cognitive symptoms. Side effects were systematically assessed. RESULTS: The chorea subscore was significantly reduced postoperatively (-47% six months, -40% twelve months postoperatively). The UHDRS total motor score was significantly reduced at six months postoperatively (- 17%) but the effect was not sustained twelve months after the operation (- 5%). Pallidal DBS did not improve other motor symptoms or functional impairment. There was no effect on psychiatric symptoms or cognition. A number of side effects were noted, especially spasticity in three of the patients. CONCLUSIONS: Pallidal DBS is a treatment option for HD patients with severe pharmacologically refractory chorea. Further studies are needed to define optimal candidates for this procedure.

Brain stimulation in obesity.

Obesity is taking up epidemic proportions worldwide with significant impacts on the health of both the affected individual and on society as a whole. Treatment approaches consist of behavioural and pharmacological approaches, however, these are often found to be ineffective. In severe obesity, bariatric surgery is frequently performed. Unfortunately, 40% of patients show substantial weight gain over the long term or display the associated metabolic syndrome, making the development of novel therapies necessary. This review summarizes some of the current conceptual models, in particularly the 'food addiction' model, and then discusses specific therapeutic targets of brain stimulation, both non-invasive (transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS) and transcutaneous vagus nerve stimulation (VNS)) and invasive (deep brain stimulation and invasive VNS). As we will show, neuromodulatory approaches represent a promising tool for targeting specific brain structures implicated in the pathophysiology of obesity. Non-invasive techniques such as TMS, tDCS and transcutaneous VNS need further investigation before they may become ready for clinical usage. The currently available study data suggest that deep brain stimulation may become an effective and acceptable therapy for otherwise treatment-resistant obese patients. The results of the currently undergoing clinical trials are eagerly awaited.

EAN guidelines on central neurostimulation therapy in chronic pain conditions.

BACKGROUND AND PURPOSE: Our aim was to update previous European Federation of Neurological Societies guidelines on neurostimulation for neuropathic pain, expanding the search to new techniques and to chronic pain conditions other than neuropathic pain, and assessing the evidence with the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system. METHODS: A systematic review and meta-analysis of trials published between 2006 and December 2014 was conducted. Pain conditions included neuropathic pain, fibromyalgia, complex regional pain syndrome (CRPS) type I and post-surgical chronic back and leg pain (CBLP). Spinal cord stimulation (SCS), deep brain stimulation (DBS), epidural motor cortex stimulation (MCS), repetitive transcranial magnetic stimulation (rTMS) and transcranial direct electrical stimulation (tDCS) of the primary motor cortex (M1) or dorsolateral prefrontal cortex (DLPFC) were assessed. The GRADE system was used to assess quality of evidence and propose recommendations. RESULTS: The following recommendations were reached: 'weak' for SCS added to conventional medical management in diabetic painful neuropathy, CBLP and CRPS, for SCS versus reoperation in CBLP, for MCS in neuropathic pain, for rTMS of M1 in neuropathic pain and fibromyalgia and for tDCS of M1 in neuropathic pain; 'inconclusive' for DBS in neuropathic pain, rTMS and tDCS of the DLPFC, and for motor cortex tDCS in fibromyalgia and spinal cord injury pain. CONCLUSIONS: Given the poor to moderate quality of evidence identified by this review, future large-scale multicentre studies of non-invasive and invasive neurostimulation are encouraged. The collection of higher quality evidence of the predictive factors for the efficacy of these techniques, such as the duration, quality and severity of pain, is also recommended.

[SCS as a treatment option for failed back surgery syndrome]. / SCS als therapeutische Option beim Postnukleotomiesyndrom.

Unfortunately, 10-40 % of patients still experience pain after spinal surgery. There are many reasons for the patients' complaints. If no identifiable cause, such as a recurrent disc herniation, is visible, this is referred to as failed back surgery syndrome. However, this definition includes a variety of possible underlying causes of the pain, which result in just as many different therapeutic approaches. In addition to pharmacological, behavioral and physical therapy, also neuromodulation techniques can be offered; the best known method is spinal cord stimulation (SCS). The following article describes evidence-based studies with regard to the beneficial treatment of failed back surgery syndrome with conventional tonic SCS and new developments in spinal cord stimulation addressing the treatment of chronic refractory back pain.

Biochemical mechanisms of pallidal deep brain stimulation in X-linked dystonia parkinsonism.

OBJECTIVE: Invasive techniques such as in-vivo microdialysis provide the opportunity to directly assess neurotransmitter levels in subcortical brain areas. METHODS: Five male Filipino patients (mean age 42.4, range 34-52 years) with severe X-linked dystonia-parkinsonism underwent bilateral implantation of deep brain leads into the internal part of the globus pallidus (GPi). Intraoperative microdialysis and measurement of gamma aminobutyric acid and glutamate was performed in the GPi in three patients and globus pallidus externus (GPe) in two patients at baseline for 25/30 min and during 25/30 min of high-frequency GPi stimulation. RESULTS: While the gamma-aminobutyric acid concentration increased in the GPi during high frequency stimulation (231 ± 102% in comparison to baseline values), a decrease was observed in the GPe (22 ± 10%). Extracellular glutamate levels largely remained unchanged. CONCLUSIONS: Pallidal microdialysis is a promising intraoperative monitoring tool to better understand pathophysiological implications in movement disorders and therapeutic mechanisms of high frequency stimulation. The increased inhibitory tone of GPi neurons and the subsequent thalamic inhibition could be one of the key mechanisms of GPi deep brain stimulation in dystonia. Such a mechanism may explain how competing (dystonic) movements can be suppressed in GPi/thalamic circuits in favour of desired motor programs.

Responsiveness of stem-like human glioma cells to all-trans retinoic acid and requirement of retinoic acid receptor isotypes α, ß and γ.

Retinoic acid (RA) is required for development and homeostasis of the normal mammalian brain and may play a role in the initiation and progression of malignant brain tumors, such as the glioblastoma multiforme (GBM) and the gliosarcoma (Gsarc). The subpopulation of stem-like glioma cells (SLGCs) was shown to resist standard glioma radio-/chemotherapy and to propagate tumor regrowth. We used phenotypically distinct, self-renewing SLGC lines from six human GBMs, two Gsarcs, and two subcloned SLGC derivatives in order to investigate their responsiveness to all-trans retinoic acid (atRA) and to identify the RA-receptor (RAR) isotypes involved. In general, atRA exerted a pro-proliferative and pro-survival effect on SLGCs, though the efficacy was distinct. By means of RAR isotype-selective retinoids we disclosed that these effects were mediated by RARα and RARγ, except for one SLGC line, in which the pro-proliferative signal was induced by the RARß-selective retinoid. Only one GBM-derived cell line (T1338) and a subpopulation of another (T1389) displayed neural differentiation in response to atRA. Differentiation of T1338 was induced by RARα and RARγ isotype-selective retinoids, associated with down-regulation of Sox2, and the failure to induce orthotopic tumors in the brains of SCID mice. The differential responsiveness of the SLGC lines appeared unrelated to the expression of RARß, as (i) atRA augmented RAR isotype mRNA expression and particularly rarß mRNA in all SLGC lines, (ii) rarß promoter hypomethylation in the SLGC lines was not related to differentiation and (iii) the induction of T1338 differentiation was by RARα- and RARγ-selective ligands.

[Neuromodulation for neuropathic pain]. / Neuromodulation bei neuropathischen Schmerzen.

In pain therapy neurostimulation procedures have replaced the previously used lesional methods with only very few exceptions. This is especially true for neuropathic pain, i.e. pain which occurs as a direct consequence of a lesion or disease of the somatosensory system. Nowadays, various stimulation procedures are included in the neurosurgical and anesthesiological armamentarium for pain therapy, depending on the site of damage. This article gives an overview of the currently used invasive stimulation procedures and the indications.

Epidural and subdural stimulation.

Cortical stimulation, either transcranial or by means of electrodes implanted epidurally or subdurally, is used increasingly to treat neuropsychiatric diseases. In cases where transcranial stimulation gives only short-term success, implanted electrodes can yield results that are similar but long-term. Epidural stimulation is used widely to treat chronic neuropathic pain, whereas newer fields are in movement disorders, tinnitus, depression, and functional rehabilitation after stroke. For epidural stimulation, computational models explain the geometry of stimulation parameters (anodal, cathodal, and bifocal) and are used for targeting to yield the best clinical results. Nevertheless, the role of the cerebrospinal fluid layer also has to be taken into consideration. Subdural or intrasulcal stimulation allows a more focused stimulation with lower current intensities. This advantage, however, is counterbalanced by a higher complication rate with regard to epileptic seizures, subdural or intracerebral hemorrhages, and wound infections.

[Development of epidural spinal cord stimulation. Fortieth anniversary of the first implantation in Germany]. / Entwicklung der epiduralen Rückenmarkstimulation. 40 Jahre seit der Erstimplantation in Deutschland.

Spinal cord stimulation is nowadays an established therapy for various neuropathic and vasculopathic pain syndromes after more conservative measures have failed. However, 40 years ago, only 5 years after the first worldwide implantation in the US, this therapy was promoted in Germany. In 1972, the first devices were implanted in the Departments of Neurosurgery at the Universities Hannover and Freiburg. These pioneering efforts and the establishment of the therapy are intimately associated with three names: Jörg-Ulrich Krainick, Uwe Thoden, and Wolfhard Winkelmüller. Nowadays about 1700 spinal cord stimulation systems are implanted annually in Germany. The development of spinal cord stimulation from the beginnings up to now taking into special consideration the early years in Germany are presented.

[Competency-based medical education: National Catalogue of Learning Objectives in surgery]. / Kompetenzorientierung in der medizinischen Ausbildung: Nationaler Lernzielkatalog Chirurgie.

Competency-based medical education is a prerequisite to prepare students for the medical profession. A mandatory professional qualification framework is a milestone towards this aim. The National Competency-based Catalogue of Learning Objectives for Undergraduate Medical Education (NKLM) of the German Medical Faculty Association (MFT) and the German Medical Association will constitute a basis for a core curriculum of undergraduate medical training. The Surgical Working Group on Medical Education (CAL) of the German Association of Surgeons (DGCH) aims at formulating a competency-based catalogue of learning objectives for surgical undergraduate training to bridge the gap between the NKLM and the learning objectives of individual medical faculties. This is intended to enhance the prominence and visibility of the surgical discipline in the context of medical education. On the basis of different faculty catalogues of learning objectives, the catalogue of learning objectives of the German Association of Orthopedics and Orthopedic Surgery and the Swiss Catalogue of Learning Objectives representatives of all German Surgical Associations cooperated towards a structured selection process of learning objectives and the definition of levels and areas of competencies. After completion the catalogue of learning objectives will be available online on the webpage of the DGCH.

Pharmacoeconomical consequences of postoperative CSF leaks after intracranial surgery--a prospective analysis.

Cerebrospinal fluid (CSF) leaks are well-known and frequent complications of intracranial procedures with their clinical aspects covered by numerous studies. Little, however, is known about the pharmacoeconomical aspects of this specific complication. 545 patients with a variety of intracranial procedures (elective and trauma) were recruited for a multicenter, prospective, observational study over a 13-month period. A specific pharmacoeconomic analysis was performed in 168 of these patients from the institution of the first author covering all clinical and pharmaco-economical aspects of this specific complication. Of all patients, 5.36% developed a postoperative CSF leak. Treatment of the leak required numerous diagnostic and therapeutic procedures such as reoperations (n = 6), lumbar punctures (n = 11) or lumbar drainages (n = 4). Costs for these procedures and prolonged hospital stays nearly doubled the costs per case (€14079/case without a fistula vs. €25499/case with a fistula). Reimbursement for the hospital covered these extra costs, but net earnings per case were diminished by €565 in cases with a CSF leak. The authors conclude that the presence of a CSF leak after an intracranial operation - although not influencing outcome in general - results in additional diagnostic and therapeutic procedures for the patient, an enormous increase in costs for the community, and a financial loss for the hospital. Strategies to lower this complication rate should therefore urgently be developed both from a clinical and a pharmacoeconomical point of view.

[Epidural spinal cord stimulation for therapy of chronic pain. Summary of the S3 guidelines]. / Epidurale Rückenmarkstimulation zur Therapie chronischer Schmerzen. Zusammenfassung der S3-Leitlinie.

Epidural spinal cord stimulation (SCS) is a reversible but invasive procedure which should be used for neuropathic pain, e.g. complex regional pain syndrome I (CRPS) and for mostly chronic radiculopathy in connection with failed back surgery syndrome following unsuccessful conservative therapy. Epidural SCS can also successfully be used after exclusion of curative procedures and conservative therapy attempts for vascular-linked pain, such as in peripheral arterial occlusive disease stages II and III according to Fontaine and refractory angina pectoris. Clinical practice has shown which clinical symptoms cannot be successfully treated by epidural SCS, e.g. pain in complete paraplegia syndrome or atrophy/injury of the sensory pathways of the spinal cord or cancer pain. A decisive factor is a critical patient selection as well as the diagnosis. Epidural SCS should always be used within an interdisciplinary multimodal therapy concept. Implementation should only be carried out in experienced therapy centers which are in a position to deal with potential complications.

Diagnostic benefits of presurgical fMRI in patients with brain tumours in the primary sensorimotor cortex.

OBJECTIVES: Reliable imaging of eloquent tumour-adjacent brain areas is necessary for planning function-preserving neurosurgery. This study evaluates the potential diagnostic benefits of presurgical functional magnetic resonance imaging (fMRI) in comparison to a detailed analysis of morphological MRI data. METHODS: Standardised preoperative functional and structural neuroimaging was performed on 77 patients with rolandic mass lesions at 1.5 Tesla. The central region of both hemispheres was allocated using six morphological and three functional landmarks. RESULTS: fMRI enabled localisation of the motor hand area in 76/77 patients, which was significantly superior to analysis of structural MRI (confident localisation of motor hand area in 66/77 patients; p < 0.002). FMRI provided additional diagnostic information in 96% (tongue representation) and 97% (foot representation) of patients. FMRI-based presurgical risk assessment correlated in 88% with a positive postoperative clinical outcome. CONCLUSION: Routine presurgical FMRI allows for superior assessment of the spatial relationship between brain tumour and motor cortex compared with a very detailed analysis of structural 3D MRI, thus significantly facilitating the preoperative risk-benefit assessment and function-preserving surgery. The additional imaging time seems justified. FMRI has the potential to reduce postoperative morbidity and therefore hospitalisation time.