Adrenal Vein Sampling: Tips and Tricks.

Adrenal vein sampling (AVS) is the standard method for distinguishing unilateral from bilateral sources of autonomous aldosterone production in patients with primary aldosteronism. This procedure has been performed at limited specialized centers due to its technical complexity. With recent advances in imaging technology and knowledge of adrenal vein anatomy in parallel with the development of adjunctive techniques, AVS has become easier to perform, even at nonspecialized centers. Although rare, anatomic variants of the adrenal veins can cause sampling failure or misinterpretation of the sampling results. The inferior accessory hepatic vein and the inferior emissary vein are useful anatomic landmarks for right adrenal vein cannulation, which is the most difficult and crucial step in AVS. Meticulous assessment of adrenal vein anatomy on multidetector CT images and the use of a catheter suitable for the anatomy are crucial for adrenal vein cannulation. Adjunctive techniques such as intraprocedural cortisol assay, cone-beam CT, and coaxial guidewire-catheter techniques are useful tools to confirm right adrenal vein cannulation or to troubleshoot difficult blood sampling. Interventional radiologists should be involved in interpreting the sampling results because technical factors may affect the results. In rare instances, bilateral adrenal suppression, in which aldosterone-to-cortisol ratios of both adrenal glands are lower than that of the inferior vena cava, can be encountered. Repeat sampling may be necessary in this situation. Collaboration with endocrinology and laboratory medicine services is of great importance to optimize the quality of the samples and for smooth and successful operation. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Modulation index predicts the effect of ethosuximide on developmental and epileptic encephalopathy with spike-and-wave activation in sleep.

PURPOSE: In developmental and epileptic encephalopathy with spike-and-wave activation in sleep (DEE-SWAS), the thalamocortical network is suggested to play an important role in the pathophysiology of the progression from focal epilepsy to DEE-SWAS. Ethosuximide (ESM) exerts effects by blocking T-type calcium channels in thalamic neurons. With the thalamocortical network in mind, we studied the prediction of ESM effectiveness in DEE-SWAS treatment using phase-amplitude coupling (PAC) analysis. METHODS: We retrospectively enrolled children with DEE-SWAS who had an electroencephalogram (EEG) recorded between January 2009 and September 2022 and were prescribed ESM at Okayama University Hospital. Only patients whose EEG showed continuous spike-and-wave during sleep were included. We extracted 5-min non-rapid eye movement sleep stage N2 segments from EEG recorded before starting ESM. We calculated the modulation index (MI) as the measure of PAC in pair combination comprising one of two fast oscillation types (gamma, 40-80 Hz; ripples, 80-150 Hz) and one of five slow-wave bands (delta, 0.5-1, 1-2, 2-3, and 3-4 Hz; theta, 4-8 Hz), and compared it between ESM responders and non-responders. RESULTS: We identified 20 children with a diagnosis of DEE-SWAS who took ESM. Fifteen were ESM responders. Regarding gamma oscillations, significant differences were seen only in MI with 0.5-1 Hz slow waves in the frontal pole and occipital regions. Regarding ripples, ESM responders had significantly higher MI in coupling with all slow waves in the frontal pole region, 0.5-1, 3-4, and 4-8 Hz slow waves in the frontal region, 3-4 Hz slow waves in the parietal region, 0.5-1, 2-3, 3-4, and 4-8 Hz slow waves in the occipital region, and 3-4 Hz slow waves in the anterior-temporal region. SIGNIFICANCE: High MI in a wider area of the brain may represent the epileptic network mediated by the thalamus in DEE-SWAS and may be a predictor of ESM effectiveness.

Exploration of urine metabolic biomarkers for new-onset, untreated pediatric epilepsy: A gas and liquid chromatography mass spectrometry-based metabolomics study.

OBJECTIVE: The discovery of objective indicators for recent epileptic seizures will help confirm the diagnosis of epilepsy and evaluate therapeutic effects. Past studies had shortcomings such as the inclusion of patients under treatment and those with various etiologies that could confound the analysis results significantly. We aimed to minimize such confounding effects and to explore the small molecule biomarkers associated with the recent occurrence of epileptic seizures using urine metabolomics. METHODS: This is a multicenter prospective study. Subjects included pediatric patients aged 2 to 12 years old with new-onset, untreated epilepsy, who had had the last seizure within 1 month before urine collection. Controls included healthy children aged 2 to 12 years old. Those with underlying or chronic diseases, acute illnesses, or recent administration of medications or supplements were excluded. Targeted metabolome analysis of spot urine samples was conducted using gas chromatography (GC)- and liquid chromatography (LC)-tandem mass spectrometry (MS/MS). RESULTS: We enrolled 17 patients and 21 controls. Among 172 metabolites measured by GC/MS/MS and 41 metabolites measured by LC/MS/MS, only taurine was consistently reduced in the epilepsy group. This finding was subsequently confirmed by the absolute quantification of amino acids. No other metabolites were consistently altered between the two groups. CONCLUSIONS: Urine metabolome analysis, which covers a larger number of metabolites than conventional biochemistry analyses, found no consistently altered small molecule metabolites except for reduced taurine in epilepsy patients compared to healthy controls. Further studies with larger samples, subjects with different ages, expanded target metabolites, and the investigation of plasma samples are required.

Comparison of Infection Rates between Single-Lumen and Double-Lumen Chest Ports among Patients with Cancer: A Propensity Score Matching Analysis.

PURPOSE: To compare the port infection rate between single-lumen (SL) and double-lumen (DL) ports and to determine whether the use of a DL port is an independent risk factor for port infection among patients with cancer. MATERIALS AND METHODS: This retrospective study included 2,573 adult oncologic patients (aged >18 years) who had either a SL (n = 841) or a DL (n = 1,732) chest port implanted between 2013 and 2020 at a single institution. Patients who had port infection, including port-site infection and port-related bloodstream infection, were identified through chart review. After propensity score matching based on 13 potentially confounding variables, a total of 493 pairs of patients with either SL (SL group) or DL (DL group) ports were subjected to analysis. The port infection rate was compared between the 2 groups using Poisson regression. Multivariate proportional subdistribution hazards regression (PSHREG) analysis was conducted to determine whether use of a DL port is an independent risk factor for port infection. RESULTS: The cumulative follow-up period for the matched cohort was 371,853 catheter-days (median, 297 catheter-days per port; range, 0-1,903 catheter-days). The port infection rate of the DL group was significantly higher than that of the SL group (0.232 vs 0.113 infections per 1,000 catheter-days; P = .001). PSHREG analysis demonstrated that use of a DL port was an independent risk factor of port infection (subdistribution hazard ratio, 2.30; 95% CI, 1.33-3.78; P = .002). CONCLUSIONS: DL ports were associated with a higher risk of port infection compared with SL ports in adult oncologic patients.

Effective Epilepsy Surgery for Post-Traumatic West Syndrome Following Abusive Head Trauma.

West syndrome, an infantile developmental and epileptic encephalopathy with a deleterious impact on long-term development, requires early treatment to minimize developmental abnormality; in such cases, epilepsy surgery should be considered a powerful therapeutic option. We describe a 10-month-old female admitted with West syndrome associated with a hemispheric lesion following abusive head trauma. Her seizures were suppressed by hemispherotomy at 12 months of age, leading to developmental improvement. Surgical treatment of West syndrome following traumatic brain injury has not been reported previously but is worth considering as a treatment option, depending on patient age and brain plasticity.

Epilepsy in Children With Congenital Heart Disease: Risk Factors and Characteristic Presentations.

BACKGROUND: Children with a congenital heart disease (CHD) are at a higher risk of developing epilepsy than the general population, but detailed characteristics of CHD-associated epilepsy have not been clarified. The purposes of this study were to determine the risk factors for developing epilepsy associated with CHD and to elucidate the characteristics of such epilepsy. METHODS: We performed a retrospective cohort study based on medical records of pediatric patients with CHD who were born between January 2006 and December 2016, underwent cardiac surgery at Okayama University Hospital, and were followed up until at least age three years. Multivariate logistic regression analysis was used to determine factors particularly associated with epilepsy occurrence. In patients who developed epilepsy, clinical data on seizure characteristics were further investigated. RESULTS: We collected data from 1024 patients, and 41 (4.0%) developed epilepsy. The presence of underlying disease (odds ratio [OR]: 2.413; 95% confidence interval [CI]: 1.150 to 4.883) and the Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery score category 2 (OR: 4.373; 95% CI: 1.090 to 29.150) and category 5 (OR: 10.385; 95% CI: 1.717 to 89.016) were significantly related to epilepsy occurrence. Of the 41 patients with epilepsy, 15 (including nine with hypoplastic left heart syndrome) had focal impaired awareness seizures specified as autonomic seizures with vomiting, which tends to escape detection. CONCLUSIONS: We clarified the risk factors for developing epilepsy in children with CHD. We also found that autonomic seizure with vomiting is an important symptom in these children.

A female patient with adolescent-onset progressive myoclonus epilepsy carrying a truncating MECP2 mutation.

BACKGROUND: MECP2 is a well-known causative gene for Rett syndrome but other phenotypes have also been reported. Here, we report a case of a female patient with adolescent-onset progressive myoclonus epilepsy (PME) carrying a novel truncating mutation in the MECP2 gene. CASE REPORT: The patient was a 29-year-old woman with infantile-onset intellectual disability of unspecified cause. She had demonstrated slow but steady development with moderate intellectual disability until the age of 16, when she started having epileptic seizures. Her epilepsy progressed intractably with multiple seizure types accompanied by myoclonus, tremor, and gradual regression. She is currently apathetic and requires extensive assistance in all aspects of life. After an extensive work-up for underlying diseases for PME turned out negative, whole-exome sequencing revealed a de novo 113-bp deletion and 3-bp insertion in MECP2, a variant of NM_004992.4:c.1099_1211delinsGGG, p.(His367Glyfs*32). CONCLUSIONS: The clinical presentation of this case was inconsistent with Rett syndrome, and the rapid regression in the patient's twenties was considered characteristic. Mutations of MECP2 may result in variable neurodevelopmental phenotypes and may also be considered a causative gene for adolescent-onset PME.

Comprehensive study of metabolic changes induced by a ketogenic diet therapy using GC/MS- and LC/MS-based metabolomics.

OBJECTIVE: The ketogenic diet (KD), a high-fat and low-carbohydrate diet, is effective for a subset of patients with drug-resistant epilepsy, although the mechanisms of the KD have not been fully elucidated. The aims of this observational study were to investigate comprehensive short-term metabolic changes induced by the KD and to explore candidate metabolites or pathways for potential new therapeutic targets. METHODS: Subjects included patients with intractable epilepsy who had undergone the KD therapy (the medium-chain triglyceride [MCT] KD or the modified Atkins diet using MCT oil). Plasma and urine samples were obtained before and at 2-4 weeks after initiation of the KD. Targeted metabolome analyses of these samples were performed using gas chromatography-tandem mass spectrometry (GC/MS/MS) and liquid chromatography-tandem mass spectrometry (LC/MS/MS). RESULTS: Samples from 10 and 11 patients were analysed using GC/MS/MS and LC/MS/MS, respectively. The KD increased ketone bodies, various fatty acids, lipids, and their conjugates. In addition, levels of metabolites located upstream of acetyl-CoA and propionyl-CoA, including catabolites of branched-chain amino acids and structural analogues of γ-aminobutyric acid and lactic acid, were elevated. CONCLUSIONS: The metabolites that were significantly changed after the initiation of the KD and related metabolites may be candidates for further studies for neuronal actions to develop new anti-seizure medications.

Routine and sleep EEG: Minimum recording standards of the International Federation of Clinical Neurophysiology and the International League Against Epilepsy.

This article provides recommendations on the minimum standards for recording routine ("standard") and sleep electroencephalography (EEG). The joint working group of the International Federation of Clinical Neurophysiology (IFCN) and the International League Against Epilepsy (ILAE) developed the standards according to the methodology suggested for epilepsy-related clinical practice guidelines by the Epilepsy Guidelines Working Group. We reviewed the published evidence using the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement. The quality of evidence for sleep induction methods was assessed by the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) method. A tool for Quality Assessment of Diagnostic Studies (QUADAS-2) was used to assess the risk of bias in technical and methodological studies. Where high-quality published evidence was lacking, we used modified Delphi technique to reach expert consensus. The GRADE system was used to formulate the recommendations. The quality of evidence was low or moderate. We formulated 16 consensus-based recommendations for minimum standards for recording routine and sleep EEG. The recommendations comprise the following aspects: indications, technical standards, recording duration, sleep induction, and provocative methods.

Routine and sleep EEG: Minimum recording standards of the International Federation of Clinical Neurophysiology and the International League Against Epilepsy.

This article provides recommendations on the minimum standards for recording routine ("standard") and sleep electroencephalography (EEG). The joint working group of the International Federation of Clinical Neurophysiology (IFCN) and the International League Against Epilepsy (ILAE) developed the standards according to the methodology suggested for epilepsy-related clinical practice guidelines by the Epilepsy Guidelines Working Group. We reviewed the published evidence using the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement. The quality of evidence for sleep induction methods was assessed by the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) method. A tool for Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) was used to assess the risk of bias in technical and methodological studies. Where high-quality published evidence was lacking, we used modified Delphi technique to reach expert consensus. The GRADE system was used to formulate the recommendations. The quality of evidence was low or moderate. We formulated 16 consensus-based recommendations for minimum standards for recording routine and sleep EEG. The recommendations comprise the following aspects: indications, technical standards, recording duration, sleep induction, and provocative methods.

Artificial Intelligence-based Detection of Epileptic Discharges from Pediatric Scalp Electroencephalograms: A Pilot Study.

We developed an artificial intelligence (AI) technique to identify epileptic discharges (spikes) in pediatric scalp electroencephalograms (EEGs). We built a convolutional neural network (CNN) model to automatically classify steep potential images into spikes and background activity. For the CNN model' training and validation, we examined 100 children with spikes in EEGs and another 100 without spikes. A different group of 20 children with spikes and 20 without spikes were the actual test subjects. All subjects were ≥ 3 to < 18 years old. The accuracy, sensitivity, and specificity of the analysis were >0.97 when referential and combination EEG montages were used, and < 0.97 with a bipolar montage. The correct classification of background activity in individual patients was significantly better with a referential montage than with a bipolar montage (p=0.0107). Receiver operating characteristic curves yielded an area under the curve > 0.99, indicating high performance of the classification method. EEG patterns that interfered with correct classification included vertex sharp transients, sleep spindles, alpha rhythm, and low-amplitude ill-formed spikes in a run. Our results demonstrate that AI is a promising tool for automatically interpreting pediatric EEGs. Some avenues for improving the technique were also indicated by our findings.

Folic acid inhibits 5-methyltetrahydrofolate transport across the blood-cerebrospinal fluid barrier: Clinical biochemical data from two cases.

Objective: The use of folic acid (FA) has been discouraged in cerebral folate deficiency (CFD) because, theoretically, it could inhibit the transport of 5-methyltetrahydrofolic acid (5MTHF) across the blood-cerebrospinal fluid (CSF) barrier. We present the clinical biochemical data of two cases with CFD to support this hypothesis. Methods: We measured CSF and serum 5MTHF concentrations in a patient with Kearns-Sayre syndrome (KSS) and a patient homozygous for MTHFR C677T polymorphism before and during folate supplementation therapy. To evaluate these 5MTHF concentrations, we also analyzed CSF and serum samples in pediatric patients without folate supplementation. Results: Both patients had low CSF 5MTHF before treatment and high-dose FA therapy did not normalize CSF 5MTHF. There was a dissociation between serum total folate and 5MTHF concentrations during FA therapy, which was considered to be due to the appearance of unmetabolized FA. The addition of folinic acid did not improve low CSF 5MTHF in the KSS patient and the cessation of FA resulted in the normalization of CSF 5MTHF. In the patient homozygous for MTHFR C677T, minimization of the FA dosage resulted in the normalization of CSF 5MTHF and an increased CSF-to-serum 5MTHF ratio. Conclusions: Our data suggest that excess supplementation of FA impaired 5MTHF transport across the blood-CSF barrier. In the treatment of CFD, supplementation of folinic acid or 5MTHF (in cases of impaired 5MTHF synthesis) is preferred over the use of FA. The reference values of CSF 5MTHF concentration based on 600 pediatric cases were also provided.

Simultaneous assay of urine sepiapterin and creatinine in patients with sepiapterin reductase deficiency.

OBJECTIVES: Sepiapterin reductase deficiency (SRD) causes central nervous system symptoms due to dopamine and serotonin depletion because sepiapterin reductase plays an important role in tetrahydrobiopterin biosynthesis. SRD cannot be detected by newborn screening because of the absent hyperphenylalaninemia. To diagnose SRD biochemically, confirmation of reduced monoamine metabolites and elevated sepiapterin in the cerebrospinal fluid (CSF) has been considered necessary, because a past study showed no elevation of urine sepiapterin. Recently, however, the elevation of urine sepiapterin in SRD was reported. METHODS: We developed a fast method to measure sepiapterin and creatinine simultaneously using high-performance liquid chromatography with fluorescence and ultraviolet detection. Urine sepiapterin and creatinine were measured in three SRD patients, two SRD carriers, four SRD siblings, and 103 non-SRD patients. RESULTS: In the three SRD cases, concentrations of urine sepiapterin were 1086, 914, and 575 µmol/mol creatinine (upper limit: 101.7 µmol/mol creatinine), and were markedly higher than those in other groups. CSF sepiapterin concentration was also measured in one SRD case and it was 4.1 nmol/L (upper limit: 0.5 nmol/L). CONCLUSIONS: The simultaneous determination of urine sepiapterin and creatinine appears helpful for the diagnosis of SRD. This assay system can also be used to measure sepiapterin in the CSF.

A Case of a Solitary Cortical Tuber with No Other Manifestations of Tuberous Sclerosis Complex Mimicking Focal Cortical Dysplasia Type II with Calcification.

Cortical tubers are one of the typical intracranial manifestations of tuberous sclerosis complex (TSC). Multiple cortical tubers are easy to diagnose as TSC; however, a solitary cortical tuber without any other cutaneous or visceral organ manifestations can be confused with other conditions, particularly focal cortical dysplasia. We report a surgical case of refractory epilepsy caused by a solitary cortical tuber mimicking focal cortical dysplasia type II, and describe the radiological, electrophysiological, and histopathological findings of our case.

High-frequency oscillations in scalp EEG: A systematic review of methodological choices and clinical findings.

OBJECTIVE: Pathological high-frequency oscillations (HFOs) in intracranial EEG are promising biomarkers of epileptogenic tissue, and their physiological counterparts play a role in sensorimotor and cognitive function. HFOs have also been found in scalp EEG, but an overview of all studies is lacking. In this systematic review, we assessed the methodology to detect scalp HFOs and their clinical potential. METHODS: We searched PubMed, Embase and the Cochrane Library for studies on HFOs in scalp EEG, and extracted methodological and clinical data. RESULTS: We included 60 studies with data from 1149 unique individuals. Two-thirds of studies analyzed HFOs visually in the time or time-frequency domain, and one-third automatically with visual validation. Most studies evaluated interictal ripples during sleep in children. Pathological HFOs were overall better than spikes in localizing the epileptogenic zone and predicting outcome, correlated negatively with cognition and positively with disease activity and severity, and decreased after medical and surgical treatment. CONCLUSIONS: The methodologies of the 60 studies were heterogeneous, but pathological scalp HFOs were clinically valuable as biomarkers in various situations, particularly in children with epilepsy. SIGNIFICANCE: This systematic review gives an extensive overview of methodological and clinical data on scalp HFOs, establishing their clinical potential and discussing their limitations.

Burden of seizures and comorbidities in patients with epilepsy: a survey based on the tertiary hospital-based Epilepsy Syndrome Registry in Japan.

OBJECTIVE: To examine the current medical and psychosocial status of patients with epilepsy, aiming to facilitate appropriate application of the Intractable/Rare Diseases Act of Japan. METHODS: By analysing the cross-sectional data of patients registered in the tertiary hospital-based Epilepsy Syndrome Registry of Japan, we investigated the proportion of patients who met the severity criteria as defined by the Act (seizure frequency of at least once a month, or presence of intellectual/neurological/psychiatric symptoms, or both) and whether there are candidate syndrome/diseases to be added to the existing list in the Act. RESULTS: In total, 2,209 patients were registered. After excluding self-limited/idiopathic epilepsies, 1,851 of 2,110 patients (87.7%) met the severity criteria. The patients were classified into eight main epilepsy syndromes (594 patients), 20 groups based on aetiology (1,078 patients), and three groups without known aetiology (427 patients). Most of the groups classified by syndrome or aetiology had high proportions of patients satisfying the severity criteria (>90%), but some groups had relatively low proportions (<80%) resulting from favourable outcome of surgical therapy. Several small groups with known syndrome/aetiology await detailed analysis based on a sufficiently large enough number of patients registered, some of whom may potentially be added to the list of the Act. SIGNIFICANCE: The registry provides data to examine the usefulness of the severity criteria and list of diseases that are operationally defined by the Act. Most epilepsy patients with various syndromes/diseases and aetiology groups are covered by the Act but some are not, and the list of designated syndromes/diseases should be complemented by further amendments, as suggested by future research.

Case Report: High-Gamma Oscillations on an Ictal Electroencephalogram in a Newborn Patient With Hypoxic-Ischemic Encephalopathy.

Fast oscillations (FOs) >40 Hz in electroencephalograms (EEGs) are associated with ictogenesis and epileptogenesis in adults and children with epilepsy. However, only a few previous studies showed FOs in neonates. Reported frequencies of such neonatal FOs were in the low-gamma (<60 Hz) band and, therefore, they were not high compared to those in pediatric patients. We herein report a newborn patient with severe hypoxic-ischemic encephalopathy (HIE), who showed pathological FOs with a frequency in the high-gamma band. She was born at a gestational age of 39 weeks 4 days by emergency cesarean section because of non-reassuring fetal status. She had focal motor seizures involving unilateral upper and lower limbs lasting for tens of seconds on days 0, 1, 4, 5, 8, and 9 and subclinical seizures on days 4-11. Phenobarbital (PB) was intravenously administered on days 0, 2, 4, 5, and 6. We found FOs that were superimposed on the ictal delta activities using visual inspection and time-frequency analysis on 8-11 days of age. Among them, we detected high-gamma (71.4-100 Hz) oscillations that appeared to be temporally independent of low-gamma activities in the ictal EEG on 11 days of age. To the best of our knowledge, this is one of the earliest reports showing pathological FOs with a frequency of >60 Hz in the high-gamma band in human neonatal seizures, which were previously observed in animal studies. Further studies are needed to elucidate the pathophysiology of ictal FOs in neonatal seizures.

Single-session versus two-session placement of chest port and gastrostomy tube in patients with head and neck cancer: Is there any difference in the device-related early infection rates?

BACKGROUND: It is unknown whether placement of a chest port (port) and a gastrostomy tube (G-tube) in a single session increases the risk of the early device infections in patients with head and neck cancer (HNC) undergoing chemoradiation. PURPOSE: To compare the incidence of early (≤30 days) port and G-tube infections placed in a single session compared to two separate sessions in patients with HNC. MATERIAL AND METHODS: Between January 2012 and December 2019, 169 patients with HNC undergoing chemoradiation had a port and a G-tube placed in a single session (single-session group), while 25 had both devices placed in two separate sessions (two-session group) within 30 days of each other. The incidence of early device infections was compared between groups. Logistic regression analysis was conducted to determine if the number of sessions was a variable affecting device infections. RESULTS: A total of 6 (3%) early port infections and 13 (6.7%) early G-tube infections were identified. The two groups did not significantly differ in the incidence of early port infections (3.0%, 5/169 and 4.0%, 1/25, p = 0.59) nor early G-tube infections (7.1%, 12/169 and 4.0%, 1/25, p = 1.0). The number of sessions for device placement was not a variable affecting overall device infections in logistic regression analyses (odds ratio: 1.24, 95% confidence interval: 0.20-7.82, p = 0.82) after controlling for potential confounding variables. CONCLUSIONS: The risk of early device infections in single-session placement appeared to be the same as two-session placement in patients with HNC undergoing chemoradiation.

Exclusion of the Possibility of "False Ripples" From Ripple Band High-Frequency Oscillations Recorded From Scalp Electroencephalogram in Children With Epilepsy.

AIM: Ripple-band epileptic high-frequency oscillations (HFOs) can be recorded by scalp electroencephalography (EEG), and tend to be associated with epileptic spikes. However, there is a concern that the filtration of steep waveforms such as spikes may cause spurious oscillations or "false ripples." We excluded such possibility from at least some ripples by EEG differentiation, which, in theory, enhances high-frequency signals and does not generate spurious oscillations or ringing. METHODS: The subjects were 50 pediatric patients, and ten consecutive spikes during sleep were selected for each patient. Five hundred spike data segments were initially reviewed by two experienced electroencephalographers using consensus to identify the presence or absence of ripples in the ordinary filtered EEG and an associated spectral blob in time-frequency analysis (Session A). These EEG data were subjected to numerical differentiation (the second derivative was denoted as EEG″). The EEG″ trace of each spike data segment was shown to two other electroencephalographers who judged independently whether there were clear ripple oscillations or uncertain ripple oscillations or an absence of oscillations (Session B). RESULTS: In Session A, ripples were identified in 57 spike data segments (Group A-R), but not in the other 443 data segments (Group A-N). In Session B, both reviewers identified clear ripples (strict criterion) in 11 spike data segments, all of which were in Group A-R (p < 0.0001 by Fisher's exact test). When the extended criterion that included clear and/or uncertain ripples was used in Session B, both reviewers identified 25 spike data segments that fulfilled the criterion: 24 of these were in Group A-R (p < 0.0001). DISCUSSION: We have demonstrated that real ripples over scalp spikes exist in a certain proportion of patients. Ripples that were visualized consistently using both ordinary filters and the EEG″ method should be true, but failure to clarify ripples using the EEG″ method does not mean that true ripples are absent. CONCLUSION: The numerical differentiation of EEG data provides convincing evidence that HFOs were detected in terms of the presence of such unusually fast oscillations over the scalp and the importance of this electrophysiological phenomenon.