Benign partial epilepsy and related conditions: multifactorial pathogenesis with hereditary impairment of brain maturation.

The main clinical and bioelectrical features of the benign partial epilepsies and related conditions are described. Based on highly selected groups, the definition of these suggested syndromes disregards the considerable overlap between borderline and intermediate cases. To understand the great phenotypic variability of these epilepsies, the complexity of causal especially genetic factors must be considered. Different genetic traits, expressed in certain EEG patterns, determine the level of cerebral excitability. These hereditary variables are widespread in the general population. Most are polygenic, focal sharp waves possibly autosomal dominant. In individuals, the coincidence of different traits with little or no clinical significance, results in additive effects lowering the seizure threshold and raising the risk of clinical manifestation. The complexity of causal factors, which, potentially include organic brain lesions, account for the wide spectrum of epileptic and non-epileptic conditions ranging from mild selective performance deficits to complex psychomental retardation, and from simple rolandic epilepsy to severe epilepsies with minor seizures or bioelectrical status. These conditions are not "syndromes" in the stricter sense, but sets of variably weighted symptoms of a complex pathogenetic background. A genetic disposition to focal pathogenetic background. A genetic disposition to focal anomalies of brain function is of decisive importance. The biological background is as of yet unknown. The marked age-dependency of symptoms and almost regular disappearance of seizures and EEG abnormalities at puberty justify the assumption of an hereditary impairment of brain maturation. The hypothesis of autosomal dominant inheritance awaits appraisal by studies of larger populations and quantitative genetic approaches.