High-Density Electroencephalographic Recordings During Sleep in Children and Adolescents With Acquired Brain Injury

Local sleep: A new concept in brain plasticity

Traditionally, sleep and wakefulness have been considered as two global, mutually exclusive states. However, this view has been challenged by the discovery that sleep and wakefulness are actually locally regulated and that islands of these two states may often coexist in the same individual. Importantly, such a local regulation seems to be the key for many essential functions of sleep, including the maintenance of cognitive efficiency and the consolidation of new skills and memories. Indeed, local changes in sleep-related oscillations occur in brain areas that are used and involved in learning during wakefulness. In turn, these changes directly modulate experience-dependent brain adaptations and the consolidation of newly acquired memories. In line with these observations, alterations in the regional balance between wake- and sleep-like activity have been shown to accompany many pathologic conditions, including psychiatric and neurologic disorders. In the last decade, experimental research has started to shed light on the mechanisms involved in the local regulation of sleep and wakefulness. The results of this research have opened new avenues of investigation regarding the function of sleep and have revealed novel potential targets for the treatment of several pathologic conditions.

Sleep disturbances after pediatric traumatic brain injury: a systematic review of prevalence, risk factors, and association with recovery

STUDY OBJECTIVES

Sleep is vital for brain development and healing after injury, placing children with sleep-wake disturbances (SWD) after traumatic brain injury (TBI) at risk for worse outcomes. We conducted a systematic review to quantify SWD after pediatric TBI including prevalence, phenotypes, and risk factors. We also evaluated interventions for SWD and the association between SWD and other posttraumatic outcomes.

METHODS

Systematic searches were conducted in MEDLINE, PsychINFO, and reference lists for English language articles published from 1999 to 2019 evaluating sleep or fatigue in children hospitalized for mild complicated, moderate, or severe TBI. Two independent reviewers assessed eligibility, extracted data, and assessed risk of bias using the Newcastle-Ottowa Score for observational studies.

RESULTS

Among 966 articles identified in the search, 126 full-text articles were reviewed, and 24 studies were included (11 prospective, 9 cross-sectional, and 4 case studies). Marked heterogeneity was found in study populations, measures defining SWD, and time from injury to evaluation. Studies showed at least 20% of children with TBI had trouble falling or staying asleep, fatigue, daytime sleepiness, and nightmares. SWD are negatively correlated with posttraumatic cognitive, behavioral, and quality of life outcomes. No comparative intervention studies were identified. The risk of bias was moderate-high for all studies often related to lack of validated or objective SWD measures and small sample size. Heterogeneity precluded meta-analyses.

CONCLUSIONS

SWD are important morbidities after pediatric TBI, though current data are limited. SWD have implications for TBI recovery and may represent a modifiable target for improving outcomes after pediatric TBI.

Neural correlates of memory recovery: Preliminary findings in children and adolescents with acquired brain injury

Background:

After acquired brain injury (ABI), patients show various neurological impairments and outcome is difficult to predict. Identifying biomarkers of recovery could provide prognostic information about a patient’s neural potential for recovery and improve our understanding of neural reorganization. In healthy subjects, sleep slow wave activity (SWA, EEG spectral power 1–4.5 Hz) has been linked to neuroplastic processes such as learning and brain maturation. Therefore, we suggest that SWA might be a suitable measure to investigate neural reorganization underlying memory recovery.

Objectives:

In the present study, we used SWA to investigate neural correlates of recovery of function in ten paediatric patients with ABI (age range 7–15 years).

Methods:

We recorded high-density EEG (128 electrodes) during sleep at the beginning and end of rehabilitation. We used sleep EEG data of 52 typically developing children to calculate age-normalized values for individual patients. In patients, we also assessed every-day life memory impairment at the beginning and end of rehabilitation.

Results:

In the course of rehabilitation, memory recovery was paralleled by longitudinal changes in SWA over posterior parietal brain areas. SWA over left prefrontal and occipital brain areas at the beginning of rehabilitation predicted memory recovery.

Conclusions:

We show that longitudinal sleep-EEG measurements are feasible in the clinical setting. While posterior parietal and prefrontal brain areas are known to belong to the memory “core network”, occipital brain areas have never been related to memory. While we have to remain cautious in interpreting preliminary findings, we suggest that SWA is a promising measure to investigate neural reorganization.

Power spectrum slope is related to motor function after focal cerebral ischemia in the rat

Electroencephalography (EEG) changes across vigilance states have been observed after ischemic stroke in patients and experimental stroke models, but their relation to functional recovery remains unclear. Here, we evaluate motor function, as measured by single pellet reaching (SPR), as well as local EEG changes in nonrapid eye movement (NREM), rapid eye movement (REM), and wakefulness during a 30 day recovery period after middle cerebral artery occlusion or sham surgery in rats. Small cortical infarcts resulted in poor SPR performance and induced widespread changes in EEG spectra in the ipsilesional hemisphere in all vigilance states, without causing major changes in sleep-wake architecture. Ipsilesional 1-4 Hz power was increased after stroke, whereas power in higher frequencies was reduced, resulting in a steeper slope of the power spectrum. Microelectrode array analysis of ipsilesional M1 showed that these spectral changes were present on the microelectrode level throughout M1 and were not related to increased synchronization between electrodes. Spectrum slope was significantly correlated with poststroke motor function and may thus be a useful readout of recovery-related plasticity.

Objective sleep outcomes 20 years after traumatic brain injury in childhood

Purpose: To assess objective sleep outcomes and correlates in young adults with a history of childhood traumatic brain injury.Materials and methods: Participants included 45 young adults who sustained brain injury in childhood (mild = 12, moderate = 22, and severe = 11) and 13 typically developing control participants. Sleep was assessed with actigraphy and sleep diaries recorded over 14 consecutive days. Rates of good sleep (sleep efficiency ≥ 85%) and poor sleep (sleep efficiency < 85%) were also evaluated.Results: At 20-years postinjury, participants with traumatic brain injury and controls presented with similar outcomes across the objective sleep parameters (all p > 0.050) and rates of poor sleepers were also similar between these groups (p = 0.735): 67% and 77%, respectively. However, moderate and severe traumatic brain injury and female sex were associated with longer sleep duration.Conclusions: These findings provide preliminary insights into objective sleep outcome and associated factors in the very-long-term after childhood brain injuries. They also indicate the need to monitor sleep outcomes in young adults with and without traumatic brain injury.Implication for rehabilitationSustaining traumatic brain injury in childhood can impact on several functional domains including sleep.Sleep disturbances, particularly insomnia-related symptoms, are common in this population, with evidence of poor outcomes reported until adolescence postinjury, while outcomes beyond adolescence remain unexplored.In this first investigation of objective sleep outcomes in young adults with a history of childhood traumatic brain injury, we showed that insomnia-related symptoms are highly prevalent in both young adults with traumatic brain injury (67%) and healthy controls (77%).These findings suggest the need to routinely evaluate and treat sleep problem in young adults in general, irrespective of history of childhood traumatic brain injury.

Parametric Description of EEG Profiles for Assessment of Sleep Architecture in Disorders of Consciousness

We propose a fully parametric approach to the assessment of sleep architecture, based upon the classical electroencephalographic criteria, applicable also to the recordings of patients with disorders of consciousness (DOC). Sleep spindles and slow waves are automatically detected from the matching pursuit decomposition of overnight EEG recordings. Their evolution can be presented in the form of EEG profiles, yielding a continuous description of sleep architecture, compatible with the classical criteria used in sleep staging. We propose assessment of these EEG profiles by five parameters, which can be combined by a linear classifier, assessing the quality of sleep architecture. Proposed methodology is evaluated on 59 overnight EEG recordings from 19 patients from a hospital for children with severe brain damage, in relation to their behavioral diagnosis according to the Coma Recovery Scale-Revised. Presented results indicate robustness of the proposed approach, which may serve as a valuable aid in diagnosis of DOC patients. Complete software environment for computing and presentation of EEG profiles is freely available from http://svarog.pl .

Neuroimaging of the Injured Pediatric Brain: Methods and New Lessons

Traumatic brain injury (TBI) is a significant public health problem in the United States, especially for children and adolescents. Current epidemiological data estimate over 600,000 patients younger than 20 years are treated for TBI in emergency rooms annually. While many patients experience a full recovery, for others there can be long-lasting cognitive, neurological, psychological, and behavioral disruptions. TBI in youth can disrupt ongoing brain development and create added family stress during a formative period. The neuroimaging methods used to assess brain injury improve each year, providing researchers a more detailed characterization of the injury and recovery process. In this review, we cover current imaging methods used to quantify brain disruption post-injury, including structural magnetic resonance imaging (MRI), diffusion MRI, functional MRI, resting state fMRI, and magnetic resonance spectroscopy (MRS), with brief coverage of other methods, including electroencephalography (EEG), single-photon emission computed tomography (SPECT), and positron emission tomography (PET). We include studies focusing on pediatric moderate-severe TBI from 2 months post-injury and beyond. While the morbidity of pediatric TBI is considerable, continuing advances in imaging methods have the potential to identify new treatment targets that can lead to significant improvements in outcome.