Cortical Excitability in Chronic Migraine Coppola, Gianluca; Schoenen, Jean
Current pain and headache reports,
02/2012, Letnik:
16, Številka:
1
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A proportion of episodic migraine patients experiences a progressive increase in attack frequency leading to chronic migraine (CM). The most frequent external factor that leads to headache ...chronification is medication overuse. The neurobiological bases of headache chronification and of the vicious circle of medication overconsumption are not completely elucidated. More recently, the same neurophysiological methods used to study episodic migraine were applied to CM and medication-overuse headache (MOH). Studies of cortical responsivity tend overall to indicate an increase in excitability, in particular of somatosensory and visual cortices, reflected by increased amplitude of evoked responses, decreased activity of inhibitory cortical interneurons reflected in the smaller magnetic suppression of perceptual accuracy, and, at least for visual responses, an increase in habituation. In MOH, overconsumption of triptans or NSAIDs influences cortical excitability differently. Generalized central sensitization is suggested to play an important role in the pathophysiology of headache chronification.
Alzheimer's disease (AD) is a neurodegenerative disorder, which is likely to start as mild cognitive impairment (MCI) several years before the its full-blown clinical manifestation. Optical coherence ...tomography (OCT) has been used to detect a loss in peripapillary retina nerve fiber layer (RNFL) and a reduction in macular thickness and volume of people affected by MCI or AD. Here, we performed an aggregate meta-analysis combining results from different studies.
Data sources were case-control studies published between January 2001 and August 2014 (identified through PubMed and Google Scholar databases) that examined the RNFL thickness by means of OCT in AD and MCI patients compared with cognitively healthy controls.
11 studies were identified, including 380 patients with AD, 68 with MCI and 293 healthy controls (HC). The studies suggest that the mean RNFL thickness is reduced in MCI (weighted mean differences in μm, WMD = -13.39, 95% CI: -17.34 to -9.45, p = 0.031) and, even more so, in AD (WMD = -15.95, 95% CI: -21.65 to -10.21, p<0.0001) patients compared to HC. RNFL in the 4 quadrants were all significantly thinner in AD superior (superior WMD = -24.0, 95% CI: -34.9 to -13.1, p<0.0001; inferior WMD = -20.8, 95% CI: -32.0 to -9.7, p<0.0001; nasal WMD = -14.7, 95% CI: -23.9 to -5.5, p<0.0001; and temporal WMD = -10.7, 95% CI: -19.9 to -1.4, p<0.0001); the same significant reduction in quadrant RNFL was observed in MCI patients compared with HC (Inferior WMD = -20.22, 95% CI: -30.41 to -10.03, p = 0.0001; nasal WMD = -7.4, 95% CI: -10.08 to -4.7, p = 0.0000; and temporal WMD = -6.88, 95% CI: -12.62 to -1.13, p = 0.01), with the exception of superior quadrant (WMD = -19.45, 95% CI: -40.23 to 1.32, p = 0.06).
Results from the meta-analysis support the important role of OCT for RNFL analysis in monitoring the progression of AD and in assessing the effectiveness of purported AD treatments.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Clinical neurophysiology of migraine with aura Coppola, Gianluca; Di Lorenzo, Cherubino; Parisi, Vincenzo ...
Journal of headache and pain,
04/2019, Letnik:
20, Številka:
1
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Background
The purpose of this review is to provide a comprehensive overview of the findings of clinical electrophysiology studies aimed to investigate changes in information processing of migraine ...with aura patients.
Main body
Abnormalities in alpha rhythm power and symmetry, the presence of slowing, and increased information flow in a wide range of frequency bands often characterize the spontaneous EEG activity of MA. Higher grand-average cortical response amplitudes, an increased interhemispheric response asymmetry, and lack of amplitude habituation were less consistently demonstrated in response to any kind of sensory stimulation in MA patients. Studies with single-pulse and repetitive transcranial magnetic stimulation (TMS) have reported abnormal cortical responsivity manifesting as greater motor evoked potential (MEP) amplitude, lower threshold for phosphenes production, and paradoxical effects in response to both depressing or enhancing repetitive TMS methodologies. Studies of the trigeminal system in MA are sparse and the few available showed lack of blink reflex habituation and abnormal findings on SFEMG reflecting subclinical, probably inherited, dysfunctions of neuromuscular transmission. The limited studies that were able to investigate patients during the aura revealed suppression of evoked potentials, desynchronization in extrastriate areas and in the temporal lobe, and large variations in direct current potentials with magnetoelectroencephalography. Contrary to what has been observed in the most common forms of migraine, patients with familial hemiplegic migraine show greater habituation in response to visual and trigeminal stimuli, as well as a higher motor threshold and a lower MEP amplitude than healthy subjects.
Conclusion
Since most of the electrophysiological abnormalities mentioned above were more frequently present and had a greater amplitude in migraine with aura than in migraine without aura, neurophysiological techniques have been shown to be of great help in the search for the pathophysiological basis of migraine aura.
To evaluate whether treatment with Citicoline in oral solution (OS-Citicoline) would increase visual function, retinal ganglion cells (RGCs) function, and neural conduction along visual pathways ...(neuroenhancement), and/or induce preservation of RGCs fibers' loss (neuroprotection) in non-arteritic ischemic optic neuropathy (NAION), a human model of neurodegeneration.
Thirty-six patients with NAION and 20 age-matched controls were enrolled. Nineteen NAION patients received 500 mg/day of OS-Citicoline for a 6-month period followed by 3-month of wash-out (NC Group); 17 NAION patients were not treated (NN Group) from baseline to 9 months. In all subjects at baseline, and in NC and NN eyes at 6 and 9 months of follow-up, we assessed Visual Acuity (VA), Pattern Electroretinogram (PERG), Visual Evoked Potentials (VEP), retinal nerve fiber layer thickness (RNFL-T), and Humphrey 24-2 visual field mean deviation (HFA MD). Mean differences were statistically evaluated with ANOVA between Groups, and linear correlations were analysed with Pearson's test.
At 6 months, significant differences between groups for all parameters were observed (ANOVA, p<0.01). In NC eyes, VA increased, PERG responses increased, VEP recordings improved and were significantly correlated with increases in HFA MD (p<0.01), and RNFL-T was unmodified or improved. In contrast, in NN eyes, VA, PERG, VEP responses, RNFL-T, and HFA MD were further worsened. Significant differences were still present at 9-month follow-up in the NN Group and after 3 months of OS-Citicoline wash-out in NC eyes.
OS-Citicoline treatment induced neuroenhancement (improvement in RGCs function and neural conduction along visual pathways related to improvement of visual field defects) and neuroprotection (unmodified or improved RNFL morphological condition) in a human model of NAION involving fast RGCs degeneration.
ClinicalTrials.gov NCT03758118.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The aim of this study was to determine which supervised machine learning (ML) algorithm can most accurately classify people with Parkinson's disease (pwPD) from speed-matched healthy subjects (HS) ...based on a selected minimum set of IMU-derived gait features. Twenty-two gait features were extrapolated from the trunk acceleration patterns of 81 pwPD and 80 HS, including spatiotemporal, pelvic kinematics, and acceleration-derived gait stability indexes. After a three-level feature selection procedure, seven gait features were considered for implementing five ML algorithms: support vector machine (SVM), artificial neural network, decision trees (DT), random forest (RF), and K-nearest neighbors. Accuracy, precision, recall, and F1 score were calculated. SVM, DT, and RF showed the best classification performances, with prediction accuracy higher than 80% on the test set. The conceptual model of approaching ML that we proposed could reduce the risk of overrepresenting multicollinear gait features in the model, reducing the risk of overfitting in the test performances while fostering the explainability of the results.
The hypothalamus has been attributed an important role during the premonitory phase of a migraine attack. Less is known about the role played by the hypothalamus in the interictal period and its ...relationship with the putative neurocognitive networks previously identified in the pathophysiology of migraine. Our aim was to test whether the hypothalamic microstructure would be altered during the interictal period and whether this co-existed with aberrant connectivity at cortical level. We collected multimodal MRI data from 20 untreated patients with migraine without aura between attacks (MO) and 20 healthy controls (HC) and studied fractional anisotropy, mean (MD), radial (RD), and axial diffusivity of the hypothalamus ROI as a whole from diffusion tensor imaging (DTI). Moreover, we performed an exploratory analysis of the same DTI metrics separately for the anterior and posterior hypothalamic ROIs bilaterally. From resting-state functional MRI, we estimated the Higuchi's fractal dimension (FD), an index of temporal complexity sensible to describe non-periodic patterns characterizing BOLD signature. Finally, we correlated neuroimaging findings with migraine clinical features. In comparison to HC, MO had significantly higher MD, AD, and RD values within the hypothalamus. These findings were confirmed also in the exploratory analysis on the sub-regions of the hypothalamus bilaterally, with the addition of lower FA values on the posterior ROIs. Patients showed higher FD values within the salience network (SN) and the cerebellum, and lower FD values within the primary visual (PV) network compared to HC. We found a positive correlation between cerebellar and SN FD values and severity of migraine. Our findings of hypothalamic abnormalities between migraine attacks may form part of the neuroanatomical substrate that predisposes the onset of the prodromal phase and, therefore, the initiation of an attack. The peculiar fractal dimensionality we found in PV, SN, and cerebellum may be interpreted as an expression of abnormal efficiency demand of brain networks devoted to the integration of sensory, emotional, and cognitive information related to the severity of migraine.
In an fMRI study, Baksa et al. found that different circadian peaks of migraine attack onset are associated with different interictal brain activity in response to threatening fearful stimuli. ......considering the plethora of pathologies with which migraine, especially when it evolves into a chronic form, is comorbid (see Altamura et al.), we think it is time to move from the original definition of migraine as a “disease” to the definition of a “migraine syndrome,” which incorporates both the pain manifestation and the parade of central and systemic symptoms and pathologies with which it shares comorbidity. Conflict of Interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Background: Retinal ganglion cells (RGCs) are the nervous retinal elements which
connect the visual receptors to the brain forming the nervous visual system. Functional and/or morphological
...involvement of RGCs occurs in several ocular and neurological disorders and therefore
these cells are targeted in neuroprotective strategies.
Cytidine 5-diphosphocholine or Citicoline is an endogenous compound that acts in the biosynthesis
of phospholipids of cell membranes and increases neurotransmitters’ levels in the Central Nervous
System. Experimental studies suggested the neuromodulator effect and the protective role of
Citicoline on RGCs. This review aims to present evidence of the effects of Citicoline in experimental
models of RGCs degeneration and in human neurodegenerative disorders involving RGCs.
Methods: All published papers containing experimental or clinical studies about the effects of
Citicoline on RGCs morphology and function were reviewed.
Results: In rodent retinal cultures and animal models, Citicoline induces antiapoptotic effects,
increases the dopamine retinal level, and counteracts retinal nerve fibers layer thinning. Human studies
in neurodegenerative visual pathologies such as glaucoma or non-arteritic ischemic neuropathy
showed a reduction of the RGCs impairment after Citicoline administration. By reducing the RGCs'
dysfunction, a better neural conduction along the post-retinal visual pathways with an improvement
of the visual field defects was observed.
Conclusion: Citicoline, with a solid history of experimental and clinical studies, could be considered
a very promising molecule for neuroprotective strategies in those pathologies (i.e. Glaucoma)
in which morpho-functional changes of RGCc occurs.
The most commonly cited descriptions of the behavioral characteristics of habituation come from two papers published almost 40 years ago Groves, P. M., & Thompson, R. F. (1970). Habituation: A ...dual-process theory.
Psychological Review,
77, 419–450; Thompson, R. F., & Spencer, W. A. (1966). Habituation: A model phenomenon for the study of neuronal substrates of behavior.
Psychological Review,
73, 16–43. In August 2007, the authors of this review, who study habituation in a wide range of species and paradigms, met to discuss their work on habituation and to revisit and refine the characteristics of habituation. This review offers a re-evaluation of the characteristics of habituation in light of these discussions. We made substantial changes to only a few of the characteristics, usually to add new information and expand upon the description rather than to substantially alter the original point. One additional characteristic, relating to long-term habituation, was added. This article thus provides a modern summary of the characteristics defining habituation, and can serve as a convenient primer for those whose research involves stimulus repetition.
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