A propositional AI system for supporting epilepsy diagnosis based on the 2017 epilepsy classification: Illustrated by Dravet syndrome.

PURPOSE: The 2017 epilepsy and seizure diagnosis framework emphasizes epilepsy syndromes and the etiology-based approach. We developed a propositional artificial intelligence (AI) system based on the above concepts to support physicians in the diagnosis of epilepsy. METHODS: We analyzed and built ontology knowledge for the classification of seizure patterns, epilepsy, epilepsy syndrome, and etiologies. Protégé ontology tool was applied in this study. In order to enable the system to be close to the inferential thinking of clinical experts, we classified and constructed knowledge of other epilepsy-related knowledge, including comorbidities, epilepsy imitators, epilepsy descriptors, characteristic electroencephalography (EEG) findings, treatments, etc. We used the Ontology Web Language with Description Logic (OWL-DL) and Semantic Web Rule Language (SWRL) to design rules for expressing the relationship between these ontologies. RESULTS: Dravet syndrome was taken as an illustration for epilepsy syndromes implementation. We designed an interface for the physician to enter the various characteristics of the patients. Clinical data of an 18-year-old boy with epilepsy was applied to the AI system. Through SWRL and reasoning engine Drool's execution, we successfully demonstrate the process of differential diagnosis. CONCLUSION: We developed a propositional AI system by using the OWL-DL/SWRL approach to deal with the complexity of current epilepsy diagnosis. The experience of this system, centered on the clinical epilepsy syndromes, paves a path to construct an AI system for further complicated epilepsy diagnosis.

The visual system in eyelid myoclonia with absences.

OBJECTIVE: To investigate the functional and structural brain correlates of eyelid myoclonus and absence seizures triggered by eye closure (eye closure sensitivity [ECS]). METHODS: Fifteen patients with eyelid myoclonus with absences (EMA, Jeavons syndrome), 14 patients with idiopathic generalized epilepsies (IGE) without ECS, and 16 healthy controls (HC) underwent an electroencephalography (EEG)-correlated functional magnetic resonance imaging (fMRI) and voxel brain morphometry (VBM) protocol. The functional study consisted of 30-second epochs of eyes-open and eyes-closed conditions. The following EEG events were marked and the relative fMRI maps obtained: (1) eye closure times, (2) spontaneous blinking, and (3) spontaneous and eye closure-triggered spike and wave discharges (SWD; for EMA and IGE). Within-group and between-groups comparisons were performed for fMRI and VBM data as appropriate. RESULTS: In EMA compared to HC and IGE we found: (1) higher blood oxygenation level-dependent (BOLD) signal related to the eye closure over the visual cortex, the posterior thalamus, and the network implicated in the motor control of eye closure, saccades, and eye pursuit movements; and (2) increments in the gray matter concentration at the visual cortex and thalamic pulvinar, whereas decrements were observed at the bilateral frontal eye field area. No BOLD differences were detected when comparing SWD in EMA and IGE. INTERPRETATION: Results demonstrated altered anatomo-functional properties of the visual system in EMA. These abnormalities involve a circuit encompassing the occipital cortex and the cortical/subcortical systems physiologically involved in the motor control of eye closure and eye movements. Our work supports EMA as an epileptic condition with distinctive features and provides a contribution to its classification among epileptic syndromes.

The classification and differential diagnosis of absence seizures with short-term video-EEG monitoring during childhood.

Absence seizures are idiopathic epilepsies characterized by impairment of consciousness and generalized 2.5-4 Hz spike and slow wave discharges. This prospective study was performed to classify and define properties of subgroups of absence epilepsies. We included 31 patients, of whom seven were in the differential diagnosis group. On admission, absence epilepsy provisional diagnosis was considered in 16 patients clinically and in the other 15 patients based on routine EEG findings. Ictal EEGs were recorded by video-EEG monitoring in 23 of the patients (totally 202 ictal recordings). Patients were diagnosed as childhood absence epilepsy (n=8), juvenile absence epilepsy (n=10), juvenile myoclonic epilepsy (n=3), eyelid myoclonia with absences (n=2), and perioral myoclonia with absences (n=1). Neuroimaging, video-EEG monitoring and especially ictal recordings are important for classification of epilepsies in addition to history, physical examination and routine EEG findings. Video-EEG monitoring is required to classify, to make differential diagnosis and to determine the treatment plan and prognosis.

Borderline Dravet syndrome: a useful diagnostic category?

The term "borderline" severe myoclonic epilepsy of infancy (SMEIB) has been used to designate patients in whom myoclonic seizures or generalized spike and wave activity are absent. It has also been used loosely to indicate mild forms of the syndrome. It is now acknowledged that the course and outcome of patients with SMEIB are the same as in the core syndrome. The rate of patients exhibiting SCN1A gene mutations is also similar, and it has been observed that the same mutations can cause both typical and "borderline" forms, indicating causal homogeneity. Defining a borderline form of a syndrome would mean setting the criteria of semiology and severity whereby a given phenotype falls within and outside the core syndrome. Such process has never been made for Dravet syndrome and is of course unrealistic in view its polymorphic expression. The eponym Dravet syndrome has been preferred to designate a syndrome spectrum that also embraces SMEIB. Therefore the term "borderline" Dravet syndrome is improper. The definition "mild form" of Dravet syndrome would certainly be more suitable to indicate those patients exhibiting a less severe or incomplete form of the syndrome. Variability in severity favors the concept that SCN1A loss of function causes a spectrum of epilepsy phenotypes in which seizures, often prolonged and precipitated by fever, are the prominent feature and schematic subdivisions would be inappropriate, at least in the early stages. An initial definition of SCN1A gene-related epilepsy would perhaps be more suitable when a mutation of this gene is ascertained and the clinical picture is still ill defined.

Dravet syndrome history.

Severe myoclonic epilepsy of infancy (SMEI) is a complex form of epilepsy that was first described in France in 1978. Because the myoclonic component of this epilepsy is not always present and because some variability has been observed in the symptomatology, the name was changed to Dravet syndrome in 1989. The genetic aetiology of this epilepsy was discovered in 2001, and since then numerous studies have contributed to a better knowledge of the disease. Around 70% of affected patients are carriers of a mutation on the alpha subunit of the SCN1A gene. An accurate analysis of the clinical features leads to the distinction between typical and atypical forms, both with the same unfavourable prognosis and the same genetic background. However, many studies are being conducted in order to establish correlations between phenotypes and genotypes, and to understand the factors underlying the cognitive impairment of the affected patients.

Photoparoxysmal response and its characteristics in a large EEG database using the SCORE system.

OBJECTIVE: To characterize photoparoxysmal EEG response (PPR) using a standardized protocol of intermittent photic stimulation (IPS) and standardized definitions for PPR, classified into six types. METHODS: Using the SCORE system (Standardized Computer-Based Organized Reporting of EEG) we prospectively built a large database of standardized EEG annotations. In this study, we extracted the features related to PPR from the structured dataset consisting of 10,671 EEG recordings with IPS, from 7,188 patients. RESULTS: The standardized IPS protocol elicited PPR in 375 recordings (3.5%), in 288 patients (4%), with a preponderance among young (11-20 years) and female patients (67%). PPR was persistent in patients with multiple recordings. The most frequent type of PPR was activation of preexisting epileptogenic area (58%), followed by generalized-PPR limited to the stimulus train (22%). We could not find any recording with self-sustained posterior response. Seizures were elicited in 27% of patients with PPR, most often myoclonic seizures and absences, in patients with self-sustained generalized PPR. CONCLUSIONS: The most common type of PPR was accentuation of preexisting epileptogenic area. Self-sustained posterior response could not be documented. Self-sustained generalized-PPR had the highest association with seizures. SIGNIFICANCE: Using standardized stimulation protocol and definitions for PPR types, IPS provides high diagnostic yield.

[Myoclonus and epilepsy: diagnosis and pathophysiology]. / Myoclonies et myoclonies épileptiques: orientation diagnostique et connaissances physiopathologiques.

Myoclonus presents as a sudden brief involuntary jerk triggered by the central nervous system. Electromyographic studies enable determining whether the jerk is caused by a muscular contraction, i.e. positive myoclonus, or by an interruption of muscular activity, i.e. negative myoclonus. Many classifications have been proposed, reflecting our lack of understanding about myoclonus. Myoclonus is a symptom and should never be considered as a diagnosis. Clinical history and physical examination are the basis to diagnosis. Clinical neurophysiology testing can reveal a neuroanatomical localization and certain patterns have some etiological specificity. Etiological hypotheses can be put forward on the basis of clinical and neurophysiological data. The cortex is the most commonly identified source of myoclonus, but the subcortical area and spinal area can also be involved. Myoclonus is considered epileptic when it is combined with an epileptiform discharge on the EEG. The International Classification of Epileptic Syndromes should be applied in this situation. Myoclonic epilepsies are a collection of syndromes in which myoclonic seizures are a prominent feature. Myoclonus can occur as one among several seizure components, as the only manifestation of seizure, or as one of multiple seizure types within an epileptic syndrome. Neurophysiological studies are needed to investigate the pathophysiological mechanisms of the myoclonus. Electrophysiological studies report that myoclonic seizures are produced through a cortical generator via a polysynaptic mechanism acting on muscles. Apparently, the epileptiform discharges stimulate the motor cortex resulting in myoclonus jerk. Despite recent progress, advances are still needed to achieve a better understanding of the pathophysiological mechanisms involved in myoclonus. In myoclonic epileptic syndromes, more useful information can probably be obtained from studies grouping several patients with a same epileptic syndrome than from single case reports.

Crossing the lines between epilepsy syndromes: a myoclonic epilepsy variant with prominent eyelid myoclonia and atonic components.

Accurate diagnosis of a distinct epilepsy syndrome is based on well-defined electroclinical features that differentiate separate nosological entities. In clinical practice, however, syndromes may overlap and cases may present with unusual manifestations posing a diagnostic challenge. This heterogeneity has been documented in several cases presenting with eyelid myoclonia with or without absences (EMA) diagnosed either as Jeavons syndrome (JS) variants or as genetic generalised epilepsies defined by the presence of this unique clinical entity. The hallmark of JS is the triad: (1) eyelid myoclonia with or without absences, (2) eye closure-induced paroxysms, and (3) photosensitivity. The presence of massive myoclonus, intellectual disability, or slowing of the EEG background are not typical features of the syndrome and may cause delay in making the correct diagnosis. Adding to the variability of clinical features, we describe two female paediatric patients with probable genetic epilepsy who presented with EMA but demonstrated clear atypical features, such as prominent myoclonic seizures, atonic components on video-EEG, and cognitive impairment. We also note the presence of interictal and ictal posterior discharges during eyelid myoclonia in one, supporting similar previous observations leading to consideration of EMA as an occipital cortex-initiated seizure activity. [Published with video sequences on www.epilepticdisorders.com].

Some genetic and biochemical aspects of myoclonus.

Can a gene defect be responsible for the occurrence in an individual, at a particular age, of such a muscle twitch followed by relaxation called: "myoclonus" and defined as sudden, brief, shock-like movements? Genetic defects could indeed determine a subsequent cascade of molecular events (caused by abnormal encoded proteins) that would produce new aberrant cellular relationships in a particular area of the CNS leading to re-built "myoclonogenic" neuronal networks. This can be illustrated reviewing some inherited neurological entities that are characterized by a predominant myoclonic picture and among which a clear gene defect has been identified. In the second part of this chapter, we will also propose a new point of view on how some structural genes could, under certain conditions, when altered, produced idiopathic generalized epilepsy with myoclonic jerks, taking juvenile myoclonic epilepsy (JME) and the myoclonin (EFHC-1) gene as examples.

Idiopathic generalized epilepsy of adolescence: are the syndromes clinically distinct?

Juvenile myoclonic epilepsy, juvenile absence epilepsy, and epilepsy with generalized tonic-clonic seizures (GTCS) on awakening are the three syndromes of idiopathic generalized epilepsy of adolescent onset currently included in the classification of epilepsy syndromes of the International League Against Epilepsy (ILAE). Although they differ in their predominant seizure types, the syndromes share several clinical features, thus giving rise to questions of phenotypic overlap and purity. We studied the clinical features of 101 patients with idiopathic generalized epilepsy beginning in adolescence. A standardized interview was used to elucidate seizure phenomenology, precipitants, frequency, and response to treatment. Groups defined by seizure type were compared and their similarities examined. The group with myoclonic but not absence seizures (21 patients) corresponded to the ILAE syndrome of juvenile myoclonic epilepsy, whereas those with absences but not myoclonus (37 patients) resembled juvenile absence epilepsy. Twenty-six patients shared the features of juvenile myoclonic epilepsy and juvenile absence epilepsy. Epilepsy with GTCS on awakening was not a specific syndromic entity; 10 patients had this seizure type alone. Seven patients were without a syndromic diagnosis. In these patients only GTCS occurred, but neither on awakening nor in the evening period of relaxation. We conclude that whilst syndromes of idiopathic generalized epilepsy of adolescence can be recognized, the current classification does not include all patients. In addition, the boundaries between the syndromes are indistinct, suggesting underlying neurobiological, possibly genetic, relationships.

Myoclonus and epilepsy in childhood: a review of treatment with valproate, ethosuximide, lamotrigine and zonisamide.

Based on small numbers of patients, it is possible to make the following suggestions rather than categorical statements. For myoclonic seizures and epilepsies which are not otherwise specified, valproate seems of proven efficacy. Ethosuximide may be a useful adjunct. The exact place of lamotrigine, which controls some myoclonia and makes them worse in other patients, requires further study. The findings are clearer when specific syndromes are considered. Valproate is the treatment of first choice for benign myoclonic epilepsy in infants, myoclonic astatic epilepsy, epilepsy with myoclonic absences, eyelid myoclonia with absences, juvenile myoclonic epilepsy and progressive myoclonus epilepsy. The addition of ethosuximide to valproate can be helpful to those with myoclonic absences, where this combination appears more beneficial than either valproate or ethosuximide alone and in eyelid myoclonia with absences. Lamotrigine can be effective therapy for juvenile myoclonic epilepsy and eyelid myoclonia with absences when used alone and, in conjunction with other antiepileptic drugs (AED) (usually valproate) for early myoclonic encephalopathy, myoclonic-astatic epilepsy and particularly, epilepsy with myoclonic absences. The myoclonia of infantile neuronal ceroid lipofuscinosis respond to lamotrigine. Severe myoclonic epilepsy of infants usually worsens with lamotrigine, but occasionally, children improve. Zonisamide added to clonazepam and valproate or a barbiturate, can reduce the cascade of myoclonia in progressive myoclonus epilepsies for at least 2 years, but relapse may occur thereafter.

Recognizing and classifying epileptic seizures and epileptic syndromes.

The appropriate diagnosis of the patient with epilepsy is first dependent on a determination of the type of seizure. When the type of seizure has been determined, consideration must be given to the nature of the epileptic syndrome, including concerns regarding the etiology of the attacks. The gradual evolution of the various classification schemes of epileptic seizures and epileptic syndromes complicates the task of the physician but also affords evidence of the dynamism extant in clinical epilepsy research. Intensive monitoring will assist not only in the diagnosis of the individual patient but also in the long-term re-evaluation and revision of the empirical classifications.

Favorable outcome of epileptic blindness in children.

Acute blindness is a rare presentation of epileptic seizures, referring to loss of sight without loss of consciousness associated with electroencephalographic (EEG) epileptic discharges, mainly representing an ictal phase but also either pre- or postictal. We report a series of 14 children with documented epileptic blindness, describing the accompanying fits and thereafter the response to therapy to resolve the blindness and control associated seizures. All patients experienced episodes of acute complete visual obscuration lasting for 1 to 10 minutes. Seven patients hadaccompanying generalized seizures, with a photosensitive response recorded in three of them. All of these seven children were treated with valproic acid, regaining full vision, and six of them became seizure free. Three patients with acute blindness who had accompanying focal motor seizures and unilateral temporooccipital posterior epileptic discharges were treated with carbamazepine regained full vision and complete seizure control. Four additional children had the constellation of migrainous headaches, focal motor phenomena, and complete blindness, along with occipital discharges compatible with Gastaut syndrome, benign childhood epilepsy with occipital paroxysms. All four patients were started on carbamazepine and became asymptomatic. Our overall experience suggests that epileptic blindness in children is associated with a favorable outcome when promptly diagnosed and treated appropriately, resulting in complete resolution of blindness in all children and satisfactory control of seizures in most of them. We therefore recommend performing a prompt EEG in any child presenting with acute visual obscuration, even in the absence of other epileptic phenomena.

Myoclonic-astatic epilepsy of early childhood--clinical and EEG analysis of myoclonic-astatic seizures, and discussions on the nosology of the syndrome.

PURPOSE: The aim of this study is to elucidate the clinical and neurophysiological characteristics of the myoclonic, myoclonic-astatic, or astatic seizures in patients with myoclonic-astatic epilepsy (MAE) of early childhood, and to discuss on the nosology of this unique epileptic syndrome. SUBJECTS: The subjects included 30 patients, who fulfilled the following modified International League Against Epilepsy (ILAE) criteria for MAE, and whose main seizures were captured by video-electroencephalographs (EEG) or polygraphs. The modified ILAE criteria includes: (1) normal development before onset of epilepsy and absence of organic cerebral abnormalities; (2) onset of myoclonic, myoclonic-astatic or astatic seizures between 7 months and 6 years of age; (3) presence of generalized spike- or polyspike-wave EEG discharges at 2-3 Hz, without focal spike discharges; and (4) exclusion of severe and benign myoclonic epilepsy (SME, BME) in infants and cryptogenic Lennox-Gastaut syndrome based on the ILAE definitions. RESULTS: The seizures were investigated precisely by video-EEG (n=5), polygraph (n=2), and video-polygraph (n=23), which identified myoclonic seizures in 16 cases (myoclonic group), atonic seizures, with or without preceding minor myoclonus, in 11 cases (atonic group), and myoclonic-atonic seizures in three cases. All patients had a history of drop attacks, apart from ten patients with myoclonic seizures. Myoclonic seizures, involving mainly the axial muscles were classified into those with mild intensity not sufficient to cause the patients to fall (n=10) and those that are stronger and sufficient to cause astatic falling due to flexion of the waist or extension of the trunk (n=6). Patients in the atonic group fell straight downward, landed on their buttocks, and recovered immediately. Analysis of the ictal EEGs showed that all attacks corresponded to the generalized spike or polyspikes-and-wave complexes. In the atonic form, the spike-and-wave morphology was characterized by a positive-negative-deep-positive wave followed by a large negative slow wave. In two patients, the intensity of the atonia appeared to correspond to the depth of the positive component of the spike-and-wave complexes. We did not detect any significant differences in the clinical and EEG features and prognosis, between the atonic and myoclonic groups. CONCLUSIONS: Although the determination of exact seizure type is a prerequisite for diagnosing an epileptic syndrome, the strict differentiation of seizure type into either a myoclonic or atonic form, does not appear to have a significant impact on the outcome or in delineating this unique epileptic syndrome. At present, we consider it better to follow the current International Classification of Epileptic Syndromes and Epilepsies until a more appropriate system than the clinico-electrical approach for classifying patients with MAE is available.

[Myoclonus in the adult: diagnostic approach]. / Les myoclonies chez l'adulte: démarche diagnostique.

Myoclonus, defined as shock-like involuntary movement, may be physiological or caused by a very wide variety of hereditary and acquired conditions. Because myoclonus can originate from different disorders and lesions affecting quite varied levels of the central and peripheral nervous systems, it represents from many points of view a diagnostic challenge. Moreover, new entities have been recently individualized, such as cortical tremor, which deserve renewed attention. The aim of this review is to propose a rationale for a diagnostic approach based on clinical and electrophysiological grounds. In this setting, we successively address 1) the clinical features allowing a positive diagnosis of myoclonus; 2) the clinical clues to the etiology; 3) the relevance of the clinical context to the diagnosis; and 4) the contribution of neurophysiology. Differentiating myoclonus from tics, spasm, chorea and dystonia can be difficult, and a careful reappraisal of clinical features allowing precise identification is presented. Moreover, the topographical distribution of myoclonus, the temporal pattern of muscle recruitment, the condition of occurrence and the rhythm of the event, may provide clinical clues relevant to the diagnosis. Myoclonus without associated epilepsy, myoclonus with epilepsy, myoclonus with encephalopathy, parkinsonism and/or dementia represent overlapping clinical categories, although they remain useful for the diagnostic approach. Using electrophysiology (including back-averaging EEG, MEG, SEP, C-reflex studies) to determine the origin of myoclonus may not allow us to focus on the underlying condition. Indeed, in many instances, the myoclonus is cortical in origin, but the pathology is found elsewhere.

Case summary: Benjamin.

Benjamin was diagnosed with Aspberger's syndrome on starting school. Prior to that, at the age of five years he presented with seizures involving deviation of the head and eyes to the right and jerking of the limbs. EEG was very abnormal with multifocal paroxysmal activity and occasional bursts of spike and slow wave activity. CT scan and MRI were normal and investigations failed to identify any underlying aetiology for the seizures. Carbamazepine was initially successful in controlling the seizures but improvement was not sustained despite maximal tolerated doses. A similar course of events was seen with sodium valproate, initially in combination with ethosuximide (for emergent tonic-clonic and absence seizures), then with vigabatrin (which unmasked myoclonic seizures), clonazepam and finally lamotrigine. The EEG remained abnormal even during periods of improved seizure control and there was no improvement in his Aspberger's syndrome. His epilepsy syndrome has not been classified. Subsequent treatment options include lamotrigine monotherapy.

Reading epilepsy in a patient with previous idiopathic focal epilepsy with centrotemporal spikes.

RATIONALE: Reading epilepsy (RE) is a form of reflex epilepsy currently classified as an idiopathic localization-related epilepsy (ILAE, 1989). METHODS: We describe a 30 year-old right-handed male who suffered since the age of 8 from nocturnal partial motor seizures. Clinical features were typical of BECT. We reviewed the EEG recorded at that time which showed centrotemporal spike and waves. He was seizure-free from the age of 12 to the age of 17 when seizures evoked only by reading appeared. No other stimuli provoked seizures. Neurological and neuroradiological (CT and MR) investigations were normal. Baseline video-polygraphic EEG recordings were normal while reading aloud provoked myoclonic jerks in the facial muscles related to bilateral spike and wave discharges. Therapy with carbamazepine and valproic acid strongly reduced seizure frequency. CONCLUSION: Recent papers have debated the difficulties in classifying RE among the generalized or focal syndromes. Literature reports describe an association with RE and juvenile myoclonic epilepsy, supporting the hypothesis of an idiopathic generalized form. We report the first documented case with a clear-cut idiopathic localization-related epilepsy evolving to a primary reading epilepsy.

[Juvenile myoclonic epilepsy]. / Epilepsie myoclonique juvénile.

Juvenile myoclonic epilepsy is an age-related form of idiopathic generalized epilepsy (mean age of onset: 12-14 years). The diagnosis is based on a cluster of clinical features: types of seizures, namely myoclonic jerks associated with generalized tonic-clonic or clonic-tonic-clonic seizures in 90% of the cases, absence seizures in one third of the cases; triggering factors and circadian rhythm of seizures on awakening or after sleep deprivation; a characteristic EEG pattern, i.e. bilateral symmetrical polyspike-waves. The clinical pattern is so suggestive that in clinical practice EEG is not necessary. Seventy percent of the patients are seizure-free with one-drug therapy. Treatment must be life-long, as relapse occurs in most cases after drug withdrawal, whatever the duration of control.

[Myoclonus and epilepsies in children]. / Myoclonies et épilepsies chez l'enfant.

The possible associations of myoclonic phenomena, progressive or non progressive encephalopathies and epileptic phenomena are reviewed with special emphasis on childhood. This leads to the following five groups of conditions: (1) myoclonus without encephalopathy and without epilepsy; (2) encephalopathies with non-epileptic myoclonus; (3) progressive encephalopathies with myoclonic seizures or epileptic syndromes (Progressive myoclonus epilepsies); (4) epileptic encephalopathies with myoclonic seizures; (5) myoclonic epilepsies. In the first group, which also includes physiological myoclonus, a more thorough description of "benign sleep myoclonus of newborn" and "benign myoclonus of early infancy" is given. Characteristic of group 2 are "Kinsbourne syndrome" and certain types of "Hyperekplexia" which pose interesting differential diagnosis problems with stimulus-sensitive epilepsies. In group 3, the concept of progressive encephalopathies is stressed, meaning that "Progressive Myoclonus Epilepsies" are always in fact progressive encephalopathies presenting with myoclonic types of seizures or epileptic syndromes among other neurologic and psychologic signs and symptoms. Major and rare causes are reviewed. The term major is applied to typical features or to frequency, whereas rare causes include not only those what are rarely seen, but also some myoclonic variants of diseases which usually have different symptoms. The fourth group refers to severe epilepsies, mainly in infancy and childhood, which lead to mental retardation irrespective of their cause. The assumption is that diffuse and persistent epileptic activity may interfere with normal development of the higher cerebral functions. "West syndrome" and "Lennox-Gastaut syndrome" are the more representative examples and may present with myoclonic type of seizures, but they are not dealt with in detail here. Group 5 comprises true myoclonic epilepsies, differentiating syndromes recognized as idiopathic, such as "benign myoclonic epilepsy of infancy" and "juvenile myoclonic epilepsy", from those which are cryptogenic and carry a more cautious prognosis--i.e.: "cryptogenic myoclonic and myoclono-astatic epilepsies" and "Severe myoclonic epilepsy of infancy". Finally other epileptic syndromes usually not considered as myoclonic epilepsies, but presenting sometimes myoclonic seizures, are mentioned.

A sensitive and semi-quantitative pediatric myoclonus evaluation scale.

One of the difficulties in evaluating myoclonus in childhood is the lack of a standardized scale which addresses the constraints of pediatric scoring. The scale needs to be simple and rapid as well as sensitive and semi-quantitative and applicable across different ages. We videotaped children and young adults with myoclonus of various etiologies, such as progressive myoclonus epilepsy, opsoclonus-myoclonus and other acquired etiologies, and scored the videotapes using a new scale. Each clinical type of myoclonus (spontaneous, action and sensory-evoked myoclonus) was graded separately on a five-point scale for severity, intensity and distribution. Data were evaluated as separate scores and also combined for a total score. Validity and reliability were tested using a judge panel of three blinded, trained observers. Action myoclonus was the predominant form of myoclonus in our patients, and was significantly greater than spontaneous and sensory-evoked myoclonus in frequency, intensity and distribution. Separate statistical analysis performed for progressive myoclonus epilepsy and for opsoclonus-myoclonus showed the same pattern. Total scores between etiologies of myoclonus for frequency and distribution categories were significantly different. Subscores and total scores were highly correlated. We found the new scale to be flexible and adaptable for children and there were few missing values due to non-applicability of a scale item. It was useful for all pediatric age groups. The scale and videotape instructions provide a reliable tool for use in pediatric myoclonic disorders.