Epilepsy in children with mental retardation of undetermined origin

R. Gaggero, S. Pignatelli, R. Devescovi

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In population studies it was found that 15%-20% of children and adolescents with mental retardation (MR) had epilepsy (E). In these studies, the case-series are not homogeneous hecause MR is associated with variable conditions (e.g. cerebral palsy, chromosome abnormalities, genetic diseases). Consequently, also the characteristics of E are variable. We study E in a selected group of children with MR of undetermined origin, not associated with other conditions. Patients and methods The cohort consists of patients with MR (IQ <70) and active E, more than 3 years old, without brain lesions, malformations, chromosome abnormalities or genetic syndromes. In these cases a retrospective evaluation of the E (clinical and EEC characteristics, course) was carried out. Results 33 cases ( 16 males, 17 females; mean age: 10 years 6 months) were selected. MR was mild (IQ, 50-70) in 24 and severe (IQ <50) in 9. The mean age at onset was 4 years 9 months (in 6 <12 months). Specific epileptic syndromes were diagnosed only in 3 cases; the classification of the seizures allowed us to distinguish three groups: (a) generalized seizures, overall atypical absences, myoclonic, atonic, in 13 cases (39%): age at onset 3 years 7 months; (b) partial seizures in 17 (51%), simple in 11 and complex in 6; the epiletic focus was frontal in 3, temporal in 6 and occipital in 4; age at onset, 5 years 9 months; and (c) unclassified seizures in 3 patients. The evolution in the 24 cases with a follow-up > 4 years showed a remission (no seizures > 3 years) in 10 (42%), persistent seizures, in 14 (58%). Severity of MR, and type and frequency of seizures were not correlated with the outcome. Only the small group with E onset <12 months showed a worse outcome. Conclusions A syndromic classification is rarely possible for the atypical characteristics. The seizure classification shows a higher percentage of partial seizures in relation with the literature; also generalized minor motor seizures are frequently observed. No relationship between seizure type and degree of MR is shown. The severity of the E, the not favourable evolution in > 50% of cases and the negative prognostic value of an early onset confirm previous observations. Probably also in this selected population, the relationship between E and MR is not homogeneous; in some cases it is possible to presume that the association of E and low mental level is casual, whereas especially in patients with severe MR, a common developmental disorder of CNS has to be assumed.

Original languageEnglish
Pages (from-to)339
Number of pages1
JournalItalian Journal of Neurological Sciences
Issue number5
Publication statusPublished - 1999

ASJC Scopus subject areas

  • Neuroscience(all)
  • Clinical Neurology

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