Relationship between sleep duration and childhood obesity: Systematic review including the potential underlying mechanisms

AIM

The prevalence of obesity is continually increasing worldwide. Determining risk factors for obesity may facilitate effective preventive programs. The present review focuses on sleep duration as a potential risk factor for childhood obesity. The aim is to summarize the evidence on the association of sleep duration and obesity and to discuss the underlying potential physiological and/or pathophysiological mechanisms.

DATA SYNTHESIS

The Ovid MEDLINE, Scopus and Cochrane Central Register of Controlled Trials (CENTRAL) databases were searched for papers using text words with appropriate truncation and relevant indexing terms. All studies objectively measuring sleep duration and investigating the association between sleep duration and obesity or factors (lifestyle and hormonal) possibly associated with obesity were included, without making restrictions based on study design or language. Data from eligible studies were extracted in tabular form and summarized narratively. After removing duplicates, 3540 articles were obtained. Finally, 33 studies (including 3 randomized controlled trials and 30 observational studies) were included in the review.

CONCLUSION

Sleep duration seems to influence weight gain in children, however, the underlying explanatory mechanisms are still uncertain. In our review only the link between short sleep duration and the development of insulin resistance, sedentarism and unhealthy dietary patterns could be verified, while the role of other mediators, such as physical activity, screen time, change in ghrelin and leptin levels, remained uncertain. There are numerous evidence gaps. To answer the remaining questions, there is a need for studies meeting high methodological standards and including a large number of children.

Neurophysiology of juvenile myoclonic epilepsy: EEG-based network and graph analysis of the interictal and immediate preictal states

INTRODUCTION

The neuronal mechanisms of enduring seizure propensity and seizure precipitation in juvenile myoclonic epilepsy (JME) are not known. We investigated these issues, within the framework of the "network concept" of epilepsy.

METHODS

Design1: 19, unmedicated JME patients were compared with nineteen, age-, and sex-matched normal control persons (NC). A total of 120s, artifact-free, paroxysm-free, eyes-closed, resting state EEG background activity was analyzed for each person. Design2: interictal and immediate preictal periods of the JME patients were compared in order to explore interictal-preictal network differences. For both comparison designs, statistically significant differences of EEG functional connectivity (EEGfC), nodal and global graph parameters were evaluated.

MAIN RESULTS

Design1: maximum abnormalities were: increased delta, theta, alpha1 EEGfC and decreased alpha2 and beta EEGfC in the JME group as compared to the NC group, mainly among cortical areas that are involved in sensory-motor integration. Nodal degree and efficiency of three, medial, basal frontal nodes were greater in JME than in NC, in the alpha1 band. Design2: preictal delta EEGfC showed further increase in the above-mentioned areas, as compared to the interictal state.

DISCUSSION

Increased EEGfC indicates a hypercoupled state among the specified cortical areas. This interictal abnormality further increases in the preictal state. Nodal graph statistics indicates abnormal neuronal dynamics in the cortical area that is the ictal onset zone in JME.

SIGNIFICANCE

Interictal and preictal neuronal dysfunction has been described in terms of network dynamics and topography in JME patients. Forthcoming investigations of seizure precipitation and therapeutic drug effects are encouraged on this basis.

EEG-LORETA endophenotypes of the common idiopathic generalized epilepsy syndromes

OBJECTIVE

We tested the hypothesis that the cortical areas with abnormal local EEG synchronization are dissimilar in the three common idiopathic generalized epilepsy (IGE) phenotypes: IGE patients with absence seizures (ABS), juvenile myoclonic epilepsy (JME) and epilepsy with generalized tonic-clonic seizures exclusively (EGTCS).

PATIENTS AND METHODS

Groups of unmedicated ABS, JME and EGTCS patients were investigated. Waking EEG background activity (without any epileptiform potentials) was analyzed by a source localization method, LORETA (Low Resolution Electromagnetic Tomography). Each patient group was compared to a separate, age-matched group of healthy control persons. Voxel-based, normalized broad-band (delta, theta, alpha, and beta) and very narrow band (VNB, 1Hz bandwidth, from 1 to 25Hz) LORETA activity (=current source density, A/m(2)) were computed for each person. Group comparison included subtraction (average patient data minus average control data) and group statistics (multiple t-tests, where Bonferroni-corrected p<0.05 values were accepted as statistically significant).

RESULTS

Statistically not significant main findings were: overall increased delta and theta broad band activity in the ABS and JME groups; decrease of alpha and beta activity in the EGTCS group. Statistically significant main findings were as follows. JME group: bilaterally increased theta activity in posterior (temporal, parietal, and occipital) cortical areas; bilaterally increased activity in the medial and basal prefrontal area in the 8Hz VNB; bilaterally decreased activity in the precuneus, posterior cingulate and superior parietal lobule in the 11Hz and 21-22Hz VNBs. ABS group: bilaterally increased theta activity emerged in the basal prefrontal and medial temporal limbic areas. Decreased activity was found at 19-21Hz in the right postcentral gyrus and parts of the right superior and medial temporal gyri. EGTCS group: decreased activity was found in the frontal cortex and the postcentral gyrus at 10-11Hz, increased activity in the right parahippocampal gyrus at 16-18Hz.

DISCUSSION

Increased theta activity in the posterior parts of the cortex is the endophenotype for JME. Increased theta activity in the fronto-temporal limbic areas is the endophenotype for ABS. Statistically not significant findings might indicate diffuse biochemical abnormality of the cortex in JME and ABS.

SIGNIFICANCE

EEG-LORETA endophenotypes may correspond to the selective propensity to generate absence and myoclonic seizures in the ABS and JME syndromes.

EEG background activity is abnormal in the temporal and inferior parietal cortex in benign rolandic epilepsy of childhood: a LORETA study

INTRODUCTION

Benign rolandic epilepsy of childhood (BERS) is an epilepsy syndrome with presumably genetic-developmental etiology. The pathological basis of this syndrome is completely unknown. We postulated that a developmental abnormality presumably results in abnormal EEG background activity findings.

PATIENTS AND METHODS

20 children with typical BERS and an age- and sex-matched group of healthy control children underwent EEG recording and analysis. 60×2 s epochs of waking EEG background activity (without epileptiform potentials and artifacts) were analyzed in the 1-25 Hz frequency range, in very narrow bands (VNB, 1 Hz bandwidth). LORETA (Low Resolution Electromagnetic Tomography) localized multiple distributed sources of EEG background activity in the Talairach space. LORETA activity (current source density) was computed for 2394 voxels and 25 VNBs. Normalized LORETA data were processed to voxel-wise comparison between the BERS and control groups. Bonferroni-corrected p<0.05 Student's t-values were accepted as statistically significant.

RESULTS

Increased LORETA activity was found in the BERS group (as compared to the controls) in the left and right temporal lobes (fusiform gyri, posterior parts of the superior, middle and inferior temporal gyri) and in the angular gyri in the parietal lobes, in the 4-6 Hz VNBs, mainly at 5 Hz.

DISCUSSION

(1) Areas of abnormal LORETA activity exactly correspond to the temporal and parietal cortical areas that are major components of the Mirsky attention model and also the perisylvian speech network. Thus the LORETA findings may correspond to impaired attention and speech in BERS patients. (2) The LORETA findings may contribute to delineating the epileptic network in BERS.

SIGNIFICANCE

The novel findings may contribute to investigating neuropsychological disturbances and organization of the epileptic network in BERS.

Ultrasound-guided, intraglandular injection of botulinum toxin A in children suffering from excessive salivation

Background: The aim of this study was to describe the authors' minimally invasive procedure developed to significantly decrease excessive salivation in children suffering from chronic neurological diseases, using botulinum toxin A.

Objective: Ultrasound-guided, intraglandular injection of botulinum toxin blocks the parasympathetic innervation of salivary glands, resulting in a temporary decrease in saliva production and improved quality of life, lasting about three to four months.

Materials and methods: Prior to introducing the method into clinical practice, animal experiments were conducted in order to verify the lack of histological changes three months following botulinum toxin administration. Twenty-one children were included in the clinical study, with ages ranging from two and a half to 14 years.

Results: The animal studies did not reveal any histological changes three months after botulinum toxin administration. Although botulinum toxin A proved to be ineffective in a single case, the majority of the other 20 patients responded well, with a highly significant reduction of their symptoms. The parents of 18 responder children requested repeated treatment with botulinum toxin A. However, two families refused to be further involved in the study, despite good results. The protein content of saliva, regulated by sympathetic innervation, was not affected by the treatment.

Conclusion: This minimally invasive method, applied repeatedly three to four times a year, may be a viable alternative to surgical procedures such as submandibular duct relocation, duct ligature or nervus tympanicus neurectomy.

Lamotrigine decreases EEG synchronization in a use-dependent manner in patients with idiopathic generalized epilepsy

OBJECTIVE

To investigate the quantitative EEG effects of lamotrigine (LTG) monotherapy.

HYPOTHESIS

LTG was predicted to decrease thalamo-cortical neuronal synchronization in idiopathic generalized epilepsy (IGE).

METHODS

Waking EEG background activity of 19 IGE patients was investigated before treatment and in the course of LTG monotherapy. Raw absolute power (RAP), raw percent power (RRP), and raw mean frequency (RMF) were computed for 19 electrodes and four frequency bands (delta=1.5-3.5Hz, theta=3.5-7.5Hz, alpha=7.5-12.5Hz, and beta=12.5-25.0Hz). Inter- and intrahemispheric coherence was computed for eight electrode pairs and the four frequency bands. In addition, scalp-averages were calculated for each variable. Group differences were computed by means of nonparametric statistics including correction for multiple comparisons.

RESULTS

Main results were decreased delta and theta RAP (p<0.05 for scalp-averages). LTG compressed the delta, theta, and alpha RAP datasets, reducing the upper limit of the scatter in particular. Spearman r-values indicated marked correlation between the starting values (RAPuntreated) and the LTG-related decrease (RAPtreated-RAPuntreated) in three bands: delta (r=-0.72; p=0.0005), theta (r=-0.59; p=0.007), and alpha (r=-0.61; p=0.006). Thus, the greater the baseline neuronal synchronization, the marked the dampening effect of LTG on it. The remaining findings were decreased theta RRP, theta RMF, and increased alpha RMF (p<0.05 for scalp-averages). The electrode-related changes were small but topographically consistent across the 19 electrode sites. LTG did not affect coherence.

CONCLUSIONS

1. LTG partially normalized the spectral composition of EEG background activity. LTG decreased pathological thalamo-cortical synchronization in use-dependent manner. 2. LTG did not cause quantitative EEG alterations suggesting worsening of the physiological brain functions. Instead, its profile suggested a mild psychostimulant effect.

SIGNIFICANCE

The results contribute to the understanding of the effect of LTG at the network level.

[Refsum disease]

For the first time in literature the authors interpret the pathography of Refsum's disease, in the case of their patient, as pseudo-hypervitaminosis A. The biochemical basis of the clinical picture is a defect in the activity of phytanic-acid-alpha-hydrolase belonging to the peroxisomal system. As a consequence, phytanic acid accumulates in the serum and in the parenchymal tissues. Retinol, an alcohol with high molecular weight, is a natural ligand of nuclear RXR (retinoid-X-receptor), which plays an important role in the regulation of peroxisoma synthesis. In Refsum's disease the phytanic acid accumulated because of the enzyme defect competes with the biotransformation derivates (all-trans-retinoic acid, 9-cis-retinoic acid) of the all-trans-retinol (vitamin A) for the nuclear RX receptor binding sites, and as a very potent receptoractivator it causes the intestinal symptoms of hypervitaminosis A. The authors review the procedure of fatty-acid chromatography necessary for the establishment of the diagnosis and discuss--in addition to dietary restrictions--recent therapeutic possibilities, like plasmapheresis, cascade filtration, lipapheresis and oral batylalcohol treatment.

[Hallervorden-Spatz disease]

Based on the history of a 5-year-old boy, the clinical picture and the natural history of Hallervorden-Spatz disease are reviewed. In the past, the diagnosis of Hallervorden-Spatz disease has usually been made only post mortem. In the T2 weighted MRI images "eye of the tiger" sign is seen. This is due to iron-accumulation in the pallidum and it makes the earlier, in vivo diagnosis of the disease possible.

[PEHO syndrome (progressive encephalopathy, edema, hypsarrhythmia. optic atrophy)]

The authors report the case of a now 2-year-old boy with PEHO syndrome. The syndrome is rare and it has not been published yet in Hungary. The syndrome was named after the first letters of its main characteristic signs: progressive encephalopathy, edema, hypsarrhythmia and optic atrophy. The aetiology of the syndrome is still unknown. Autosomal recessive inheritance is likely. The prognosis is poor. Intractable infantile spasms and the arrest of the psychomotoric and mental development can be expected.

[A case of herpes simplex encephalitis requiring surgical management]

The authors report about surgical treatment of herpes simplex encephalitis, although conservative management of this disease is the method of choice in the first place. They draw a lesson from this case that certain cases of large space occupying lesions of infectious origin leading to brain stem compression may require surgical management, even if they customary treatment is conservative.

[Glucosylated proteins and perinatal growth]

The concentration of HbA1c and glycosylated serum proteins were measured colorimetrically in 30 and 29 newborn infants of various gestational age, at the postnatal age of 0-24 hrs and 19-23 days, respectively. No relationship was found either between the maturity and the prenatal and early postnatal growth of the studied infants or the concentration of glycosylated haemoglobin and serum proteins.

[Concentration of C-reactive protein in neonatal pathology]

C-reactive protein concentration was measured in 56 preterm and 61 full term newborn infants with various pathology, at the postnatal age of 0-24 hrs and 1, 2, 3, 4 weeks. One third of all study babies had an increased (greater than 10 mg/l) CRP level measured within 24 hrs of birth. On the first day, CRP concentration in neonates with a pronounced perinatal asphyxia was as high as in those who suffered from perinatal infection. Further postnatal changes in CRP level need individual evaluation in every case, considering the diagnosis, clinical course and treatment. In connection with the results the clinical usefulness of CRP determinations in neonatal medicine is shortly discussed.