Idiopathic generalized epilepsy with absences: syndrome classification

In a cohort of 275 Caucasians with a broad IGE phenotype, patients with absences were classified. Criteria of the 1989 Commission on Classification of the International League Against Epilepsy for Childhood Absence Epilepsy (CAE 1989 criteria) were compared with the stricter criteria of the ILAE Task Force for Classification and Terminology (CAE 2005 criteria). Among the 129 patients with absences without significant myoclonus, 50 had juvenile absence epilepsy 44 had CAE according to the CAE 1989 criteria and only 30 had CAE according to the CAE 2005 criteria. We found a significantly better outcome in patients considered as CAE by the CAE 2005 criteria, compared with those excluded. Strict criteria for classification of absence syndromes leave many patients unclassified. However, diagnostic criteria used to classify CAE patients have prognostic significance. We propose that patients are classified as having benign CAE or as having CAE with the adverse prognostic factors indicated.     

Childhood absence epilepsy: evolution and prognostic factors

PURPOSE: To evaluate how diagnostic criteria influence remission rates for patients with childhood absence epilepsy (CAE) and to assess clinical and EEG parameters as predictors of outcome. METHODS: One hundred nineteen patients were diagnosed with CAE, according to International League Against Epilepsy (ILAE) classification criteria. They were subsequently evaluated according to stricter diagnostic criteria. Sixty-two subjects fulfilled these criteria as group 2; 57 did not and constituted group 1. Diagnostic parameters that prevented patients of group 1 from entering group 2, and variables such as sex, familial history of generalized epilepsy, and personal history of febrile convulsions also were tested as prognostic factors for terminal remission. RESULTS: Compared with those in group 1, patients of group 2 had significantly higher rates of seizure control (95% vs. 77%), higher rates of terminal remission (82% vs. 51%), fewer generalized tonic-clonic seizures (8% vs. 30%), and shorter mean periods of treatment (2.2 vs. 3.8 years). Significantly fewer patients were receiving polytherapy in group 2 than in group 1 (11% vs. 47%), and fewer patients had seizure relapses at antiepileptic drug discontinuation (0 vs. 22%). CONCLUSIONS: Remission rates of patients with CAE are greatly influenced by the classification criteria used for selection. Stricter diagnostic criteria allow the definition of a homogeneous group of patients with excellent prognosis. Factors predicting unfavorable prognosis were generalized tonic-clonic seizures in the active stage of absences, myoclonic jerks, eyelid myoclonia or perioral myoclonia, and EEG features atypical for CAE.     

Magnetoencephalography localizing spike sources of atypical benign partial epilepsy

Rationale: Atypical benign partial epilepsy (ABPE) is characterized by centro-temporal electroencephalography (EEG) spikes, continuous spike and waves during sleep (CSWS), and multiple seizure types including epileptic negative myoclonus (ENM), but not tonic seizures. This study evaluated the localization of magnetoencephalography (MEG) spike sources (MEGSSs) to investigate the clinical features and mechanism underlying ABPE. Methods: We retrospectively analyzed seizure profiles, scalp video EEG (VEEG) and MEG in ABPE patients. Results: Eighteen ABPE patients were identified (nine girls and nine boys). Seizure onset ranged from 1.3 to 8.8 years (median, 2.9 years). Initial seizures consisted of focal motor seizures (15 patients) and absences/atypical absences (3). Seventeen patients had multiple seizure types including drop attacks (16), focal motor seizures (16), ENM (14), absences/atypical absences (11) and focal myoclonic seizures (10). VEEG showed centro-temporal spikes and CSWS in all patients. Magnetic resonance imaging (MRI) was reported as normal in all patients. MEGSSs were localized over the following regions: both Rolandic and sylvian (8), peri-sylvian (5), peri-Rolandic (4), parieto-occipital (1), bilateral (10) and unilateral (8). All patients were on more than two antiepileptic medications. ENM and absences/atypical absences were controlled in 14 patients treated with adjunctive ethosuximide. Conclusion: MEG localized the source of centro-temporal spikes and CSWS in the Rolandic-sylvian regions. Centro-temporal spikes, Rolandic-sylvian spike sources and focal motor seizures are evidence that ABPE presents with Rolandic-sylvian onset seizures. ABPE is therefore a unique, age-related and localization-related epilepsy with a Rolandic-sylvian epileptic focus plus possible thalamo-cortical epileptic networks in the developing brain of children.     

Atypical childhood absence epilepsy with preceding or simultaneous generalized tonic clonic seizures

Objective

Although the current diagnostic criteria for childhood absence epilepsy (CAE) do not specifically exclude children with generalized tonic clonic seizures (GTCSs) occurring before or early in the course of the active absence seizures, some workers have suggested that they should be interpreted as doing so. The aim of this study was to compare the clinical features between children with typical CAE and those with atypical CAE with preceding or simultaneous episodes of GTCS (atypical CAE-GTCS).

Methods

A total of 11 patients with atypical CAE-GTCS and 30 with typical CAE were identified by using the current CAE criteria. Their clinical data, including age, sex, family history of epilepsy, personal history of febrile convulsions, onset ages of absences and GTCS, treatment, and outcome were statistically analyzed.

Results

The two groups had the same mean onset age of absences (6 years), and their seizure outcome was comparably favorable in terms of both absences and GTCS. There was no significant difference in other clinical data except for the onset age of GTCS between the groups.

Conclusion

These findings show the similarity in the main clinical features between the groups, suggesting that some patients with atypical CAE-GTCS may have a variant form of CAE with early onset of GTCS.     

Pretreatment electroencephalographic features in patients with childhood absence epilepsy

ObjectiveTo analyze the ictal and interictal electroencephalographic (EEG) features in newly diagnosed childhood absence epilepsy (CAE) and determine the association between seizure onset topography, interictal focal spike-wave discharges (FSWDs) and accompanying clinical features of absence seizures.MethodsThe authors searched the EEG database for a definite diagnosis of CAE according to ILAE 2017 criteria. Video-EEGs of untreated pediatric patients during sleep and wakefulness were evaluated retrospectively.ResultsThe study included 47 patients (25 males, 22 females). Interictal FSWDs were observed in 49% of patients with CAE during wakefulness and in 85.1% during sleep (p = 0.001). Interictal FSWDs were most frequently observed in the frontal regions (awake: 34%; asleep: 74.5%), followed by the posterior temporoparietooccipital region (awake: 21.2%; asleep: 36.1%), and the centrotemporal region (awake: 6.4%; asleep: 8.5%). Eleven patients (23.4%) had polyspikes during sleep. Both bilateral symmetric and asymmetric seizure onset were noted in 32%, whereas focal seizure onset was observed in 14.9% of the patients. Absence seizures with and without motor components were seen in 72.3% and 61.7% of patients, respectively, and in 33% of patients both occurred. There were no associations between the existence of interictal FSWDs, focal/asymmetric seizure onset, and absence seizures with and/or without motor components.ConclusionAsymmetric and/or focal seizure onset, interictal FSWDs, and absence seizures with motor components are commonly observed in drug-naive CAE. This study found no association between seizure onset topography, interictal FSWDs, and semiological features of absence seizures.     

Long-term prognosis for childhood and juvenile absence epilepsy

Abstract. Purpose: To analyse prognostic factors for long term seizure remission in patients with childhood (CAE) and juvenile absence epilepsy (JAE). Study design: A retrospective analysis of a hospital based prevalence cohort. Methods: The cohort consisted of 163 patients (104 females, 59 males) treated at the Universitätsklinik für Neurologie, Innsbruck between 1970 and 1997. All had absences according to the ILAE classification. Follow up was in 1999 to 2000. We assessed multiple clinical and EEG factors as predictors of outcome and compared a classification according to the predominant pattern of seizure recurrence (pyknoleptic, PA or non pyknoleptic absence, NPA) with the ILAE classification with respect to prognosis. Results: The mean age at seizure onset was 10.9 years (range, 3 to 27); age at follow up was 36.7 years (range, 13 to 81); duration of follow up was 25.8 years (range, 3 to 69). Sixty four patients (39 %) had CAE and 64 (39 %) JAE, while 35 (22%) had typical absences but could not be clearly defined as either CAE or JAE, and were therefore called the overlap group. Patients with JAE or patients in the overlap group developed more often generalized tonic clonic seizures (GTCS) (p<0.001) and myoclonic attacks (p<0.05) during the course of the disease. At follow up 36 (56 %) of patients with CAE, 40 (62%) with JAE and 19 (54 %) of the overlap group were seizure free for at least two years (p=ns). When classified according to the predominant absence pattern at seizure onset 42 (51%) patients with PA and 53 (65%) with NPA were in remission (p=ns). In a stepwise binary logistic regression analysis the pattern of absence (PA or NPA) together with the later development of additional seizure types (myoclonias or GTCS), but not the CAE/JAE classification was predictive for long term lack of remission with a correct prediction of 66% of all patients. Conclusion: Only 58% of patients with absences were in remission after a long term follow up. CAE and JAE are closely related syndromes with large overlap of the age of onset. A classification according to the predominant seizure pattern at onset, together with later development of myoclonic attacks or GTCS is useful in predicting seizure remission in absence epilepsies.     

Absence Epilepsies

Summary: Individuals fulfilling diagnostic criteria for childhood absence epilepsy (CAE) and juvenile absence epilepsy (JAE) were selected from a large group of patients who were born between 1945 and 1973 and had presented with absence seizures (AS). Updated data allowed an analysis of 52 patients with CAE and of 62 patients with JAE aged ≥20 years. In CAE, complete control was achieved in 90% of patients (95%, AS only; 77%, AS + generalized tonic-clonic seizures, GTCS). Only 16% of patients with an onset <9 years had developed GTCS. In JAE, complete control was achieved in 37% of patients (47%, AS; 37%, GTCS). These figures support the validity of the International Classification of Epilepsy (ICE). Stricter diagnostic criteria are discussed.     

Vagus nerve stimulation for medically refractory absence epilepsy

PurposeA proportion of patients with childhood and juvenile absence epilepsies (CAE, JAE) are likely to be classified as medically refractory. In view of evidence gap for the treatment of such patients, this series is reported to generate estimate for efficacy of vagus nerve stimulation (VNS) in this patient population.MethodsPatients were identified by a chart review of all VNS recipients between January 1, 2006 and December 31, 2011. The diagnosis of CAE and JAE was based on conventional criteria. Details of demography, epilepsy phenomenology, management and outcomes were extracted. The outcome measures included reduction in daily seizure frequency measured as a percentage of pre-VNS seizure frequency and classified on International League Against Epilepsy (ILAE) outcome scale.ResultsNine patients (7 CAE, 2 JAE) with a mean age of seizure onset of 5.4 years (±3.9) were identified. Mean duration of epilepsy prior to VNS implant was found to be 3.9 years (±1.4). These patients had failed a median of 5 anti-epileptic drugs before being referred for consideration of surgical treatment. After a mean follow-up of 33.9 months (±25.5, minimum 4 months), 1 patient attained complete seizure freedom (ILAE class 1), 6 had ILAE class 4 and 2 had ILAE class 5 outcomes, respectively. Mean reduction in daily seizure frequency was found to be 53.5 ± 60.3% (1-sided p-value for paired t-test = 0.04), with a 50% responder rate of 55.6%.ConclusionVNS may be considered as a therapeutic option in patients with medically refractory absence epilepsy.     

Idiopathic epilepsy with generalized tonic–clonic seizures only versus idiopathic epilepsy with phantom absences and generalized tonic–clonic seizures: One or two syndromes?

Purpose: To define the relationship between two syndromes of idiopathic generalized epilepsy (IGE) with apparently similar phenotypes: The form with generalized tonic–clonic seizures only (IGE‐GTCS) and that with phantom absences (IGE‐PA). Methods: We compared the electroclinical features of 33 consecutive patients with GTCS and generalized spike wave (GSW); 18 had only GTCS and were diagnosed as IGE‐GTCS, and 15 had hitherto unnoticed mild absences on the electroencephalography (EEG) and were diagnosed as IGE‐PA. All patients were subjected to the same diagnostic workout, including video EEG during hyperventilation with breath counting (HBC). Patients with a clinical history of absences or myoclonic seizures were excluded. Results: PA were easily identified with the first or second EEG in 14 of 15 patients with IGE‐PA and always with sleep‐deprived EEGs; conversely, PA did not occur in the IGE‐GTCS patients despite using more EEGs. GTCS were twice as frequent in the IGE‐GTCS group and tended to occur on awakening, whereas episodes of absence status affected twice as many patients with IGE‐PA. The hereditary risk was 30% in the IGE‐GTCS and 6.7% in IGE‐PA. GSW had a strong polyspike component in IGE‐PA and were briefer in IGE‐GTCS. There is no evidence for a maturational influence on the duration of GSW in either syndrome. Conclusion: Our findings clearly indicate that IGE‐GTCS and IGE‐PA are two distinct IGE syndromes and emphasize the role of PA for patients' diagnosis and management and for syndromic classification. They also appear to validate HBC as a simple, sensitive, and pragmatic method for the clinical identification of typical absences.     

Familial form of typical childhood absence epilepsy in a consanguineous context

Causative genes for childhood absence epilepsy (CAE) are unknown partly because families are small or phenotypically heterogeneous. In five consanguineous Tunisian families with at least two sibs with CAE, 14 patients fulfilled the diagnostic criteria for CAE (Epilepsia 1989;30:389–399). Linkage analyses or direct sequencing excluded CACNG2, CACNA1A, CACNB4, and CACNA2D2, orthologs of genes responsible for autosomal recessive (AR) absence seizures in mice. These families will help identify (a) gene(s) responsible for CAE.     

Epilepsia ausencia infantil. Pronóstico a largo plazo

Introduction

Childhood absence epilepsy (CAE) is considered easily manageable with medication provided that a strict patient classification system is employed. It accounts for 10% of all childhood epilepsy cases starting before the age of 15 and it is most frequent in school-aged girls. The aim of this study is to analyse long-term outcomes of patients diagnosed with CAE according to the Loiseau and Panayiotopoulos criteria and treated during childhood.

Typical absence seizures associated with localization-related epilepsy: a clinical and electroencephalographic characterization

INTRODUCTION: This paper describes the characteristics of patients with typical absence seizures associated with localization related epilepsy (LRE) and compares electroclinical features of absences occurring in these patients with those having childhood absence epilepsy (CAE). METHODS: Consecutive patients presenting with both LRE and typical absences in their epilepsy history were included in the study (Group 1). Clinical assessments and EEG investigations were conducted during the follow-up. Patients observed during the same period, but with typical absences fulfilling the CAE diagnostic criteria, were assigned to a second group (Group 2). RESULTS: Fourteen patients were included in Group 1. These patients had a mean age at their last visit of 11.3 years (range 7.2-16.8), with a mean follow-up period of 6.8 years. In all patients LRE was the first type of seizure to occur at median age of 4.95+/-2.1 years (range 1.9-8.8). Typical absences appeared at median age of 7.5+/-2.5 years (range 4.5-12.5), and were well controlled by therapy. Ictal EEG and semiology features of typical absences did not show any distinctive features when compared to those of Group 2 represented by 53 patients affected by CAE. However, age at onset was significantly higher in Group 1, as was the number of patients who underwent polytherapy, and the number with relapses after drug discontinuation. None of patients in Group 1 showed terminal remission. CONCLUSION: Although clinically heterogeneous and rare, the association of LRE with typical absences may be more than coincidental. In these patients, typical absences responded well to therapy, but terminal remission rates were lower than for CAE patients.     

Idiopathic occipital and absence epilepsies appearing in the same children

Our aim is to report the association between idiopathic occipital epilepsy and childhood absence epilepsy in the same children. Six children met the diagnostic criteria for both idiopathic occipital epilepsy and childhood absence epilepsy, five patients with idiopathic occipital epilepsy Gastaut type and another with Panayiotopoulos type. All patients were monitored for 2 to 10 years with repeated electroencephalograms when awake and during sleep. Age at onset of seizures ranged from 4.6 to 8 years. Five patients had focal sensory visual seizures, all with migraine-like episodes. One patient presented ictal vomiting followed by oculocephalic deviation. All patients presented typical absences, with onset at least 1 year after having had idiopathic occipital epilepsy Gastaut type in three patients. In the other two patients with idiopathic occipital epilepsy Gastaut type and the patient with idiopathic occipital epilepsy Panayiotopoulos type, both types of epilepsy appeared at the same time. The electroencephalograms documented occipital paroxysms in all cases, with positive reactivity to the eye closure in five patients. All children presented spike-wave discharges at 3 cycles per second activated by hyperventilation. More genetic information would be necessary to demonstrate either a close genetic relationship between these syndromes or common markers with variable phenotypes.     

Safety of video-EEG monitoring and surgical outcome in patients with mesial temporal sclerosis and psychosis of epilepsy

PurposeCortico-amygdalohippocampectomy (CAH) has become an important treatment option for patients with refractory temporal lobe epilepsy and mesial temporal sclerosis (TLE-MTS); it has resulted in a 60–70% seizure remission rate and significant quality of life (QOL) improvements. Video-electroencephalography (VEEG) monitoring has been widely used in epilepsy centers for pre-surgical evaluation. A major concern in epilepsy surgery is whether to consider CAH treatment in patients with psychosis of epilepsy (POE). This study analyzed the safety and adverse events (AEs) of VEEG monitoring and the post-surgical outcomes of patients with refractory TLE-MTS and POE who underwent CAH.MethodClinical, sociodemographic and VEEG data from 18 patients with TLE-MTS and POE were analyzed. Psychiatric evaluations were performed using DSM-IV and ILAE criteria. The seizure outcome was evaluated using Engel's criteria.ResultsTwo patients (11.2%) presented AEs that did not result in increased lengths of hospitalization. Of the 10 patients (55.5%) who underwent CAH, 6 (60%) became free of disabling seizures (Engel I). The psychiatric and QOL evaluations revealed improvements of psychotic symptoms (p = 0.01) and in Physical Health (p = 0.01) following surgery.ConclusionThese data reinforce that VEEG monitoring is a safe method to evaluate patients with refractory TLE-MTS and POE in epilepsy centers.     

Lamotrigine in typical absence epilepsy.

Lamotrigine (LTG) is an anti-epileptic drug effective in partial seizures and generalized epilepsy. There is growing evidence of the usefulness of LTG in childhood (CAE) orjuvenile (JAE) absences resistant to previous treatment. In this study all patients were identified using strict diagnostic criteria and subdivided into two groups. (1) Eight patients affected by absence seizures resistant to valproic acid or ethosuximide, received LTG as an-add-on therapy, (2) seven patients affected by typical absence seizures not previously treated, received LTG monotherapy after the diagnosis. In the patients with resistant absence seizures, a full control of seizures was obtained. In five of them, after a mean period of 12.5 months, the previous anti-epileptic drugs were withdrawn leaving the patients on LTG monotherapy. In one patient, absences relapsed and valproic acid was therefore added again to LTG to regain control of the seizures. In six of the seven patients on LTG monotherapy after the diagnosis, a full control of seizures was obtained. In the seventh patient the drug was stopped due to a skin rash. In conclusion LTG appears to be effective in resistant absence seizures in combination with valproic acid. Moreover, our preliminary data suggest that lamotrigine might be used as monotherapy in typical absence seizures. The advantages and disadvantages of LTG monotherapy in this type of epilepsy are discussed.     

Psychiatric disorders as “hidden” contraindications for presurgical VEEG in patients with refractory epilepsy: A retrospective cohort study in a tertiary center

Given the high frequency of psychiatric disorders (PDs) observed among patients with epilepsy, studies have highlighted the necessity of psychiatric evaluation for these patients, especially for those with refractory temporal lobe epilepsy with mesial temporal sclerosis (TLE-MTS) who are surgical candidates. Current evidence highlights the safety of video-electroencephalography (VEEG) as a means of investigation in patients with TLE-MTS and PDs. However, the presence of such disorders has still been seen as a contraindication for presurgical evaluation with VEEG in some epilepsy centers mainly because of the risk of negative behavioral events. The present retrospective cohort study performed in a Brazilian tertiary epilepsy center aimed to identify whether the presence of a PD remains a contraindication for presurgical VEEG. Clinical, sociodemographic, and psychiatric data from 41 patients who underwent VEEG as part of their presurgical evaluation were compared to data from 32 patients with refractory TLE-MTS who had not undergone VEEG. Psychiatric diagnoses were determined using the DSM-IV and ILAE criteria. Psychiatric disorders were diagnosed in 34 patients (46.6%). Major depressive disorder was the most frequent PD and was observed in 22 patients (30.1%). Anxiety disorders were observed in 14 patients (19.2%). Of the 41 patients (56.2%) who underwent presurgical VEEG, only 12 (29.2%) were found to have a PD during the presurgical psychiatric evaluation compared to 22 of the 32 (68.7%) who did not undergo VEEG (p = 0.001; RR = 2.35). The present findings suggest that the presence of a PD alone should not be a contraindication for VEEG monitoring and epilepsy surgery.     

EEG features of absence seizures in idiopathic generalized epilepsy: Impact of syndrome, age, and state

Purpose:   Factors influencing the electroencephalography (EEG) features of absence seizures in newly presenting children with idiopathic generalized epilepsy (IGE) have not been rigorously studied. We examined how specific factors such as state, provocation, age, and epilepsy syndrome affect the EEG features of absence seizures.
Methods:   Children with untreated absence seizures were studied using video-EEG recording. The influence of state of arousal, provocation (hyperventilation, photic stimulation), age, and epilepsy syndrome on specific EEG features was analyzed.
Results:   Five hundred nine seizures were evaluated in 70 children with the following syndromes: childhood absence epilepsy (CAE) 37, CAE+ photoparoxysmal response (PPR) 10, juvenile absence epilepsy (JAE) 8, juvenile myoclonic epilepsy (JME) 6, and unclassified 9. Polyspikes occurred in all syndromes but were more common in JME. They were brought out by drowsiness and sleep in fragments of generalized spike and wave (GSW). Polyspikes were more likely to occur during photic stimulation, but were not influenced by age independently. GSW was more likely to be disorganized in JME than JAE, and in JAE than CAE. Increasing age and levels of arousal were more likely to result in organized GSW. Factors specific to each child independently influenced EEG features; the nature of these factors has not been identified.
Discussion:   The EEG features of absence seizures are influenced by a complex interaction of age, epilepsy syndrome, level of arousal, provoking factors, and other intrinsic factors. Epilepsy syndrome alone cannot predict specific features of GSW; however, JME is more frequently associated with polyspikes and disorganization of the paroxysm.     

Idiopathic generalised epilepsy in adults manifested by phantom absences, generalised tonic-clonic seizures, and frequent absence status

OBJECTIVES—To describe the clinical and EEGfeatures of adult patients with very mild absences, late onsetgeneralised tonic clonic seizures, and frequent absence status.
METHODS—Patients were referrals to a clinic forepilepsies. They all had clinical assessment and EEG, video EEG, orboth for documentation of absences.
RESULTS—Of 86 adults with idiopathic generalisedepilepsies and EEG/video-EEG documented absences, 13 patients showedsimilar clinico-EEG features with: (a) "phantomabsences" consisting of mild ictal impairment of cognition associatedwith brief (3-4 s), generalised 3-4 Hz spike/multiple spike and slowwave discharges; (b) infrequent, mainly late onset,generalised tonic clonic seizures, and (c), absence statuswhich occurred in six of them either in isolation or terminating withgeneralised tonic clonic seizures. None of the patients had myoclonicjerks or photosensitivity. Two patients were father and daughter andanother patient had a family history of infrequent generalised tonicclonic seizures.
CONCLUSION—It seems that this is an idiopathicgeneralised epilepsy syndrome in adults which has not been previously recognised.

     

Diagnosing psychogenic nonepileptic seizures: Video-EEG monitoring,suggestive seizure induction and diagnostic certainty

Psychogenic nonepileptic seizures (PNES) can remain undiagnosed for many years, leading to unnecessary medication and delayed treatment. A recent report by the International League Against Epilepsy Nonepileptic Seizures Task Force recommends a staged approach to the diagnosis of PNES (LaFrance, et al., 2013). We aimed to investigate its practical utility, and to apply the proposed classification to evaluate the role of long-term video-EEG monitoring (VEEG) and suggestive seizure induction (SSI) in PNES workup.Using electronic medical records, 122 inpatients (mean age 36.0 ± 12.9 years; 68% women) who received the diagnosis of PNES at our epilepsy center during a 4.3-year time period were included. There was an 82.8% agreement between diagnostic certainty documented at discharge and that assigned retroactively using the Task Force recommendations. In a minority of cases, having used the Task Force criteria could have encouraged the clinicians to give more certain diagnoses, exemplifying the Task Force report's utility.Both VEEG and SSI were effective at supporting high level diagnostic certainty. Interestingly, about one in four patients (26.2%) had a non-diagnostic (“negative”) VEEG but a positive SSI. On average, this subgroup did not have significantly shorter mean VEEG recording times than VEEG-positive patients. However, VEEG-negative/SSI-positive patients had a significantly lower habitual seizure frequency than their counterparts. This finding emphasizes the utility of SSI in ascertaining the diagnosis of PNES in patients who do not have a spontaneous habitual event during VEEG due to, for example, low seizure frequency.     

Syndromes of Idiopathic Generalized Epilepsies Not Recognized by the International League Against Epilepsy

Summary:  This chapter assesses probable epileptic syndromes within the idiopathic generalized epilepsies (IGE) that have not yet been recognized by the International League Against Epilepsy (ILAE). Jeavons syndrome, a purely reflex IGE that predominantly manifests with eyelid myoclonia and electroencephalogram (EEG) abnormalities on eye closure, is the most distinct and undisputed of the syndromes. Another is autosomal-dominant cortical tremor, myoclonus, and epilepsy, a purely monogenic disorder that has been documented in numerous reports, mainly from Japan and Italy. Perioral myclonia with absences is certainly a seizure type that may constitute an IGE syndrome when it is associated with a number of other clinical and EEG manifestations. Similarly, many patients suffer for years from phantom absences, a type of mild absence, before a first generalized tonic-clonic seizure that usually occurs in adulthood. Both perioral myoclonia with absences and phantom absences are clinically significant because they are probably lifelong and are associated with a very high incidence (around 50%) of absence status epilepticus that may escape diagnosis and appropriate treatment. The position of early childhood IGE, which manifests mainly with typical absence seizures that are distinctly different from childhood absence epilepsy and other recognized IGE syndromes, is less clear. The prevalence of these syndromes is significant. Their identification allows better clinical management and is important for genetic research and counselling. In addition, their recognition permits application of exclusion criteria for a more purified definition and a better understanding of the true boundaries of the other IGE syndromes already accepted by the ILAE.