Electroencephalography Patterns in Children with First Unprovoked Seizure

First unprovoked seizure (FUS) is a neurological health problem that occurs in an estimated 2% of children aged 16 years or younger. Electroencephalography (EEG) is an electrophysiological technique to record electrical activities arising from the brain; this technique can be used to evaluate patients with suspected seizures, epilepsy, and unusual concomitants. The objective of this study is to describe the EEG patterns in children with FUS and the factors associated with these EEG results. A retrospective analytic study was conducted in the Neuropaediatric Clinic, Dr Soetomo General Academic Hospital. The medical record data were obtained from January 2018 to December 2019. Children aged one month to 18 years with FUS and their complete EEG records were included. Descriptive statistics and the chi-square test with Cochran's Q test and Mantel–Haenszel tests were used for statistical calculations. focal generalized sharp and generalized spikes, years


Introduction
Seizure is one of the most common neurological problems occurring in children. According to the International League Against Epilepsy, the rst seizure in paediatric patients is de ned to include one or more seizures within 24 hours with recovery of consciousness between the seizures. 1 In the latest classi cation, rst unprovoked seizure (FUS) can be considered epilepsy when the risk of recurrent seizures is greater than 60%. 2 Population-based studies of the prevalence of FUS show that there are 25,000 to 40,000 children per year who experience FUS in the United States. 3 Several studies suggest that abnormal electroencephalography (EEG) ndings in FUS are associated with a risk of recurrent seizures. 4 EEG is an important modality for the clinical diagnosis of seizures and epilepsy. Having an EEG examination 30 minutes after FUS is very helpful in identifying the type of seizure that has occurred and determining the risk of recurrence after the rst event. 5 However, there is a long ongoing debate regarding the bene t of EEG examinations in determining whether a seizure will recur. Several studies have reported high abnormal EEG results in children with FUS, and those with abnormal EEG results have a risk of recurrent seizures. 6 One study conducted in Japan showed that seizure recurrence in FUS cases occurred in 16.7% of children whose EEG showed general wave spikes and 61.9% of children with focal epileptic waves (p <0.0001). Thus, an abnormal EEG can be a consistent predictor of recurrent seizure probability. 7 Therefore, this research was conducted to describe the EEG patterns in children with FUS and the factors associated with their EEG results.

Patient and methods
This study used a retrospective research design. As secondary data, medical records were obtained at Dr Soetomo General Academic Hospital, Surabaya, from January 2018 to December 2019. The target population of this study consisted of all seizure patients who had EEG recordings and were treated at the Paediatric Neurology Clinic at an age of 1 month to 18 years. The inclusion criteria called for patients diagnosed with FUS based on history taking, physical diagnostics, and supporting examinations. The exclusion criteria eliminated patients whose medical records was incomplete (e.g., missing age, gender, duration of seizures, type of seizure, or EEG images); children found to suffer from fever, head trauma, epilepsy, central nervous system infection, tumours, or metabolic disorders such as hypoglycaemia, and children whose seizures were suspected to have been triggered by medication. Total population sampling was applied to FUS patients who ful lled the inclusion criteria. EEG was performed for at least 30 minutes, within 48 hours after the event using a Nihon Kohden EEG-1200 machine and interpreted by an internationally certi ed electroencephalographer. In addition, data were collected on the clinical characteristics of FUS patients based on their medical records; this information included age, sex, duration of seizures, type of seizure, and EEG results.

Statistical analysis
The collected data were then processed with International Business Machines Statistical Package for the Social Sciences (IBM SPSS) Statistics version 21. The data were analysed using descriptive statistics and the chi-square test along with Cochran's Q test and the Mantel-Haenszel test to reveal the relationship between variables. The data are presented in tabular and narrative form.

Page 4/12
The study was reviewed and approved by the Research and Ethics Scienti c Committee at Dr Soetomo General Academic Hospital, Surabaya, Indonesia (1860/KEPK/III/2020). Table 1 portrays the characteristics of 100 subjects, who were predominantly boys (62%) predominantly over ve years old (56%). The most common type of seizure was generalized (86%), and the most common duration was < 5 minutes (64%). The majority of EEG examinations showed abnormal results (54%), predominantly epileptiform waves (68.5%).  These results indicate that, the older the child and the longer the duration of seizures, the more likely it is that the EEG results will contain an abnormality. Moreover, the focal seizures in children with FUS often led to abnormal EEG results.

Discussion
First-time seizures may take the form of isolated seizures, repeated seizures or status epilepticus.
Repeated seizures within one day are considered a single seizure episode. 1 Electroencephalography is a noninvasive, readily available, and inexpensive investigative tool in diagnosis, identi cation of speci c syndromes, and long-term prognosis. It also helps differentiate seizures and predict the risk of recurrence. 8 In this study, there were 54 abnormal EEG examinations from 100 children with FUS, and 68% of the abnormal examinations showed epileptiform discharge. The rate of abnormal EEG ranged from 41-80% in non-selected populations and from 9-63% in selected populations. 6  In addition, the present study found a relationship between age and abnormal EEG results (p = 0.007), where children ≥ 5 years old had a higher prevalence of abnormal EEG waves (50%) than younger children. A study reported by Sakir Delil et al. described abnormal EEG results in older patients. 10 Takayuki Tsuboi also noted that the amount of visible abnormal "spike-wave" EEG activity increased with age. 11 The difference in EEG features by age was probably due to the rst seizure onset and the migration of the EEG focus during the clinical course. 12 Seizures are produced by abnormal excessive electrical activity in neurons. A focal seizure is a type of seizure that begins in one part of the brain. Focal seizures can be caused by irritation, infection, or injury in the brain. Many children with focal seizures are eventually diagnosed with epilepsy. 13,14 The present study found an association between seizure type and abnormal EEG waves (p = 0.03), with abnormal EEG waves being more common in focal than generalized seizures. A study undertaken by Khair et al., which examined the EEG results from children who suffered rst-time seizure without fever, stated that children with focal seizures had a higher prevalence of abnormal EEG waves than children with generalized seizures (47.5% > 44.44%); however, this difference was not statistically signi cant. Despite the nonsigni cance of this result, doctors still tended to obtain abnormal EEGs more easily following a focal rst seizure than a generalized rst seizure, perhaps in the process of trying to localize the epileptic focus. 14 Prolonged seizures (lasting 5 minutes or longer) have a remarkably unfavourable long-term prognosis, with a high risk of events such as neurological death, nerve injury, and changes in neural tissue, especially if the seizure duration is longer than 30 minutes. 15 The American Academy of Pediatrics advised parents whose children had seizures to contact emergency medical services if the seizure lasted more than 5 minutes and there was no rescue medication available at home or if the seizure lasted more than 5 minutes after the rescue medication was given. 16 Our ndings con rmed that seizure duration is an essential factor related to abnormal EEG results (p < 0.001), with an increased prevalence of abnormal EEG in patients whose seizures lasted ≥ 5 minutes. Several previous studies also reported that extended seizure duration was associated with intracranial abnormalities and generally increased the risk of recurrent seizures. [17][18][19] Strengths and limitations The main limitation of the present study was that it used conventional EEG and not 24-hour EEG; thus, limited inferences can be made from the available recordings. The strength in this study is that brief EEG recording for maximum 48 hours after FUS can depicts the abnormality clearer and more visible. The evidence from our study expands the knowledge on the abnormality of EEG after FUS, especially in resource limited country settings.

Conclusion
In this study, more than 50% of children with FUS had abnormal EEG results. Therefore, the present study suggests that EEG examination is essential for children with FUS, especially in children who have experienced focal seizures and/or long-lasting seizures (≥ 5 minutes). Availability of data and material: The datasets generated and/or analysed during the current study are not publicly available due to institution policy, but are available from the corresponding author on reasonable request.

Abbreviations
Competing interests: The authors declare that they have no competing interests.

Funding: No funding
Author's contributions: Gunawan design conceptual framework, data collection, analysis and interpretation, discussion and summary. Kurube contribute to data analysis, statistics, literature review and discussion. Noviandi collected data, revised the manuscript and supervised. Samosir revised the manuscript, gures and tables editing and literature review. All authors discussed the results and to the nal version of the manuscript. Type of abnormal EEG.