The Value of Preoperative Planning Based on Navigated Transcranical Magnetic Stimulation for Surgical Treatment of Brain Metastases Located in the Perisylvian Area.

BACKGROUND: Brain metastases are the most common neoplasms in adults. When brain metastases are located in eloquent areas, their treatment still seems controversial and not clearly defined. It is therefore essential to provide correct preoperative planning to better define extension and characterization of brain metastasis. METHODS: We retrospectively looked for the tumor database of our institution, patients with single brain metastasis, located in the sylvian area, who underwent resection with the support of intraoperative neurophysiologic monitoring between 2008 and 2018. RESULTS: We retrieved data for 30 adults, each with a single brain metastasis that was located in the sylvian area, including the insula and the lower portion of the motor cortex. Neuronavigation and the intraoperative visualization of the navigated transcranial magnetic stimulation-based reconstruction of functional networks were used to delineate the ideal trajectory toward the lesion. The Karnofsky Performance Status significantly improved in the postoperative period. CONCLUSIONS: The correct planning of brain metastasis allows more secure removal of the neoplastic lesion, avoiding and/or reducing the appearance of neurologic deficits. Navigated transcranial magnetic stimulation represents a new method that can promote a more complete and safer resection of the metastatic lesion in eloquent areas. An optimal surgical result, in the absence of postoperative neurologic deficits, allows the patient to undertake adjuvant therapy able to prolong survival.

Recent developments in the surgical management of paediatric epilepsy.

Among the 1% of children affected by epilepsy, failure of pharmacological therapy and early age of seizure onset can lead to worse long-term cognitive outcomes, mental health disorders and impaired functional status. Surgical management often improves functional and cognitive outcomes in children with medically refractory epilepsy, especially when seizure remission is achieved. However, surgery remains underused in children with drug-resistant epilepsy, creating a large treatment gap. Several recent innovations have led to considerable improvement in surgical technique, including the recent development of minimally invasive diagnostic and therapeutic techniques such as stereotactic EEG, transcranial magnetic stimulation, MRI-guided laser ablation, as well as novel paradigms of neurostimulation. This article discusses the current landscape of surgical innovation in the management of paediatric epilepsy, leading to a paradigm shift towards minimally invasive therapy and closing the treatment gap in children suffering from drug-resistant seizures.

Transcranial motor evoked potential waveform changes in corrective fusion for adolescent idiopathic scoliosis.

OBJECTIVE Corrective surgery for spinal deformities can lead to neurological complications. Several reports have described spinal cord monitoring in surgery for spinal deformity, but only a few have included patients younger than 20 years with adolescent idiopathic scoliosis (AIS). The goal of this study was to evaluate the characteristics of cases with intraoperative transcranial motor evoked potential (Tc-MEP) waveform deterioration during posterior corrective fusion for AIS. METHODS A prospective database was reviewed, comprising 68 patients with AIS who were treated with posterior corrective fusion in a prospective database. A total of 864 muscles in the lower extremities were chosen for monitoring, and acceptable baseline responses were obtained from 819 muscles (95%). Intraoperative Tc-MEP waveform deterioration was defined as a decrease in intraoperative amplitude of ≥ 70% of the control waveform. Age, Cobb angle, flexibility, operative time, estimated blood loss (EBL), intraoperative body temperature, blood pressure, number of levels fused, and correction rate were examined in patients with and without waveform deterioration. RESULTS The patients (3 males and 65 females) had an average age of 14.4 years (range 11-19 years). The mean Cobb angles before and after surgery were 52.9° and 11.9°, respectively, giving a correction rate of 77.4%. Fourteen patients (20%) exhibited an intraoperative waveform change, and these occurred during incision (14%), after screw fixation (7%), during the rotation maneuver (64%), during placement of the second rod after the rotation maneuver (7%), and after intervertebral compression (7%). Most waveform changes recovered after decreased correction or rest. No patient had a motor deficit postoperatively. In multivariate analysis, EBL (OR 1.001, p = 0.085) and number of levels fused (OR 1.535, p = 0.045) were associated with waveform deterioration. CONCLUSIONS Waveform deterioration commonly occurred during rotation maneuvers and more frequently in patients with a larger preoperative Cobb angle. The significant relationships of EBL and number of levels fused with waveform deterioration suggest that these surgical invasions may be involved in waveform deterioration.

An ethical discussion of the use of transcranial direct current stimulation for cognitive enhancement in healthy individuals: a fictional case study

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique. Because of its low cost, ease of use, safety, and portability, tDCS has been increasingly investigated for therapeutic purposes in neuropsychiatric disorders and in experimental neuropsychological studies with healthy volunteers. These experiments on healthy cognition have shown significant effects on working memory, decision-making, and language. Such promising results have fomented reflections on studying tDCS to enhance or modify normal cognitive function, a concept described by some as "cosmetic" neurology. As the field evolves, discussing whether the use of tDCS in these situations is appropriate is important, including how bioethical principles may help resolve these challenges. In this article, we present some examples of the effects of tDCS on cognition in healthy participants as a starting point for this ethical debate. We envision a futuristic "Brain Boosting" tDCS clinic that specializes in cosmetic neurology and cognitive enhancement. Using the typical cases of a fictitious Dr. Icarus as a discussion starting point, we raise some issues that are both humorous and provocative about the use of tDCS in healthy people. The importance of this work is to ask relatively new questions regarding cosmetic neurology in the field of neuromodulation and discuss the related ethical conflicts...

Presente y futuro de la estimulación magnética transcraneal / Present and future of the transcranial magnetic stimulation

La estimulación magnética transcraneal ha llamado la atención de neurocientíficos y público en general por la posibilidad de estimular y “controlar” el sistema nervioso de forma no invasiva, realizar diagnósticos más exactos, y aplicar tratamientos y programas de rehabilitación más efectivos en múltiples enfermedades que afectan el sistema nervioso. Así mismo, esta novedosa herramienta ha ayudado a develar la complejidad del comportamiento neural, sus conexiones y su modulación plástica. La estimulación magnética aplicada de manera simple o pareada, se ha convertido en una alternativa útil en el diagnóstico de enfermedades como esclerosis múltiple, enfermedad de Parkinson, epilepsia, distonía, esclerosis lateral amiotrófica, enfermedad cerebro vascular, así como el sueño y sus trastornos, entre otras alteraciones. A nivel terapéutico, se ha sugerido el uso de la estimulación magnética repetitiva con diferentes niveles de evidencia en depresión refractaria a tratamiento farmacológico convencional, tinitus, afonía psicógena, enfermedad de Alzheimer, autismo, enfermedad de Parkinson, distonías, accidente cerebro vascular, epilepsia, trastornos de ansiedad generalizada, estrés post-traumático, alucinaciones auditivas, dolor crónico, afasias, trastorno obsesivo compulsivo, disquinesias inducidas por L-Dopa, manía y síndrome de Rasmussen, entre otros trastornos. Su beneficio en neurorehabilitación es una realidad inocultable, en cuyo caso se ha podido usar con efectividad y, prácticamente, sin efectos secundarios.

Magnetic stimulation has called the attention of neuroscientists and the public due to the possibility to stimulate and “control” the nervous system in a non-invasive way. It has helped to make more accurate diagnosis, and apply more effective treatments and rehabilitation protocols in several diseases that affect the nervous system. Likewise, this novel tool has increased our knowledge about complex neural behavior, its connections as well as its plastic modulation. Magnetic stimulation applied in simple or paired-pulse protocols is a useful alternative in the diagnosis of diseases such as multiple sclerosis, Parkinson disease, epilepsy, dystonia, amyotrophic lateral sclerosis, cerebrovascular disease, and sleep disorders. From the therapeutic perspective, magnetic stimulation applied repetitively has been found useful, with different degrees of efficacy, in treating resistant depression, tinnitus, psychogenic dysphonia, Alzheimer disease, autism, Parkinson disease, dystonia, stroke, epilepsy, generalized anxiety as well as post traumatic stress disorder, auditory hallucinations, chronic pain, aphasias, obsessive-compulsive disorders, L-dopa induced dyskynesia, mania and Rasmussen syndrome, among others. The potential of magnetic stimulation in neurorehabilitation is outstanding, with excellent range of safety and, in practical terms, without side effects.

Promising avenues of therapeutics for bipolar illness.

Basic scientific advances in understanding the neuropsychobiology of bipolar disorder have given us a multitude of opportunities to explore and exploit new avenues of therapeutics. Pharmacotherapeutic approaches include: neuropeptides (agonists such as thyrotropin-releasing hormone and antagonists such as corticotropin-releasing hormone), neurotrophic factors (especially brain-derived neurotrophic factor), and glutamatergic mechanisms (such as riluzole, ketamine, and antagonists of the NR-2B subunit of the glutamate receptor). Physiological interventions that would offer alternatives to electroconvulsive therapy include: repeated transcranial magnetic stimulation, especially at more intense stimulation parameters; magnetic stimulation therapy (seizures induced more focally by magnetic rather than electrical stimulation with resulting reduced meaning loss); vagal nerve stimulation, and deep brain stimulation. However, these, as well as the panoply of existing treatments, require further intensive investigation to place each of them in the proper therapeutic sequence and combination for the individual patient, based on development of better clinical and biological predictors of response. Large clinical trial networks and development of systematic research in clinical practice settings, such as that featured by the National Cancer Institute for cancer chemotherapy, would greatly accelerate the progress in incorporating new, as well as existing, agents into the best treatment strategies. The bipolar disorders, which are increasingly recognized as complex, highly comorbid conditions with a high morbidity and mortality, of which the majority start in childhood and adolescence, are not likely to respond completely to any single new treatment agent, and new public health initiatives and research strategies are needed as much as any new single treatment advance.

Use of repetitive transcranial magnetic stimulation in pain relief.

Repetitive transcranial magnetic stimulation (rTMS) of the cerebral cortex is a noninvasive strategy that could have the potential to relieve severe chronic pain, at least partially and transiently. The most studied target of stimulation is the precentral (motor) cortex, but other targets, such as the dorsolateral prefrontal cortex or the parietal cortex, could be of interest. Analgesic effects have been produced by rTMS in patients with neuropathic pain, fibromyalgia or visceral pain. Therapeutic applications of rTMS in pain syndromes are limited by the short duration of the induced effects, but prolonged pain relief can be obtained by performing rTMS sessions every day for several weeks. In patients who respond to rTMS but relapse, surgical implantation of epidural cortical electrodes and a pulse generator can be proposed to make clinical effects more permanent. The rate of improvement produced by rTMS may be predictive for the outcome of the implanted procedure. The place of rTMS as a therapeutic tool in the management of chronic pain remains to be determined.

Motor cortex stimulation for chronic non-malignant pain: current state and future prospects.

Motor cortex stimulation (MCS) was proposed by Tsubokawa in 1991 for the treatment of post-stroke thalamic pain. Since that time, the indications have been increased and included trigeminal neuropathic pain and later other types of central and peripheral deafferentation pain. The results reported in the literature are quite good; the mean long-term success rate is 80% in facial pain and 53% in non-facial pain. Our own results are less impressive: 4 of 14 patients (28%) experienced a greater than 40% pain relief, but in 2 of them the effect faded with time. Only few minor complications have been reported. The accurate placement of the epidural electrode over the motor cortex that somatotopically corresponds to the painful area is believed to be essential for pain relief. Predictive factors included the response to pharmacological tests, the relative sparing from the disease process of the cortico-spinal tract and the sensory system, and the analgesic response achieved during the test period of MCS. A possible predictive factor might be a test of repetitive transcranial magnetic stimulation (rTMS) of the motor cortex. MCS may act by rebalancing the control of non-nociceptive sensory inputs over nociceptive afferents at cortical, thalamic, brainstem and spinal level. In addition, it may interfere with the emotional component of nociceptive perception. Biochemical processes involving endorphins and GABA may also be implicated in the mechanism of MCS. It is time for a large multicenter prospective randomized double blind study evaluating not only the effect of MCS on pain (based on the available guidelines for assessment of neuropathic pain), but also the optimal electrode placement and stimulation parameters, and the possible relationship with the response to rTMS. New electrode design and a new generation of stimulators may help in improving the results.

Slow-frequency rTMS reduces fibromyalgia pain.

OBJECTIVE: Evidence suggests that fibromyalgia (FM) is a centrally mediated pain disorder. Antidepressants, including electroconvulsive therapy, provide some symptomatic relief in FM and other pain disorders. Repetitive transcranial magnetic stimulation (rTMS) is a new antidepressant treatment, which may also be useful in treating chronic pain. DESIGN: As part of a larger study, four women with depression, FM, and borderline personality disorder received 1-Hz rTMS applied to the right dorsolateral prefrontal cortex. Subjects rated pain using an 11-point Likert scale. RESULTS: Pretreatment pain averaged 8.2 (7-9.5) and reduced to 1.5 (0-3.5) after treatment (P < 0.009). All had improvement in pain, and two had complete resolution of pain. Only one of the four subjects had an antidepressant response. CONCLUSIONS: These preliminary findings suggest a possible role for rTMS in treating FM.