1,721,053 research outputs found
Decreased sleep stage transition pattern complexity in narcolepsy type 1
No full textObjective To analyze the complexity of the nocturnal sleep stage sequence in central disorders of hypersomnolence (CDH), with the hypothesis that narcolepsy type 1 (NT1) might exhibit distinctive sleep stage sequence organization and complexity. Methods Seventy-nine NT1 patients, 22 narcolepsy type 2 (NT2), 22 idiopathic hypersomnia (IH), and 52 patients with subjective hypersomnolence (sHS) were recruited and their nocturnal sleep was polysomnographically recorded and scored. Group between-stage transition probability matrices were obtained and compared. Results Patients with NT1 differed significantly from all the other patient groups, the latter, in turn, were not different between each other. The individual probability of the R-to-N2 transition was found to be the parameter showing the difference of highest significance between the groups (lowest in NT1) and classified patients with or without NT1 with an accuracy of 78.9% (sensitivity 78.5% and specificity 79.2%), by applying a cut-off value of 0.15. Conclusions The main result of this study is that the structure of the sleep stage transition pattern of hypocretin-deficient NT1 patients is significantly different from that of other forms of CDH and sHS, with normal hypocretin levels. Significance The lower probability of R-to-N2 transition occurrence in NT1 appears to be a reliable polysomnographic feature with potential application at the individual level, for supportive diagnostic purposes
Automatic detection of cataplexy
Full text linkObjective: Although being the most specific symptom of narcolepsy type 1 (NT1), cataplexy is currently investigated by clinical interview only, with potential diagnostic pitfalls. Our study aimed at testing the accuracy of an automatic video detection of cataplexy in NT1 patients vs. non-cataplectic subjects undergoing a standardized test with emotional stimulation. Methods: Fifteen drug-naive NT1 patients and 15 age- and sex-balanced non-cataplectic subjects underwent a standardized video recording procedure including emotional stimulation causing laughter. Video recordings were visually inspected by human scorers to detect three typical cataplexy facial motor patterns (ptosis, mouth opening and head drop), and then analysed by SHIATSU (Semantic-based HIearchical Automatic Tagging of videos by Segmentation using cUts). Expert-based and automatic attack detection was compared in NT1 patients and non-cataplectic subjects. Results: All NT1 patients and none of the non-cataplectic subjects displayed cataplexy during emotional stimulation. Automatic detection correlated well with experts’ assessments in NT1 with an overall accuracy of 81%. In non-cataplectic subjects, automatic detection falsely identified cataplexy in two out of 15 (13.3%) subjects who showed active eyes closure during intense laughter as a confounder with ptosis. Conclusions: Automatic cataplexy detection by applying SHIATSU to a standardized test for video documentation of cataplexy is feasible, with an overall accuracy of 81% compared to human examiners. Further studies are warranted to enlarge the range of elementary motor patterns detected, analyse their temporal/spatial relations and quantify cataplexy for diagnostic purposes
Structural Organization of Dream Experience During Daytime Soremp Sleep of Patients with Narcolepsy Type 1
Full text linkTo assess the frequency of dream experience (DE) developed during naps at Multiple Sleep Latency Test (MSLT) by patients with narcolepsy type-1 (NT1) and establish, using story-grammar analysis, the structural organization of DEs developed during naps with sleep onset REM period (SOREMP) sleep compared with their DEs during early-and late-night REM sleep
Characteristics of Maintenance of Wakefulness Test (MWT) in drug-naïve patients with narcolepsy type 1 and type 2, and relationship with other measures of sleepiness
No full textStudy objectives: We aimed to describe the characteristics of standard maintenance of wakefulness test (MWT), outside of clinical trials, in a sample of drug-na & iuml;ve patients with narcolepsy type 1 (NT1) and type 2 (NT2). Methods: Consecutive drug-na & iuml;ve patients with narcolepsy underwent two days of continuous PSG recording, the multiple sleep latency test (MSLT), then night-PSG and, on the following day, MWT. MWT results were correlated with MSLT and Epworth Sleepiness Scale (ESS). Patients in the two lower tertiles of MWT mean sleep latency (mSL) were compared to those in the upper tertile. Results: Seventy-eight NT1 (30.6 +/- 11.4 years, 35 males) and 19 NT2 (31.0 +/- 9.9 years, 12 males) were included. MWT results showed a bimodal distribution with a large peak with reduced mSL and a small peak with values towards 40 minutes. MWT mSL was lower in NT1 than in NT2 (10.7 +/- 10.8 min vs 23.9 +/- 11.5 min, p<.001). In the entire sample, lower MWT mSL was moderately correlated with lower MSLT mSL (Rho = 0.347, p=.001) and higher ESS (Rho = -0.398, p<.001). Patients with NT1 with MWT mSL in the two lower tertiles (<= 11.2 min) had higher ESS than those in the upper tertile, without any difference in other clinical or neurophysiological features. In NT2, no significant correlations emerged between MWT, MSLT, and ESS. Conclusions: MWT mSL is reduced in drug-naive narcolepsy, more severely in NT1 than in NT2. However, a minority of patients show normal MWT results. MSLT, MWT, and ESS measure different aspects of sleepiness in narcolepsy, and none can be considered a comprehensive measure of its severity
Combining information on nocturnal rem sleep latency and atonia to facilitate diagnosis of pediatric narcolepsy type 1
No full textSTUDY OBJECTIVES: the diagnosis of narcolepsy type 1 (NT1) at its onset in children and adolescents is often difficult, with substantial diagnostic delay. We aimed to test and validate the effectiveness of rapid-eye-movement (REM) sleep latency (REML), the REM sleep atonia index (RAI), and their combination for the automatic identification of pediatric patients with NT1 based on the standard scoring of nocturnal polysomnograms.METHODS: a retrospective cohort of 71 pediatric patients with NT1 and 42 controls was subdivided in test and validation cohorts. A novel index (COM) was developed as a nonlinear function of REML and RAI. The effectiveness of REML, RAI, and COM in identifying patients with NT1 was assessed with Receiver Operating Characteristic (ROC) curves.RESULTS: REML, RAI and COM significantly identified patients with NT1 both in the test and validation cohorts. Optimal thresholds that maximized identification accuracy were estimated in the test cohort (REML, 49.5min; RAI, 0.91; COM, 4.57 AU) and validated in the other cohort. COM performed significantly better in identifying patients with NT1 than either REML or RAI, with ROC area under the curve of 94-100%, sensitivity 85-96%, and specificity 92-100%, and with good night-to-night agreement (Cohen's k = 0.69).CONCLUSIONS: the analysis of REML, RAI, and particularly their combination in the COM index may help shorten diagnostic delay of NT1 in children and adolescents based on the standard scoring of nocturnal polysomnography
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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