Idiopathic (genetic) generalized epilepsies with absences: clinical and electrographic characteristics and seizure outcome

Idiopathic generalized epilepsy with phantom absences, absence status, and generalized tonic-clonic seizures: A case report

RATIONALE

Phantom absences refer to mild and short-lasting absence seizures, which are usually accompanied by infrequent generalized tonic-clonic seizures and absence status. Generally, phantom absences do not impair the individual neurological functions. Herein, we report the case of a young woman with idiopathic generalized epilepsy, phantom absences, absence status, and generalized tonic-clonic seizures.

PATIENT CONCERNS

A 31-year-old woman presented with a 16-year history of paroxysmal convulsions.

DIAGNOSES

Electroencephalogram (EEG) showed recurrent universal and synchronized 3~4 Hz spike waves and spike-slow waves in the interictal phase with normal background activity. During the ictal phases, EEG revealed bursts of 3~4 Hz spike waves and spike-slow waves that were universal, synchronized, and symmetrical. Additionally, there was 1 seizure episode induced by a 3-Hz flash in the current case. Based on these findings, a diagnosis of idiopathic generalized epilepsy was made.

INTERVENTIONS

The patient was treated with oral sodium valproate, and the epileptic seizures were controlled.

OUTCOMES

The frequency of absence seizures was significantly reduced and there were no generalized tonic-clonic seizures.

LESSONS

Idiopathic generalized epilepsy with phantom absences, absence status, and generalized tonic-clonic seizures is an extremely rare condition. EEG is the exclusive method for diagnosis. Antiepileptic drugs are effective for controlling epileptic seizures in this disease.

Relationship Between Electroencephalography and Seizure Outcome in Typical Absence Seizures in Children

BACKGROUND

Typical absence seizures (TAS) are seen in idiopathic generalized epilepsy. Electroencephalography (EEG) contributes to syndrome characterization and counseling in an area where genetics does not currently play a significant role. Prominent interictal EEG findings are seen in juvenile absence epilepsy (JAE) and are thus thought to be associated with less favorable outcome in any TAS case despite lack of evidence. Our study evaluates EEG findings and their association with seizure outcomes in children with TAS.

METHODS

Retrospective cohort study of 123 children over 10 years with extensive EEG analysis and medical record review. Phone interviews ascertained longer-term outcomes. EEG reviewers were unaware of outcomes.

RESULTS

Total cohort included 123 children with phone review completed in 98. Median follow-up was 5 years 9 months. Seizure freedom was seen in 59% off antiseizure medicines (ASMs). Interictal findings included focal discharges in 29%, fragments of spike-wave (SW) discharges in 82.1%, and generalized interictal discharges in 63.4%. Interictal SW was more likely in those who slept (100%, 18 of 18) versus those who did not (57%, 60 of 105) (P < 0.001). Outcome analysis found no associations between focal or generalized interictal findings and seizure freedom, relapse off ASM, occurrence of other seizure types, or response to first ASM.

CONCLUSION

Focal and generalized interictal EEG discharges are common in children with TAS and are not associated with poorer outcomes. These interictal findings were traditionally associated with JAE rather than childhood absence epilepsy and were thus believed to be associated with potentially poorer outcome, which is probably not the case.

Drug-resistant epilepsy: Definition, pathophysiology, and management

There are currently >51 million people with epilepsy (PWE) in the world and every year >4.9 million people develop new-onset epilepsy. The cornerstone of treatment in PWE is drug therapy with antiseizure medications (ASMs). However, about one-third of PWE do not achieve seizure control and do not respond well to drug therapy despite the use of appropriate ASMs [drug-resistant epilepsy (DRE)]. The aims of the current narrative review are to discuss the definition of DRE, explain the biological underpinnings and clinical biomarkers of this condition, and finally to suggest practical management strategies to tackle this issue appropriately, in a concise manner.

Idiopathic generalized epilepsies: Which seizure type is more difficult to control?

OBJECTIVES

The purpose of the current study was to investigate that which seizure type is more difficult to be brought under control with antiseizure medication treatment in patients with idiopathic generalized epilepsy (IGE).

METHODS

This was a retrospective study of a large database of patients with epilepsy, which was built over more than a decade. All patients with a diagnosis of IGE, with at least 12 months of follow-up at our center, were studied at the epilepsy center at Shiraz University of Medical Sciences, Shiraz, Iran, from 2008 until 2022.

RESULTS

358 patients were included. The seizure types were generalized tonic-clonic seizures (GTCSs) (in 87.2%), myoclonic seizures (in 57.5%), and absence seizures (in 51.7%). Among patients who had GTCSs (N = 312), 160 patients (51.3%) became free of this seizure type. Among patients who had myoclonic seizures (N = 206), 122 patients (59.2%) became seizure-free. Among patients who had absences (N = 185), 127 patients (68.6%) became seizure-free. The difference between the groups was significant (p = 0.0007). Receiving valproate was significantly associated with a myoclonus-free status (compared with other drugs).

SIGNIFICANCE

The likelihood of achieving seizure control is different for various seizure types in patients with IGE (achievement of seizure control is less likely for GTCSs and more likely for absences). Antiseizure drug efficacy should be considered along with other variables (e.g., sex) when selecting an ASM for a patient with IGE. Specifically designed clinical trials are needed to develop more efficacious and safe drugs to treat various syndromes of IGE.

Thalamocortical circuits in generalized epilepsy: Pathophysiologic mechanisms and therapeutic targets

Generalized epilepsy affects 24 million people globally; at least 25% of cases remain medically refractory. The thalamus, with widespread connections throughout the brain, plays a critical role in generalized epilepsy. The intrinsic properties of thalamic neurons and the synaptic connections between populations of neurons in the nucleus reticularis thalami and thalamocortical relay nuclei help generate different firing patterns that influence brain states. In particular, transitions from tonic firing to highly synchronized burst firing mode in thalamic neurons can cause seizures that rapidly generalize and cause altered awareness and unconsciousness. Here, we review the most recent advances in our understanding of how thalamic activity is regulated and discuss the gaps in our understanding of the mechanisms of generalized epilepsy syndromes. Elucidating the role of the thalamus in generalized epilepsy syndromes may lead to new opportunities to better treat pharmaco-resistant generalized epilepsy by thalamic modulation and dietary therapy.

Typical absence seizures in children: Review with focus on EEG predictors of treatment response and outcome

Typical absence seizures (TAS) occur in idiopathic generalized epilepsy (IGE) syndromes and are a common presentation to paediatric neurologists. Considerable overlap in clinical features of IGE syndromes comprising TAS often complicates prognostication. Clinical and EEG diagnostic features in TAS are well known. However, knowledge of prognostic features for each syndrome, whether clinical or EEG-related, is less clear. Perpetuated impressions in clinical practice regarding the role of EEG when used for prognostication in TAS are known. Assumed prognostic features, particularly those relating to EEG have been rarely studied systematically. Despite rapid expansion in epilepsy genetics, the complex and presumed polygenic inheritance of IGE, means that clinical and EEG features are likely to remain the main guide to management and prognostication of TAS for the foreseeable future. We comprehensively reviewed available literature and hereby summarize current knowledge of clinical and EEG characteristics (ictal and interictal) in children with TAS. The literature focuses predominantly on ictal EEG. Where studied, interictal findings reported relate to focal discharges, polyspike discharges, and occipital intermittent rhythmic delta activity, with generalized interictal discharges not thoroughly studied. Furthermore, reported prognostic implications of EEG findings are often conflicting. Limitations of available literature include inconsistent clinical syndrome and EEG finding definitions, and variable EEG analysis methods, particularly lack of raw EEG data analysis. These conflicting findings coupled with varying study methodologies cause lack of clear information or evidence on features which may influence treatment response, outcome, or natural history of TAS.

A comprehensive narrative review of epilepsy with eyelid myoclonia

Epilepsy with eyelid myoclonia (EEM) is a generalized epilepsy syndrome with childhood-onset and 2:1 female predominance that consists of: 1. eyelid myoclonia with or without absence seizures, 2. eye closure induced seizures or EEG paroxysms, 3. clinical or EEG photosensitivity. While eyelid myoclonia is the disease hallmark, other seizure types, including absence seizures and generalized tonic-clonic seizures, may be present. It is thought to have a genetic etiology, and around one-third of patients may have a positive family history of epilepsy. Recently, specific genetic mutations have been recognized in a minority patients, including in SYNGAP1, NEXMIF, RORB, and CHD2 genes. There are no randomized controlled trials in EEM, and the management literature is largely restricted to small retrospective studies. Broad-spectrum antiseizure medications such as valproate, levetiracetam, lamotrigine, and benzodiazepines are typically used. Seizures typically persist into adulthood, and drug-resistant epilepsy is reported in over 50%.

ILAE definition of the Idiopathic Generalized Epilepsy Syndromes: Position statement by the ILAE Task Force on Nosology and Definitions

In 2017, the International League Against Epilepsy (ILAE) Classification of Epilepsies described the "genetic generalized epilepsies" (GGEs), which contained the "idiopathic generalized epilepsies" (IGEs). The goal of this paper is to delineate the four syndromes comprising the IGEs, namely childhood absence epilepsy, juvenile absence epilepsy, juvenile myoclonic epilepsy, and epilepsy with generalized tonic-clonic seizures alone. We provide updated diagnostic criteria for these IGE syndromes determined by the expert consensus opinion of the ILAE's Task Force on Nosology and Definitions (2017-2021) and international external experts outside our Task Force. We incorporate current knowledge from recent advances in genetic, imaging, and electroencephalographic studies, together with current terminology and classification of seizures and epilepsies. Patients that do not fulfill criteria for one of these syndromes, but that have one, or a combination, of the following generalized seizure types: absence, myoclonic, tonic-clonic and myoclonic-tonic-clonic seizures, with 2.5-5.5 Hz generalized spike-wave should be classified as having GGE. Recognizing these four IGE syndromes as a special grouping among the GGEs is helpful, as they carry prognostic and therapeutic implications.

Association between autophagy-related protein 5 gene polymorphisms and epilepsy in Chinese patients

Autophagy is a highly conserved degradative process that has been associated with a number of neurological diseases. Autophagy-related protein 5 (ATG5) is one of the key genes for the regulation of the autophagy pathway. In this study, we investigated the potential relationship between ATG5 gene polymorphisms and epilepsy in Han Chinese population. We enrolled 112 patients with epilepsy and 100 healthy controls and detected the genotypic and allelic data of 6 single nucleotide polymorphisms (SNPs) in ATG5 (rs2245214, rs510432, rs548234, rs573775, rs6568431 and rs6937876). The associations of 6 SNPs and epilepsy were evaluated. The results revealed the genotypes of overdominant of rs510432 between controls and patients showed significant differences (P_overdominant = 0.003). Subgroup analysis showed a highly significant association of rs510432 with late-onset epilepsy (P_overdominant = 0.006), and rs548234 were associated with the susceptibility to temporal lobe epilepsy (P_codominant = 0.002, P_overdominant = 0.006). Furthermore, ATG5 was not linked to either early-onset epilepsy or drug-resistant epilepsy (p > 0.0083). These results demonstrated an association of an ATG5 gene variant with epilepsy, and stronger associations with several subgroups of epilepsy were identified. Our study may provide novel evidence for the role of ATG5 in epilepsy, and contribute to our understanding of the molecular mechanisms of this chronic neurological disease.

Sex differences in characteristics of idiopathic generalized epilepsies

PURPOSE

We compared the demographic, clinical, and electroencephalographic (EEG) characteristics between females and males with idiopathic generalized epilepsy (IGE).

METHODS

In this retrospective study, all patients with a clinical diagnosis of IGE were recruited at the outpatient epilepsy clinic at Shiraz University of Medical Sciences, from 2008 through 2019. Age, gender, age at seizure onset, seizure type(s), epilepsy risk factors, and EEG findings of all patients were registered routinely.

RESULTS

Six hundred one patients with IGE were studied: 361 patients (60%) were females, and 240 people (40%) were males. The mean age at onset of seizures was 1.3 years earlier in males compared with that in females. Myoclonic seizures were more frequently reported by females than that by males. Photoparoxysmal response during intermittent photic stimulation in the EEG laboratory was more often observed in females than that in males. The difference in the syndromic diagnosis between the sexes was significant (p = 0.02). Among male patients, 88% were on valproate, and among female patients, 49% were on valproate (p = 0.0001). At the last follow-up visit, 83 males (61%) and 108 females (49%) were seizure-free (p = 0.02).

CONCLUSION

There are significant demographic, clinical, and electrographic differences between females and males with IGEs. The reasons behind these sex differences among patients with IGE are not clear. However, it is likely that sex hormones and sex chromosome genes-related brain differences play a role in the development of these differences. These interesting findings and the proposed hypothesis should be explored in future studies.