Patients awaiting surgery for neurosurgical diseases during the first wave of the COVID-19 pandemic in Spain: a multicentre cohort study.

OBJECTIVES: The large number of infected patients requiring mechanical ventilation has led to the postponement of scheduled neurosurgical procedures during the first wave of the COVID-19 pandemic. The aims of this study were to investigate the factors that influence the decision to postpone scheduled neurosurgical procedures and to evaluate the effect of the restriction in scheduled surgery adopted to deal with the first outbreak of the COVID-19 pandemic in Spain on the outcome of patients awaiting surgery. DESIGN: This was an observational retrospective study. SETTINGS: A tertiary-level multicentre study of neurosurgery activity between 1 March and 30 June 2020. PARTICIPANTS: A total of 680 patients awaiting any scheduled neurosurgical procedure were enrolled. 470 patients (69.1%) were awaiting surgery because of spine degenerative disease, 86 patients (12.6%) due to functional disorders, 58 patients (8.5%) due to brain or spine tumours, 25 patients (3.7%) due to cerebrospinal fluid (CSF) disorders and 17 patients (2.5%) due to cerebrovascular disease. PRIMARY AND SECONDARY OUTCOME MEASURES: The primary outcome was mortality due to any reason and any deterioration of the specific neurosurgical condition. Second, we analysed the rate of confirmed SARS-CoV-2 infection. RESULTS: More than one-quarter of patients experienced clinical or radiological deterioration. The rate of worsening was higher among patients with functional (39.5%) or CSF disorders (40%). Two patients died (0.4%) during the waiting period, both because of a concurrent disease. We performed a multivariate logistic regression analysis to determine independent covariates associated with maintaining the surgical indication. We found that community SARS-CoV-2 incidence (OR=1.011, p<0.001), degenerative spine (OR=0.296, p=0.027) and expedited indications (OR=6.095, p<0.001) were independent factors for being operated on during the pandemic. CONCLUSIONS: Patients awaiting neurosurgery experienced significant collateral damage even when they were considered for scheduled procedures.

Deep brain stimulation for extreme behaviors associated with autism spectrum disorder converges on a common pathway: a systematic review and connectomic analysis.

OBJECTIVE: Individuals with autism spectrum disorder (ASD) may display extreme behaviors such as self-injury or aggression that often become refractory to psychopharmacology or behavioral intervention. Deep brain stimulation (DBS) is a surgical alternative that modulates brain circuits that have yet to be clearly elucidated. In the current study the authors performed a connectomic analysis to identify brain circuitry engaged by DBS for extreme behaviors associated with ASD. METHODS: A systematic review was performed to identify prior reports of DBS as a treatment for extreme behaviors in patients with ASD. Individual patients' perioperative imaging was collected from corresponding authors. DBS electrode localization and volume of tissue activated modeling were performed. Volumes of tissue activated were used as seed points in high-resolution normative functional and structural imaging templates. The resulting individual functional and structural connectivity maps were pooled to identify networks and pathways that are commonly engaged by all targets. RESULTS: Nine patients with ASD who were receiving DBS for symptoms of aggression or self-injurious behavior were identified. All patients had some clinical improvement with DBS. Connectomic analysis of 8 patients (from the systematic review and unpublished clinical data) demonstrated a common anatomical area of shared circuitry within the anterior limb of the internal capsule. Functional analysis of 4 patients identified a common network of distant brain areas including the amygdala, insula, and anterior cingulate engaged by DBS. CONCLUSIONS: This study presents a comprehensive synopsis of the evidence for DBS in the treatment of extreme behaviors associated with ASD. Using network mapping, the authors identified key circuitry common to DBS targets.

Impact of the first wave of the SARS-CoV-2 pandemic on the outcome of neurosurgical patients: a nationwide study in Spain.

OBJECTIVE: To assess the effect of the first wave of the SARS-CoV-2 pandemic on the outcome of neurosurgical patients in Spain. SETTINGS: The initial flood of COVID-19 patients overwhelmed an unprepared healthcare system. Different measures were taken to deal with this overburden. The effect of these measures on neurosurgical patients, as well as the effect of COVID-19 itself, has not been thoroughly studied. PARTICIPANTS: This was a multicentre, nationwide, observational retrospective study of patients who underwent any neurosurgical operation from March to July 2020. INTERVENTIONS: An exploratory factorial analysis was performed to select the most relevant variables of the sample. PRIMARY AND SECONDARY OUTCOME MEASURES: Univariate and multivariate analyses were performed to identify independent predictors of mortality and postoperative SARS-CoV-2 infection. RESULTS: Sixteen hospitals registered 1677 operated patients. The overall mortality was 6.4%, and 2.9% (44 patients) suffered a perioperative SARS-CoV-2 infection. Of those infections, 24 were diagnosed postoperatively. Age (OR 1.05), perioperative SARS-CoV-2 infection (OR 4.7), community COVID-19 incidence (cases/105 people/week) (OR 1.006), postoperative neurological worsening (OR 5.9), postoperative need for airway support (OR 5.38), ASA grade ≥3 (OR 2.5) and preoperative GCS 3-8 (OR 2.82) were independently associated with mortality. For SARS-CoV-2 postoperative infection, screening swab test <72 hours preoperatively (OR 0.76), community COVID-19 incidence (cases/105 people/week) (OR 1.011), preoperative cognitive impairment (OR 2.784), postoperative sepsis (OR 3.807) and an absence of postoperative complications (OR 0.188) were independently associated. CONCLUSIONS: Perioperative SARS-CoV-2 infection in neurosurgical patients was associated with an increase in mortality by almost fivefold. Community COVID-19 incidence (cases/105 people/week) was a statistically independent predictor of mortality. TRIAL REGISTRATION NUMBER: CEIM 20/217.

Surgery and Radiosurgery in Autism: A Retrospective Study in 10 Patients.

INTRODUCTION: A subgroup of patients with autism spectrum disorder (ASD) show self or heteroaggression, dyscontrol episodes, and others are of obsessive-compulsive disorder (OCD) profile; some of them are resistant to medical and behavioural treatment. We describe the long-term outcome in a group of these patients, treated with radiofrequency brain lesions or combined stereotactic surgery and Gamma Knife (GK) radiosurgery. METHODS: We reviewed the medical records of 10 ASD patients with pathological aggressiveness and OCD, who had undergone radiofrequency lesions and/or radiosurgery with GK in our institution. RESULTS: The 10 patients had a significant reduction of their symptoms (PCQ 39.9 and 33, OAS 11.8 and 5, CYBOCS-ASD 30.4 and 20), preoperatively and in the last follow-up, respectively; p < 0.005 (in all cases), although all but 2 needed more than 1 treatment to maintain this improvement. CONCLUSIONS: We observed a marked improvement in behaviour, quality of life, and relationship with the environment in all our 10 patients after the lesioning treatments, without long-lasting side effects.

Posteromedial Hypothalamic Deep Brain Stimulation for Refractory Aggressiveness in a Patient With Weaver Syndrome: Clinical, Technical Report and Operative Video.

BACKGROUND AND IMPORTANCE: Deep brain stimulation of the posteromedial hypothalamus (PMH DBS) appears to be an effective treatment for drug-resistant aggressiveness. Weaver syndrome (WS) is a rare genetic disorder in which patients develop some degree of intellectual disability and rarely severe behavioral alterations that may benefit from this procedure. CLINICAL PRESENTATION: We present the case of a 26-yr-old man diagnosed with WS presenting with uncontrollable self and heteroaggressiveness and disruptive behavior refractory to pharmacological treatment and under severe physical and mechanical restraining measures. The patient was successfully treated with bilateral PMH DBS resulting in affective improvement, greater tolerance for signs of affection, regularization in his sleep pattern and appetite disturbances at 12-mo follow-up. A detailed description and video of the procedure are presented, and a review of the clinical characteristics of WS and the utility and benefits of PMH DBS for refractory aggressiveness are reviewed. CONCLUSION: To our knowledge, this is the first case of refractory aggressiveness described in WS as well as the first patient with WS successfully treated with PMH DBS.

Language hemispheric dominance analyzed with magnetic resonance DTI: correlation with the Wada test.

OBJECTIVE: Language lateralization is a major concern in some patients with pharmacoresistant epilepsy who will face surgery; in these patients, hemispheric dominance testing is essential to avoid further complications. The Wada test is considered the gold standard examination for language localization, but is invasive and requires many human and material resources. Functional MRI and tractography with diffusion tensor imaging (DTI) have demonstrated that they could be useful for locating language in epilepsy surgery, but there is no evidence of the correlation between the Wada test and DTI MRI in language dominance. METHODS: The authors performed a retrospective review of patients who underwent a Wada test before epilepsy surgery at their institution from 2012 to 2017. The authors retrospectively analyzed fractional anisotropy (FA), number and length of fibers, and volume of the arcuate fasciculus and uncinate fasciculus, comparing dominant and nondominant hemispheres. RESULTS: Ten patients with temporal lobe epilepsy were reviewed. Statistical analysis showed that the mean FA of the arcuate fasciculus in the dominant hemisphere was higher than in the nondominant hemisphere (0.369 vs 0.329, p = 0.049). Also, the number of fibers in the arcuate fasciculus was greater in the dominant hemisphere (881.5 vs 305.4, p = 0.003). However, no differences were found in the FA of the uncinate fasciculus or number of fibers between hemispheres. The length of fibers of the uncinate fasciculus was longer in the dominant side (74.4 vs 50.1 mm, p = 0.05). Volume in both bundles was more prominent in the dominant hemisphere (12.12 vs 6.48 cm3, p = 0.004, in the arcuate fasciculus, and 8.41 vs 4.16 cm3, p = 0.018, in the uncinate fasciculus). Finally, these parameters were compared in patients in whom the seizure focus was situated in the dominant hemisphere: FA (0.37 vs 0.30, p = 0.05), number of fibers (114.4 vs 315.6, p = 0.014), and volume (12.58 vs 5.88 cm3, p = 0.035) in the arcuate fasciculus were found to be statistically significantly higher in the dominant hemispheres. Linear discriminant analysis of FA, number of fibers, and volume of the arcuate fasciculus showed a correct discrimination in 80% of patients (p = 0.024). CONCLUSIONS: The analysis of the arcuate fasciculus and other tract bundles by DTI could be a useful tool for language location testing in the preoperative study of patients with refractory epilepsy.

Deep brain stimulation for aggressiveness: long-term follow-up and tractography study of the stimulated brain areas.

OBJECTIVE: Initial studies applying deep brain stimulation (DBS) of the posteromedial hypothalamus (PMH) to patients with pathological aggressiveness have yielded encouraging results. However, the anatomical structures involved in its therapeutic effect have not been precisely identified. The authors' objective was to describe the long-term outcome in their 7-patient series, and the tractography analysis of the volumes of tissue activated in 2 of the responders. METHODS: This was a retrospective study of 7 subjects with pathological aggressiveness. The findings on MRI with diffusion tensor imaging (DTI) in 2 of the responders were analyzed. The authors generated volumes of tissue activated according to the parameters used, and selected those volumes as regions of interest to delineate the tracts affected by stimulation. RESULTS: The series consisted of 5 men and 2 women. Of the 7 patients, 5 significantly improved with stimulation. The PMH, ventral tegmental area, dorsal longitudinal fasciculus, and medial forebrain bundle seem to be involved in the stimulation field. CONCLUSIONS: In this series, 5 of 7 medication-resistant patients with severe aggressiveness who were treated with bilateral PMH DBS showed a significant long-lasting improvement. The PMH, ventral tegmental area, dorsal longitudinal fasciculus, and medial forebrain bundle seem to be in the stimulation field and might be responsible for the therapeutic effect of DBS.

Neurophysiological Characterization of Thalamic Nuclei in Epileptic Anaesthetized Patients.

Deep brain stimulation (DBS) requires precise localization, which is especially difficult at the thalamus, and even more difficult in anesthetized patients. We aimed to characterize the neurophysiological properties of the ventral intermediate (V.im), ventral caudal (V.c), and centromedian parvo (Ce.pc) and the magnocellular (Ce.mc) thalamic nuclei. We obtained microelectrode recordings from five patients with refractory epilepsy under general anesthesia. Somatosensory evoked potentials recorded by microelectrodes were used to identify the V.c nucleus. Trajectories were reconstructed off-line to identify the nucleus recorded, and the amplitude of the action potential (AP) and the tonic (i.e., mean frequency, density, probability of interspike interval) and phasic (i.e., burst index, pause index, and pause ratio) properties of the pattern discharges were analyzed. The Mahalanobis metric was used to evaluate the similarity of the patterns. The mean AP amplitude was higher for the V.im nucleus (172.7 ± 7.6 µV) than for the other nuclei, and the mean frequency was lower for the Ce.pc nucleus (7.2 ± 0.8 Hz) and higher for the V.c nucleus (11.9 ± 0.8 Hz) than for the other nuclei. The phasic properties showed a bursting pattern for the V.c nucleus and a tonic pattern for the centromedian and V.im nuclei. The Mahalanobis distance was the shortest for the V.im/V.c and Ce.mp/Ce.pc pairs. Therefore, the different properties of the thalamic nuclei, even for patients under general anesthesia, can be used to positively define the recorded structure, improving the exactness of electrode placement in DBS.

Prediction of Laterality in Temporal Lobe Epilepsy Using White Matter Diffusion Metrics.

BACKGROUND: Diagnostic methods of the epileptogenic area continue to be a challenge in epilepsy surgery research. We hypothesized that temporal lobe epilepsy (TLE) will result in white matter changes that can be detected using diffusion tensor imaging. Measurement of white matter diffusivity will therefore be useful for presurgical assessment. METHODS: Twelve patients with TLE who had undergone temporal lobectomy and amygdalohippocampectomy were included. In 6 patients, magnetic resonance imaging (MRI) showed evidence of mesial temporal sclerosis (m-TLE), whereas the 6 remaining MRI studies were informed without any abnormality (nl-TLE). All had excellent outcomes from surgery. Patients were compared with 12 age- and sex-matched controls. Five pairs of white matter fiber tracts were traced, and fiber tract fractional anisotropy and mean diffusivity were calculated. RESULTS: There were several alterations in diffusion parameters in white matter tracts, both ipsilateral and on the contralateral side, these alterations were more pronounced in the hemisphere ipsilateral to the epileptogenic focus. m-TLE patients had more alterations on ipsilateral side than nl-TLE patients, but similar alterations on contralateral side and bilateral fornix. The discriminant function analysis successfully lateralized all the patients with left TLE, 83.3% of the patients with right TLE, and all nl-TLE. CONCLUSIONS: Our results suggest that there are alterations in diffusion parameters in white matter tracts both in m-TLE and nl-TLE patients. Diffusion tensor imaging could be a useful presurgical tool to help establish the laterality of TLE, including patients with "normal" MRI. Further studies with a larger number of patients would be necessary to confirm these results.

Traumatic atlantoaxial rotatory fixation in an adult patient.

INTRODUCTION: Atlantoaxial rotational fixation (AARF) is a rare entity in adults, with only a few cases reported in the English literature and often associated with a traumatic mechanism. It is an underdiagnosed condition that must be taken into account in the initial assessment of all craniocervical trauma. Both diagnostic and therapeutic delay may be a potential cause of severe neurological damage or even death of the patient. The therapeutic management is controversial given the difficulty of achieving optimum stability and permanent reduction. METHODS AND RESULTS: A 28-year-old woman was involved in a traffic accident a week before coming to the emergency with rotation and irreducible cervical flexion from trauma and severe neck pain. CT and MRI column were performed and showed a cervical spinal AARF with transverse and alar ligaments intact and preserved atlantoaxial distance (Fielding I). The patient was treated by progressive cervical traction with 5 kg and manual reduction was completed in 24 h. Subsequently, an external immobilization was performed by cervical rigid collar for 16 weeks. The clinical course was good, with the patient regaining full mobility with cervical neck pain improvement. CONCLUSIONS: The purpose of this paper is to show a case of a young woman with a posttraumatic AARF successfully treated conservatively. This case delineates the difficulties in diagnosing this pathology, as well as the challenges encountered in its management.

Effectiveness of vagal nerve stimulation in medication-resistant epilepsy. Comparison between patients with and without medication changes.

BACKGROUND: Vagal nerve stimulation (VNS) response is not immediate. A progressive decline in seizure frequency is usually found during a period of 12-18 months after implantation. During this time, the patient's medication is usually modified, which can create doubts about whether their clinical improvement is due to medication changes or to VNS itself. Our goal is to compare two groups of patients treated with VNS, with and without changes in their medication. METHODS: We prospectively analyze 85 patients who were treated with VNS in our hospital between 2005 and 2014. In 43 patients, changes in the antiepileptic drugs (EAD) were not allowed during the postoperative follow-up and they were compared with 42 patients who were left at the option of neurologist make changes in medication. We analyzed the clinical situation at 18 months and compared the two groups. RESULTS: Overall, 54.1% of patients had a reduction in seizures of 50% or higher (responders). In the group with no changes in medication, responders reached 63%, while in the group in which changes in medication were allowed, 45.2% were responders. Between responders and non-responders, there were no statistical differences in type of epilepsy, frequency, previous surgery, or intensity of stimulation. CONCLUSIONS: We did not find a statistical difference in seizure frequency reduction between patients with or without changes in medication during their follow-up, so changes in medication did not improve the outcome. Furthermore, the absence of changes in AED can help to optimize the parameters of the stimulator in order to improve its effectiveness.

Infratentorial angioleiomyoma: case report and review of the literature.

INTRODUCTION: Intracranial angioleiomyomas are extremely rare lesions. Only 22 intracranial angioleiomyomas have been described in the literature and only three were infratentorial. CASE REPORT: We report a case of an infratentorial angioleiomyoma in a 43 year-old-man, who underwent a brain computer tomography because of hearing loss. The MRI showed a 1.4 cm tumor, initially described as a meningioma, with progressive enhancement after gadolinium injection, an augmented apparent diffusion coefficient and a generalized metabolite decreased in the spectroscopy. The lesion was surgically removed through a suboccipital approach with a good evolution and without postoperative complications. In the immunohistological study, the lesion was mainly composed of multiple vessels and the immunohistochemistry was positive for actin and caldesmon. Two years after surgery, no recurrence has been found in the MRI. CONCLUSION: Angioleiomyomas diagnostic may be complex, but some radiological features could help in the differential diagnostic. Angioleiomyomas are benign tumors associated with favorable outcomes after total resection, that in our case, did not show a significant bleeding risk.

TITLE: Angioleiomioma infratentorial: caso clinico y revision de la bibliografia.Introduccion. Los angioleiomiomas intracraneales son lesiones muy poco frecuentes. Solo se han descrito 22 casos en la bibliografia hasta la actualidad, unicamente tres de ellos de localizacion infratentorial. Caso clinico. Varon de 43 años con un angioleiomioma infratentorial descubierto de forma incidental tras la realizacion de una tomografia computarizada por hipoacusia. La resonancia magnetica mostro una tumoracion de 1,4 cm, descrita inicialmente como un meningioma, con un realce progresivo tras la administracion de gadolinio, un aumento del coeficiente de difusion aparente y un descenso generalizado de metabolitos en la espectroscopia. La lesion se reseco quirurgicamente mediante un abordaje suboccipital con buena evolucion y sin complicaciones postoperatorias. En el estudio histologico, la lesion presentaba un abundante componente vascular, y en la tincion inmunohistoquimica era positiva para actina y caldesmona. Dos años despues de la cirugia, el paciente no presentaba recurrencia en la resonancia magnetica de control. Conclusion. El diagnostico de los angioleiomiomas puede ser complejo, pero algunas de sus caracteristicas radiologicas pueden facilitarlo. Los angioleiomiomas son tumores benignos asociados con un resultado funcional favorable tras su reseccion completa, que en nuestro caso no presento un alto riesgo de sangrado.

Network Analysis of Foramen Ovale Electrode Recordings in Drug-resistant Temporal Lobe Epilepsy Patients.

Approximately 30% of epilepsy patients are refractory to antiepileptic drugs. In these cases, surgery is the only alternative to eliminate/control seizures. However, a significant minority of patients continues to exhibit post-operative seizures, even in those cases in which the suspected source of seizures has been correctly localized and resected. The protocol presented here combines a clinical procedure routinely employed during the pre-operative evaluation of temporal lobe epilepsy (TLE) patients with a novel technique for network analysis. The method allows for the evaluation of the temporal evolution of mesial network parameters. The bilateral insertion of foramen ovale electrodes (FOE) into the ambient cistern simultaneously records electrocortical activity at several mesial areas in the temporal lobe. Furthermore, network methodology applied to the recorded time series tracks the temporal evolution of the mesial networks both interictally and during the seizures. In this way, the presented protocol offers a unique way to visualize and quantify measures that considers the relationships between several mesial areas instead of a single area.

[Stimulation of the centromedian nucleus in refractory epilepsy associated to ring chromosome 20]. / Estimulacion del nucleo centromediano en la epilepsia farmacorresistente asociada al cromosoma 20 en anillo.

INTRODUCTION: Ring chromosome 20 syndrome is a rare genetic disorder, with a late diagnosis. CASE REPORT: A 43-year-old woman who had had refractory epilepsy since the age of six years, for which she was treated with deep brain stimulation of the centromedian nucleus, and also a ring chromosome 20. CONCLUSIONS: From the findings of the study it can be concluded that deep brain stimulation of the centromedian nucleus is ineffective in patients with ring chromosome, but note must be taken of the importance of genetic characterisation for the management of refractory epilepsy.

TITLE: Estimulacion del nucleo centromediano en la epilepsia farmacorresistente asociada al cromosoma 20 en anillo.Introduccion. El sindrome del cromosoma 20 en anillo es una alteracion genetica infrecuente, con un diagnostico tardio. Caso clinico. Mujer de 43 años con epilepsia farmacorresistente desde los 6 años, tratada mediante estimulacion cerebral profunda del nucleo centromediano y con un cromosoma 20 en anillo. Conclusiones. Del estudio se extrae la conclusion de la inefectividad de la estimulacion cerebral profunda del nucleo centromediano en pacientes con cromosoma en anillo, pero se apunta la importancia de la caracterizacion genetica para el manejo de la epilepsia farmacorresistente.

Dumbbell-Shaped Epidural Capillary Hemangioma Presenting as a Lung Mass: Case Report and Review of the Literature.

STUDY DESIGN: A case report and literature review. OBJECTIVE: We present the fourth case of a spinal epidural capillary hemangioma with a dumbbell-shaped appearance in the magnetic resonance image reported in the literature and the second presented as a lung mass. SUMMARY OF BACKGROUND DATA: Hemangiomas are congenital vascular malformations that pathologists frequently consider to be hamartomatous malformations. Hemangiomas of the spine are usually lesions of the vertebral bodies, but they can sit in other locations such as the intramedullary or epidural space. Purely epidural hemangiomas are rare and most of them are of cavernous type. METHODS: We present a 67-year-old female with a thoracic dumbbell-shaped capillary hemangioma with both foraminal and intrathoracic extensions, whose presentation was pleural effusion associated with mediastinal mass suggestive of pulmonary neoplasia. Surgical treatment consisted of total removal en bloc of the lesion. RESULTS: Microscopic evaluation showed a fibrofatty tissue with a proliferation of vascular structures that were generally of a small size, with areas of myxoid appearance. To date, there have been 8 epidural capillary hemangiomas of the thoracic and lumbar spine reported in the literature, and only 3 of them were dumbbell-shaped with extraforaminal extension. CONCLUSION: It is important to consider the diagnosis of hemangiomas in the differential diagnosis of epidural lesions with dumbbell-shaped appearance in the magnetic resonance image, especially at the thoracic level. It is a benign and potentially curable disease and the most appropriate surgical treatment is en bloc resection of the entire lesion. They are usually presented as a progressive myelopathy, so early treatment may prevent permanent neurological deficits. LEVEL OF EVIDENCE: 5.

[Occipital nerve stimulation for refractory chronic migraine]. / Estimulación de nervios occipitales en el tratamiento de la migraña crónica refractaria.

INTRODUCTION: Occipital nerve stimulation (ONS) is an emerging and promising preventive treatment for refractory chronic migraine. AIM: To evaluate the mechanisms of actions, clinical studies, implantation techniques and inclusion criteria of the ONS as a preventive treatment for migraine. DEVELOPMENT: This work includes a non-systematic review of the literature on the above-mentioned aspects of ONS as a treatment for refractory chronic migraine. This disease affects approximately 2% of the population and results in a significant impairment in quality of life, economic burden and interference with labor and social activities. ONS is an emerging and promising therapy for the treatment of chronic migraine with greater than 50% pain reduction in most of open-label studies and published clinical trials. Although the mechanisms of action remain unknown, there seem to be a neuromodulation of the transmitted nociceptive trigeminal information in the trigeminal caudal nucleus, what could be explained by means of the Melzack and Wall pain gate theory. ONS is a safe and well tolerated treatment, and its most frequent side effects are usually local such as electrodes displacement or infections of the surgical incision. These complications do not usually require the electrodes withdrawal. CONCLUSIONS: ONS is an effective, well tolerated and safe treatment for the prevention of chronic migraine and could emerge as a useful option for those patients with medically refractory chronic migraine.

TITLE: Estimulacion de nervios occipitales en el tratamiento de la migraña cronica refractaria.Introduccion. La estimulacion de nervios occipitales (ENO) es un tratamiento preventivo de la migraña cronica refractaria que esta adquiriendo una importancia creciente en los ultimos años. Objetivo. Evaluar el mecanismo de accion, estudios clinicos, tecnica de implantacion y criterios de inclusion de la ENO en el tratamiento preventivo de la migraña. Desarrollo. Se realiza una revision no sistematica de la bibliografia sobre los aspectos anteriormente expuestos en la ENO como tratamiento para la migraña cronica. Esta patologia afecta aproximadamente al 2% de la poblacion y da lugar a una importante disminucion de la calidad de vida e interferencia con las actividades laborales y sociales. La ENO es una terapia emergente y prometedora para el tratamiento de la migraña cronica que ha demostrado una disminucion superior al 50% en el dolor en la mayoria de los estudios abiertos y ensayos clinicos publicados. Aunque el mecanismo de accion es desconocido, parece existir una neuromodulacion de la informacion nociceptiva trigeminal en el nucleo caudal del trigemino explicada mediante la teoria de la puerta de entrada de Melzack y Wall. La ENO es un tratamiento seguro y bien tolerado, y los efectos secundarios son habitualmente locales, como desplazamiento de los electrodos o infecciones de la herida quirurgica, que habitualmente no requieren su retirada. Conclusiones. La ENO es un tratamiento eficaz, bien tolerado y seguro en la prevencion de la migraña cronica, y supone una opcion util para aquellos pacientes con migraña cronica refractaria a los tratamientos medicos convencionales.

Integrating diffusion tensor imaging-based tractography into deep brain stimulation surgery: a review of the literature.

BACKGROUND: It has been generally accepted that deep brain stimulation (DBS) not only acts in the nucleus where it is being applied, as initially thought, but that chronic stimulation activates axons located in its scope, and that this activation can exert its effects in distant areas. Considering this, DBS target identification should be made based on techniques that identify white matter tracts, such as tractography, rather than only by identifying specific nuclei on conventional magnetic resonance imaging. METHODS: In this study, we performed a review of the literature on the use of tractography in DBS surgery and provide an overview of the main results. RESULTS: Tractography has been used in the field of DBS to help clarify relevant aspects in the selection of targets and in evaluating its therapeutic effects in movement disorders, psychiatric diseases and pain. CONCLUSIONS: Studies are scarce so far, but they have provided data that, if confirmed, may optimize DBS surgery. Tractography might become a routine tool for DBS surgery in the near future.