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HISTORICAL NOTE AND NOMENCLATURE
The 1989 classification of epilepsies and epileptic syndromes of the International League Against Epilepsy (Commission on Classification and Terminology of the International League Against Epilepsy 1989) includes only familial and nonfamilial neonatal convulsions and benign myoclonic epilepsy from among the idiopathic forms with onset during the first year of life. Other epileptic syndromes with onset during the same period, idiopathic etiology, and benign outcome are also now recognized.
In 1963, Fukuyama reported cases occurring in the first 2 years of life that were characterized by partial seizures, absence of etiologic factors, and benign outcome (Fukuyama 1963). Later, other reports of this clinical entity evidenced the localization and semiology of seizures (Watanabe et al 1987; 1990; 1993) and prognosis (Sugiura et al 1983).
On several occasions, Watanabe and coworkers described cases with partial seizures of a different type, proposing the terms "benign partial epilepsy of infancy with complex partial seizures" and "benign partial epilepsy with secondarily generalized seizures in infancy." Most of these cases were not familial. In 1990, Vigevano and coworkers described benign seizures with familial occurrence and subsequently proposed the term "benign infantile familial convulsions" (Vigevano et al 1990; 1992).
Just as benign convulsions with neonatal onset are distinguished in familial and nonfamilial forms, benign infantile convulsions are also divided into familial and nonfamilial forms, although the 2 forms can overlap.
Considering that the convulsive manifestations are limited to a restricted period of time, some authors have hypothesized the existence of particular etiologic factors in some sporadic cases, particularly with reports of cases of benign infantile convulsions associated with prolonged episodes of diarrhea caused by rotavirus infections (Itou et al 1988; Contino et al 1994; Imai et al 1999). A clear cause-effect relation still needs to be demonstrated.
CLINICAL MANIFESTATIONS
All of the reported cases have common fundamental clinical elements. This clinical entity is characterized by the following:
- partial seizures in clusters
- subacute onset
- affecting children in the first or second year of life
- no clear etiologic factors
- normal psychomotor development
Age at onset has been described from 3 to 20 months of age. Findings for all etiologic investigations, especially metabolic and neuroimaging tests, are normal. History of pregnancy and delivery are unremarkable.
All children have normal psychomotor development before the onset of seizures.
A common characteristic is the occurrence of seizures in a cluster: they are mostly brief, successive seizures, with a maximum of 8 to 10 daily, which do not reach a true status epilepticus. Interictal clinical condition is normal, with occasional sopor that could be attributed mostly to drug treatments.
Seizures are usually longer in the beginning, lasting 2 to 5 minutes, and become shorter as treatment takes effect. The cluster can last 1 to 3 days.
The seizures are mainly characterized by motor arrest, impairment of consciousness, staring, and convulsive movements.
Watanabe stressed the presence of limb or oral and facial automatisms in cases described as benign partial epilepsy with complex partial seizures (Watanabe et al 1990) and the presence of prompt generalization with tonic-clonic manifestations in cases described as benign partial epilepsy with secondary generalized seizures (Watanabe et al 1993).
When described, interictal EEG before and after the cluster is normal. Ictal EEG may disclose a focal discharge characterized by recruiting rhythm of increasing amplitude spreading over the hemisphere, then involving the entire brain.
According to Watanabe, the site of origin of the seizures in the cases described as benign partial epilepsy with complex partial seizures (Watanabe et al 1990) is the temporal area, while the site varies in cases described as benign partial epilepsy with secondary generalized seizures (Watanabe et al 1993).
Generally, no further seizures are observed in cases treated pharmacologically. In untreated cases, there can be isolated seizures or brief clusters before 1 year of age.
ETIOLOGY
The brutal onset of seizures in clusters led to the search for particular etiologic factors, but alterations of metabolic or infectious nature were never identified, and neuroimaging findings were always normal.
There have been reports of similar clinical pictures closely associated with episodes of diarrhea caused by rotavirus infection, but in these cases there is no clear evidence that the diarrhea is the etiologic factor of the seizure (Itou et al 1988; Contino et al 1994; Imai et al 1999). A simple casual coincidence cannot be excluded.
BIOLOGICAL BASIS
Sporadic and familial benign idiopathic convulsions may appear in the neonatal period (Miles and Holmes 1990; Plouin 1985); similarly, sporadic and familial idiopathic convulsions may appear in the first year of life, especially around the sixth month.
It can be hypothesized that epileptic seizures are particularly likely to appear during this period of life. It should not be forgotten that other forms of cryptogenic or symptomatic epilepsy, especially infantile spasms, also appear during this period. This could explain why subjects with a specific genetic predisposition have seizures in this period of life.
With the exclusion of any etiologic or favoring factor in the sporadic cases, and the consequent symptomatic nature of these seizures, we must, in any case, hypothesize the existence of a genetic predisposition to convulsions, even if aspecific. We cannot exclude the possibility that the sporadic cases are actually identical to the familial ones, only with less expressivity.
EPIDEMIOLOGY
The first descriptions of sporadic cases are to be attributed to Japanese authors.
Later, this form was reported in other parts of the world (Capovilla et al 1998). At present, we are not aware of any reliable epidemiological study on the incidence of this form of epilepsy.
PREVENTION
Not applicable.
DIFFERENTIAL DIAGNOSIS
The diagnosis of benign infantile epilepsy with partial seizures is difficult (Okumura et al 2000). Early diagnosis is possible only in the familial forms. In the sporadic forms with either complex partial or secondarily generalized seizures, diagnosis can be suspected in consideration of the criteria presented above, with exclusion of any possible etiologic factors.
As mentioned previously, the cases described that were associated with prolonged episodes of diarrhea have clinical and EEG characteristics that coincide with those described in benign infantile convulsions. The etiologic role of the viral infection that causes the diarrhea has not been demonstrated. A facilitating role cannot be excluded.
In sporadic cases, the hypothetical diagnosis can be confirmed only with the demonstration of benign outcome.
Capovilla and Beccaria described 12 nonfamilial cases of benign partial epilepsy with onset in infancy or early childhood with vertex spikes and waves during sleep on EEG (Capovilla and Beccaria 2000). This form differs from benign infantile convulsions because of later onset (13 to 30 months), less frequent seizures that are rarely in clusters, lack of ictal automatisms, and presence of peculiar interictal EEG anomalies.
DIAGNOSTIC WORKUP
Diagnosis is based, first of all, on precise investigation of history to find familial cases, prenatal, perinatal or postnatal etiologic factors, data on psychomotor development, and clinical condition prior to seizure onset. Normal neurologic examination must be confirmed. Blood and urine tests must be performed to exclude infectious or metabolic disorders (complete blood count, velocity of erythrocyte sedimentation, lactate, pyruvate, ammonia, etc.). Examination of cerebrospinal fluid is justified only if encephalitis is suspected, or in the presence of fever or alterations in blood values. Because the seizures are repetitive, EEG or video-EEG monitoring is advisable, as this will easily permit the recording of a seizure. Neuroimaging tests (CT scan or MR) should be performed because normal findings are fundamental for diagnosis.
PROGNOSIS AND COMPLICATIONS
Benign outcome is an integral part of diagnosis. Children with benign infantile seizures have normal psychomotor development and do not later present other forms of epilepsy. Particularly in cases not treated pharmacologically, there can be recurrence of isolated seizures, more rarely of seizures in clusters, in the first months after onset, but later the children are seizure-free. EEGs performed at follow-up are normal.
MANAGEMENT
Because outcome is benign, it is theoretically possible to not treat these patients. In practice, however, withholding treatment is not easy for various reasons: most patients have recurring seizures (every 2 to 3 hours); patients not treated after the first cluster of seizures can have other seizures or clusters; and diagnosis is not simple at onset, except for the familial forms.
There are reports in the literature of equally effective treatment with carbamazepine, phenobarbital, valproate, or zonisamide for periods varying from 1 to 5 years.
PREGNANCY
Not applicable.
ANESTHESIA
Not applicable.
REFERENCES CITED
Capovilla G, Beccaria F. Benign partial epilepsy in infancy and early childhood with vertex spikes and waves during sleep: a new epileptic form. Brain Dev 2000;22:93-9.
Capovilla G, Giordano L, Tiberti S, Valseriati D, Menegati E. Benign partial epilepsy in infancy with complex partial seizures (Watanabe's syndrome): 12 non-Japanese new cases. Brain Dev 1998;20:105-11.
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.
Contino MF, Lebby T, Arcinue EL. Rotavirus gastrointestinal infection causing afebrile seizures in infancy and childhood. Am J Emerg Med 1994;12:94-5.
Fukuyama Y. Borderland of epilepsy with special reference to febrile convulsions and so-called infantile convulsions. Seishing-Igaku (Clin Psychiatry) 1963;5:211-23.
Imai K, Otani K, Yanagihara K, et al. Ictal Video-EEG recording of three partial seizures in a patient with the benign infantile convulsions associated with mild gastroenteritis. Epilepsia 1999;40:1455-8.
Itou J, Takahashi Y, Kusunoki Y, Oki J, Chou K. Convulsions associated with mild acute diarrhea. Shounika-Rinsho Jpn J Pediatr 1988;41:2011-5.
Miles KD, Holmes GL. Benign neonatal seizures. J Clin Neurophysiol 1990;7:369-79.
Okumura A, Hayakawa F, Kato T, Kuno K, Negoro T, Watanabe K. Early recognition of benign partial epilepsy in infancy. Epilepsia 2000;41:714-7.
Plouin P. Benign neonatal convulsions (familial and nonfamilial). In: Roger J, Dravet C, Bureau M, Dreifuss FE, Wolf P, eds. Epileptic syndromes in infancy, childhood and adolescence. London: John Libbey, 1985:2-11.
Sugiura M, Matsumoto A, Watanabe K, Negoro T, Takaesu E, Iwase K. Long-term prognosis of generalized convulsions in the first year of life, with special reference to benign infantile convulsions. Jpn J Epil Soc 1983;1:116-21.
Vigevano F, Di Capua M, Fusco L, Ricci S, Sebastianelli R, Lucchini P. Sixth-month benign familial convulsions. Epilepsia 1990;31:613.
Vigevano F, Fusco L, Di Capua M, Ricci S, Sebastianelli R, Lucchini P. Benign infantile familial convulsions. Eur J Pediatr 1992;151:608-12.
Watanabe K, Negoro T, Aso K. Benign partial epilepsy with secondarily generalized seizures in infancy. Epilepsia 1993;34:635-8.
Watanabe K, Yamamoto N, Negoro T, et al. Benign complex partial epilepsies in infancy. Pediatr Neurol 1987;3:208-11.
Watanabe K, Yamamoto N, Negoro T, Takahashi I, Aso K, Maehara M. Benign infantile epilepsy with complex partial seizures. J Clin Neurophysiol 1990;7:409-16.
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