RESUMEN

Primary headache disorders can be remarkably disabling and the therapeutic options available are usually limited to medication with a high rate of adverse events. Here, we discuss the mechanism of action of non-invasive vagal nerve stimulation, as well as the findings of the main studies involving patients with primary headaches other than migraine or cluster headache, such as hemicrania continua, paroxysmal hemicrania, cough headache, or short-lasting neuralgiform headache attacks (SUNCT/SUNA), in a narrative analysis. A bibliographical search of low-prevalence disorders such as rare primary headaches retrieves a moderate number of studies, usually underpowered. Headache intensity, severity, and duration showed a clinically significant reduction in the majority, especially those involving indomethacin-responsive headaches. The lack of response of some patients with a similar diagnosis could be due to a different stimulation pattern, technique, or total dose. The use of non-invasive vagal nerve stimulation for the treatment of primary headache disorders represents an excellent option for patients with these debilitating and otherwise refractory conditions, or that cannot tolerate several lines of preventive medication, and should always be considered before contemplating invasive, non-reversible stimulation techniques.

RESUMEN

Objectives: Implantation and use of vagus nerve stimulation (VNS) systems is a proven treatment strategy for epilepsy and depression, and extensive research regarding vagal control of the heart has led to the idea of VNS as a potential adjunct treatment for heart failure with reduced ejection fraction (HFrEF). We describe our experience with the implantation of an investigational VNS system to manage patients living with HFrEF. Methods: As part of the ongoing ANTHEM-HFrEF (Autonomic Regulation Therapy to Enhance Myocardial Function and Reduce Progression of Heart Failure with Reduced Ejection Fraction) Pivotal Study, a 67-year-old male patient with a history of ischemic cardiomyopathy was randomized to implantation of the VITARIA System (LivaNova Inc). The electrical lead requires no mapping for placement around the vagus nerve. The surgical procedure was completed uneventfully under general anesthesia, and the device was activated in the operating room after surgery. Results: Following successful implantation and activation of the VNS system, the patient was discharged to home on the same day. Conclusions: Current, ongoing studies, such as the ANTHEM-HFrEF Pivotal Study, are designed to determine the long-term effects of VNS on heart failure symptoms, hospitalization rates, and survival. The VNS-implantation procedure was straightforward.

RESUMEN

Neuromodulation is a key therapeutic tool for clinicians managing patients with drug-resistant epilepsy. Multiple devices are available with long-term follow-up and real-world experience. The aim of this review is to give a practical summary of available neuromodulation techniques to guide the selection of modalities, focusing on patient selection for devices, common approaches and techniques for initiation of programming, and outpatient management issues. Vagus nerve stimulation (VNS), deep brain stimulation of the anterior nucleus of the thalamus (DBS-ANT), and responsive neurostimulation (RNS) are all supported by randomized controlled trials that show safety and a significant impact on seizure reduction, as well as a suggestion of reduction in the risk of sudden unexplained death in epilepsy (SUDEP). Significant seizure reductions are observed after 3 months for DBS, RNS, and VNS in randomized controlled trials, and efficacy appears to improve with time out to 7 to 10 years of follow-up for all modalities, albeit in uncontrolled follow-up or retrospective studies. A significant number of patients experience seizure-free intervals of 6 months or more with all three modalities. Number and location of epileptogenic foci are important factors affecting efficacy, and together with comorbidities such as severe mood or sleep disorders, may influence the choice of modality. Programming has evolved-DBS is typically initiated at lower current/voltage than used in the pivotal trial, whereas target charge density is lower with RNS, however generalizable optimal parameters are yet to be defined. Noninvasive brain stimulation is an emerging stimulation modality, although it is currently not used widely. In summary, clinical practice has evolved from those established in pivotal trials. Guidance is now available for clinicians who wish to expand their approach, and choice of neuromodulation technique may be tailored to individual patients based on their epilepsy characteristics, risk tolerance, and preferences.

Asunto(s)

RESUMEN

Lennox-Gastaut syndrome (LGS) is a severe epileptic encephalopathy but there is limited literature characterizing the disease burden despite this being crucial for disease management strategies, and for designing and interpreting clinical trials. We searched the Vagus Nerve Stimulation (VNS) Therapy Patient Outcome Registry including over 7000 patients with drug­resistant epilepsy (DRE). Propensity Score Matching (PSM) matched LGS-DRE patients and non-LGS-DRE patients and frequencies of individual seizure types were assessed. The PSM population included 705 and 1410 DRE patients with and without LGS. 40% of the LGS-DRE group had polypharmacy with 3 antiseizure medications (ASM) while 42% in non-LGS-DRE had polypharmacy with 2 ASMs. Median total monthly seizure frequency was over double in the LGS group: 90 (IQR, 28-312) versus 40 (IQR, 10-150); p < 0.001. This analysis suggests that seizure frequency in LGS patients who later receive VNS is more than double than in non-LGS DRE patients with mostly bilateral tonic-clonic seizures contributing to this difference. Furthermore, ASM burden with poorer seizure control may be greater in LGS patients, however data collection ceased in 2003 and therefore does not take recent ASMs approved for LGS into account. This analysis offers quantitative insight into the burden of disease in patients with LGS.

RESUMEN

Background: Left cervical vagus nerve stimulation (l-VNS) is an FDA-approved treatment for neurological disorders including epilepsy, major depressive disorder, and stroke, and l-VNS is increasingly under investigation for a range of other neurological indications. Traditional l-VNS is thought to induce therapeutic neuroplasticity in part through the coordinated activation of multiple broadly projecting neuromodulatory systems in the brain. Recently, it has been reported that striking lateralization exists in the anatomical and functional connectivity between the vagus nerves and the dopaminergic midbrain. These emerging findings suggest that VNS-driven activation of this important plasticity-promoting neuromodulatory system may be preferentially driven by targeting the right, rather than the left, cervical nerve. Objective: To compare the effects of right cervical VNS (r-VNS) vs. traditional l-VNS on self-administration behavior and midbrain dopaminergic activation in rats. Methods: Rats were implanted with a stimulating cuff electrode targeting either the right or left cervical vagus nerve. After surgical recovery, rats underwent a VNS self-administration assay in which lever pressing was paired with r-VNS or l-VNS delivery. Self-administration was followed by extinction, cue-only reinstatement, and stimulation reinstatement sessions. Rats were sacrificed 90 min after completion of behavioral training, and brains were removed for immunohistochemical analysis of c-Fos expression in the dopaminergic ventral tegmental area (VTA) and substantia nigra pars compacta (SNc), as well as in the noradrenergic locus coeruleus (LC). Results: Rats in the r-VNS cohort performed significantly more lever presses throughout self-administration and reinstatement sessions than did rats in the l-VNS cohort. Moreover, this appetitive behavioral responding was associated with significantly greater c-Fos expression among neuronal populations within the VTA, SNc, and LC. Differential c-Fos expression following r-VNS vs. l-VNS was particularly prominent within dopaminergic midbrain neurons. Conclusion: Our results support the existence of strong lateralization within vagal-mesencephalic signaling pathways, and suggest that VNS targeted to the right, rather than left, cervical nerve preferentially activates the midbrain dopaminergic system. These findings raise the possibility that r-VNS could provide a promising strategy for enhancing dopamine-dependent neuroplasticity, opening broad avenues for future research into the efficacy and safety of r-VNS in the treatment of neurological disease.

RESUMEN

Large clinical trials designed to test the efficacy of vagus nerve stimulation (VNS) in patients with heart failure did not demonstrate benefits with respect to the primary endpoints. The nonselective nature of VNS may account for the failure to translate promising results of preclinical and earlier clinical studies. This study showed that optogenetic stimulation of vagal pre-ganglionic neurons transduced to express light-sensitive channels preserved left ventricular function and exercise capacity in a rat model of myocardial infarction-induced heart failure. These data suggested that stimulation of vagal efferent activity is critically important to deliver the therapeutic benefit of VNS in heart failure.

RESUMEN

Globally, drug-resistant epilepsy affects one third of people living with epilepsy. With limitations in treatment options for refractory epilepsy in resource-limited regions, ketogenic diet therapy is an important option to consider. Utilizing the 2015 International League Against Epilepsy recommended minimum requirements for ketogenic diet therapy, three male children with refractory epilepsy, aged 2.5, 6.5 and 10 years, were initiated on the classical ketogenic diet using locally available food in August 2017 at University Teaching Hospitals-Children's Hospital in Lusaka, Zambia, through partnership with the Epilepsy Program at Boston Children's Hospital in the United States. Following successful initiation in all three children, the diet was discontinued in the 10-year-old due to difficulties complying with the diet. The youngest child demonstrated an over 50% seizure reduction and gained developmental milestones. The third child achieved seizure freedom and showed marked improvement in behaviour. This pilot demonstrates the feasibility of ketogenic diet as an important therapeutic option for refractory epilepsy in Zambia. Given the limitations in treatment choices and medication accessibility, dietary therapy offers an alternative management strategy in our setting. Collaboration with an established ketogenic diet centre contributes to a successful program.

RESUMEN

In 30% of epileptic individuals, intractable epilepsy represents a problem for the management of seizures and severely affects the patient's quality of life due to pharmacoresistance with commonly used antiseizure drugs (ASDs). Surgery is not the best option for all resistant patients due to its post-surgical consequences. Therefore, several alternative or complementary therapies have scientifically proven significant therapeutic potential for the management of seizures in intractable epilepsy patients with seizure-free occurrences. Various non-pharmacological interventions include metabolic therapy, brain stimulation therapy, and complementary therapy. Metabolic therapy works out by altering the energy metabolites and include the ketogenic diets (KD) (that is restricted in carbohydrates and mimics the metabolic state of the body as produced during fasting and exerts its antiepileptic effect) and anaplerotic diet (which revives the level of TCA cycle intermediates and this is responsible for its effect). Neuromodulation therapy includes vagus nerve stimulation (VNS), responsive neurostimulation therapy (RNS) and transcranial magnetic stimulation therapy (TMS). Complementary therapies such as biofeedback and music therapy have demonstrated promising results in pharmacoresistant epilepsies. The current emphasis of the review article is to explore the different integrated mechanisms of various treatments for adequate seizure control, and their limitations, and supportive pieces of evidence that show the efficacy and tolerability of these non-pharmacological options.

RESUMEN

Forced normalization is the development of psychiatric symptoms in a patient experiencing remission of seizures. We present a case of Lennox Gastaut syndrome in which forced normalization developed after vagus nerve stimulation was stopped. The patient had drug resistant epilepsy and failed anti-seizure drugs, vagus nerve stimulation, and a partial callosotomy. The patient had multiple types of seizures including drop attacks, absences, and tonic-clonic seizures. He tried vagus nerve stimulation for two years without success. Forced normalization developed after the vagus nerve stimulator was turned off. This is the first case to our knowledge to describe forced normalization after turning off the vagus nerve stimulator.

RESUMEN

Functional, molecular and genetic neuroimaging has highlighted the existence of brain anomalies and neural vulnerability factors related to obesity and eating disorders such as binge eating or anorexia nervosa. In particular, decreased basal metabolism in the prefrontal cortex and striatum as well as dopaminergic alterations have been described in obese subjects, in parallel with increased activation of reward brain areas in response to palatable food cues. Elevated reward region responsivity may trigger food craving and predict future weight gain. This opens the way to prevention studies using functional and molecular neuroimaging to perform early diagnostics and to phenotype subjects at risk by exploring different neurobehavioral dimensions of the food choices and motivation processes. In the first part of this review, advantages and limitations of neuroimaging techniques, such as functional magnetic resonance imaging (fMRI), positron emission tomography (PET), single photon emission computed tomography (SPECT), pharmacogenetic fMRI and functional near-infrared spectroscopy (fNIRS) will be discussed in the context of recent work dealing with eating behavior, with a particular focus on obesity. In the second part of the review, non-invasive strategies to modulate food-related brain processes and functions will be presented. At the leading edge of non-invasive brain-based technologies is real-time fMRI (rtfMRI) neurofeedback, which is a powerful tool to better understand the complexity of human brain-behavior relationships. rtfMRI, alone or when combined with other techniques and tools such as EEG and cognitive therapy, could be used to alter neural plasticity and learned behavior to optimize and/or restore healthy cognition and eating behavior. Other promising non-invasive neuromodulation approaches being explored are repetitive transcranial magnetic stimulation (rTMS) and transcranial direct-current stimulation (tDCS). Converging evidence points at the value of these non-invasive neuromodulation strategies to study basic mechanisms underlying eating behavior and to treat its disorders. Both of these approaches will be compared in light of recent work in this field, while addressing technical and practical questions. The third part of this review will be dedicated to invasive neuromodulation strategies, such as vagus nerve stimulation (VNS) and deep brain stimulation (DBS). In combination with neuroimaging approaches, these techniques are promising experimental tools to unravel the intricate relationships between homeostatic and hedonic brain circuits. Their potential as additional therapeutic tools to combat pharmacorefractory morbid obesity or acute eating disorders will be discussed, in terms of technical challenges, applicability and ethics. In a general discussion, we will put the brain at the core of fundamental research, prevention and therapy in the context of obesity and eating disorders. First, we will discuss the possibility to identify new biological markers of brain functions. Second, we will highlight the potential of neuroimaging and neuromodulation in individualized medicine. Third, we will introduce the ethical questions that are concomitant to the emergence of new neuromodulation therapies.

Asunto(s)