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Studio Multidisciplinare sulle complicanze neurologiche in bambini affetti da Anemia Falciforme Valutazione con metodiche Ultrasonografiche, Neuroradiologiche, test Neuropsicologici e Neurofisiologici
Full text linkABSTRACT
Sickle cell disease (SCD) is a genetic disorder caused by abnormal haemoglobin that damages and deforms red blood cells. Sickle cell anemia (SCA) is the most severe form of SCD developing when two sickle genes are inherited (homozygotic HbSS) . Sickle cell disease is in the world, the most common genetic disease. Each year more than 300,000 children are born with SCD, mainly in Africa, India and Albania (data WHO 2008). The SCA is an increasing global health problem (Weatherall DJ 2001) .
Neurologic complications are frequent among the most serious and disabling. Stroke is a frequent complication of SCD. Approximately 11% of children have a clinical stroke before 20 years of age (Ohene-Frempong K. 1998) and another 35% have a silent infarcts on magnetic resonance imaging (Pegelow C. 2002) with serious sequelae psycho-cognitive and learning difficulties (Schatz J 2002).
Screening programs for stroke prevention in SCD children have been implemented using Transcranial Doppler (TCD) (Adams R. 1998) by STOP study and SPREAD guidelines.TCD can measure flow velocities in the large intracranial arteries; long term prospective studies have demonstrated the validity of TCD in identifying children at risk of stroke due to increased cerebral velocities.
A blood flow velocity > 200 cm/s in the middle cerebral artery (MCA), correlates with a high risk of stroke in cohorts of African-american HbS/HbS patients (STOP study Adams 1998-2000). The risk is reduced by 90% if those patients are receiving chronic transfusion therapy (STOP2). Another study, using MRI, revealed the prevalence of silent infarcts in school-aged children with homozygous but without associated focal neurological symptoms (Pegelow et al. 2002). Silent cerebral infarcts are increasingly recognized as a major cause of school problems, lower intelligence quotient (IQ) and other neurocognitive deficits. The effect of increased tissue injury in children with sickle cell disease and silent cerebral infarcts is not known.
The purpose of the research was to examine the various aspects of the problem of management of patients with sickle cell anemia.
The assessment of the risk of stroke, silent infarcts and any impairment of cognitive. how to have an early prediction of the fact. These goals require a necessarily multidisciplinary approach to the study.
The STOP study has defined the parameters that require treatment (TAMM> 200 cm/s) (SPREAD guidelines): is to be noted that the parameters are based only in non-imaging TCD.
The first phase of the present study was devoted to the comparison between the two neurosonological methods of non-imaging and imaging TCD (TCCS and TCD). A cross sectional and a follow up analysis were carried out in a group of children in which both methods were used. This study can support the hypothesis that the TCCS is more suitable for screening in SCD and useful to refine the stroke risk in SCD children.
In the second stage we evaluated the hypothesis that the combination of results obtained with the Doppler, AngioRMN and MRI could identify children who developed IS compared to those not developing. Our results
In the third step we evaluated the cognitive performance of children with and without IS. Neuropsychological tests were used (Whechsler Intelligence Scales for Children, WISC and Wechsler Preschool and Primary Scale of Intelligence, WPPSI).Finally, the fourth phase has set itself the objective to evaluate any differences in the group with and without IS, from a neurophysiological point of view, through the analysis of P300 LORETA, and a point of view of quantifying the volume and thickness of the cortex and the amount of white matter through the SoftwareFreeSurfer.5
RIASSUNTO
La Drepanocitosi, chiamata anche Anemia a Cellule Falciformi (SCD sickle cell disease) è una malattia congenita ed ereditaria dell’emoglobina e rappresenta nel mondo, la più comune malattia genetica.
Ogni anno nascono più di 300.000 bambini con SCD, la maggior parte in Africa, India e Albania, secondo i dati dell’OMS nel 2008. La SCD è diventata un problema in crescita a livello mondiale. Le complicanze neurologiche sono frequenti e tra le più serie e disabilitanti. Lo stroke sintomatico accade in circa 11% dei pazienti con SCD prima dei 20 anni (Ohene-Frempong K. 1998) e circa il 35% presenta lesioni silenti alla RMN (Pegelow C. 2002) con relativo coinvolgimento psico-cognitivo e deficit di apprendimento (Schatz J 2002).
Programmi di screening per la prevenzione dell’ictus (studio STOP e linee guida SPREAD) sono stati condotti con l’uso del TCD (Adams R. 1998). Il TCD può misurare le velocità di flusso ematico delle grandi arterie della base cranica. Lo studio STOP ha dimostrato la validità del TCD nell’identificare i bambini a rischio stroke: le velocità ematiche > 200 cm/s a livello dell’Arteria Cerebrale Media correlavano con elevato rischio di stroke in una coorte di bambini Afro-americani omozigoti HbS/HbS (STOP study Adams 1998-2000).
Il rischio si riduceva del 90% quando questi bambini venivano sottoposti a terapia trasfusionale cronica (STOP2).
Altri studi effettuati con uso di RMN, hanno rilevato la prevalenza di Infarti Silenti (I.S.) in bambini con SCD senza sintomi neurologici associati (Pegelow et al. 2002).
Gli Infarti Cerebrali Silenti sono responsabili di deficit neuro-cognitivi, basso QI e problemi scolastici.
Lo scopo di questa ricerca è stato quello di valutare da un punto di vista multidisciplinare i vari aspetti di coinvolgimeno neurologico in pazienti con SCD. Sono stati quindi utilizzate metodiche Ultrasonografiche (TCD e TCCS) , Neuropsicologiche, Neurofisiologiche, e Neuroradiologiche.
La prima parte dello studio ha riguardato la comparazione tra due metodiche Ultrasonografiche : TCCS e TCD: una “cross sectional” e un’analisi di “follow up”. L’obiettivo è stato quello di supportare l’ipotesi che il TCCS possa essere più utile e indicato nello screening per identificare il rischio di stroke nelle SCD
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La seconda fase si è poi sviluppata nel verificare l’ipotesi che la combinazione dei risultati ottenuti con TCD, Angio-RMN e MRI potesse identificare i bambini che sviluppavano I.S. rispetto a quelli che non li sviluppavano. I nostri risultati non hanno però supportato tale ipotesi.
La terza fase è stata quella di valutare le performance cognitive dei bambini con e senza I.S. Sono stati somministrati test Neuropsicologici (Wechsler Intelligence Scales for Children, WISC and Wechsler Preschool and Primary Scale of Intelligence, WPPSI). Il QIP (quoziente intellettivo di Performance) e altri subtest si sono dimostrati significativamente compromessi nel gruppo di bambini SCD con presenza di I.S.
Infine l’obiettivo della quarta fase è stato quello di valutare dal punto di vista neurofisiologico (analisi morfologica e di LORETA nella P300) e studio volumetrico della RMN (Free Surfer software) la differenza tra un sottogruppo di pazienti con e senza I.S. e un gruppo di controllo di età sovrapponibile.
I generatori della P300 sono stati dimostrati essere gli stessi nel gruppo SCD e nei controlli, senza significativa differenza tra I.S. verso non I.S. Il gruppo SCD ha mostrato il coinvolgimento di più networks corticali e che permanevano attivi più a lungo: ciò suggerisce la probabile presenza di un processo compensativo.
Lo studio volumetrico ha evidenziato differenze significative in alcune aree corticali ma non nella regione ippocampale: questo risultato può essere dovuto al fatto che il circolo posteriore risulta meno compromesso nelle SCD
Cognitive evoked potentials and neural networks are abnormal in children with sickle cell disease and not related to the degree of anaemia, pain and silent infarcts
No full textThe Impact of Age and Duration of Cochlear Implant in a Congenital Deaf Population: An ERP Study
Full text linkObjective: It is well known that patients with Cochlear Implant (CI) have a large inter-individual
variability in linguistic and auditory performances. This can be related to individual auditory
processing abilities and integrity of auditory system from auditory nerve to cerebral cortex. P300
can be used for the evaluation of central auditory functions in people with hearing loss and CI. No
studies considered the P300 in the population of prelingually deafened adults that underwent CI
in old age. The aim of this study is to assess Event Related Potential (ERP) in patients with congenital
profound hearing loss with early or late implantation and evaluate these results respect to an
age-matched normal hearing group. Methods: ERPs (N100, N200 and P300) and auditory benefit
testing (pure tone average and speech audiometric test) and auditory perception testing (Categories
of Auditory Performance—CAP) were evaluated in all subjects with their device. Results: All
mean latencies (N100, N200 and P300) were found greater in patients group compared to control
group. When analyzing all measures in patient group, we did not find any significant differences
according to age of implant while significant difference (p > 0.05) in N100 amplitude (p = 0.045)
and P300 latency (p = 0.035) were found according to time of CI use. A linear correlation between
N200 and P300 latency in control and patients groups was found. Conclusion: In summary, ERPs
analysis in the evaluation of CI showed a great importance of long use of the device in addiction to
an early time of implant
Top-down regulation of left temporal cortex by hypnotic amusia for rhythm: a pilot study on mismatch negativity.
No full textTo evaluate the effect of hypnotically induced amusia for
rhythm (a condition in which individuals are unable to recognize
melodies or rhythms) on mismatch negativity (MMN), 5 highly (HH)
and 5 poorly (LH) hypnotizable nonmusician volunteers underwent
MMN recording before and during a hypnotic suggestion for amusia.
MMN amplitude was recorded using a 19-channel montage and
then processed using the low-resolution electromagnetic tomography
(LORETA) to localize its sources. MMN amplitude was significantly
decreased during hypnotic amusia (p < .04) only in HH, where the
LORETA maps of MMN showed a decreased source amplitude in
the left temporal lobe, suggesting a hypnotic top-down regulation
of activity of these areas and that these changes can be assessed by
neurophysiological investigations
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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