Source EEG reveals that Rolandic epilepsy is a regional epileptic encephalopathy

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Children with RE have fewer spindles but they have typical time–frequency features.

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Spindle deficits extend to multiple cortical regions in Rolandic epilepsy.

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Cognitive deficits are predicted by spindle rate in Rolandic epilepsy.

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Regional spindle rate predicts motor deficits better than Rolandic spindle deficit.

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Spindle features in RE identify a regional thalamocortical epileptic encephalopathy.

Rolandic epilepsy is the most common form of epileptic encephalopathy, characterized by sleep-potentiated inferior Rolandic epileptiform spikes, seizures, and cognitive deficits in school-age children that spontaneously resolve by adolescence. We recently identified a paucity of sleep spindles, physiological thalamocortical rhythms associated with sleep-dependent learning, in the Rolandic cortex during the active phase of this disease. Because spindles are generated in the thalamus and amplified through regional thalamocortical circuits, we hypothesized that: 1) deficits in spindle rate would involve but extend beyond the inferior Rolandic cortex in active epilepsy and 2) regional spindle deficits would better predict cognitive function than inferior Rolandic spindle deficits alone. To test these hypotheses, we obtained high-resolution MRI, high-density EEG recordings, and focused neuropsychological assessments in children with Rolandic epilepsy during active (n = 8, age 9–14.7 years, 3F) and resolved (seizure free for > 1 year, n = 10, age 10.3–16.7 years, 1F) stages of disease and age-matched controls (n = 8, age 8.9–14.5 years, 5F). Using a validated spindle detector applied to estimates of electrical source activity in 31 cortical regions, including the inferior Rolandic cortex, during stages 2 and 3 of non-rapid eye movement sleep, we compared spindle rates in each cortical region across groups. Among detected spindles, we compared spindle features (power, duration, coherence, bilateral synchrony) between groups. We then used regression models to examine the relationship between spindle rate and cognitive function (fine motor dexterity, phonological processing, attention, and intelligence, and a global measure of all functions). We found that spindle rate was reduced in the inferior Rolandic cortices in active but not resolved disease (active P = 0.007; resolved P = 0.2) compared to controls. Spindles in this region were less synchronous between hemispheres in the active group (P = 0.005; resolved P = 0.1) compared to controls; but there were no differences in spindle power, duration, or coherence between groups. Compared to controls, spindle rate in the active group was also reduced in the prefrontal, insular, superior temporal, and posterior parietal regions (i.e., “regional spindle rate”, P < 0.039 for all). Independent of group, regional spindle rate positively correlated with fine motor dexterity (P < 1e-3), attention (P = 0.02), intelligence (P = 0.04), and global cognitive performance (P < 1e-4). Compared to the inferior Rolandic spindle rate alone, models including regional spindle rate trended to improve prediction of global cognitive performance (P = 0.052), and markedly improved prediction of fine motor dexterity (P = 0.006). These results identify a spindle disruption in Rolandic epilepsy that extends beyond the epileptic cortex and a potential mechanistic explanation for the broad cognitive deficits that can be observed in this epileptic encephalopathy.

Diazepam induced sleep spindle increase correlates with cognitive recovery in a child with epileptic encephalopathy

BACKGROUND

Continuous spike and wave of sleep with encephalopathy (CSWS) is a rare and severe developmental electroclinical epileptic encephalopathy characterized by seizures, abundant sleep activated interictal epileptiform discharges, and cognitive regression or deceleration of expected cognitive growth. The cause of the cognitive symptoms is unknown, and efforts to link epileptiform activity to cognitive function have been unrevealing. Converging lines of evidence implicate thalamocortical circuits in these disorders. Sleep spindles are generated and propagated by the same thalamocortical circuits that can generate spikes and, in healthy sleep, support memory consolidation. As such, sleep spindle deficits may provide a physiologically relevant mechanistic biomarker for cognitive dysfunction in epileptic encephalopathies.

CASE PRESENTATION

We describe the longitudinal course of a child with CSWS with initial cognitive regression followed by dramatic cognitive improvement after treatment. Using validated automated detection algorithms, we analyzed electroencephalograms for epileptiform discharges and sleep spindles alongside contemporaneous neuropsychological evaluations over the course of the patient's disease. We found that sleep spindles increased dramatically with high-dose diazepam treatment, corresponding with marked improvements in cognitive performance. We also found that the sleep spindle rate was anticorrelated to spike rate, consistent with a competitively shared underlying thalamocortical circuitry.

CONCLUSIONS

Epileptic encephalopathies are challenging electroclinical syndromes characterized by combined seizures and a deceleration or regression in cognitive skills over childhood. This report identifies thalamocortical circuit dysfunction in a case of epileptic encephalopathy and motivates future investigations of sleep spindles as a biomarker of cognitive function and a potential therapeutic target in this challenging disease.

Dysmature superficial white matter microstructure in developmental focal epilepsy

Benign epilepsy with centrotemporal spikes is a common childhood epilepsy syndrome that predominantly affects boys, characterized by self-limited focal seizures arising from the perirolandic cortex and fine motor abnormalities. Concurrent with the age-specific presentation of this syndrome, the brain undergoes a developmentally choreographed sequence of white matter microstructural changes, including maturation of association u-fibres abutting the cortex. These short fibres mediate local cortico-cortical communication and provide an age-sensitive structural substrate that could support a focal disease process. To test this hypothesis, we evaluated the microstructural properties of superficial white matter in regions corresponding to u-fibres underlying the perirolandic seizure onset zone in children with this epilepsy syndrome compared with healthy controls. To verify the spatial specificity of these features, we characterized global superficial and deep white matter properties. We further evaluated the characteristics of the perirolandic white matter in relation to performance on a fine motor task, gender and abnormalities observed on EEG. Children with benign epilepsy with centrotemporal spikes (n = 20) and healthy controls (n = 14) underwent multimodal testing with high-resolution MRI including diffusion tensor imaging sequences, sleep EEG recordings and fine motor assessment. We compared white matter microstructural characteristics (axial, radial and mean diffusivity, and fractional anisotropy) between groups in each region. We found distinct abnormalities corresponding to the perirolandic u-fibre region, with increased axial, radial and mean diffusivity and fractional anisotropy values in children with epilepsy (P = 0.039, P = 0.035, P = 0.042 and P = 0.017, respectively). Increased fractional anisotropy in this region, consistent with decreased integrity of crossing sensorimotor u-fibres, correlated with inferior fine motor performance (P = 0.029). There were gender-specific differences in white matter microstructure in the perirolandic region; males and females with epilepsy and healthy males had higher diffusion and fractional anisotropy values than healthy females (P ≤ 0.035 for all measures), suggesting that typical patterns of white matter development disproportionately predispose boys to this developmental epilepsy syndrome. Perirolandic white matter microstructure showed no relationship to epilepsy duration, duration seizure free, or epileptiform burden. There were no group differences in diffusivity or fractional anisotropy in superficial white matter outside of the perirolandic region. Children with epilepsy had increased radial diffusivity (P = 0.022) and decreased fractional anisotropy (P = 0.027) in deep white matter, consistent with a global delay in white matter maturation. These data provide evidence that atypical maturation of white matter microstructure is a basic feature in benign epilepsy with centrotemporal spikes and may contribute to the epilepsy, male predisposition and clinical comorbidities observed in this disorder.

Beta oscillations in the sensorimotor cortex correlate with disease and remission in benign epilepsy with centrotemporal spikes

INTRODUCTION

Benign epilepsy with centrotemporal spikes (BECTS) is a common form of childhood epilepsy with the majority of those afflicted remitting during their early teenage years. Seizures arise from the lower half of the sensorimotor cortex of the brain (e.g. seizure onset zone) and the abnormal epileptiform discharges observed increase during NREM sleep. To date no clinical factors reliably predict disease course, making determination of ongoing seizure risk a significant challenge. Prior work in BECTS have shown abnormalities in beta band (14.9-30 Hz) oscillations during movement and rest. Oscillations in this frequency band are modulated by state of consciousness and thought to reflect intrinsic inhibitory mechanisms.

METHODS

We used high density EEG and source localization techniques to examine beta band activity in the seizure onset zone (sensorimotor cortex) in a prospective cohort of children with BECTS and healthy controls during sleep. We hypothesized that beta power in the sensorimotor cortex would be different between patients and healthy controls, and that beta abnormalities would improve with resolution of disease in this self-limited epilepsy syndrome. We further explored the specificity of our findings and correlation with clinical features. Statistical testing was performed using logistic and standard linear regression models.

RESULTS

We found that beta band power in the seizure onset zone is different between healthy controls and BECTS patients. We also found that a longer duration of time spent seizure-free (corresponding to disease remission) correlates with lower beta power in the seizure onset zone. Exploratory spatial analysis suggests this effect is not restricted to the sensorimotor cortex. Exploratory frequency analysis suggests that this phenomenon is also observed in alpha and gamma range activity. We found no relationship between beta power and the presence or rate of epileptiform discharges in the sensorimotor cortex or a test of sensorimotor performance.

CONCLUSION

These results provide evidence that cortical beta power in the seizure onset zone may provide a dynamic physiological biomarker of disease in BECTS.

Low glycemic index treatment for seizures in Angelman syndrome

PURPOSE

The low glycemic index treatment (LGIT) is a high fat, limited carbohydrate diet used in the treatment of epilepsy. The purpose of this study was to assess the efficacy and tolerability of the LGIT for the treatment of refractory seizures in pediatric patients with Angelman syndrome.

METHODS

A pediatric Angelman syndrome cohort with refractory epilepsy was treated with the LGIT and followed prospectively over 4 months. Parents recorded a daily seizure log for a minimum of 1 month prior to the start of treatment as well as throughout the LGIT trial. Electroencephalography (EEG) and neuropsychological assessments (Scales of Independent Behavior-Revised and the Vineland Adaptive Behavior Scales-2nd Edition were obtained for each subject at both baseline and 4-month follow-up time points. Clinical evaluations of subjects were completed by a neurologist and dietitian at the time of enrollment, as well as following both the first and fourth months of dietary therapy. At each time point, blood for laboratory chemistries was drawn and anthropometric measures were obtained.

KEY FINDINGS

Six children (mean age 3.3 years, range 1.1-4.8) with genetically confirmed Angelman syndrome initiated the LGIT, and completed the trial with no significant adverse events. Cohort averages for indices of seizure severity were as follows: age of 1.6 years at seizure onset, 3 lifetime antiepileptic drugs tried (range 1-6), and baseline seizure frequency of 10.1 events/week (range: 0.4-30.9). All subjects had a decrease in seizure frequency on the LGIT, with five of six exhibiting >80% seizure frequency reduction. All posttrial EEG studies showed improvement and three of four children with epileptiform activity on his or her baseline EEG had no discharges present on follow-up EEG. Developmental gains were noted by parents in all cases, although few of these neurocognitive gains were statistically significant on neuropsychological assessment.

SIGNIFICANCE

This is the first prospective study assessing the LGIT for epilepsy. Our results indicate that this dietary therapy is highly effective in treating Angelman syndrome-related seizures. The diet was well tolerated by subjects as evidenced by five of six subjects remaining on the LGIT after completion of the trial. Beyond the prospective trial window, all five subjects who remained on the diet had >90% seizure reduction after 1 year of LGIT therapy. Despite the small sample size in this prospective study, the results indicate a potentially higher degree of efficacy of the LGIT for the Angelman syndrome population than that observed in the general epilepsy population. Although this study is too small to make definitive recommendations, these results suggest that the LGIT is a promising treatment option for Angelman syndrome-related epilepsy.

Palliative home care in a rural setting: reflections on selective interactions

Despite the fact that terminally ill patients are approaching the end-stage of their lives, the need for information and continuing involvement in their own care remains paramount and does not necessarily diminish as their dependency increases. This paper supports the view that nurses working in the area of rural palliative care are in an optimum position to establish the kind of relationship with patients and informal carers that augments a sense of involvement, self determination, equity and trust. This is of particular significance to rural palliative care where service provision may be under-resourced and where domiciliary nurses are often the key provider for continuing care and support.

Client education experiences in professional nursing practice--a phenomenological perspective

This paper reports a small-scale phenomenological study of registered nurses' experiences with their client education role. Its purpose was to investigate phenomena associated with actual experiences as they were encountered by participants. A review of the literature provides an overview of client education in terms of its definition and utility, and draws attention to the notion of compliance and the influence of power in health provider-client relationships. Phenomenology offers an appropriate methodological framework for investigating symbolic experiences, and three central concepts are yielded from aggregate data in the form of confirming experiences, disconfirming experiences and educational processes. Findings indicate that nurses' value the uniqueness of the client and, where possible, tend to initiate educational processes that actually empower individuals. However, disconfirming experiences are associated with demands on nurses' work schedules, low client motivation and non-compliance. Physician interjection is also perceived as problematical, resulting in feelings which undermine the nurses' professional integrity, and which lead to a diminished sense of self-worth.

Acute inhalation toxicity of aliphatic (C1-C5) nitrites in rats

The 4-hr inhalation LC50 was determined for methyl-, ethyl-, n-propyl-, n-butyl-, isobutyl-, and isopentyl nitrite in Sprague-Dawley rats. LC50 values were 176, 160, 300, 420, 777, and 716 ppm, respectively. The dose-mortality curves were characterized by extremely steep slopes. Toxic signs observed during exposure included cyanosis, prostration, and rarely, convulsions. There were no effects of exposure on body weight gain during a 14-day postexposure observation period. Signs of pulmonary hemorrhage were apparent in rats which died during exposure but were much less prominent in rats sacrificed at study termination. No animals died after cessation of exposure, and rapid recovery was apparent after exposure. Concentration X Time (CT) relationships suggested that the actual concentration was more important than the "dose" in determining the lethal effects of inhalation exposure to nitrites. Because of the extremely steep dose-mortality curves, the aliphatic nitrites are more hazardous than the LC50 values would indicate.

Physiological stress responses in big gamefish after capture: observations on plasma chemistry and blood factors

The plasma electrolytes, Na+, K+, Ca2+, Cl- and osmolarities had high values in capture-stressed big gamefish. Blood metabolites measured after stress showed glucose and lactate elevations. The activity of the plasma enzymes alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, creatine kinase and lactate dehydrogenase suggested tissue disruptions following severe capture stress. Haematocrit values and methaemoglobin were high in capture-stressed gamefish. The plasma chemistry of resting and capture-stressed snapper (Chrysophrys auratus) was studied for comparison. Specific differences in plasma biochemistry appeared to be the result of different strategies of fish behaviour during capture.

Lugol's iodine: its effect on thyroid blood flow in patients with thyrotoxicosis

It has been established practice for 60 years to prepare thyrotoxic patients undergoing thyroidectomy with Lugol's iodine. However, evidence in support of its claimed benefits, namely a reduction in the vascularity and friability of the toxic thyroid gland, is scanty. We have therefore determined the effect of Lugol's iodine on thyroid blood flow, as measured by thyroid uptake of thallium-201, in nine patients with Graves' disease and one euthyroid patient. Thallium-201 uptake, as well as serum thyroxine and triiodothyronine, fell significantly after treatment with iodine. Although not correlated with thyroid function tests, thallium-201 uptake was significantly correlated with thyroid weight. These results support the contention that thyroid blood flow is reduced in thyrotoxic patients treated with Lugol's iodine.

Comparison of transcutaneous oxygen tension with arterial oxygen tension in newborn infants with severe respiratory illnesses

Transcutaneous oxygen tension (tcPO2), measured by two skin electrodes of different design, and arterial oxygen tension (PaO2), measured by an intravascular oxygen electrode, were continuously recorded for periods of six hours in 15 newborn infants with serious respiratory illnesses. Ten of the infants needed mechanical ventilation and three needed continuous positive airway pressure. One skin electrode had three microcathodes surrounded by a heated ring-shaped anode, and the other had a large heated cathode. The temperature of both electrodes was set at 44 degrees C and they were calibrated in vitro. The tcPO2 recorded by the electrode with the microcathodes was found to estimate PaO2 reasonably accurately for the whole six-hour duration of the study. The tcPO2 recorded by the electrode with the large cathode gave a similar estimate of PaO2 for three hours, but then tcPO2 often fell relative to PaO2. This fall was probably caused by skin changes at the electrode site. For a variety of reasons, our results suggest that measurement of tcPO2 is unlikely to replace continuous intravascular measurement of PaO2 in infants with severe respiratory illnesses.

Continuous comparison of transcutaneous and arterial oxygen tension in newborn infants with respiratory illnesses

Transcutaneous oxygen tension (tcPO2) measured by two skin electrodes of different design, and arterial oxygen tension (PaO2) measured by an intravascular oxygen electrode, were continuously compared for periods of 6--27 h in 45 newborn infants with respiratory illnesses. One skin electrode (Dräger) had three microcathodes surrounded by a heated ring-shaped anode and the other (Roche) a large heated cathode. The electrodes were calibrated in vitro; 44 degrees C was found to be a suitable electrode temperature for the estimation of Pao2. tcPo2 recorded by the electrode with the microcathodes estimated Pao2 reasonably accurately for 6 h without the necessity for re-siting. tcPao2 recorded by the electrode with the large cathode gave a similar estimate of Pao2 for 3 h, but then tcPao2 often fell relative to Pao2. This fall was probably caused by skin changes at the electrode site. Poor skin perfusion causing underestimation of Pao2 by tcPo2 could not be identified by a number of methods tried.