Sleep and vigilance in corticobasal degeneration: a descriptive study.

INTRODUCTION: Sleep disorders are common in extrapyramidal diseases, but have rarely been demonstrated in corticobasal degeneration (CBD). METHODS: Here, we describe sleep and vigilance in five consecutive patients with CBD. RESULTS: All five patients had insomnia, four displayed periodic limb movements during sleep (PLMS) and/or restless leg syndrome (RLS), and two had sleep respiratory disorders. None had REM sleep behaviour disorders or excessive daytime sleepiness. CONCLUSIONS: Polysomnography is useful for diagnosing treatable sleep disorders in CBD.

Vigilance troubles in Parkinson's disease: a subjective and objective polysomnographic study.

BACKGROUND AND PURPOSE: To assess the prevalence of vigilance disorders in Parkinson's disease patients, relate the observed phenomena to potential causes and confirm these troubles with polysomnographic analysis. PATIENTS AND METHODS: A questionnaire was used to gather information on demographic data, previous and current treatments, disease characteristics, sleep and vigilance troubles. Somnolence was measured using the Epworth Sleepiness Scale (ESS). Nocturnal polysomnography (PSG) and multiple sleep latency tests (MSLT) were performed for a sample of parkinsonian patients. RESULTS: Two hundred twenty-two parkinsonian patients completed the questionnaire, and 36 patients had objective analyses. Of the patients, 43.2% had an ESS score >10, and 28.4% reported somnolence in the hour after taking dopaminergic drugs, whereas 6.8% reported unintended sleep episodes. In view of questionnaire data, these vigilance disorders may be partly explained not only by the impact of nocturnal sleep disorders (e.g. sleep apnea syndromes) but also by dopaminergic therapy (especially with dopaminergic agonists). With PSG and MSLT results, we have shown a significant correlation between mean sleep latency and ESS score. Patients with unintended sleep episodes have severe sleepiness in MSLT compared with others patients. CONCLUSIONS: Vigilance disorders are frequently observed in Parkinson's disease. We recommend informing patients of the risk of occurrence of such conditions, notably for patients with unintended sleep episodes and with sleepiness in the hour after taking dopaminergic drugs.

Motor evoked potentials to magnetic stimulation: technical considerations and normative data from 50 subjects.

Magnetic stimulation of the brain and cervical and lumbar spinal roots was performed on 50 healthy volunteers. Compound muscle action potentials (CMAPs) were recorded from biceps brachii, abductor digiti minimi (ADM), rectus femoris and tibialis anterior (TA). We assessed central conduction times by subtraction of peripheral from central latencies and compared results using either spinal root stimulation or the F-wave method. Side-to-side differences of total conduction time, peripheral conduction time and central conduction time (CCT) were measured and the effect of clockwise vs counterclockwise stimulations on latencies and sizes of CMAPs is emphasized. Amplitudes and areas of CMAPs were expressed as a percentage of the peripheral M response for ADM and TA. There was a positive correlation between CCT to the lumbosacral region and height, but not between the cervical region and height. No correlation was observed between genders and central conduction times, amplitudes or areas of CMAPs.

Effects of bilateral subthalamic stimulation on sleep in Parkinson's disease.

OBJECTIVE: Sleep disturbances are frequently observed in Parkinson's disease (PD). Bilateral chronic subthalamic nucleus (STN) stimulation is an alternative treatment for advanced PD. Improvements in motor disturbances after STN stimulation are well documented and seem to be associated with better sleep quality, even though the objective effect on sleep structure remains unclear. We have therefore studied the sleep/wakefulness cycle before and after surgical treatment in 10 consecutive parkinsonian patients. METHODS: Subjective sleep quality and sleep recordings were evaluated one month before and three months after initiation of STN stimulation. After surgery, the recordings were performed under two conditions: with stimulation (the "on" condition) and-if patients had given their consent-in the absence of stimulation (the "off" condition). RESULTS: With STN stimulation, subjective and objective sleep qualities were improved. Total sleep time, sleep efficiency and the durations of deep slow wave sleep and paradoxical sleep increased significantly. When stimulation was absent, sleep disturbances were similar to those observed before surgery. CONCLUSION: Chronic STN stimulation is associated with a sleep improvement, which can be explained in part by the concomitant decrease in motor disturbances but also by the reduction in dosages of antiparkinsonian medication. However, we can not exclude a direct effect of STN stimulation on sleep regulatory centres.

P300 component of the event-related potentials (ERP) during an attention task: effects of age, stimulus modality and event probability.

The effects of age, stimulus modality and event probability on event-related potentials (ERP) were studied in 12 young and 12 elderly healthy subjects. The ERP were recorded from 15 electrodes referred to linked ears. Results showed that both amplitude and latency of the P300 component are affected by aging. Study of the latency of the earlier ERP components in the two age groups revealed that the P300 delay was not imputable to a delay of the earlier components. P300 amplitude and latency were also affected by event probability and stimulus modality: infrequent stimulus involved higher and later P300, but this effect was more pronounced in the young than in the old group; higher and later P300 were also recorded during the visual task compared to the auditory. Topographical repartition of the brain wave revealed a predominance of the central sites (Fz, Cz, Pz). The findings are discussed in relation to the sensitivity of the ERP assessment procedures in age related modifications of information processing.

[Characterization of the functional relations between cerebral structures: the linear and non-linear]. / Caractérisation des relations fonctionnelles entre structures cérébrales: du linéaire au non linéaire.

Two kinds of methods are available in order to assess the functional relationships between different cerebral structures from the analysis of EEG signals: linear and non-linear methods. In this paper, we describe didactically the methodological bases of signal processing. After recalling the significance of the fundamental parameters of a sine wave: frequency, amplitude and phase, we show, from a first example about an epileptic seizure propagation, how a linear variation between phase and frequency can be interpreted as a small time difference between two EEG channels. This linear method hypothesises that these two signals are respectively the input and the output of a linear system. Then, we point out the limits of this method and we introduce non-linear methods. Among the latter, a recent approach introduces a realistic model of EEG which try to relate signal measured quantities to relations between underlying structures which produce them.

[Spatiotemporal study of event-related desynchronization during self-paced movement]. / Etude spatiotemporelle des désynchronisations liées à l'événement au cours d'une activité motrice autocommandée.

The desynchronization of Alpha band components during a self-paced movement of the thumb was studied in 7 subjects. The EEG was recorded from 23 electrodes located on the frontocentral, central, and parietocentral regions, referred to the right mastoïde, 4 s before and 2 s after movement onset. The data were then transformed to obtain 11 source derivations. The temporal evolution of the power of the signal within the Alpha band, every 250 ms, associated to the non parametric statistic test of Wilcoxon, authentifies the event-related desynchronization (ERD). The spatiotemporal analysis of ERD underlines on the central regions, two principal locations of ERD: one controlateral to the movement, starting more than 1 s before the movement; the other, ipsilateral, shorter, during the movement. However, no significance desynchronization was underlined on the vertex. The ANOVA used to analyse these results confirms the principal location of ERD on the central region, and seems to indicate a right lateralisation during the right or the left movement.

Effect of aging on the spatio-temporal pattern of event-related desynchronization during a voluntary movement.

Event-related desynchronization (ERD) of alpha components was studied in young and elderly subjects during planning of voluntary movement. ERD was quantified from 11 source derivations covering regions of the scalp corresponding to the supplementary motor area, the left and right primary sensorimotor areas, the vertex, and the medial posterior parietal cortex. Spatio-temporal display of ERD showed a very different pattern in elderly subjects, with mainly a spatial diffusion of ERD over the parietal and frontal regions. On the contrary, ERD in young subjects was limited to the central regions. ERD was also more lasting in elderly subjects. Changes of the ERD pattern in elderly subjects could indicate a change of cortical activation during voluntary movement. The data also confirm that ERD study is a useful electrophysiological exploration to observe the changes of cortical activation during cerebral aging.

Evaluation of event-related desynchronization (ERD) during a recognition task: effect of attention.

Event-related desynchronization (ERD) was studied in 10 subjects during a verbal recognition task. The attentional load of the task varied according to the difficulty to discriminate targets and distractors. The EEG recorded from 29 electrodes was used to compute ERD from 14 source derivations in 125 msec intervals and displayed as spatio-temporal maps. The results show that large brain areas of both hemispheres are significantly activated when the attentional load is high. This cerebral activation pattern is less pronounced when the load is low. ANOVA reveals main effects of attention and time and a significant interaction between attention and time.