Classification of epileptic seizures: a comparison of two systems

Using sEMG to identify seizure semiology of motor seizures

PURPOSE

Accurate characterization and quantification of seizure types are critical for optimal pharmacotherapy in epilepsy patients. Technological advances have made it possible to continuously monitor physiological signals within or outside the hospital setting. This study tested the utility of single-channel surface-electromyography (sEMG) for characterization of motor epileptic seizure semiology.

METHODS

Seventy-one subjects were prospectively enrolled where vEEG and sEMG were simultaneously recorded. Three epileptologists independently identified and classified seizure events with upper-extremity (UE) motor activity by reviewing vEEG, serving as a clinical standard. Surface EMG recorded during the events identified by the clinical standard were evaluated using automated classification methods and expert review by a second group of three independent epileptologists (blinded to the vEEG data). Surface EMG classification categories included: tonic-clonic (TC), tonic only, clonic only, or other motor seizures. Both automated and expert review of sEMG was compared to the clinical standard.

RESULTS

Twenty subjects experienced 47 motor seizures. Automated sEMG event classification methods accurately classified 72 % (95 % CI [0.57, 0.84]) of events (15/18 TC seizures, 5/9 tonic seizures, 1/3 clonic seizures, and 13/17 other seizures). Three independent reviewers' majority-rule analysis of sEMG correctly classified 81 % (95 % CI [0.67, 0.91]) of events (16/18 TC seizures, 8/9 tonic seizures, 1/3 clonic seizures, and 13/17 other manifestations).

CONCLUSIONS

Continuous monitoring of sEMG data provides an objective measure to evaluate motor seizure activity. Using sEMG from a wearable monitor recorded from the biceps, automated and expert review may be used to characterize the semiology of events with UE motor activity, particularly TC and tonic seizures.

Differential diagnosis of a paroxysmal neurological event: Do neurologists know how to clinically recognize it?

PURPOSE

To investigate ability to recognize paroxysmal neurological events (PNE) based on video-recorded events alone in a group of physicians treating prevalent neurological conditions.

METHODS

Total of 12 patients' videos (6 epileptic seizures (ES), 4 psychogenic nonepileptic seizures (PNES), 2 other nonepileptic seizures (oNES)) were selected. Videos were displayed once to physicians blind to clinical data and final diagnosis. Physicians determined their clinical choice: ES, PNES, oNES, and I don't know (IDK). When ES was chosen, subjects determined type of ES: focal ES, secondary generalized tonic-clonic seizure (GTCS), primary GTCS, and IDK.

RESULTS

In total 145 physicians (62% female, mean age 46.2±9years) (neurologists 58.6%, neuropsychiatrists 25.5%, psychiatrists 5%, and neurology residents 10.3%) were enrolled. Physician's exposure to patients with epilepsy per week was diverse: ≤1 patient (43.7%); 1-7 patients (37.2%); >7 patients (14.5%). Reported frequency of observation of PNE was as follows: frequent (21.4%), sometimes (47.6%); rarely (26.9%); never (2.1%). Majority of subjects were not EEG readers (60.7%). Median percentage (Mdn%) of correct answers (CA) was 75% (range 25-100). Predictor of better PNE recognition was higher frequency of clinical exposure to PNE (OR 1.65; CI95% 1.11-2.45; p=0.013). Mdn% of ES CA was 83.3%, (range 33.3-100), and of PNES CA was 50% (range 0-100). Physicians were more accurate in ES than PNES identification (p<0,001). Mdn% of type of ES CA was 50%, (range 0-100).

CONCLUSIONS

We demonstrate the need for education about clinical features of PNE across subgroups of physicians who deliver neurological service, with emphasis on PNES and ES type classification.

Interobserver variability of seizure semiology between two neurologist and caregivers

PURPOSE

We aimed to compare the extent of inter-observer variability in the description of seizure semiology between both neurologists and caregivers.

METHOD

We prospectively investigated 93 consecutive patients monitored over the past 5 years in our video-EEG unit. The videotaped seizures of the patients were reviewed independently by two neurologists who were blind to the clinical data. The questionnaires were completed by neurologists and caregivers. Interobserver rate of agreement between neurologists and caregivers was analyzed by using the kappa analysis and intraclass correlation coefficients.

RESULTS

There was excellent agreement for questions regarding whether the patient's eyes remained open, laterality of head deviation, arm movements, and ictal period. On the other hand, interobserver rate of agreement was fair to moderate for the laterality of hand automatisms, the presence of nose-wiping, and oral clonic jerks.

CONCLUSION

Besides variability in interobserver agreement among clinicians, the variability or concordance between physicians and caregivers are also of great importance, especially in case of epilepsy, where the accurate description of the attacks is the major determinant of an accurate diagnosis.

The effect of thymoquinone on intractable pediatric seizures (pilot study)

INTRODUCTION

despite administration of numerous combinations of epileptic drugs, nearly 15% of childhood seizures are resistant to treatment and it is still a problem in pediatric practice. In traditional medicine, Nigella sativa was known to have anticonvulsant effects. Recent studies also have shown its anticonvulsant effects. Most of the properties of N. sativa or its extracts are mainly attributed to thymoquinone. It has been shown that thymoquinone has several therapeutic effects and no evidence of toxicity or side effects is reported.

MATERIALS AND METHODS

in this pilot, double-blinded crossover clinical trial study on children with refractory epilepsy, thymoquinone with dose of 1mg/kg was administered as an adjunctive therapy and its effects on frequency of seizures were compared with those of a placebo. Twenty-two patients entered in the study. They were assigned in two groups and received either thymoquinone or placebo for a period of four weeks, and then during the two weeks of wash out period, they received only their pre-existing anti-epileptic drugs; then, after cross-overing, they received thymoquinone or placebo for a period of four weeks again. During these periods their effects on seizure frequency were investigated.

RESULTS

the reduction of frequency of seizures at the end of first period in comparison with the same period before the study demonstrated a significant difference between two groups (thymoquinone and placebo) (P=0.04). Also reduction of frequency of seizure has shown significant difference between two groups at the end of second period in comparison with end of first period (P=0.02). The parental satisfaction showed significant difference between the two groups at the end of the first period (P=0.03).

CONCLUSION

it can be concluded that thymoquinone has anti-epileptic effects in children with refractory seizures.

Semiologic seizure classification: the effectiveness of a modular education program for health professionals in pediatrics

We tested the effectiveness of a modular education program on Semiologic Seizure Classification (SSC) in helping health professionals in pediatrics correctly recognize seizures in childhood. The study samples included 20 residents, 20 nurses, and 10 EEG technicians working in pediatrics. The study was conducted in two steps. First, a modular education program comprising CD-ROMs including 58 video clips of epileptic seizures designed for the original SSC was developed. Second, each participant took a pretest by viewing the pretest CD-ROM, participated in the modular education program with a CD-ROM, and finally took a posttest with the posttest CD-ROM. The pretest scores were found to be low in each subgroup of the study population: the average scores were 8 for the residents (minimum 4-maximum 10), 2 for the nurses (min 0-max 4), and 2.5 for the EEG technicians (min 0-max 8). After participating in the modular education program, correct recognition of seizures increased in the posttest: the average scores were 15.5 for the residents (min 9-max 20), 15 for the nurses (min 13-max 20), and 13.5 for the EEG technicians (min 3-max 19). The increase in the scores in the subgroups and in all study groups in general was found to be statistically significant (P<0.05). The modular education program developed for SSC was found to be highly effective in teaching health professionals working in general pediatric clinics to correctly recognize seizure types.

Restoring melancholia in the classification of mood disorders

The present DSM criteria for major depression poorly identify samples for treatment selection, prognosis, and assessments of pathophysiology. Melancholia, in contrast, is a disorder with definable clinical signs that can be verified by laboratory tests and treatment response. It identifies more specific populations than the present system and deserves individual identification in psychiatric classification. Its re-introduction will refine diagnosis, prognosis, treatment selection, and studies of pathophysiology of a large segment of the psychiatrically ill.

Semiological seizure classification: before and after video-EEG monitoring of seizures

The study objective was to assess the applicability and reliability of the semiological seizure classification in children with epilepsy in outpatient clinics. Ninety patients (age range, 2-16 years) who experienced clinical seizures during prolonged video-electroencephalogram (EEG) monitoring were evaluated. Semiological seizure classification was performed, first based on history obtained from parents of the patient during outpatient follow-up visits and then based on video EEG-monitoring. Kappa statistics (kappa) were used to evaluate the consistency of the two rounds of semiological seizure classification. Classification based on history yielded the following distribution: simple motor seizures (66.3%), aura (28%), complex motor seizures (15.8%), special seizures (15.8%), dialeptic seizures (9.3%), and autonomic seizures (3.7%). Classification based on video EEG-monitoring yielded a different distribution: simple motor seizures (55.7%), complex motor seizures (26.9%), automotor seizures (26.9%), aura (23%), dialeptic seizures (22.1%), special seizures (9.6%), and autonomic seizures (1.9%). Negative myoclonic seizures (kappa = 1, P = 0.000) and hypermotor seizures (kappa = 0.85, P = 0.000) had excellent consistency; somatosensory aura (kappa = 0.26, P = 0.012) and automotor seizures (kappa = 0.28, P = 0.004) had the lowest consistency. The families or doctors often defined simple motor seizures (decrease of 10.6% from before to after monitoring, kappa = 0.44); the proportion of complex motor seizures changed rather from before to after monitoring (11.1%, kappa = 0.33). Generally, parents can describe seizures quite well. We suggest that semiological seizure classification is a reliable method applicable for everyday use during outpatient visits, especially if seizure semiology is evaluated individually for each component or if the semiological seizure classification is modified or refined for some seizure components (tonic, clonic, versive, conscious, automotor seizures).

Resurrecting melancholia

OBJECTIVE

To define melancholia as a distinct mood disorder, identified by unremitting depressed mood, vegetative dysfunction, and psychomotor disturbances, verifiable by neuroendocrine tests, and treatable by electroconvulsive therapy and tricyclic antidepressants.

METHOD

A review of the literature of two centuries finds descriptions of severe mood disorders, either depression or mania or circular, defined as 'melancholia.' In the 1980 diagnostic revision (DSM-III), melancholia was relegated to a features specifier only.

RESULTS

DSM classification criteria develop heterogeneous patient samples that are neither guides to prognosis nor to treatment response, and confound studies of pathophysiology. Within the large population of mood disorders, a syndrome of melancholia is identifiable by specific behaviors, vegetative signs, and validated by neuroendocrine abnormalities (cortisolemia). Populations so identified are clinically homogeneous and have improved treatment responses. Patients meeting criteria for melancholia are now identified as psychotic depressed, geriatric depressed, postpartum psychosis, and pharmacotherapy resistant.

CONCLUSION

The review supports the establishment of melancholia by empirically derived criteria rather than by a checklist is an alternative to the major depression choice and offers an improved model for psychiatric classification.

Basic principles of the ILAE syndrome classification

The basic principles of the ILAE syndrome classification can be summarised as: clear definitions; reference to the seizure classification; expert consensus based on literature research; providing a taxonomy rather than a diagnostic manual; use of the dichotomies generalised versus localisation-related and idiopathic versus symptomatic; openness for the incorporation of new findings; and promotion of nosological thought. In fact, the publication of the classification stimulated research, especially in the fields of genetics, reflex epileptic mechanisms and advanced imaging, which will probably lead to a major revision of the nosology of epilepsies. Both localisation-related and "generalised" idiopathic epilepsies are about to be understood as related variants of system disorders of the brain, with an ictogenesis making pathological use of existing functional anatomic networks.

Classification of partial seizure symptoms in genetic studies of the epilepsies

OBJECTIVES

To develop standardized definitions for classification of partial seizure symptoms for use in genetic research on the epilepsies, and evaluate inter-rater reliability of classifications based on these definitions.

METHODS

The authors developed the Partial Seizure Symptom Definitions (PSSD), which include standardized definitions of 41 partial seizure symptoms within the sensory, autonomic, aphasic, psychic, and motor categories. Based on these definitions, two epileptologists independently classified partial seizures in 75 individuals from 34 families selected because one person had ictal auditory symptoms or aphasia. The data used for classification consisted of standardized diagnostic interviews with subjects and family informants, and medical records obtained from treating neurologists. Agreement was assessed by kappa.

RESULTS

Agreement between the two neurologists using the PSSD was "substantial" or "almost perfect" for most symptom categories.

CONCLUSIONS

Use of standardized definitions for classification of partial seizure symptoms such as those in the Partial Seizure Symptom Definitions should improve reliability and accuracy in future genetic studies of the epilepsies.

Management Guidelines for Children with Idiopathic Generalized Epilepsy

Most idiopathic generalized epilepsy (IGE) begins in childhood. Clinicians face many important management decisions for these children; however the existing literature provides little scientific guidance.

TIME OF DIAGNOSIS

At the time of presentation, it is unclear how accurately IGE seizures and syndromes are diagnosed and how consistent are the EEG correlates. Investigations beyond EEG are of uncertain value but probably are not needed. Selection of an initial antiepileptic drug (AED) is not based on any adequately powered, blinded, randomized comparative trials; however, reasonable evidence supports the use of valproic acid (VPA), lamotrigine and ethosuccimide as initial treatment for childhood absence epilepsy (CAE). Many large case series suggest the value of VPA for juvenile myoclonic epilepsy (JME) but the relative value of other, newer AEDs has not been established.

FIRST YEARS OF TREATMENT

Once AED treatment is started, it is difficult to establish that absence seizures are completely controlled and the importance of interictal spike-wave discharge remains uncertain. The value of restrictions on the child's activities has not been well studied; however serious accidents appear to be a justifiable concern in children with uncontrolled absence. Assessing the risk from photosensitivity in JME is challenging.

LENGTH OF TREATMENT

The optimal length of treatment for IGE is unclear. There is a high rate of remission in CAE when AEDs are discontinued after 1-2 years of seizure freedom; however, long-term remission in CAE occurs in only 65%. It is usually assumed that treatment for JME is life long, although about 10% appear to have permanent remission in adolescence. Discontinuing AED treatment in JME requires a very individual risk assessment.

PREPARATION FOR ADULT LIFE

Long-term social outcome for children with CAE is often unsatisfactory even if the epilepsy remits. The reasons are unclear and successful interventions have not been described. Long-term social outcome for JME has not been adequately described.

CONCLUSIONS

Further research is needed to justify the direction of many of the necessary management decisions in the diagnosis and treatment of IGE syndromes.

Comparison of classifications of seizures: a preliminary study with 28 participants and 48 seizures

PURPOSE

Our aim was to compare three available seizure classifications (SCs), namely, the international classification of epileptic seizures published in 1981 (ICES; Epilepsia 1981;22:489-50); the semiological seizure classification (SSC) by H. Luders, J. Acharya, C. Baumgartner, et al. (Epilepsia 1998;39:1006-13; Acta Neurol Scand 1999;99:137-41); and the proposal of a new diagnostic scheme for seizures (PDSS) by J. Engel, Jr. (Epilepsia 2001;42:796-803) published in 2001. The three SCs were compared with respect to diagnostic success rates, usefulness, and consistency by a large group of neurologists in this preliminary study.

METHODS

After a training period, 28 blindfed participants with different levels of experience with epilepsy classified videos or written descriptions of 48 randomly selected seizures according to the three SCs. Definite diagnoses of the seizures were established based on all clinical, ictal/interictal EEG, and MRI data. All the participants answered a questionnaire concerning their preferences for SCs after the study.

RESULTS

The overall diagnostic success rates were 81.4% for ICES, 80.5% for PDSS, and 87.5%, for SSC. Various parameters concerning experience with epilepsy affected success rates positively, without reaching statistical significance, whereas experience with epilepsy surgery appeared to be a parameter significantly affecting the success rate in all SCs. In reliability analysis, Cronbach's alpha was 0.94 for ICES, 0.88 for PDSS, and 0.70 for SSC, all showing good agreement in the group. Nineteen reviewers chose SSC, eight chose ICES, and one chose PDSS as their preference in the questionnaire, completed after the end of the study.

CONCLUSION

The results of this preliminary study demonstrate that with proper training, physicians treating epilepsy patients can handle new SCs, and emphasize the need for revision of the current classification.

A pilot study of compassionate use of Levetiracetam in patients with generalised epilepsy

Levetiracetam (LEV) has proven effective for partial seizures, suggesting the need to trial it in generalised epilepsy. Ten patients with generalised epilepsy were given compassionate use of LEV as a pilot study, attending 7 visits with seizure count (using diary) and compliance checked (pill count) with option for long term use. Seizure frequency was compared to baseline mean of the last 2 months and mean of follow-up. Patients were commenced on 500 mg I b.d, and titrated to a maximum of 3 g/day. There were 10 patients (7 females), aged 28-48, of whom 6 had primary generalised epilepsy (PGE) and 4 Lennox-Gastaut syndrome (LGS). At 7 month evaluation: 1 was seizure-free, 1 was 70% reduced, 3 were > or = 50% reduced, 2 were 30-35% reduced; 1 had no change; 1 was 10% increased and 1 was excluded because confounding pseudo seizures. Follow-up was 8-17 months (mean 13.8). The seizure-free patient became pregnant and had 2 seizures, but has been seizure-free for 2 months, at time of submission. A 16 months are three months seizure-free. One was 50% reduced at months 6 and 7, was 2 months seizure-free but then reverted to 50% per baseline. With respect to LGS, 1 withdrew due to aggression, 2 had 40% and 35% reduction at 13 and 15 months respectively and 1 had 25% increase (10% at 7 months). All patients were compliant. These data suggest that LEV may be effective for generalised epilepsy with a need for a larger clinical trial.

Specific Epileptic Syndromes Are Rare Even in Tertiary Epilepsy Centers: A Patient‐oriented Approach to Epilepsy Classification

PURPOSE

To assess the practicability and reliability of a five-dimensional patient-oriented epilepsy classification and to compare it with the International League Against Epilepsy (ILAE) classification of epilepsy and epileptic syndromes. The dimensions consist of the epileptogenic zone, semiologic seizure type(s), etiology, related medical conditions, and seizure frequency.

METHODS

The 185 epilepsy patients (94 adults, 91 children, aged 18 years or younger) were randomly selected from the database of a tertiary epilepsy center and the general neurological department of a metropolitan hospital (28 adults). The charts were reviewed independently by two investigators and classified according to both the ILAE and the patient-oriented classification. Interrater reliability was assessed, and a final consensus among all investigators was established.

RESULTS

Only four (4%) adults and 19 (21%) children were diagnosed with a specific epilepsy syndrome of the ILAE classification. All other patients were in unspecific categories. The patient-oriented classification revealed that 64 adults and 56 children had focal epilepsy. In an additional 34 adults and 45 children, the epileptogenic zone could be localized to a certain brain region, and in 14 adults and five children, the epileptogenic zone could be lateralized. Fourteen adults and 21 children had generalized epilepsy. In 16 adults and 14 children, it remained unclear whether the epilepsy was focal or generalized. Generalized simple motor seizures were found in 66 adults and 52 children, representing the most frequent seizure type. Etiology could be determined in 40 adults and 45 children. Hippocampal sclerosis was the most frequent etiology in adults (10%), and cortical dysplasia (9%), in children. Seven adults and 31 children had at least daily seizures. Seventeen adults and 26 children had rare or no seizures at their last documented contact. The most frequent related medical conditions were psychiatric disorders and mental retardation. Interrater agreement was high (kappa values of 0.8 to 0.9) for both the patient-oriented and the ILAE classification.

CONCLUSIONS

Specific epilepsy syndromes included in the current ILAE classification are rare even in a tertiary epilepsy center. Most patients are included in unspecific categories that provide only incomplete information. In contrast, all of the patients could be classified by the five-dimensional patient-oriented classification, providing all essential information for the management of the patients with a high degree of interrater reliability.

Seizure Semiology in the Elderly: A Video Analysis

PURPOSE

To describe the seizure semiology of patients older than 60 years and to compare it with that of a control group of younger adults matched according to the epilepsy diagnosis.

METHODS

Available videotapes of all patients aged 60 years and older who underwent long-term video-EEG evaluation at the Cleveland Clinic Foundation (CCF) between January 1994 and March 2002 were analyzed by two observers blinded to the clinical data. A younger adult control group was matched according to the epilepsy diagnosis, and their seizures also were analyzed.

RESULTS

Fifty-four (3.3%) of the 1,633 patients were 60 years or older at the time of admission. For 21 of them, at least one epileptic seizure was recorded. Nineteen patients had focal epilepsy (nine temporal lobe, two frontal lobe, two parietal lobe, eight nonlocalized), and two patients had generalized epilepsy. Seventy-three seizures of the elderly patients and 85 seizures of the 21 control patients were analyzed. In nine elderly patients and 14 control patients, at least one of their seizures started with an aura. Eleven elderly patients and 19 control patients lost responsiveness during their seizures. Approximately two thirds of the patients in both groups had automatisms during the seizures. Both focal and generalized motor seizures (e.g., clonic or tonic seizures) were seen less frequently in the elderly.

CONCLUSIONS

Only a small percentage of the patients admitted to a tertiary epilepsy referral center for long-term video-EEG monitoring are older than 60 years. All seizure types observed in the elderly also were seen in the younger control group, and vice versa. Simple motor seizures were seen less frequently in the elderly.

Classification of seizures and epilepsy

The management of seizures and epilepsy begins with forming a differential diagnosis, making the diagnosis, and then classifying seizure type and epileptic syndrome. Classification guides treatment, including ancillary testing, management, prognosis, and if needed, selection of the appropriate antiepileptic drug (AED). Many AEDs are available, and certain seizure types or epilepsy syndromes respond to specific AEDs. The identification of the genetics, molecular basis, and pathophysiologic mechanisms of epilepsy has resulted from classification of specific epileptic syndromes. The classification system used by the International League Against Epilepsy is periodically revised. The proposed revision changes the classification emphasis from the anatomic origin of seizures (focal vs generalized) to seizure semiology (ie, the signs or clinical manifestations). Modified systems have been developed for specific circumstances (eg, neonatal seizures, infantile seizures, status epilepticus, and epilepsy surgery). This article reviews seizure and epilepsy classification, emphasizing new data.

[Classification of seizures in childhood obtained from seizures symptomatology descriptions of parents and guardians]

The aim of this study was to determine the frequency of seizures descriptions from parents and guardians of epileptic children which are useful for clinical classification of epileptic seizures. The data were obtained from 112 children using recurrent and spontaneous epileptic seizures as the selection criteria. The study was realized in two parts. In the part I the following aspects were studied: age of onset and the preictal, ictal and postictal symptoms. In the part II the specific kinds of seizures were classified by motor semiology, as convulsive and nonconvulsive, and by using the International League Against Epilepsy (ILAE,1981) scheme. The results showed that 42.9% patients present epileptic auras and 36.6% present lateralizing signs. Concerning the semiologic events were motor in 95.5%, neurovegetative in 56.3%, psychic in 32.1%, and neurosensorials in 4.5%. Finally, the ILAE schema classified the seizures as partial in 59.9%, as generalized in 27.2%, and as not classified in 12.5%. All findings demonstrate a good level of clinical semiology information from parents and guardians that allow us to classify 87.5% of the seizures, and identify auras and lateralized signs. Theses results permit us to conclud that if a standard protocol is used, the descriptions from parents and guardian of epileptic children appears to be very reliable to clinical classification of epileptic seizure.

Childhood epilepsy: what is the evidence for what we think and what we do?

This article reviews the strength of the evidence that underlies the current approach to the management of childhood epilepsy. The authors reviewed published, peer-reviewed English literature accessed through PubMed and Cochrane reviews with evidence rated as Class 1 (strongest) to Class 4 (weakest). There is considerable inaccuracy in the diagnosis of seizures and epilepsy syndromes. Sound information supports the consensus that the diagnosis of epilepsy should await two unprovoked seizures. Population-based studies indicate that remission from childhood onset epilepsy occurs in at least 50% of children. It is easier to predict a good seizure outcome than a poor one. Absence of concomitant neurologic handicap and onset before about 12 years of age are the most consistent predictors of remission. Intractability is poorly defined and difficult to predict until several antiepilepsy drugs have been used and failed to control the seizures. Most epilepsy syndrome diagnoses do not yield an accurate prognosis. Social outcome appears unsatisfactory in about 50% of cases without intellectual handicap. Death is rare in childhood epilepsy. Those without severe neurologic handicaps have the same mortality as the general population. We identified only 27 published randomized trials of antiepilepsy drugs in children that compare the efficacy of antiepilepsy drugs, offer treatment of syndromes currently without successful treatment, or have negative effects. There is a pressing need for better definitions of seizures and epilepsy syndromes. The causes of poor social outcome are unclear. Intractability needs a clear definition and randomized trials comparing treatment regimes are sadly lacking.

Application of semiological seizure classification to epileptic seizures in children

To better define seizure characteristics and to examine whether semiological seizure classification (SSC) can be appropriately applied to the seizures of infants and children, we studied 152 videotaped seizures recorded in 133 children. Seizure semiology was described on the basis of a series of behavioural, sensory, and motor phenomena according to SSC. Special emphasis was placed on whether one semiology can be representative of a patient's whole semiology sequence. If one semiology was able to represent the whole sequence, the seizure was classified according to SSC. Ninety of 152 seizures (59.2%) could be classified as a single seizure type by SSC. However, only 19 of 53 seizures (35.9%) consisting of two semiologies, three of 24 seizures (12.5%) consisting of three semiologies, and one of eight seizures (12.5%) consisting of four semiologies could be classified according to SSC. Although SSC is very efficient, it is more accurately a descriptive terminology for clinical ictal events than a classification system.

The localizing value of the abdominal aura and its evolution: a study in focal epilepsies

OBJECTIVE

To evaluate the localizing value of abdominal aura and its evolution into other seizure types.

METHODS

The seizures of 491 consecutive patients with focal epilepsies were prospectively classified according to a recently introduced semiologic seizure classification. All patients underwent prolonged EEG video monitoring and MRI scan. Two hundred twenty-three patients (45%) had temporal lobe epilepsies (TLE); 113 patients (23%) had extratemporal epilepsies; and for 155 (32%) patients, the epilepsy could not be localized to one lobe.

RESULTS

Abdominal auras were more frequent with TLE (117 of 223 patients, 52%) than in extratemporal epilepsy (13 of 113 patients, 12%, p < 0.0001) and more frequent in mesial TLE (70 of 110 patients, 64%) than in neocortical TLE (16 of 41 patients, 39%, p = 0.007). No preponderance to one side existed. Abdominal auras were followed by ictal oral and manual automatisms (automotor seizure) in at least one seizure evolution in all patients with TLE (117 patients, 100%). In contrast, only two patients with extratemporal epilepsy (2 of 13 patients, 15%, p < 0.0001) had abdominal auras evolving into automotor seizures. An abdominal aura is associated with TLE with a probability of 73.6%. The evolution of an abdominal aura into an automotor seizure, however, increases the probability of TLE to 98.3%.

CONCLUSIONS

These results demonstrate that evolution of abdominal aura into automotor seizure permits differentiation between temporal lobe epilepsy and extratemporal epilepsy, showing that analysis of seizure evolution provides more localizing information than does the frequency of particular seizure types.

Seizure types, epilepsy syndromes, etiology, and diagnosis

The clinical manifestation of epileptic seizures may vary widely from patient to patient, depending on the region of the brain involved. Over the centuries, many seizure classification systems have been used, and the current most widely used classification system is that of the International League Against Epilepsy (ILAE). The ILAE system divides seizures into those of partial onset and those of generalized onset, depending on whether the initial clinical manifestations indicate that one cortical region or both hemispheres are involved at the onset of the seizure. Partial seizures are then divided into simple partial seizures, in which a fully conscious state is retained, or complex partial seizures, in which consciousness is impaired. A more recent classification system based purely on symptom features and signs has been proposed, and this system may provide advantages for localization, and especially for surgical evaluation. Epilepsy is a condition characterized by recurrent unprovoked seizures. Epilepsy may be idiopathic, cryptogenic, or symptomatic. Idiopathic epilepsies are generally genetic, and while many such syndromes have been described, advances in molecular genetics will undoubtedly reveal many more syndromes in the near future. Cryptogenic epilepsies are those in which an underlying cause is suspected, but the etiology remains undetected. Epilepsies for which there is an underlying structural cause or major metabolic derangement are considered symptomatic. Common causes and diagnostic evaluation are described in this article.