Consequences of epilepsy in the developing brain: implications for surgical management

Investigation of the Effect of Antiseizure Medications on Cognition in Patients With Epilepsy

Background. The effect of antiseizure medications (ASMs) on cognition varies depending on the type of ASM. We aimed to investigate the effects of ASMs on patients with epilepsy based on the conflicting findings in the literature. Methods. Patients diagnosed with epilepsy who were taking ASMs were included. All patients underwent a neuropsychiatric assessment, Beck Depression and Anxiety Inventories, Positive and Negative Syndrome Scale, and general psychopathological tests. The patients were divided into polytherapy and monotherapy groups. Subgroups were categorized according to the type of ASMs, dosage, and duration of monotherapy. Results. Ninety-seven patients were included in this study. The polytherapy group showed a significant decrease in attention, total learning, and interpretation of proverbs compared to the monotherapy group. In the monotherapy group, carbamazepine use had a moderate positive correlation with working memory (r = .669; P = .034), and a strong negative correlation with maintaining attention (r = -.740; P = .014). The duration of levetiracetam monotherapy was negatively correlated with verbal memory (immediate recall r = -.436, P = .038; free recall r = .426, P = .043) and negatively weakly correlated with naming performance (r = -.488, P = .025). Conclusion. The study showed polytherapy may affect verbal and working memory. Carbamazepine may affect working memory and the maintenance of attention in a dose-dependent manner. Levetiracetam may cause impairments in verbal memory and naming, depending on the duration of usage.

Escaping the Procrustean Bed: A Perspective on Pediatric Stereoelectroencephalography

SUMMARY

Stereoelectroencephalography is an established, hypothesis-driven method for investigating refractory epilepsy. There are special considerations and some limitations that apply to children who undergo stereoelectroencephalography. A key principle in stereoelectroencephalography is taking an individualized approach to investigating refractory epilepsy. A crucial factor for success in a personalized pediatric epilepsy surgery is understanding some of the fundamental and unique aspects of it, including, but not limited to, diverse etiology, epilepsy syndromes, maturation, and age-related characteristics as well as neural plasticity. Such features are reflected in the ontogeny of semiology and electrophysiology. In addition, special considerations are taken into account during cortical stimulation in children. Stereoelectroencephalography can guide a tailored surgical intervention where it is sufficient to render the patient seizure-free but it also lessens collateral damage with a minimum or no functional deficit. Epilepsy surgery outcomes remain stagnant despite advances in noninvasive testing modalities. A stereoelectroencephalography "way of thinking" and guided mentorship may influence outcomes positively.

Investigation on the Influencing Factors Related to Quality of Life of Adult Epilepsy Patients in Wenzhou, China, Based on Structural Equation Model

Objective. The aim of the study is to investigate the influencing factors of quality of life in adult patients with epilepsy in Wenzhou in China. Methods. A total of 190 patients who visited our hospital from July 2019 to February 2021 were included in the study. Demographic data and disease status were collected. Moreover, QOLIE-31, PSQI, ESS, HAMD-17, and GAD-7 were used in the questionnaire survey. Structural equation model fitting was used to analyze the influencing factors of quality of life in adult patients with epilepsy. Results. The scores of the dimension of onset worry in men were greater than those of women (P = 0.049), and the scores of the dimension of life satisfaction were lower than women (P = 0.047). The scores of cognitive function decreased with age (P = 0.047). The scores of quality of life of unemployed and drinking patients significantly decreased $\left(P<\mathit{0.05}\right)$ . The score of quality of life positively correlated with good economic status and family relations $\left(P<\mathit{0.05}\right)$ . The score of emotional health increased first and then decreased with the course of the disease. With the decrease in seizure frequency and the extension of months without a seizure, the score of quality of life gradually increased. Furthermore, the structural equation model showed that health status was directly correlated to the quality of life of patients with epilepsy. Conclusion. Male, unemployment, drinking, older age, and disease are negatively related to the quality of life in patients with epilepsy. However, good economic status, good family relations, and good colleague relationships are positively related to the quality of life.

Changes in Pre- and Postsurgery for Drug Resistant Epilepsy: Cognition and Sleep

BACKGROUND

Most patients with drug-resistant epilepsy (DRE) have cognitive impairment and sleep disturbance. There was a significant correlation between sleep disorders and cognitive dysfunction. This study performed surgical treatment on patients with DRE and observed seizures, sleep, and cognition in patients with DRE in 6th month after operation to clarify the correlation between sleep and cognition in DRE patients.

METHODS

21 individuals with DRE were recruited to enroll in this trial. Each participant completed epileptic focus resection. Seizure frequency was the principle index; the mean seizure frequency was 1 month before surgery and six months after surgery. Cognitive function was assessed by MMSE, and sleep status was assessed by PSQI and ActiGraph; assessments were performed before and 6 months after surgery.

RESULTS

There were significant differences between conditions on all outcome measures; after 6 months of surgery, compared with before treatment, the monthly average seizure frequency of DRE decreased, which was statistically significant (P < 0.001) compared with that before treatment. The MMSE score of DRE patients was significantly higher than before (P < 0.01), especially the ability of attention, calculation, and recall in MMSE score, which was significantly higher than before operation (respectively, P < 0.001 and P < 0.01). The subjective sleep evaluation index PSQI and objective measurement of sleep latency, total sleep time, and sleep efficiency of patients with DRE by ActiGraph were statistically significant (respectively, P < 0.01) compared with that before treatment. There was a correlation between seizure frequency and MMSE (r = -0.8887, P < 0.0001), PSQI (0.5515, P < 0.01), sleep latency (0.5353, P < 0.05), total sleep time (-0.7814, P < 0.0001), and sleep efficiency (-0.4380, P < 0.05).

CONCLUSIONS

Surgery can effectively reduce the epileptic seizures frequency in patients with DRE and indirectly improve the computational power, attention, recall ability, and sleep status of patients. However, this result did not show a correlation between improved cognitive function and sleep, so the patient's cognitive function may be caused by surgery to improve the frequency of seizures. So, whether the improvement of patients' sleep conditions can also significantly improve the frequency of attacks and cognitive function in patients with DRE needs further exploration.

Increase in cognitive function is seen in many single-operated pediatric patients after epilepsy surgery

PURPOSE

The recurrent seizures of pediatric drug-resistant epilepsy (DRE) are known to impair brain development and can lead to a loss in cognitive functioning. Surgery is increasingly being used to treat children with DRE. This study investigates the pre- and postoperative cognitive function in a pediatric epilepsy surgery cohort as well as predictive determinants of change in intelligence quotient (IQ) following surgery.

METHODS

A consecutive series of 91 Danish children who underwent focal resective epilepsy surgery between January 1996 and December 2016 were included. All underwent preoperative cognitive evaluation and were reevaluated at 1-year and/or 2-year follow-up. Single-operated and multi-operated patients were examined separately.

RESULTS

79 of 91 patients were single-operated. Single-operated patients received less anti-epileptic drugs (AED) and experienced a decrease in seizure frequency postoperatively, p < 0.001. IQ increased postoperatively (IQ change ± standard deviation: 3.3 ± 14.0), p < 0.05. High preoperative seizure frequency was a significant predictor for decreased IQ, p < 0.01. Multi-operated patients did not experience a reduction in AED treatment. Surgery and continued AED treatment did, however, result in significantly better seizure control, p < 0.01. IQ remained unchanged in multi-operated patients.

CONCLUSION

Epilepsy surgery allowed for IQ gains in single-operated patients. Preoperative seizure frequency was a significant predictor of IQ change following surgery. Interactions between other, not included, possible predictors remain to be examined. Single-operated patients had the best cognitive outcome. The inclusion of a non-surgical control group is needed to assess the extent of the beneficial effects of surgery on cognitive ability.

2-Deoxyglucose terminates pilocarpine-induced status epilepticus in neonatal rats

OBJECTIVE

Neonatal status epilepticus (SE) is a life-threatening medical emergency. Unfortunately, up to 50% of neonates with SE are resistant to current antiseizure drugs, highlighting the need for better treatments. This study aims to explore a novel metabolic approach as a potential alternative treatment to control neonatal SE, using the glycolytic inhibitor 2-deoxyglucose (2-DG).

METHODS

SE was induced by pilocarpine (300 mg/kg, intraperitoneally [ip]) in neonatal Sprague Dawley rats (postnatal day 10 [P10]-P17) and was monitored by video-electroencephalography (V-EEG). After 30 minutes of SE, 2-DG or one of two conventional antiseizure drugs with different mechanisms of action, phenobarbital or levetiracetam, was administrated ip, and V-EEG recording was continued for ~60 additional minutes. The time to seizure cessation after drug injection, EEG scores, and power spectra before and after drug or saline treatment were used to assess drug effects.

RESULTS

Once SE became sustained, administration of 2-DG (50, 100, or 500 mg/kg, ip) consistently stopped behavioral and electrographic seizures within 10-15 minutes; lower doses took longer (25-30 minutes) to stop SE, demonstrating a dose-dependent effect. Administration of phenobarbital (30 mg/kg, ip) or levetiracetam (100 mg/kg, ip) also stopped SE within 10-15 minutes in neonatal rats.

SIGNIFICANCE

Our results suggest that the glycolysis inhibitor 2-DG acts quickly to reduce neuronal hyperexcitability and effectively suppress ongoing seizure activity, which may provide translational value in the treatment of neonatal SE.

Neuropsychological development in children belonging to BECTS spectrum: long-term effect of epileptiform activity

Benign epilepsy with centrotemporal spikes (BECTS) is an idiopathic focal epileptic syndrome in childhood. It is called "benign" because the seizure and cognitive outcomes are usually favorable, but a significant number of children with BECTS present heterogeneous cognitive deficits correlated to NREM sleep epileptiform discharges. The atypical evolutions of BECTS form a spectrum of conditions suggesting that slow sleep nocturnal interictal epileptiform discharges (IEDs) specifically determine the neuropsychological deficit. Few follow-up studies of neuropsychological outcome in BECTS are available, and very often, slow sleep has not been recorded throughout night sleep. The present study analyzed the long-term effects of IEDs during NREM sleep on neuropsychological development in children with rolandic spikes. Thirty-three children with a diagnosis of BECTS were monitored for at least two years. Results show that these children are at higher risk for residual verbal difficulties, and the abnormal neuropsychological development is significantly correlated with a greater frequency of NREM sleep discharges, school-age epilepsy onset, and a higher number of antiepileptic drugs (AEDs). The findings are discussed in terms of how slow sleep IEDs affect the consolidation of verbal skills during critical epochs of neuropsychological development.

Epilepsy surgery in children: results and predictors of outcome on seizures

PURPOSE

To retrospectively analyze the results on seizures of surgery in children with drug-resistant focal epilepsy. To identify the factors predicting seizure control among several presurgical, surgical, and postsurgical variables.

METHODS

One hundred thirteen patients (67 male, 46 female), younger than 16 years, operated on from 1996 to 2004 and followed-up for at least 2 years were identified. Individualized microsurgical resections, aimed at removal of the epileptogenic zone, were performed according to the results of tailored presurgical evaluations, which included stereo-electroencephalographic recording with intracerebral electrodes when needed. Risk of seizure recurrence was assessed for the considered variables by bivariate and multivariate analysis.

RESULTS

Mean age at surgery was 8.8 years, mean duration of epilepsy was 5.7 years, and mean age at seizure onset was 3.1 years. One hundred eight patients (96%) had an abnormal magnetic resonance imaging. At postoperative follow-up (mean duration 55.1 month), 77 patients (68%) were in Engel's class I, with 68 patients (60%) being seizure free (Engel's classes Ia and Ic). At multivariate analysis, variables associated with a significantly lower risk of seizure recurrence were unifocal lesion at MRI and older age at seizure onset (presurgical variables), temporal unilobar resection and complete lesionectomy (surgical variables), diagnosis of glial-neuronal tumors (postsurgical variables).

CONCLUSIONS

Surgery is a valuable option for children with drug-resistant focal epilepsies which may provide excellent results in a considerable amount of cases. Since results of surgery for epilepsy strongly depend on the presurgical identification of the Epileptogenic Zone, future work should be focused on refinement and implementation of diagnostic strategies.

Models of epilepsy in the developing and adult brain: implications for neuroprotection

Repeated seizures cause a sequence of molecular and cellular changes in both the developing and adult brain, which may lead to intractable epilepsy. This article reviews this sequence of neuronal alterations, with emphasis on the kindling model. At each step, the opportunity exists for strategic intervention to prevent or reduce the downstream consequences of epileptogenesis and seizure-induced adverse plasticity. The concept of seizure-induced brain damage must be expanded to include behavioral and cognitive deficits, as well as structural neuronal damage and increased predisposition to seizures.

Seizures in the developing brain cause adverse long-term effects on spatial learning and anxiety

PURPOSE

Seizures in the developing brain cause less macroscopic structural damage than do seizures in adulthood, but accumulating evidence shows that seizures early in life can be associated with persistent behavioral and cognitive impairments. We previously showed that long-term spatial memory in the eight-arm radial-arm maze was impaired in rats that experienced a single episode of kainic acid (KA)-induced status epilepticus during early development (postnatal days (P) 1-14). Here we extend those findings by using a set of behavioral paradigms that are sensitive to additional aspects of learning and behavior.

METHODS

On P1, P7, P14, or P24, rats underwent status epilepticus induced by intraperitoneal injections of age-specific doses of KA. In adulthood (P90-P100), the behavioral performance of these rats was compared with that of control rats that did not receive KA. A modified version of the radial-arm maze was used to assess short-term spatial memory; the Morris water maze was used to evaluate long-term spatial memory and retrieval; and the elevated plus maze was used to determine anxiety.

RESULTS

Compared with controls, rats with KA seizures at each tested age had impaired short-term spatial memory in the radial-arm maze (longer latency to criterion and more reference errors), deficient long-term spatial learning and retrieval in the water maze (longer escape latencies and memory for platform location), and a greater degree of anxiety in the elevated plus maze (greater time spent in open arms).

CONCLUSIONS

These findings provide additional support for the concept that seizures early in life may be followed by life-long impairment of certain cognitive and behavioral functions. These results may have clinical implications, favoring early and aggressive control of seizures during development.

Epilepsy and cognition

Patients with epilepsy are more prone to cognitive and behavioral deficits. Epilepsy per se may induce or exacerbate an underlying cognitive impairment, a variety of factors contribute to such deficits, i.e., underlying neuropathology, seizure type, age of onset, psychosocial problems, and treatment side effects. Epilepsy treatment may offset the cognitive and behavioral impairments by stopping or decreasing the seizures, but it may also induce untoward effects on cognition and behavior. The neurocognitive burden of epilepsy may even start through in utero exposure to medications. Epilepsy surgery can also induce certain cognitive deficits, although in most cases this can be minimized. Clinicians should consider cognitive side effect profiles of antiepileptic medications, particularly in extreme age groups. While no effective treatments are available for cognitive and behavioral impairments in epilepsy, comprehensive pretreatment evaluation and meticulous selection of antiepileptic drugs or surgical approach may minimize such untoward effects.

Transition from interictal to ictal activity in limbic networks in vitro

The transition from brief bursts of synchronous population activity characteristic of interictal epileptiform discharges (IEDs) to more prolonged epochs of population activity characteristic of seizures (ictal-like activity) was recorded in juvenile rat hippocampal-entorhinal cortex slices and hippocampal slices using multiple-site extracellular electrodes. Epileptiform activity was elicited by either increased extracellular potassium or 4-AP. IEDs originated in the CA3 a-b region and spread bidirectionally into CA1 and CA3c dentate gyrus. The transition from IEDs to ictal-like sustained epileptiform activity was reliably preceded by (1) increase in IED propagation velocity, (2) increase in IED secondary afterdischarges and their reverberation between CA3a and CA3c, and (3) shift in the IED initiation area from CA3 a-b to CA3c. Ictal-like sustained network oscillations (10-20 Hz) originated in CA3c and spread to CA1. The pattern of hippocampal ictal-like activity was unaffected by removal of the entorhinal cortex. These findings indicate that interictal and ictal activity can originate in the same neural network, and that the transition from interictal to ictal-like-sustained activity is preceded by predictable alterations in the origin and spread of IEDs. These findings elucidate new targets for investigating the proximate causes, prediction, and treatment of seizures.

Epilepsy surgery. Presurgical evaluation

The presurgical evaluation should result in a clear understanding of whether surgery can be undertaken and its associated risks and potential for benefit. The results of surgery are best when there is congruence in the seizure semiology, the irritative zone on interictal EEG, and the ictal onset zone with the epileptogenic lesion as defined on MRI and PET, and when there is a clear understanding of the ictal onset zone's relationship to eloquent cortex as defined by neuropsychologic evaluation, the intracarotid amobarbital test, and cortical functional mapping.

Assessing the behavioral and cognitive effects of seizures on the developing brain

The degree to which seizures lead to 'brain damage' is not fully known, but this question has important clinical implications. Seizure-induced brain damage can be defined in several ways: structural, physiological, and behavioral. The behavioral and cognitive effects of seizures are difficult to ascertain in patients, because it is hard to differentiate the effects of the seizures from the underlying brain pathology, anticonvulsant treatment, and developmental variables. In animal models, the ability to control seizure variables allows detailed investigation of factors that cannot be easily distinguished in clinical studies. In models of experimental epilepsy, both brief and prolonged seizures lead to brain damage. While the consequences of seizures are much more extensive in the adult brain, long-term alterations are also seen in the developing brain. This chapter focuses on the effects of seizures during development on subsequent behavior and cognition in experimental epilepsy models. The investigator must choose carefully among the various tests of behavior, learning, memory, and cognition, since the existence or extent of deficits may depend upon which test is selected and how the data are analyzed. The experimental evidence suggests that seizures early in life are associated with subtle deficits in behavior and cognition, even in the absence of overt structural neuronal damage. These deficits are dependent upon the age at which seizures occur (less severe deficits at younger ages), seizure frequency and seizure severity, but are largely independent of seizure etiology, occurring after several types of chemoconvulsants and electrical stimulation. Seizure-induced behavioral and cognitive deficits, which may not become obvious until long after the onset of the epilepsy, might be equally or more detrimental to a child's overall function than the seizures themselves.

Spontaneous long-term remission of intractable partial epilepsy in childhood

Drug-resistant partial epilepsy in children often has a major impact on cognitive development, and early surgical intervention has been advocated to prevent adverse neurobehavioral effects of seizures in such patients. We report a 5-year-old boy who had cryptogenic partial epilepsy of right parietal origin as documented by ictal electroencephalogram (EEG) and glucose metabolism positron emission tomographic (PET) scan. His atonic seizures could not be controlled by multiple antiepilepsy drugs; therefore, cortical resection was scheduled. However, his seizures remitted spontaneously after 1 year of failed medical treatment. The epileptiform abnormality disappeared on the follow-up EEGs, and a glucose PET scan also normalized. This boy has fully retained his cognitive and motor functions and has remained seizure free in the past 4z\x years off medications.