Interrater reliability of Engel, International League Against Epilepsy, and McHugh seizure outcome classifications following vagus nerve stimulator implantation

OBJECT

Interrater reliability as measured by the kappa (κ) statistic is a widely used and valuable tool to measure the robustness of a scoring system. Seizure frequency reduction is a central outcome measure following vagus nerve stimulation (VNS). A specific VNS scoring system has been proposed by McHugh, but its interrater reliability has not been tested. The authors assessed its interrater reliability and compared it with that of the Engel and International League Against Epilepsy (ILAE) systems.

METHODS

Using the Engel, ILAE, and McHugh scoring systems, 3 observers independently rated the medical records of children who had undergone vagus nerve stimulator implantation between January 2001 and April 2011 at the Southampton University Hospital. The interrater agreements were then calculated using the κ statistic.

RESULTS

Interrater reliability for the McHugh scale (κ0.693) was very good and was superior to those of the Engel (κ0.464) and ILAE (κ0.491) systems for assessing outcome in patients undergoing VNS.

CONCLUSIONS

The authors recommend considering the McHugh scoring system when assessing outcomes following VNS.

Peripheral vascular response to inspiratory breath hold in paediatric homozygous sickle cell disease

New Findings

• What is the central question of this study?

Autonomic nervous dysfunction is implicated in complications of sickle cell anaemia (SCA). In healthy adults, a deep inspiratory breath hold (IBH) elicits rapid transient SNS- mediated vasoconstriction detectable using Laser Doppler Flux (LDF) assessment of the finger-tip cutaneous micovasculature.

• What is the main finding and its importance?

We demonstrate significantly increased resting peripheral blood flow and sympathetic activity in African children with SCA compared to sibling controls and increased sympathetic stimulation in response to vasoprovocation with DIG.

This study is the first to observe an inverse association between resting peripheral blood flow and haemoglobin oxygen saturation (SpO2). These phenomena may be an adaptive response to the hypoxic exposure in SCA.

There is increasing evidence that autonomic dysfunction in adults with homozygous sickle cell (haemoglobin SS) disease is associated with enhanced autonomic nervous system-mediated control of microvascular perfusion. However, it is unclear whether such differences are detectable in children with SS disease. We studied 65 children with SS disease [38 boys; median age 7.2 (interquartile range 5.1–10.6) years] and 20 control children without symptoms of SS disease [8 boys; 8.7 (5.5–10.8) years] and recorded mean arterial blood pressure (ABP) and daytime haemoglobin oxygen saturation (). Cutaneous blood flux at rest (RBF) and during the sympathetically activated vasoconstrictor response to inspiratory breath hold (IBH) were measured in the finger pulp of the non-dominant hand using laser Doppler fluximetry. Local factors mediating flow motion were assessed by power spectral density analysis of the oscillatory components of the laser Doppler signal. The RBF measured across the two study groups was negatively associated with age (r=−0.25, P < 0.0001), ABP (r=−0.27, P= 0.02) and daytime (r=−0.30, P= 0.005). Children with SS disease had a higher RBF (P= 0.005) and enhanced vasoconstrictor response to IBH (P= 0.002) compared with control children. In children with SS disease, higher RBF was associated with an increase in the sympathetic interval (r=−0.28, P= 0.022). The SS disease status, daytime and age explained 22% of the variance in vasoconstrictor response to IBH (P < 0.0001). Our findings suggest that blood flow and blood flow responses in the skin of young African children with SS disease differ from those of healthy control children, with increased resting peripheral blood flow and increased sympathetic stimulation from a young age in SS disease. They further suggest that the laser Doppler flowmetry technique with inspiratory breath hold manoeuvre appears to be robust for use in young children with SS disease, to explore interactions between , ABP and autonomic function with clinical complications, e.g. skin ulceration.

Silent cerebral infarcts: a review on a prevalent and progressive cause of neurologic injury in sickle cell anemia

Silent cerebral infarct (SCI) is the most common form of neurologic disease in children with sickle cell anemia (SCA). SCI is defined as abnormal magnetic resonance imaging (MRI) of the brain in the setting of a normal neurologic examination without a history or physical findings associated with an overt stroke. SCI occurs in 27% of this population before their sixth, and 37% by their 14th birthdays. In adults with SCA, the clinical history of SCI is poorly defined, although recent evidence suggests that they too may have ongoing risk of progressive injury. Risk factors for SCI include male sex, lower baseline hemoglobin concentration, higher baseline systolic blood pressure, and previous seizures. Specific morbidity associated with SCI includes a decrement in general intellectual abilities, poor academic achievement, progression to overt stroke, and progressive SCI. In addition, children with previous stroke continue to have both overt strokes and new SCI despite receiving regular blood transfusion therapy for secondary stroke prevention. Studies that only include overt stroke as a measure of CNS injury significantly underestimate the total cerebral injury burden in this population. In this review, we describe the epidemiology, natural history, morbidity, medical management, and potential therapeutic options for SCI in SCA.

Seizures in 204 comatose children: incidence and outcome

Purpose

Seizures are common in comatose children, but may be clinically subtle or only manifest on continuous electroencephalographic monitoring (cEEG); any association with outcome remains uncertain.

Methods

cEEG (one to three channels) was performed for a median 42 h (range 2–630 h) in 204 unventilated and ventilated children aged ≤15 years (18 neonates, 61 infants) in coma with different aetiologies. Outcome at 1 month was independently determined and dichotomized for survivors into favourable (normal or moderate neurological handicap) and unfavourable (severe handicap or vegetative state).

Results

Of the 204 patients, 110 had clinical seizures (CS) before cEEG commenced. During cEEG, 74 patients (36 %, 95 % confidence interval, 95 % CI, 32–41 %) had electroencephalographic seizures (ES), the majority without clinical accompaniment (non-convulsive seizures, NCS). CS occurred before NCS in 69 of the 204 patients; 5 ventilated with NCS had no CS observed. Death (93/204; 46 %) was independently predicted by admission Paediatric Index of Mortality (PIM; adjusted odds ratio, aOR, 1.027, 95 % CI 1.012–1.042; p < 0.0005), Adelaide coma score (aOR 0.813, 95 % CI 0.700–0.943; p = 0.006), and EEG grade on admission (excess slow with >3 % fast, aOR 5.43, 95 % CI 1.90–15.6; excess slow with <3 % fast, aOR 8.71, 95 % CI 2.58–29.4; low amplitude, 10th centile <9 µV, aOR 3.78, 95 % CI 1.23–11.7; and burst suppression, aOR 10.68, 95 % CI 2.31–49.4) compared with normal cEEG, as well as absence of CS at any time (aOR 2.38, 95 % CI 1.18–4.81). Unfavourable outcome (29/111 survivors; 26 %) was independently predicted by the presence of ES (aOR 15.4, 95 % CI 4.7–49.7) and PIM (aOR 1.036, 95 % CI 1.013–1.059).

Conclusion

Seizures are common in comatose children, and are associated with an unfavourable outcome in survivors. cEEG allows the detection of subtle CS and NCS and is a prognostic tool.

Continuous EEG monitoring in Kenyan children with non-traumatic coma

BACKGROUND

The aim of this study was to describe the EEG and clinical profile of seizures in children with non-traumatic coma, compare seizure detection by clinical observations with that by continuous EEG, and relate EEG features to outcome.

METHODS

This prospective observational study was conducted at the paediatric high dependency unit of Kilifi District Hospital, Kenya. Children aged 9 months to 13 years presenting with acute coma were monitored by EEG for 72 h or until they regained consciousness or died. Poor outcome was defined as death or gross motor deficits at discharge.

RESULTS

82 children (median age 2.8 (IQR 2.0-3.9) years) were recruited. An initial medium EEG amplitude (100-300 mV) was associated with less risk of poor outcome compared to low amplitude (≤100 mV) (OR 0.2, 95% CI 0.1 to 0.7; p<0.01). 363 seizures in 28 (34%) children were observed: 240 (66%) were electrographic and 112 (31%) electroclinical. In 16 (20%) children, electrographic seizures were the only seizure types detected. The majority (63%) of electroclinical seizures had focal clinical features but appeared as generalised (79%) or focal with secondary generalisation (14%) on EEG. Occurrence of any seizure or status epilepticus during monitoring was associated with poor outcome (OR 3.2, 95% CI 1.2 to 8.7; p=0.02 and OR 4.5, 95% CI 1.3 to 15.3; p<0.01, respectively).

CONCLUSION

Initial EEG background amplitude is prognostic in paediatric non-traumatic coma. Clinical observations do not detect two out of three seizures. Seizures and status epilepticus after admission are associated with poor outcome.

Endoscopic third ventriculostomy in the treatment of childhood hydrocephalus: validation of a success score that predicts long-term outcome

OBJECT

The goal of this study was to externally validate the proposed Endoscopic Third Ventriculostomy Success Score (ETVSS), which predicts successful treatment for hydrocephalus on the basis of a child's individual characteristics.

METHODS

The authors retrospectively identified 181 cases of consecutive endoscopic third ventriculostomy (ETV) performed in children at a single neurosurgery center in the United Kingdom. They compared actual success at both 6 and 36 months, with mean predicted probabilities for low, moderate, and high chance of success strata based on the ETVSS. Long-term success was calculated using Kaplan-Meier methods and comparisons were made by means of unpaired t-tests.

RESULTS

Overall, 166 primary ETVs were performed; ETV success was 72.9% at 6 and 64.5% at 36 months. At long-term follow-up, the mean predicted probability of success was significantly higher in those with a successful ETV (99 patients) than in those with a failed ETV (67 patients) (p = 0.001). The ETVSS accurately predicted outcome at 36 months; the low, medium, and high chance of success strata had mean predicted probabilities of success of 82%, 63%, and 36%, and actual success of 76%, 66%, and 42%, respectively. The overall complication rate was 6%.

CONCLUSIONS

The ETVSS closely predicted the overall long-term success rates in high-, moderate-, and low-risk groups. The results of this study suggest that the ETVSS will aid clinical decision making in predicting outcome of ETV.

Very good inter-rater reliability of Engel and ILAE epilepsy surgery outcome classifications in a series of 76 patients

The inter-rater reliability, expressed as kappa score, k, of the Engel and International League Against Epilepsy (ILAE) classifications of epilepsy surgery seizure outcome has not previously been evaluated. In a consecutive series of 76 patients (40 male; 25 children), 75 undergoing resective and 1 disconnective surgery at a mean age of 27.5 years (13 months-62 years), one observer classified 88% (n=67) and a second observer classified 87% (n=66) of patients as either Engel I or II (free from or rare disabling seizures) after a median follow up of 36 months (range 12-92 months); comparably, both observers classified 84% (n=64) as ILAE 1-3. Correlation for Engel versus ILAE for observer 1 was 0.933 (p<.0005) and for observer 2 was 0.931 (p<.0005). Both ILAE (k 0.81, 95% confidence intervals 0.69, 0.91) and Engel (k 0.77, 95% CI 0.65, 0.87) classifications have very acceptable inter-rater reliability as well as significant correlation.

Movement disorder emergencies in childhood

The literature on paediatric acute-onset movement disorders is scattered. In a prospective cohort of 52 children (21 male; age range 2mo-15y), the commonest were chorea, dystonia, tremor, myoclonus, and Parkinsonism in descending order of frequency. In this series of mainly previously well children with cryptogenic acute movement disorders, three groups were recognised: (1) Psychogenic disorders (n = 12), typically >10 years of age, more likely to be female and to have tremor and myoclonus (2) Inflammatory or autoimmune disorders (n = 22), including N-methyl-d-aspartate receptor encephalitis, opsoclonus-myoclonus, Sydenham chorea, systemic lupus erythematosus, acute necrotizing encephalopathy (which may be autosomal dominant), and other encephalitides and (3) Non-inflammatory disorders (n = 18), including drug-induced movement disorder, post-pump chorea, metabolic, e.g. glutaric aciduria, and vascular disease, e.g. moyamoya. Other important non-inflammatory movement disorders, typically seen in symptomatic children with underlying aetiologies such as trauma, severe cerebral palsy, epileptic encephalopathy, Down syndrome and Rett syndrome, include dystonic posturing secondary to gastro-oesophageal reflux (Sandifer syndrome) and Paroxysmal Autonomic Instability with Dystonia (PAID) or autonomic 'storming'. Status dystonicus may present in children with known extrapyramidal disorders, such as cerebral palsy or during changes in management e.g. introduction or withdrawal of neuroleptic drugs or failure of intrathecal baclofen infusion; the main risk in terms of mortality is renal failure from rhabdomyolysis. Although the evidence base is weak, as many of the inflammatory/autoimmune conditions are treatable with steroids, immunoglobulin, plasmapheresis, or cyclophosphamide, it is important to make an early diagnosis where possible. Outcome in survivors is variable. Using illustrative case histories, this review draws attention to the practical difficulties in diagnosis and management of this important group of patients.

Changing patterns of neuropsychological functioning in children living at high altitude above and below 4000 m: a report from the Bolivian Children Living at Altitude (BoCLA) study

The brain is highly sensitive to environmental hypoxia. Little is known, however, about the neuropsychological effects of high altitude residence in the developing brain. We recently described only minor changes in processing speed in native Bolivian children and adolescents living at approximately 3700 m. However, evidence for loss of cerebral autoregulation above this altitude (4000 m) suggests a potential threshold of hypoxia severity over which neuropsychological functioning may be compromised. We conducted physiological and neuropsychological assessments in 62 Bolivian children and adolescents living at La Paz (∼3700 m) and El Alto (∼4100 m) in order to address this issue. Groups were equivalent in terms of age, gender, social class, schooling, parental education and genetic admixture. Apart from percentage of hemoglobin saturated with oxygen in arterial blood (%SpO(2)), participants did not differ in their basal cardiac and cerebrovascular performance as explored by heart rate, mean arterial pressure, end-tidal carbon dioxide, and cerebral blood flow velocity at the basilar, anterior, middle and posterior cerebral arteries. A comprehensive neuropsychological assessment was administered, including tests of executive functions, attention, memory and psychomotor performance. Participants living at extreme altitude showed lower levels of performance in all executive tests (Cohen effect size = -0.91), whereas all other domains remained unaffected by altitude of residence. These results are compatible with earlier physiological evidence of a transitional zone for cerebral autoregulation at an altitude of 4000 m. We now show that above this threshold, the developing brain is apparently increasingly vulnerable to neuropsychological deficit.

Hypertension impairs vascular reactivity in the pediatric brain

BACKGROUND AND PURPOSE

Chronic hypertension impairs cerebrovascular regulation in adults, but its effects on the pediatric population are unknown. The objective of this study was to investigate cerebrovascular abnormalities in hypertensive children and adolescents.

METHODS

Sixty-four children and adolescents aged 7 to 20 years underwent transcranial Doppler examinations of the middle cerebral artery at the time of rebreathing CO2. Time-averaged maximum mean cerebral blood flow velocity and end-tidal CO2 were used to quantify cerebrovascular reactivity during hypercapnia. Patients were clinically categorized as hypertensive, prehypertensive, or white coat hypertensive based on 24-hour ambulatory blood pressure measurements. Their reactivities were compared with 9 normotensive control subjects and evaluated against baseline mean blood pressure z-scores and loads.

RESULTS

Untreated hypertensive children had significantly lower hypercapnic reactivity than normotensive children (2.556 +/- 1.832 cm/s x mm Hg versus 4.256 +/- 1.334 cm/s x mm Hg, P < 0.05). Baseline mean diastolic blood pressure z-scores (r = -0.331, P = 0.037) and diastolic blood pressure loads (r = -0.351, P = 0.026) were inversely related to reactivity.

CONCLUSIONS

Untreated hypertensive children and adolescents have blunted reactivity to hypercapnia, indicating deranged vasodilatory reactivity. The inverse relationship between diastolic blood pressure indices and reactivity suggests that diastolic blood pressure may be a better predictor of cerebral end organ damage than systolic blood pressure.

Nocturnal haemoglobin oxygen saturation variability is associated with vitamin C deficiency in Tanzanian children with sickle cell anaemia

Aim

To compare pulse oximetry in children with sickle cell anaemia (SCA) and controls and test the hypothesis that vitamin C deficiency (VCD; <11.4 μmol/L) is associated with nocturnal haemoglobin oxygen desaturation in SCA.

Methods

We undertook nocturnal and daytime pulse oximetry in 23 children with SCA (median age 8 years) with known steady-state plasma vitamin C concentrations and 18 siblings (median 7 years).

Results

Median nocturnal delta 12 s index (delta12 s), a measure of haemoglobin oxygen saturation (SpO₂) variability, was 0.38 (interquartile range 0.28–0.51) in SCA and 0.35 (0.23–0.48) in controls, with 9/23 and 6/18, respectively, having a delta12 s >0.4, compatible with obstructive sleep apnoea (OSA). Eleven of twenty-three with SCA had VCD; logged vitamin C concentrations showed a 66% decrease per 0.1 unit increase in delta12 s ([95% CI −86%, −15%]; p = 0.023) and delta12 s >0.4 was associated with VCD (odds ratio 8.75 [1.24–61.7], p = 0.029). Daytime and mean nocturnal SpO₂ were lower in SCA but there was no association with vitamin C.

Conclusion

Obstructive sleep apnoea (OSA), detected from nocturnal haemoglobin oxygen saturation variability, is common in Tanzanian children and associated with vitamin C Deficiency in SCA. The direction of causality could be determined by comparing OSA treatment with vitamin C supplementation.

Cerebral venous sinus (sinovenous) thrombosis in children

Cerebral venous sinus (sinovenous) thrombosis (CSVT) in childhood is a rare, but underrecognized, disorder, typically of multifactorial etiology, with neurologic sequelae apparent in up to 40% of survivors and mortality approaching 10%. There is an expanding spectrum of perinatal brain injury associated with neonatal CSVT. Although there is considerable overlap in risk factors for CSVT in neonates and older infants and children, specific differences exist between the groups. Clinical symptoms are frequently nonspecific, which may obscure the diagnosis and delay treatment. While morbidity and mortality are significant, CSVT recurs less commonly than arterial ischemic stroke in children. Appropriate management may reduce the risk of recurrence and improve outcome, however there are no randomized controlled trials to support the use of anticoagulation in children. Although commonly employed in many centers, this practice remains controversial, highlighting the continued need for high-quality studies. This article reviews the literature pertaining to pediatric venous sinus thrombosis.

Outcome following decompressive craniectomy for malignant middle cerebral artery infarction in children

AIM

Mortality from malignant middle cerebral artery infarction (MMCAI) approaches 80% in adult series. Although decompressive craniectomy decreases mortality and leads to an acceptable outcome in selected adult patients, there are few data on MMCAI in children with stroke. This study evaluated the frequency of MMCAI and the use of decompressive craniectomy in children.

METHOD

We retrospectively reviewed cases of MMCAI from five pediatric tertiary care centers.

RESULTS

Ten children (two females, eight males; median age 9y 10mo, range 22mo-14y) had MMCAI, with a median Glasgow Coma Scale score of 6 (range 3-9). MMCAI represented fewer than 2% of cases of pediatric arterial ischemic stroke. Three patients who did not undergo decompression, all of whom had monitoring of intracranial pressure, developed intractable intracranial hypertension, and fulfilled criteria for brain death. In contrast, seven patients underwent decompressive craniectomy and survived, with rapid improvement in their level of consciousness postoperatively. All seven survivors now walk independently with mild to moderate residual hemiparesis and speak fluently, even though four had left-sided infarcts.

INTERPRETATION

Decompressive craniectomy can lead to a moderately good outcome for children with MMCAI and should be considered, even with symptomatic stroke and deep coma. Monitoring of intracranial pressure may delay life-saving treatment.

Airway hyperresponsiveness in children with sickle cell anemia

BACKGROUND

The high prevalence of airway hyperresponsiveness (AHR) among children with sickle cell anemia (SCA) remains unexplained.

METHODS

To determine the relationship between AHR, features of asthma, and clinical characteristics of SCA, we conducted a multicenter, prospective cohort study of children with SCA. Dose response slope (DRS) was calculated to describe methacholine responsiveness, because 30% of participants did not achieve a 20% decrease in FEV1 after inhalation of the highest methacholine concentration, 25 mg/mL. Multiple linear regression analysis was done to identify independent predictors of DRS.

RESULTS

Methacholine challenge was performed in 99 children with SCA aged 5.6 to 19.9 years (median, 12.8 years). Fifty-four (55%) children had a provocative concentration of methacholine producing a 20% decrease in FEV1<4 mg/mL. In a multivariate analysis, independent associations were found between increased methacholine responsiveness and age (P<.001), IgE (P=.009), and lactate dehydrogenase (LDH) levels (P=.005). There was no association between methacholine responsiveness and a parent report of a doctor diagnosis of asthma (P=.986). Other characteristics of asthma were not associated with methacholine responsiveness, including positive skin tests to aeroallergens, exhaled nitric oxide, peripheral blood eosinophil count, and pulmonary function measures indicating airflow obstruction.

CONCLUSIONS

In children with SCA, AHR to methacholine is prevalent. Younger age, serum IgE concentration, and LDH level, a marker of hemolysis, are associated with AHR. With the exception of serum IgE, no signs or symptoms of an allergic diathesis are associated with AHR. Although the relationship between methacholine responsiveness and LDH suggests that factors related to SCA may contribute to AHR, these results will need to be validated in future studies.

Stroke and cerebrovascular disorders

PURPOSE OF REVIEW

Stroke and cerebrovascular disorders in childhood are a cause for significant morbidity in childhood. There is growing emphasis on understanding the mechanisms of stroke so as to inform developments in investigation and management.

RECENT FINDINGS

Advances have been made in the classification of pediatric stroke, aided by clinical and radiological recognition of patterns of injury and differential outcomes dependent on timing of stroke occurrence. Risk factors are multifactorial, with evidence of geographical and national variation. Causality, however, remains difficult to prove. Recent studies highlight a significant association between stroke recurrence and outcome and the presence of steno-occlusive arterial disease, Moyamoya disease and progressive arteriopathy. Focal arteriopathy of childhood is a new term proposed to refine the nomenclature of childhood arteriopathy. The association between infection and childhood stroke is increasingly recognized, with associations with sinovenous thrombosis and childhood arteriopathy. The recommendation to screen for arteriopathy in genetic conditions such as sickle cell disease is now extended to include children with neurofibromatosis type 1. Perfusion and magnetic resonance wall imaging have helped in the determination of the cause of stroke with impact on management in adults. Two new treatment guidelines have been published (American Heart Association and Chest), but barriers remain to the use of thrombolysis in childhood stroke.

SUMMARY

Continued developments in understanding and practice in childhood stroke are encouraging. However, the absence of clinical trials and evidence-based guidelines is limiting. The conduct of such trials is a goal towards which the International Pediatric Stroke Study is moving.

Auto-adjusting positive airway pressure in children with sickle cell anemia: results of a phase I randomized controlled trial

Low nocturnal oxygen saturation (SpO(2)) is implicated in complications of Sickle Cell Anemia (SCA). Twenty-four children with SCA were randomized to receive overnight auto-adjusting continuous positive airway pressure (auto-CPAP) with supplemental oxygen, if required, to maintain SpO(2) >or=94% or as controls. We assessed adherence, safety, sleep parameters, cognition and pain. Twelve participants randomized to auto-CPAP (3 with oxygen) showed improvement in Apnea/Hypopnea Index (p<0.001), average desaturation events >3%/hour (p=0.02), mean nocturnal SpO(2) (p=0.02) and cognition. Primary efficacy endpoint (Processing Speed Index) showed no group differences (p=0.67), but a second measure of processing speed and attention (Cancellation) improved in those receiving treatment (p=0.01). No bone marrow suppression, rebound pain or serious adverse event resulting from auto-CPAP use was observed. Six weeks of auto-CPAP therapy is feasible and safe in children with SCA, significantly improving sleep-related breathing disorders and at least one aspect of cognition.

Growth monitoring following traumatic brain injury

Hypopituitarism is an important consequence of traumatic brain injury (TBI). Growth monitoring can be used as an indicator of pituitary function in children. A retrospective audit of case notes of 123 children who required intensive care unit admission with TBI found that only 71 (33%) of 212 attendances in 38 of 85 children followed up had documented height and weight measurements. Children were reviewed in 11 different specialty clinics, which showed a wide variation in the frequency of growth monitoring. Serial growth measurements were available for only 22 patients (17%), which showed a reduction in height standard deviation scores (0.17 (SD 0.33), p = 0.017) over a mean follow-up period of 25.2 (SD 21.6) months. In conclusion, growth monitoring following TBI was poorly performed in this cohort, highlighting the need for a co-ordinated approach by primary and secondary care and all departments in tertiary centres involved in the follow-up of children with TBI.