[Sleep-related movement and behavioural disorders in adults]. / Trastornos del movimiento y de la conducta durante el sueño en el adulto.

Sleep-related movement and behaviour disorders may have an impact on sleep quality and lead to daytime symptoms. These groups of conditions include diseases such as restless legs syndrome, periodic leg movements, and REM and NREM parasomnias. The knowledge of their clinical features and management is of utmost importance for the neurologist and sleep specialist. Frequently, these patients are referred to such specialists and it is relevant to know that certain sleep disorders may be associated with other neurological conditions.

TITLE: Trastornos del movimiento y de la conducta durante el sueño en el adulto.Los trastornos del movimiento y de la conducta durante el sueño pueden tener un impacto en la calidad del sueño del paciente y dar lugar a síntomas diurnos. En estos grupos de enfermedades se incluyen entidades como el síndrome de piernas inquietas, los movimientos periódicos de las piernas y las parasomnias del sueño de movimientos oculares rápidos (REM) y no REM. El conocimiento de sus características clínicas y nociones sobre su manejo es de gran importancia para el neurólogo y especialista en sueño por su frecuencia e impacto en la calidad del sujeto. Con frecuencia, estos pacientes son referidos a dichos especialistas, y es relevante conocer que ciertos trastornos del sueño pueden asociarse a otras enfermedades neurológicas.

[A comparative study of three systems for quantifying the spike and wave index in patients with continuous spikes and waves during slow sleep]. / Estudio comparativo entre tres sistemas de cuantificacion del indice de punta-onda en pacientes con punta-onda continua del sueño lento.

INTRODUCTION: Continuous spikes and waves during slow sleep (CSWS) is an epileptic encephalopathy of childhood with a pattern of epileptiform discharges during sleep, which, if prolonged over time, produce severe neuropsychological impairment. Quantification of the paroxysms by means of a spike and wave index (SWI) > 85% establishes a presumptive diagnosis and allows early therapy to be started to prevent such impairment. AIMS: To compare the results of the classic method for calculating the SWI against two proposals that optimise the relation between the analysis time employed and the diagnostic sensitivity. PATIENTS AND METHODS: The nocturnal electroencephalographic registers of 17 patients with CSWS were studied. Two observers calculated the SWI with the classic method, as well as with two other methods, M2 and M3, first in the active phase and then in the remission phase. The time required by each method, the individual SWI values and the agreement between methods and observers were compared. RESULTS: With M3 two of the patients failed to reach the cut-off point of SWI > 85%. Agreement in the active phase of CSWS after M2 and M3 was 0.762 and 0.704, respectively, while in the remission phase it was 0.951 and 0.830. Inter-observer agreement exceeded 0.905 in all cases. CONCLUSIONS: The two abbreviated methods can be used in both the active and the remission phases, with a substantial reduction in the analysis time that is needed. Our results support the current tendency to consider SWI > 60% as suggestive of CSWS. Method M2 yields results that are closer to those of the classic method than those of M3.

TITLE: Estudio comparativo entre tres sistemas de cuantificacion del indice de punta-onda en pacientes con punta-onda continua del sueño lento.Introduccion. La punta-onda continua del sueño lento (POCS) es una encefalopatia epileptiforme infantil con un patron de descargas epileptiformes durante el sueño que, prolongadas en el tiempo, producen un grave deterioro neuropsicologico. La cuantificacion de los paroxismos mediante el indice de punta-onda (SWI) > 85% establece un diagnostico de sospecha y permite iniciar una terapia precoz que puede evitar dicho deterioro. Objetivos. Comparar los resultados del metodo clasico de calculo del SWI con dos propuestas que optimicen la relacion entre el tiempo de analisis empleado y la sensibilidad diagnostica. Pacientes y metodos. Se estudiaron los registros electroencefalograficos nocturnos de 17 pacientes con POCS. Dos observadores calcularon el SWI con el metodo clasico, asi como con otros dos metodos, M2 y M3, primero en la fase activa y posteriormente en la fase de remision de la POCS. Se comparo el tiempo consumido por cada metodo, los valores individuales de SWI y la concordancia entre metodos y observadores. Resultados. Con el M3 dos pacientes no alcanzaron el corte del SWI > 85%. La concordancia en la fase activa de la POCS tras el M2 y el M3 fue de 0,762 y 0,704, respectivamente, mientras que en la fase de remision fue de 0,951 y 0,830. La concordancia entre observadores supero el 0,905 en todos los casos. Conclusiones. Los dos metodos abreviados se pueden utilizar tanto en la fase activa de la POCS como en la fase de remision, con una sustancial reduccion del tiempo de analisis empleado. Nuestros resultados apoyan la tendencia actual de considerar el SWI > 60% como sugestivo de POCS. El metodo M2 arroja resultados mas cercanos a los del metodo clasico que los de M3.

Cortico-juxtacortical involvement increases risk of epileptic seizures in multiple sclerosis.

OBJECTIVES: Previous studies have reported an increased risk for epileptic seizures in multiple sclerosis (MS) patients. However, data on the pathogenesis of seizures remain inconclusive. The aim of our study is to evaluate prevalence, clinical and paraclinical features of epileptic attacks in our MS cohort and to search MS-specific risk factors for epileptic seizures. MATERIALS AND METHODS: In this cohort of 428 MS patients, 13 patients were identified with epileptic seizures occurring at any point during the course of MS including at MS onset. As a control group, we selected 26 MS patients without seizures and matched for gender, age and date of MS onset. We compared demographic features and clinic-radiological findings between the both groups. RESULTS: Thirteen patients (3%) were identified as having epileptic attacks. Ten patients (77%) experienced focal seizures, half of whom had confirmed secondary generalization. We did not find an association between seizures and disease course. Most patients had a single or few (2-5) seizures. MS patients with seizures had a significantly higher number of cortical and juxtacortical lesions on T2-weighted/fluid attenuation inversion recovery magnetic resonance imaging than control group [OR = 2.6 CI95% (1.0-6.5); P = 0.047]. CONCLUSIONS: Our findings support a credible role of cortical and juxtacortical involvement in the development of epileptic seizures in MS.

[Bilateral facial palsy due to Epstein-Barr virus Infection]. / Parálisis facial bilateral secundaria a infección por virus de Epstein-Barr.

Two young patients with bilateral facial palsy are described. They initially presented unilateral facial palsy, followed by contralateral facial nerve involvement a few days later, together with clinical and serologic evidence of acute Epstein-Barr virus infection. The outcome was favourable in one patient but severe sequels persisted in the second. These two cases show that this infrequent complication of Epstein-Barr virus infection may not always have a good outcome. The pathogenic mechanism of bilateral facial palsy is discussed.

Application of a novel automatic duration method measurement based on the wavelet transform on pathological motor unit action potentials.

OBJECTIVE: To evaluate a recently published automatic duration method based on the wavelet transform applied on normal and pathological motor unit action potentials (MUAPs). METHODS: We analyzed 313 EMG recordings from normal and pathological muscles during slight contractions. After the extraction procedure, 339 potentials were accepted for analysis: 68 from normal muscles, 124 from myopathic muscles, 20 from chronic neurogenic muscles, 83 from subacute neurogenic muscles and also 44 fibrillation potentials, as an example of very low duration muscular potentials. A "gold standard" of the duration positions (GSP) was obtained for each MUAP from the manual measurements of two senior electromyographists. The results of the novel method were compared to five well-known conventional automatic methods (CAMs). To compare the six methods, the differences between the automatic marker positions and the GSP for the start and end markers were calculated. Then, for the different groups of normal and pathological MUAPs, we applied: a one-factor ANOVA to compare their relative mean differences, the estimated mean square error (EMSE) and a Chi-square test about the rate of automatic marker placements with differences to the GSP greater than 5 ms, taken as gross errors. RESULTS: The mean and the standard deviation of the differences, the EMSE and the gross errors for the novel method were smaller than those observed with the CAMs in the five different MUAP groups and significantly different in most of the cases. CONCLUSIONS: The novel automatic duration method is more accurate than other available algorithms in normal and pathological MUAPs. SIGNIFICANCE: Accurate MUAP duration automatic measurement is an important issue in daily clinical practice.

Benchmark quantum Monte Carlo calculations of the ground-state kinetic, interaction and total energy of the three-dimensional electron gas.

We report variational and diffusion quantum Monte Carlo ground-state energies of the three-dimensional electron gas using a model periodic Coulomb interaction and backflow corrections for N = 54, 102, 178, and 226 electrons. We remove finite-size effects by extrapolation and we find lower energies than previously reported. Using the Hellman-Feynman operator sampling method introduced in Gaudoin and Pitarke (2007 Phys. Rev. Lett. 99 126406), we compute accurately, within the fixed-node approximation, the separate kinetic and interaction contributions to the total ground-state energy. The difference between the interaction energies obtained from the original Slater-determinant nodes and the backflow-displaced nodes is found to be considerably larger than the difference between the corresponding kinetic energies.

Potenciales evocados cognitivos. Utilidad de la mismatch negativity / Cognitive evoked potentials. Perspectives for mismatch negativity

Las técnicas de potenciales evocados cognitivos están consideradas como largas y técnicamente complejas, por ello a pesar de su potencial utilidad, su uso en la práctica clínica no está muy extendida. Los recientes avances en el registro, análisis y mejoras en el software de manejo de estas señales, han reducido notablemente estos problemas. De entre todos los potenciales cognitivos es la Mismatch negativity, la que por sus especiales características en cuanto a requisitos de generación y probada utilidad clínica, destaca como la más prometedora. La capacidad de ser generada sin requerimientos atencionales la hace especialmente útil para la valoración de sujetos con bajo nivel de conciencia, sirviendo entre otras cosas, para predecir el despertar del coma. La incorporación de dicha técnica a la batería de técnicas neurofisiológicas que valoran el estado de estos sujetos va suponer una mejora sustancial en la evaluación de casos cuyo manejo en la práctica clínica es sumamente complejo (AU)

The techniques of cognitive evoked potentials are considered long and technically complex, which is why their use in clinical practice is not very widespread in spite of their potential utility. Recent advances in registering and analysis, together with improvement of the software managing these signals, have appreciably reduced these problems. Mismatch negativity stands out as the most promising of all the cognitive potentials due to its special characteristics regarding its generation requisites and its proven clinical utility. The fact that it can be generated without care requirements makes it especially useful for evaluating subjects with a low level of consciousness; it serves for predicting when they will emerge from a coma, amongst other uses. The incorporation of this technique into the arsenal of neurophysiological techniques for evaluating the state of these subjects will bring a substantial improvement in the evaluation of cases whose management in clinical practice is extremely complex (AU)

[Cognitive evoked potentials. Perspectives for mismatch negativity]. / Potenciales evocados cognitivos. Utilidad de la mismatch negativity.

The techniques of cognitive evoked potentials are considered long and technically complex, which is why their use in clinical practice is not very widespread in spite of their potential utility. Recent advances in registering and analysis, together with improvement of the software managing these signals, have appreciably reduced these problems. Mismatch negativity stands out as the most promising of all the cognitive potentials due to its special characteristics regarding its generation requisites and its proven clinical utility. The fact that it can be generated without care requirements makes it especially useful for evaluating subjects with a low level of consciousness; it serves for predicting when they will emerge from a coma, amongst other uses. The incorporation of this technique into the arsenal of neurophysiological techniques for evaluating the state of these subjects will bring a substantial improvement in the evaluation of cases whose management in clinical practice is extremely complex.

Dissociation energy of the water dimer from quantum Monte Carlo calculations.

We report a study of the electronic dissociation energy of the water dimer using quantum Monte Carlo techniques. We have performed variational quantum Monte Carlo and diffusion quantum Monte Carlo (DMC) calculations of the electronic ground state of the water monomer and dimer using all-electron and pseudopotential approaches. We have used Slater-Jastrow trial wave functions with B3LYP type single-particle orbitals, into which we have incorporated backflow correlations. When backflow correlations are introduced, the total energy of the water monomer decreases by about 4-5 mhartree, yielding a DMC energy of -76.428 30(5) hartree, which is only 10 mhartree above the experimental value. In our pseudopotential DMC calculations, we have compared the total energies of the water monomer and dimer obtained using the locality approximation with those from the variational scheme recently proposed by Casula [Phys. Rev. B 74, 161102(R) (2006)]. The time step errors in the Casula scheme are larger, and the extrapolation of the energy to zero time step always lies above the result obtained with the locality approximation. However, the errors cancel when energy differences are taken, yielding electronic dissociation energies within error bars of each other. The dissociation energies obtained in our various all-electron and pseudopotential calculations range between 5.03(7) and 5.47(9) kcalmol and are in good agreement with experiment. Our calculations give monomer dipole moments which range between 1.897(2) and 1.909(4) D and dimer dipole moments which range between 2.628(6) and 2.672(5) D.

[An epidemiological, clinical and developmental study of 37 patients with early-onset benign occipital epilepsy of childhood]. / Estudio epidemiológico, clínico y evolutivo de 37 pacientes con epilepsia occipital benigna infantil de comienzo precoz.

AIM: To analyse the epidemiological, clinical and developmental characteristics of early-onset benign occipital epilepsy of childhood in order to facilitate its diagnostic suspicion in daily clinical practice. PATIENTS AND METHODS: The medical records of 37 patients with early-onset benign occipital epilepsy of childhood were reviewed in order to collect epidemiological and clinical features, results of complementary examinations and developmental data. The diagnostic criteria applied were those of the ILAE (International League Against Epilepsy). RESULTS: The mean age at diagnosis was 5.4 years. In all, 64.9% were diagnosed at a pre-school age, with a greater prevalence of females (67.6%). The mean number of seizures per patient was 3.3 and they were mainly characterised by impaired consciousness (90.3%), vomiting (70.1%), eye deviation and/or headaches (30.6%), and generalised (32.8%) or partial (11.2%) motor crises. Seizures occurred during sleep in 67.2% of cases. In 28 cases (75.7%) occipital paroxysms were observed that coexisted with generalised and/or multifocal paroxysms. Of all recurrences, 71.3% occurred during the first 6 months, and from 2 years onwards 82.9% of the patients had no seizures; no developmental differences were found between treated and non-treated patients. One patient with an atypical development was recorded. CONCLUSIONS: Early-onset benign occipital epilepsy of childhood is relatively frequent at the paediatric age, especially in the pre-school years. Although its semiological sequence is quite characteristic, the fact that it lacks clinical and neurological specificity makes diagnostic suspicion more difficult. Its prognosis is especially favourable; however, since their progress may develop in an atypical manner, a rigorous developmental control of these patients would be of the highest priority.

Cortical gamma activity during auditory tone omission provides evidence for the involvement of oscillatory activity in top-down processing.

Perception is an active process in which our brains use top-down influences to modulate afferent information. To determine whether this modulation might be based on oscillatory activity, we asked seven subjects to detect a silence that appeared randomly in a rhythmic auditory sequence, counting the number of omissions ("count" task), or responding to each omission with a right index finger extension ("move" task). Despite the absence of physical stimuli, these tasks induced a 'non-phase-locked' gamma oscillation in temporal-parietal areas, providing evidence of intrinsically generated oscillatory activity during top-down processing. This oscillation is probably related to the local neural activation that takes place during the process of stimulus detection, involving the functional comparison between the tones and the absence of stimuli as well as the auditory echoic memory processes. The amplitude of the gamma oscillations was reduced with the repetition of the tasks. Moreover, it correlated positively with the number of correctly detected omissions and negatively with the reaction time. These findings indicate that these oscillations, like others described, may be modulated by attentional processes. In summary, our findings support the active and adaptive concept of brain function that has emerged over recent years, suggesting that the match of sensory information with memory contents generates gamma oscillations.

Quantum Monte Carlo calculations of the dissociation energies of three-electron hemibonded radical cationic dimers.

We report variational and diffusion quantum Monte Carlo (VMC and DMC) calculations of the dissociation energies of the three-electron hemibonded radical cationic dimers of He, NH3, H2O, HF, and Ne. These systems are particularly difficult for standard density-functional methods such as the local-density approximation and the generalized gradient approximation. We have performed both all-electron (AE) and pseudopotential (PP) calculations using Slater-Jastrow wave functions with Hartree-Fock single-particle orbitals. Our results are in good agreement with coupled-cluster CCSD(T) calculations. We have also studied the relative stability of the hemibonded and hydrogen-bonded water radical dimer isomers. Our calculations indicate that the latter isomer is more stable, in agreement with post-Hartree-Fock methods. The excellent agreement between our AE and PP results demonstrates the high quality of the PPs used within our VMC and DMC calculations.

Frontal and central oscillatory changes related to different aspects of the motor process: a study in go/no-go paradigms.

We studied alpha and beta EEG oscillatory changes in healthy volunteers during two different auditory go/no-go paradigms, in order to investigate their relationship with different components of the motor process. In the first paradigm (S2-centered), the initial tone (S1) was constant (warning), and the second tone (S2) indicated the subject whether to move or not. In the second paradigm (S1-centered), S1 indicated whether to move or not, while S2 just indicated the timing of the movement. A medial frontal beta energy increase was found in all conditions after the stimulus that forces the subject to decide whether to move or not (S1 or S2 depending on the paradigm). In both go conditions, a central alpha and beta energy decrease began after the go decision, reaching minimum values during the movement; it was followed by a beta post-movement increase, limited to the central contralateral area. In the no-go conditions, a marked fronto-central beta synchronization appeared after the decision not to move. In conclusion, our study was able to dissociate the beta oscillatory changes related to movement preparation and execution (central decrease/increase) from those associated with decision-making (medial frontal increase) and motor inhibition (fronto-central increase).

Gamma band responses to target and non-target auditory stimuli in humans.

We studied the EEG oscillatory changes in the gamma band during auditory oddball paradigms in two different conditions (counting targets and reading). A time-frequency analysis was performed for standard and target stimuli. The study revealed an early (26-59 ms) phase-locked oscillation. Around 200 ms, a non-phase locked response was found for standard and target stimuli in temporal posterior electrodes. At about 360 ms, a phase-locked oscillation was observed only after target stimuli in the "counting targets" condition. During the "reading" task this late activity was not found, and energy increases were lower than during "counting" task. The early oscillation may be related to the sensory processing of the stimuli. The response around 200 ms may be involved in auditory mismatch and/or memory retrieval, and late activity is probably a P300-related response. Attention enhances all these activities.

Movement-related changes in cortical oscillatory activity in ballistic, sustained and negative movements.

We studied movement-related EEG oscillatory changes in the alpha, beta and low-gamma frequency bands in three different paradigms of movement, namely ballistic, sustained, and negative (muscle relaxation). A time-frequency analysis of non-phase-locked activity in the 7-47 Hz range was performed on movement-centred EEG sweeps using wavelet filters and Gabor transforms. All three movements were accompanied by a decrease in beta activity that began contralaterally about 1.5 s prior to the onset of movement but that extended to both sides near the beginning of the movement. This decrease was followed by a rebound after the end of the movement in the ballistic and negative movements. A decrease was also seen in the alpha band during the three paradigms, which began later (1 s before movement) and lasted longer. An increase in gamma activity was only seen during ballistic and sustained movements, while a decrease in gamma energy was observed during negative movements. It was concluded that changes in the beta band of the EEG before movement are related to the preparation for the movement, but an important afferent component may be present in the later changes. Gamma band activity may be just involved in the execution of the movement, related to muscle contraction.

Beta electroencephalograph changes during passive movements: sensory afferences contribute to beta event-related desynchronization in humans.

Non-phase-locked beta oscillatory changes during passive movements were studied in six healthy volunteers, and compared with those observed in a similar group during ballistic movements. Passive movements consisted of brisk wrist extensions done with the help of a pulley system. Changes in the beta band were determined by means of wavelet and Gabor transforms, and compared statistically with a pre-movement period. In this paradigm, a marked beta energy loss (event-related desynchronization, ERD) was present after the beginning of the movement, followed by a beta energy increase (event-related synchronization, ERS). The ERD/ERS was similar to that observed during ballistic movements, but without pre-movement components. Although both changes were maximal in the contralateral central electrode, the beta ERD showed a more bilateral topography. These findings suggest that afferent proprioceptive inputs may play a role in the final part of the beta ERD observed during voluntary movements.

Gamma band activity in an auditory oddball paradigm studied with the wavelet transform.

OBJECTIVES: To examine the characteristics of evoked and induced gamma band oscillatory responses occurring during P300 development in an auditory oddball paradigm. METHODS: A time-frequency analysis method was applied to an auditory oddball paradigm in 7 healthy subjects. This method combines a multiresolution wavelet algorithm for signal extraction and the Gabor transform to represent the temporal evolution of the selected frequency components. Phase-locked or evoked activity and also non-phase-locked activity were computed for both standard and target stimuli. RESULTS: The gamma band frequency components differed between target and non-target stimuli processing. The study showed an early and mainly phase-locked oscillatory response appearing around 26--28 ms after both standard and target stimuli onset. This response showed a spectral peak around 44 Hz for both stimuli. A late oscillatory activity peaking at 37 Hz with a latency around 360 ms was observed appearing only for target stimuli. The latency of this late oscillatory activity had a high correlation (P=0.002) to the latency of the P300 wave. CONCLUSIONS: EEG signal analysis with wavelet transform allows the identification of an early oscillatory cortical response in the gamma frequency range, as well as a late P300-related response.

Síndromes neuromusculares del enfermo crítico / Neuromuscular syndromes of the critically ill

La supervivencia cada vez mayor de los enfermos críticos, está dando lugar a la aparición de nuevos y diversos síndromes neuromusculares. Generalmente consisten en cuadros de debilidad de aparición aguda o subaguda, cuya manifestación más típica es la imposibilidad para la desintubación del paciente, y se deben al desarrollo de una polineuropatía, una miopatía, un bloqueo neuromuscular prolongado (BNP) o a combinaciones de los anteriores. Aunque la etiología es multifactorial, los factores de riesgo principales para desarrollar estas alteraciones son el fallo multiorgánico y la sepsis en el caso de la polineuropatía, los esteroides y los bloqueantes neuromusculares (BNM) en el caso de la miopatía, y los BNM y el fallo renal y hepático en el caso del BNP. No hay tratamiento específico por lo que debido a la alta incidencia de estos síndromes y a su mal pronóstico, con una mortalidad mayor del 50 por ciento, conviene conocer, diagnosticar y evitar en la medida de lo posible los factores que desembocan en el desarrollo de estos cuadros. (AU)

Brainstem auditory evoked potentials (BAEPs) in the cynomolgus macaque monkey. Equivalence with human BAEPs and proposal of a new nomenclature.

Several groups have studied brainstem auditory evoked potentials (BAEPs) in non-human primates. However, the nomenclature of the waves elicited and their correspondence with human waves I-V differ among authors. BAEPs were recorded from six anaesthetised young cynomolgus macaques (Macaca fascicularis), using different sound stimuli parameters. A constant pattern of four main waveforms was present in all the animals with stimulus intensities over 60 dB SPL, although up to four smaller waveforms were observed in some of the individuals. Latency values increased with decreasing stimulus intensities and with increasing repetition rates. These results were similar to the BAEPs observed in other species of macaques. Although an approximate equivalence between human and monkey BAEPs is possible, some discrepancies suggest that there may be generators which contribute to different waves in both species. This is the reason for our proposal of a new nomenclature for BAEP waveforms in monkeys, following a descriptive order with Arabic numerals preceded by the letter M.