Nadia Gosselin

Periodic leg movements in REM sleep behavior disorder and related autonomic and EEG activation

Objective: To assess the frequency of periodic leg movements (PLM) in idiopathic REM sleep behavior disorder (RBD) and to analyze their polysomnographic characteristics and associated autonomic and cortical activation. Background: PLM during sleep (PLMS) and wakefulness (PLMW) are typical features of restless legs syndrome (RLS), but are also frequently observed in patients with RBD. Methods: Forty patients with idiopathic RBD underwent one night of polysomnographic recording to assess PLMS frequency. PLM features, PLMS-related cardiac activation during stage 2 sleep, and EEG changes were analyzed in 15 of these patients with RBD. Results were compared with similar data obtained in 15 sex- and age-matched patients with primary RLS. Results: Twenty-eight (70%) of 40 patients with RBD showed a PLMS index greater than 10. No between-group differences were found in sleep architecture or indexes of PLMW and PLMS during non-REM sleep, but a trend for a higher PLMS index during REM sleep was found in patients with RBD. PLM mean duration and interval in the two conditions were similar. A transient tachycardia followed by a bradycardia was observed in close association with every PLMS in both groups, but the amplitude of the cardiac activation was significantly reduced in patients with RBD. In addition, significantly fewer PLMS were associated with microarousal in this condition. Conclusions: Periodic leg movements are very common in idiopathic RBD, occurring in all stages of sleep, especially during REM sleep. In idiopathic RBD, the reduction of cardiac and EEG activation associated with PLMS suggests the presence of an impaired autonomic and cortical reactivity to internal stimuli.

Neurophysiological anomalies in symptomatic and asymptomatic concussed athletes.

OBJECTIVE:Concussion in sports is a problem of such magnitude that improvements in diagnosis and management are desirable. The aim of the present study was to investigate the effect of concussion on event-related potentials, in symptomatic as well as in asymptomatic athletes. METHODS:Twenty symptomatic and asymptomatic athletes who sustained a concussion were compared with 10 control athletes in a modified auditory Oddball task. The task included a sequence of tones containing standard and deviant stimuli. Participants were asked to respond to the target tone presented in the left ear and to ignore tones presented in the right ear. The electroencephalogram was recorded from 28 electrodes during the task. RESULTS:The results showed a reduction in the amplitude of N1, P2, and P3 components in symptomatic and asymptomatic athletes in comparison with control athletes. No between-group differences were observed in reaction times or in latency of the event-related potentials components, except for P3 latency, in which the controls showed shorter latency than the concussed groups. CONCLUSION:Concussions seem to produce deficits in the early and late stages of auditory information processing, which possibly reflect impaired brain functioning in symptomatic and asymptomatic concussed athletes. The fact that asymptomatic athletes have an electrophysiological profile similar to that of symptomatic athletes challenges the validity of return-to-play guidelines for which the absence of symptoms is a major issue.

Sleep following sport-related concussions.

OBJECTIVES Sleep and vigilance disorders are among the most commonly reported symptoms following a concussion. The aim of the study was thus to investigate the effects of sport-related concussions on subjective and objective sleep quality. METHODS Ten concussed athletes and 11 non-concussed athletes were included. Concussed athletes had a history of 4.6+/-2.1 concussions with at least one concussion during the last year. They were recorded for two consecutive nights in the laboratory and during a 10-min period of wakefulness. They completed questionnaires related to sleep quality and symptoms as well as neuropsychological tests and the CogSport computer battery. RESULTS Concussed athletes reported more symptoms and worse sleep quality than control athletes, but no between-group differences were found on polysomnographic variables or on REM and NREM sleep quantitative EEG variables. However, concussed athletes showed significantly more delta activity and less alpha activity during wakefulness than did control athletes. CONCLUSION In spite of the subjective complaints in sleep quality of concussed athletes, no change was observed in objective sleep characteristics. However, concussions were associated with an increase in delta and a reduction in alpha power in the waking EEG. Sport-related concussions are thus associated with wakefulness problems rather than sleep disturbances.

Comparison of functional outcome following acute care in young, middle-aged and elderly patients with traumatic brain injury

Primary objective: To compare functional physical and cognitive outcome of patients in three age groups with mild, moderate and severe traumatic brain injury (TBI) at discharge from acute care. Research design: Retrospective database review. Methods and procedures: Scores on the Extended Glasgow Outcome Scale (GOSE) and on the FIM™ instrument,discharge destination and length-of-stay (LOS) were gathered and compared for 2327 patients with TBI admitted to a level 1 trauma hospital from 1997–2003 divided into three age groups; 971 patients between 18–39 years, 672 between 40–59 years and 684 aged 60–99 years. Main outcomes and results: Relative to younger adults with similar TBI severity, elderly patients showed worse outcome on the GOSE and FIM™ instrument (physical and cognitive ratings) and longer LOS. No difference was observed between the young and middle-aged groups except for cognitive FIM™ ratings and LOS for severe TBI. A higher percentage of elderly patients went to in-patient rehabilitation, to long-term care facilities or died compared to young and middle-aged patients. A higher number of young and middle-aged patients were discharged home. Conclusions: Further development of services in early rehabilitation as well as post-rehabilitation geared to the specific needs of the elderly patient with TBI is required as the population ages.

Electrophysiology and Functional MRI in Post-Acute Mild Traumatic Brain Injury

Symptoms persisting beyond the acute phase (>2 months) after a mild traumatic brain injury (MTBI) are often reported, but their origin remains controversial. Some investigators evoke dysfunctional cerebral mechanisms, while others ascribe them to the psychological consequences of the injury. We address this controversy by exploring possible cerebral dysfunction with functional magnetic resonance imaging (fMRI) and event-related potentials (ERP) in a group of patients during the post-acute phase. Fourteen MTBI symptomatic patients (5.7±2.9 months post-injury) were tested with fMRI and ERP using a visual externally ordered working memory task, and were compared with 23 control subjects. Attenuated blood oxygen level dependent (BOLD) signal changes in the left and right mid-dorsolateral prefrontal cortex (mid-DLPFC), the putamen, the body of the caudate nucleus, and the right thalamus were found in the MTBI group compared with the control group. Moreover, symptom severity and BOLD signal changes were correlated: patients with more severe symptoms had lower BOLD signal changes in the right mid-DLPFC. For ERP, a group×task interaction was observed for N350 amplitude. A larger amplitude for the working memory task than for the control task was found in control subjects, but not in MTBI subjects, who had weak amplitudes for both tasks. This study confirms that persistent symptoms after MTBI cannot be uniquely explained by psychological factors, such as depression and/or malingering, and indicates that they can be associated with cerebral dysfunction. ERP reveals decreased amplitude of the N350 component, while fMRI demonstrates that the more severe the symptoms, the lower the BOLD signal changes in the mid-DLPFC.

Electrophysiological abnormalities in well functioning multiple concussed athletes

Objective: The present study was aimed at characterizing the short- and long-term effects of multiple concussions using an electrophysiological approach. Method: Participants for this study were recruited from college football teams. They included athletes who never sustained concussions compared to two groups of asymptomatic multiple concussed athletes, one that sustained their last concussion within the year and the other more than 2 years prior to testing. All participants were submitted to an auditory three-tone Oddball paradigm while event-related potentials (ERP) were recorded. Results: Results from ERP recordings reveal significantly reduced P3a and P3b amplitudes in the recent concussed group in the three-tone task compared to control athletes. In contrast, athletes who sustained their concussions more than 2 years prior to testing had equivalent P3a and P3b amplitude to that of controls. Conclusion: These findings suggest that, despite functioning normally in their daily lives, concussed athletes still show subtle neuronal changes in information processing. Thus, the persistence of sub-clinical abnormalities on ERP components despite normal overt functioning may indicate sub-optimal compensation in multiple concussed athletes and leave them vulnerable to subsequent concussions.

Age and gender effects on heart rate activation associated with periodic leg movements in patients with restless legs syndrome

OBJECTIVE Periodic leg movements during sleep (PLMS) are often associated with electroencephalographic (EEG) changes, such as microarousals (MA), and with heart rate (HR) variations. The aim of the present study was to evaluate the effects of age and gender on HR changes associated with PLMS in restless legs syndrome (RLS) patients. METHODS Forty-two RLS patients underwent one night of polysomnographic recordings. They were divided into 3 groups of 14 subjects (7 women and 7 men) according to age, i.e. young (25-40 years), middle-aged (41-55 years) and elderly (56-71 years) patients. The RR interval was calculated for 5 intervals before and 15 intervals after the onset of 50 PLMS in each patient. RESULTS PLMS were associated with HR changes characterized by a tachycardia followed by a bradycardia. However, a reduction in the tachycardia and the bradycardia was observed with age. Moreover, women showed a higher amplitude in the bradycardia than men. No age or gender difference was found for MA index and duration. CONCLUSIONS This study showed age and gender differences in the magnitude of the HR changes associated with PLMS. The knowledge of HR variations during sleep, including rapid HR changes associated with sleep events such as PLMS or MA, may be helpful in understanding the potential mechanisms involved in the increased cardiac risk observed in elderly.

Attentional deficits in patients with obstructive sleep apnea syndrome: An event-related potential study

OBJECTIVE Patients with obstructive sleep apnea syndrome (OSAS) show cognitive deficits, vigilance alteration and attentional decline. The aim of this study was to use event-related potentials (ERP) to further document the attentional impairments in these patients. METHODS Twelve OSAS patients and 12 age-matched controls underwent the ERP task which consisted in the presentation of short (50ms, 50%) and long tones (400ms, 50%). For these two categories, 90% were standard (1000Hz) and 10% were deviant tones (750 or 1250Hz). Subjects had to discriminate short and long tones by a motor response. RESULTS OSAS patients had a sustained and delayed P300 in comparison with control subjects following standard tones (p<0.05). A reduction in amplitude was found in OSAS patients for the P3a obtained by the subtraction of standard from deviant tones (p<0.05). No group difference was observed for N1, mismatch negativity and reorienting negativity components. CONCLUSIONS Apneas and hypopneas produce deficits related to involuntary attentional switch and stimulus classification processing. SIGNIFICANCE The changes observed in P3a and P300 components further support the hypothesis that attentional deficits play a pivotal role in cognitive deficits noted in OSAS.

Brain perfusion and markers of neurodegeneration in rapid eye movement sleep behavior disorder

Potential early markers of neurodegeneration such as subtle motor signs, reduced color discrimination, olfactory impairment, and brain perfusion abnormalities have been reported in idiopathic rapid eye movement sleep behavior disorder, a risk factor for Parkinsons disease and Lewy body dementia. The aim of this study was to reproduce observations of regional cerebral blood flow abnormalities in a larger independent sample of patients and to explore correlations between regional cerebral blood flow and markers of neurodegeneration. Twenty patients with idiopathic rapid eye movement sleep behavior disorder and 20 healthy controls were studied by single‐photon emission computerized tomography. Motor examination, color discrimination, and olfactory identification were examined. Patients with rapid eye movement sleep behavior disorder showed decreased regional cerebral blood flow in the frontal cortex and in medial parietal areas and increased regional cerebral blood flow in subcortical regions including the bilateral pons, putamen, and hippocampus. In rapid eye movement sleep behavior disorder, brain perfusion in the frontal cortex and occipital areas was associated with poorer performance in the color discrimination test. Moreover, a relationship between loss of olfactory discrimination and regional cerebral blood flow reduction in the bilateral anterior parahippocampal gyrus, a region known to be involved in olfactory functions, was found. This study provides further evidence of regional cerebral blood flow abnormalities in rapid eye movement sleep behavior disorder that are similar to those seen in Parkinsons disease and Lewy body dementia. Moreover, regional cerebral blood flow anomalies were associated with markers of neurodegeneration.

Evaluating the cognitive consequences of mild traumatic brain injury and concussion by using electrophysiology

OBJECT Mild traumatic brain injury (MTBI), often referred to as concussion when it occurs in sports, produces persistent cognitive problems in at least 15% of patients. Unfortunately, conventional neuropsychological tests usually yield results within normal limits in this population. The main objective of this event-related potential (ERP) study was to understand brain functioning during the performance of a working memory (WM) task in patients who have sustained an MTBI, mostly due to motor vehicle accident or sports concussion. This study also aimed for a better understanding of the association between brain functioning as measured with ERP, behavioral performance on the WM task, postconcussion symptoms, type of injury (that is, sports concussion vs other types), and time since the injury. METHODS Forty-four patients with MTBI (7.6 ± 8.4 months postinjury) were tested on a visual WM task with simultaneous recording of ERP, and were compared with 40 control volunteers who were their equivalent for age and sex. Amplitude and latency of frontal (N200 and N350) and parietal (P200 and P300) ERP waves were measured and were compared between groups. Correlation analyses were also performed between ERP characteristics, clinical variables, and behavioral performance. RESULTS A significant group difference was found for behavioral performance on the WM task, in which the MTBI group had a lower percentage of correct answers than the control group (p < 0.05). The patients with MTBI also had smaller amplitudes of both frontal N350 and parietal P300 ERP components when compared with control volunteers (p < 0.05). No changes were found for latency of ERP components. Smaller ERP amplitudes were associated with slower reaction times and worse accuracy on the WM task among patients with MTBI (p < 0.05). Types of injury (that is, sports concussion vs other mechanisms) were not associated with different ERP characteristics. CONCLUSIONS Abnormal ERP results are observed in patients after MTBI or sports concussion, even for those in the nonacute stage after their injury. Current standard clinical evaluations most often fail to detect cerebral dysfunction after MTBI, even when patients or athletes report symptoms. Clinicians should be aware that patients with MTBI, including sports concussion, probably have underlying mild but persistent cerebral dysfunctions that require further investigation.