Neuroimaging studies in cluster headache (CH) patients have increased understanding of attack-associated events and provided clues to the pathophysiology of the condition. They have also suggested stimulation of the ipsilateral posterior inferior hypothalamus as a treatment for chronic intractable CH. After 8 years of experience, stimulation has proved successful in controlling the pain attacks in almost 60% of chronic CH patients implanted at various centres. Although hypothalamic implant is not without risks, it has generally been performed safely. Implantation affords an opportunity to perform microrecordings of individual posterior hypothalamic neurons. These studies are at an early stage, but suggest the possibility of identifying precisely the target site by its electrophysiological characteristics. Autonomic studies of patients undergoing posterior hypothalamic stimulation provide further evidence that long-term stimulation is safe, revealing that it can cause altered modulation of the mechanisms of orthostatic adaptation without affecting the baroreflex, cardiorespiratory interactions or efferent sympathetic and vagal functions. Chronically stimulated patients have an increased threshold for cold pain at the site of the first trigeminal branch ipsilateral to the stimulated side; when the stimulator is switched off, changes in sensory and pain thresholds do not occur immediately, suggesting that long-term stimulation is required to induce sensory and nociceptive changes. Posterior inferior hypothalamic stimulation is now established as a treatment for many chronic CH patients. The technique is shedding further light on the pathophysiology of the disease, and is also providing clues to functioning of the hypothalamus itself.
Fluorescein is widely used as a fluorescent tracer for many applications. Its capacity to accumulate in cerebral areas where there has been blood-brain barrier damage makes it particularly suitable as a dye for the intraoperative visualization of malignant gliomas (MGs). In this report, we describe the results of a comprehensive review on the use of fluorescein in the surgical treatment of MGs. A comprehensive literature search and review for English-written articles concerning the use of fluorescein in the resection of MGs has been conducted. The search was executed through a PubMed literature search using the following keywords: malignant gliomas, glioblastomas, high-grade gliomas, YELLOW 560, total removal, dedicated filter, neurosurgery, brain tumors, intracranial tumors, and confocal microscopy. The literature search resulted in the retrieval of 412 evidence-based articles. Of these, 17 were found to be strictly related to the resection of MG with the aid of fluorescein. In addition to these 17, we have included 2 articles derived from a personal database of the corresponding author (FA). The analysis of the articles reviewed revealed three major applications of fluorescein during surgery for MGs that was documented: Fluorescein-guided resection of MGs with white-light illumination, fluorescein-guided resection of MGs with a surgical microscope equipped with a dedicated filter for fluorescein, and confocal microscopy for intraoperative histopathological analysis on MGs. The systemic review conducted on the use of fluorescein in MGs explored the applications and the different modalities in which fluorescein has been used. The data we have gathered indicates that fluorescein-guided surgery is a safe, effective, and convenient technique to achieve a high rate of total removal in MGs. Further prospective comparative trials, however, are still necessary to prove the impact of fluorescein-guided surgery on both progression-free survival and overall survival.
Resting state fMRI (rs-fMRI) has recently been considered as a possible complement or alternative to task-based fMRI (tb-fMRI) for presurgical mapping. However, evidence of its usefulness remains scant, because existing studies have investigated relatively small samples and focused primarily on qualitative evaluation. The aim of this study is to investigate the clinical usefulness of rs-fMRI in the context of presurgical mapping of motor functions, and in particular to determine the degree of correspondence with tb-fMRI which, while not a gold-standard, is commonly used in preoperative setting. A group of 13 patients with lesions close to the sensorimotor cortex underwent rs-fMRI and tb-fMRI to localize the hand, foot and mouth motor areas. We assessed quantitatively the degree of correspondence between multiple rs-fMRI analyses (independent-component and seed-based analyses) and tb-fMRI, with reference to sensitivity and specificity of rs-fMRI with respect to tb-fMRI, and centre-of-mass distances. Agreement with electro-cortical stimulation (ECS) was also investigated, and a traditional map thresholding approach based on agreement between two experienced operators was compared to an automatic threshold determination method. Rs-fMRI can localize the sensorimotor cortex successfully, providing anatomical specificity for hand, foot and mouth motor subregions, in particular with seed-based analyses. Agreement with tb-fMRI was only partial and rs-fMRI tended to provide larger patterns of correlated activity. With respect to the ECS data available, rs-fMRI and tb-fMRI performed comparably, even though the shortest distance to stimulation points was observed for the latter. Notably, the results of both were on the whole robust to thresholding procedure. Localization performed by rs-fMRI is not equivalent to tb-fMRI, hence rs-fMRI cannot be considered as an outright replacement for tb-fMRI. Nevertheless, since there is significant agreement between the two techniques, rs-fMRI can be considered with caution as a potential alternative to tb-fMRI when patients are unable to perform the task.
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