Automatic slow eye movement (SEM) detection of sleep onset in patients with obstructive sleep apnea syndrome (OSAS): Comparison between multiple sleep latency test (MSLT) and maintenance of wakefulness test (MWT)

ObjectiveTo determine whether automatic slow eye movement (SEM) analysis performs comparably to standard sleep onset criteria at the multiple sleep latency test (MSLT) and at the maintenance of wakefulness test (MWT) in patients with obstructive sleep apnea syndrome (OSAS).MethodsWe compared sleep latencies obtained upon standard analysis of MSLT and MWT recordings with automatically detected SEM latencies in a population of 20 severe OSAS patients that randomly underwent the two tests 1 week apart.ResultsEight of 20 OSAS patients had EDS as answered by the Epworth Sleepiness Scale (ESS). Mean SEM latency performed comparably to standard sleep onset in both the MSLT (6.4 ± 5.5 min versus 7.4 ± 5.1 min, p = 0.25) and the MWT (25.2 ± 14.5 min versus 24.4 ± 14.0 min, p = 0.45) settings. Mean SEM latency significantly correlated with the sleep latency at the MSLT (r = 0.52, p < 0.05) and at the MWT (r = 0.74, p < 0.001). Finally, the Epworth Sleepiness Scale score correlated with SEM latency at the MWT (r = ?0.62, p < 0.01), but not at the MSLT.ConclusionsAutomatic SEM detection performed comparably to standard polysomnographic assessment of sleep onset, thus providing a simplified technical requirement for the MSLT and the MWT. Further studies are warranted to evaluate SEM detection of sleep onset in other sleep disorders with excessive daytime sleepiness.     

Insomnia cycling with a 42-day infradian period: Evidence for two uncoupled circadian oscillators?

ObjectiveTo describe the unique case of a middle-aged woman with severe insomnia recurring with a regular infradian period without any other significant clinical condition. To infer the existence of a circadian dysfunction modeled according to the physical phenomenon of the “beats.”Patient/MethodsA two-year prospective observation by means of a sleep log was performed during the patient’s normal life. She underwent one month of motor activity recording and also polysomnography, circadian rhythm of body core temperature and psychiatric evaluation during periods with and without insomnia.ResultsVisual inspection of the 293-day plot of the sleep log disclosed a regular 42-day rhythm of insomnia recurrence confirmed by a Discrete Fourier Transform. During the periods of insomnia, lasting 5–7 days, only moderate mood symptoms (depressive overlapping hypomaniac symptoms) were present. Treatment with sodium valproate was effective in curtailing insomnia.ConclusionThe wax and wane infradian modulation of the sleep length suggested the presence of a basic mechanism similar to the physical phenomenon of the “beats,” i.e., a long period modulation of the amplitude of an oscillating system due to the interference of two uncoupled oscillators with a slightly different oscillation frequency. Hypothesizing a dysfunction of the circadian component of sleep, namely two uncoupled circadian cycles, a simple mathematical model estimated the difference of their periods of oscillation |34 ± 2 min| and reproduced the sleep-log data of the drug-free period of observation.     

Transient supranuclear paresis of the abduction in viral encephalitis of the brainstem

The supranuclear paresis of the abducens system, also known as posterior internuclear ophthalmoplegia of abduction, is a very rare disorder clinically characterized by unilateral or bilateral abduction paresis sometimes associated with nystagmus of the contralateral adducting eye, slowing of abduction saccades, and intact horizontal vestibulo-ocular reflex. Here, we report a 35-year-old woman who presented transient left side abduction deficit in conjunction, as the only symptom of self-limited viral encephalitis of the brainstem. Brain MRI including DWI and ADC maps showed an area of abnormal signal intensity in the mid-right ponto-mesencephalic junction. PCR analysis of cerebrospinal fluid showed an enterovirus infection. Spontaneous clinical recovery rapidly occurred 2 days after onset. The brainstem lesion was undetectable at 5-week brain MRI follow-up.     

Relationship between adverse effects of antiepileptic drugs,number of coprescribed drugs,and drug load in a large cohort of consecutive patients with drug‐refractory epilepsy

Purpose: To evaluate the adverse effects (AEs) of antiepileptic drugs (AEDs) in adults with refractory epilepsy and their relationship with number of coprescribed AEDs and AED load. Methods: Patients with refractory epilepsy were enrolled consecutively at 11 tertiary referral centers. AEs were assessed through unstructured interview and the Adverse Event Profile (AEP) questionnaire. AED loads were calculated as the sum of prescribed daily dose (PDD)/defined daily dose (DDD) ratios for each coprescribed AED. Results: Of 809 patients enrolled, 709 had localization‐related epilepsy and 627 were on polytherapy. AED loads increased with increasing number of AEDs in the treatment regimen, from 1.2 ± 0.5 for patients on monotherapy to 2.5 ± 1, 3.7 ± 1.1, and 4.7 ± 1.1 for those on two, three, and ≥4 AEDs, respectively. The number of spontaneously reported AEs correlated with the number of AEs identified by the AEP (r = 0.27, p < 0.0001). AEP scores did not differ between patients with monotherapy and patients with polytherapy (42.8 ± 11.7 vs. 42.6 ± 11.2), and there was no correlation between AEP scores and AED load (r = ?0.05, p = 0.16). Conclusions: AEs did not differ between monotherapy and polytherapy patients, and did not correlate with AED load, possibly as a result of physicians’ intervention in individualizing treatment regimens. Taking into account the limitations of a cross‐sectional survey, these findings are consistent with the hypothesis that AEs are determined more by individual susceptibility, type of AEDs used, and physicians’ skills, than number of coprescribed AEDs and AED load.     

Systematic review of pregnancy-related carpal tunnel syndrome

The reported incidence of pregnancy-related carpal tunnel syndrome (PRCTS) ranges from 0.8% to 70%, and little is known of its natural history. We systematically reviewed the reported incidence of PRCTS and evaluated its natural history. We identified 214 studies that fulfilled our selection criteria. Six publications fulfilled the inclusion criteria. Five fulfilled the incidence criteria, 3 fulfilled the natural history criteria, and 2 of the 6 publications satisfied both. The reported incidence of neurophysiologically confirmed PRCTS ranged from 7% to 43%, whereas the incidence of clinically diagnosed PRCTS ranged from 31% to 62%. Symptoms persisted in more than 50% of the patients after 1 year and in about 30% after 3 years. Our review suggests that variations in the reported incidence of PRCTS largely depend on the methods used to detect this syndrome. Our data also suggest that symptoms persist in a substantial number of patients 1 or more years after delivery.     

Environmental enrichment potentiates thalamocortical transmission and plasticity in the adult rat visual cortex

It has been demonstrated that the complex sensorimotor and social stimulation achieved by rearing animals in an enriched environment (EE) can reinstate juvenile‐like plasticity in the adult cortex. However, it is not known whether EE can affect thalamocortical transmission. Here, we recorded in vivo field potentials from the visual cortex evoked by electrical stimulation of the dorsal lateral geniculate nucleus (dLGN) in anesthetized rats. We found that a period of EE during adulthood shifted the input–output curves and increased paired‐pulse depression, suggesting an enhanced synaptic strength at thalamocortical terminals. Accordingly, EE animals showed an increased expression of the vesicular glutamate transporter 2 (vGluT‐2) in geniculocortical afferents to layer IV. Rats reared in EE also showed an enhancement of thalamocortical long‐term potentiation (LTP) triggered by theta‐burst stimulation (TBS) of the dLGN. To monitor the functional consequences of increased LTP in EE rats, we recorded visual evoked potentials (VEPs) before and after application of TBS to the geniculocortical pathway. We found that responses to visual stimulation were enhanced across a range of contrasts in EE animals. This was accompanied by an up‐regulation of the intracortical excitatory synaptic marker vGluT‐1 and a decrease in the expression of the vesicular GABA transporter (vGAT), indicating a shift in the excitation/inhibition ratio. Thus, in the adult rat, EE enhances synaptic strength and plasticity of the thalamocortical pathway associated with specific changes in glutamatergic and GABAergic neurotransmission. These data provide novel insights into the mechanisms by which EE shapes the adult brain. © 2010 Wiley‐Liss, Inc.