| Benign myoclonic
epilepsy in infancy |
HISTORICAL NOTE To our knowledge, there are presently 67 cases published
in the literature, of which 10 reported as “reflex” (Dravet
and Bureau 2002). Also of mention is that in the first description the
onset age was before 3 years, whereas in the following reports some authors
have described a later onset age, up to 4 years 8 months of age (Giovanardi
Rossi et al 1997). That means the same type of epilepsy can appear at
different ages, but with a trend to be more frequent in some periods (Guerrini
et al 1994). The myoclonic attacks involve the upper limbs and the head, though rarely the lower limbs. Their intensity is variable, rarely inducing a fall. In babies they are not easy to describe; parents report a head nod. They occur several times a day at irregular and unpredictable times. They are not favored by awakening, but they can be triggered by a sudden noise or sudden contact. The state of consciousness is difficult to assess, but the isolated seizures do not interrupt activity. Only when they are grouped in clusters of 2 or 3 pseudorhythmically repeated elements, lasting up to 5 to 10 seconds, is there a slight impairment of consciousness. They are more or less massive, involving the axis of the body and the limbs, provoking a head drop and an upwards-outwards movement of the upper limbs, with flexion of the lower limbs, and sometimes a rolling of the eyeballs. Initially, the development continues normally, and parents and pediatricians tend not to consider these movements as pathological events. When an EEG is performed, it can be normal if no myoclonic fit is recorded. But myoclonias are always associated with fast generalized spike waves and polyspike waves at more than 3 Hz, that are more or less regular, lasting 1 to 3 seconds.|{diagram:bmei1.bmp}{caption:Polysomnogram of myoclonic jerks in the head and arms}{label:Several myoclonic jerks are polygraphically recorded when awake, when persisting during drowsiness, and, attenuated, during sleep stage II in a 2-year-old girl before any treatment. The jerks are accompanied by generalized spike wave, sometimes preceded by spike wave localized in the anterior regions. The same type of generalized discharge appears during REM sleep without concomitant clinical event. R. DELT = right deltoid muscle, L. DELT = left deltoid muscle}| During drowsiness, there is an enhancement of the myoclonias that usually, but not always, disappear during sleep. Intermittent photic stimulation can also provoke myoclonic fits. Polygraphic recordings demonstrate the association of myoclonias and spike wave or polyspike wave discharges. Myoclonias are brief (1 to 3 seconds)|{diagram:bmei1.bmp}{caption:Polysomnogram of myoclonic jerks in the head and arms}{label:Several myoclonic jerks are polygraphically recorded when awake, when persisting during drowsiness, and, attenuated, during sleep stage II in a 2-year-old girl before any treatment. The jerks are accompanied by generalized spike wave, sometimes preceded by spike wave localized in the anterior regions. The same type of generalized discharge appears during REM sleep without concomitant clinical event. R. DELT = right deltoid muscle, L. DELT = left deltoid muscle}| and usually isolated. Myoclonias may be followed by a brief atonia. Sometimes, after the attack, there is a voluntary movement that is visible as a normal muscular contraction. The interictal EEG is normal for the child’s age. Spontaneous spike wave discharges are rare; some slow wave may be found over the central areas. Intermittent photic stimulation does not provoke spike wave without concomitant myoclonia. Nap sleep recordings have shown a normal organization of the sleep; generalized spike wave discharges may occur during REM sleep. No other type of seizure is observed in children with benign myoclonic epilepsy, even if they are left untreated (for up to 8.5 years in one of our patients), particularly, no absence or tonic seizures. Clinical examination is normal. Interictal myoclonus is described only by Giovanardi Rossi and colleagues in 6 patients (Giovanardi Rossi et al 1997). Many patients were not investigated, but when CT and MRI were performed, they were normal. The outcome seems to depend on an early diagnosis and
treatment. If left untreated, the patient continues to experience myoclonic
attacks, and this may lead to impaired psychomotor development and behavioral
disturbances. Myoclonias are easily controlled by valproate alone and
the child may then develop regularly, according to normal milestones. In following years, the patient was regularly seen in
our center. He continued to be seizure-free and to develop normally. Genetics is unknown. Cases are rare and no family cases
have been described. Genetic relationships with other types of idiopathic
generalized epilepsies are not established. Delgado-Escueta and colleagues
did not find cases of juvenile myoclonic epilepsy in their study of 24
affected family members of early childhood myoclonic epilepsy (Delgado-Escueta
et al 1990). The case described by Arzimanoglou and colleagues is the
second child of 2 brothers the oldest of whom was affected by a typical
epilepsy with myoclonic-astatic seizures, Doose syndrome. This association
raises the question of the relationships between these 2 epilepsies in
the large frame of generalized idiopathic epilepsies in early childhood.
In the family of the patient described by Biondi and colleagues, other
members had dubious epilepsy (Biondi et al 1991). Sleep EEGs were obtained
for the father and his 2 sisters and demonstrated brief bursts of generalized
spike waves. When both the psychomotor development and the EEG remain normal after several examinations performed awake and asleep, seizures resembling infantile spasms must suggest the diagnosis of benign nonepileptic myoclonus described by Lombroso and Fejerman (Lombroso and Fejerman 1977). In these patients, even the ictal EEG is normal (Dravet et al 1986; Pachatz et al 1999). In the first year of life, severe myoclonic epilepsy of infancy could be evoked but it always starts with long and repeated febrile seizures and not by isolated myoclonic attacks, and the psychomotor development is retarded (Dravet and Bureau 2002). When myoclonias begin after the end of the first year of life, the diagnosis of a cryptogenic Lennox-Gastaut syndrome may come to mind. In the Lennox-Gastaut syndrome (Beaumanoir and Blume 2002) seizures are not mainly myoclonic but myoclonic-atonic, or purely atonic, or more often tonic, leading to sudden falls and injuries. Their polygraphic expression is heterogeneous and the ictal EEG is either a recruiting rhythm or a flattening, or a high slow wave followed by runs of low voltage rapid rhythms. Interictal EEGs can be normal at the onset and the typical diffuse slow spike wave discharges may appear progressively. The typical electroclinical features during sleep can be delayed in time. But the diagnosis is based on the rapid association of different types of seizures such as atypical absences and axial tonic seizures, the constant impairment of behavior and learning, and the lack of efficacy of antiepileptic drugs. If myoclonic seizures remain isolated or are associated with generalized tonic-clonic seizures, the diagnosis of myoclonic astatic epilepsy of early childhood must be entertained, although the onset of myoclonic astatic seizures in this syndrome is rare before the age of 3 years (Doose 1992). There are 2 essential differences: (1) the clinical aspect of the seizures, which always consist of falls in epilepsy with myoclonic astatic seizures, whereas falls are rare in benign myoclonic seizures, and are combined with other types of seizures, particularly status of minor seizures with stupor, which are never observed in benign myoclonic epilepsy (Guerrini et al 1994); (2) the EEG features are also different. Spike waves and polyspike waves are more numerous and grouped in long bursts, associated with a typical theta rhythm over the centroparietal areas. But some cases included by Doose should probably be classified as benign myoclonic epilepsy. In the same way, the group studied by Delgado-Escueta (Delgado-Escueta et al 1990), under the name of early childhood myoclonic epilepsy, seems to include cases of both epilepsy with myoclonic astatic seizures and benign myoclonic epilepsy in infancy. Finally, one should consider other epilepsies beginning
in the first 3 years of life in which myoclonias are the main type of
seizure and which have variable prognosis. They are heterogeneous combinations
of other types of seizures, presence of EEG focal abnormalities, previous
delayed psychomotor development, poor response to drugs, and uncertain
prognosis (Dravet 1990). By definition, prognosis is good, and myoclonic attacks disappear with an appropriate treatment consisting of valproate monotherapy. Only in 5 patients was bitherapy necessary to control seizures (Giovanardi Rossi et al 1997). The length of follow-up is variable according to the series (9 months to 27 years). In 10 patients rare generalized tonic-clonic seizures occurred without associated myoclonias; in 3 they occurred during the drug withdrawal, and in others they occurred at adolescence (Dravet and Bureau 2002). The attacks provoked by noise or contact were more easily controlled than the spontaneous ones. Conversely, the photosensitivity was more difficult to control and persisted several years after the arrest of seizures. The psychological outcome is more variable. On the whole
it is rather good. The isolated cases published continue to have normal
psychomotor development. However, in the series with a long-term follow-up,
there are 12 patients who present moderate mental retardation, personality
disturbances, or slight behavioral impairment (Colamaria et al 1987; Todt
and Muller 1992; Giovanardi Rossi et al 1997; Dravet and Bureau 2002).
No patient has been institutionalized. This psychological outcome partly
depends on an early diagnostic, allowing appropriate treatment and family
reassurance. But, there are also other factors related to an abnormal
family structure and a disturbed mother-infant relationship. Not applicable. Not applicable. Arzimanoglou A, Prudent M, Salefranque F. Epilepsie myoclono-astatique et épilepsie myoclonique bénigne du nourrisson dans une même famille: quelques réflexions sur la classification des épilepsies. Epilepsies 1996;8:307-15.** Beaumanoir A, Blume W. The Lennox-Gastaut syndrome. In: Roger J, Bureau M, Dravet Ch, Genton P, Tassinari CA, Wolf P, editors. Epileptic syndromes in infancy, childhood and adolescence. 3rd ed. London: John Libbey Ltd, 2002:113-35. Biondi R, Sofia V, Tarascone M, Leocata R. Epilessia mioclonica benigna dell’infanzia: contibuto clinico. Boll Lega Ut Epil 1991;74:93-4. Colamaria V, Andrighetto G, Pinelli L, Olivieri A, Alfieri P, Dalla Bernardina B. Iperinsulinismo, ipoglicemia ed epilessia mioclonica benigna del lattante. Boll Lega It Epi 1987;58/59:231-3. Commission on Classification and Terminology of the International League Against Epilepsy. Proposal for revised classification of epilepsies and epileptic syndromes. Epilepsia 1989;30:389-99. Dalla Bernardina B, Colamaria V, Capovilla G, Bondavalli S. Nosological classification of epilepsies in the first three years of life. In: Nistico G, Di Perri R, Meinardi H, editors. Epilepsy: an update on research and therapy. New-York: Alan Liss, 1983:165-83. Delgado-Escueta AV, Greenberg D, Weissbecker K, et al. Gene mapping in the idiopathic generalized epilepsies: juvenile myoclonic epilepsy, childhood absence epilepsy, epilepsy with grand mal seizures, and early childhood myoclonic epilepsy. Epilepsia 1990;31(suppl 3):S19-29. Doose H. Myoclonic astatic epilepsy of early childhood. In: Roger J, Bureau M, Dravet C, Dreifuss FE, Perret A, Wolf P, editors. Epileptic syndromes in infancy, childhood and adolescence, 2nd ed. London: John Libbey Eurotext Ltd., 1992:103-14. Dravet C. Les épilepsies myocloniques bénignes du nourrisson. Epilepsies 1990;2:95-101. Dravet C, Bureau M. L’épilepsie myoclonique bénigne du nourrisson. Rev Electroenceph Neurophysiol Clin 1981;11:438-44. Dravet C, Bureau M, Giraud N, Roger J, Gobbi G, Dalla Bernardina B. Benign myoclonus of early infancy or benign non-epileptic spasms. Neuropediatrics 1986;17:33-8. Dravet C, Bureau M. Benign myoclonic epilepsy in infancy. In: Roger J, Bureau M, Dravet Ch, Genton P, CA Tassinari, Wolf P, editors. Epileptic syndromes in infancy, childhood and adolescence. 3rd ed. London: John Libbey Ltd., 2002:69-79.** Fusco L, Vigevano F. Ictal clinical and electroencephalographic findings of spasms in West syndrome. Epilepsia 1993;34:671-8. Giovanardi Rossi P, Parmeggiani A, Posar A, Santi A, Santucci M. Benign myoclonic epilepsy: long-term follow-up of 11 new cases. Brain Dev 1997;19:473-9 ** Guerrini R, Dravet CH, Gobbi G, Ricci S, Dulac O. Idiopathic generalized epilepsies with myoclonus in infancy and childhood. In: Malafosse A, Genton P, Hirsch E, Marescaux C, Broglin D, Bernasconi R, editors. Idiopathic generalized epilepsies: clinical, experimental, and genetic aspects. London: John Libbey Eurotext Ltd., 1994:267-80. ** Lin YP, Itomi K, Takada H, et al. Benign myoclonic epilepsy in infants: video-EEG features and long-term follow-up. Neuropediatrics 1998;29:268-71. Loiseau P, Duche B, Loiseau J. Classification of epilepsies and epileptic syndromes in two different samples of patients. Epilepsia 1991;32:303-9. Lombroso CT, Fejerman N. Benign myoclonus of early infancy. Ann Neurol 1977;1:138-43. Pachatz C, Fusco L, Vigevano F. Benign myoclonus of early infancy. Epil Disord 1999;1:57-61. Ricci S, Cusmai R, Fusco L, Cilio R, Vigevano F. Reflex myoclonic epilepsy of the first year of life. Epilepsia 1995;35:47.** Todt H, Muller D. The therapy of benign myoclonic epilepsy in infants. In: Degen R, Dreifuss FE, editors. Epilepsy research. Suppl 6. The benign localized and generalized epilepsies in early childhood. Amsterdam: Elsevier, 1992:137-9. Vigevano F, Cusmai R, Ricci S, Watanabe K. Benign epilepsies of infancy.
In: Engel Jr J, Pedley TA, editors. Epilepsy: a comprehensive textbook.
Philadelphia: Lippincott-Raven Publishers, 1997:2267-76. ILAE ILAE Copyright Notice ICD-9 Code 333.2 ASSOCIATED DISORDERS Simple febrile convulsions MAJOR KEYWORD DESCRIPTORS benign epilepsy MINOR KEYWORD DESCRIPTORS genetic epilepsy AGE OF PRESENTATION 01-23 months AGE OF TYPICAL PRESENTATION 01-23 months POPULATION GROUP(S) PREFERENTIALLY AFFECTED none selectively affected OCCUPATION GROUP(S) PREFERENTIALLY AFFECTED none selectively affected SEX male>female, >2:1 FAMILY HISTORY none HEREDITY heredity may be a factor GLOSSARY term1:definition idiopathic generalized epilepsy in infancy term2:definition
reflex idiopathic generalized epilepsy in infancy ILLUSTRATION CAPTIONS Title : figure 1 PERMUTED TOPIC, SYNONYMS, VARIANTS Benign myoclonic epilepsy in infancy RELATED TOPICS Benign epilepsy of infancy with partial seizures DIFFERENTIAL DIAGNOSIS cryptogenic infantile spasms
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