What is more harmful, seizures or epileptic EEG abnormalities? Is there any clinical data?

Abstract

Cognitive impairment is a common and often devastating co-morbidity of childhood epilepsy. While the etiology of the epilepsy is critical determinant of cognitive outcome, there is considerable evidence from both rodent and human studies that indicate that seizures and interictal epileptiform abnormalities can contribute to cognitive impairment. A critical feature of childhood epilepsy is that the seizures and epileptiform activity are occurring in a brain with developing, plastic neuronal circuits. The consequences of seizures and interictal epileptiform activity in the developing brain differ from similar paroxysmal events occurring in the relatively fixed circuitry of the mature brain. In animals it is possible to study interictal spikes independently from seizures and it has been demonstrated that interictal spikes are as detrimental as seizures during brain development. In the clinic distinguishing the differences between interictal spikes and seizures is more difficult, since both typically occur together. However, both seizures and interictal spikes result in transient cognitive impairment. Recurrent seizures, particularly when frequent, can lead to cognitive regression. While the clinical data linking interictal spikes to persistent cognitive impairment is limited, interictal spikes occurring during the formation and stabilization of neuronal circuits likely contributes to aberrant connectivity. There is insufficient clinical literature to indicate whether interictal spikes are worse than seizures during brain development.

A survey of antiepileptic drug responses identifies drugs with potential efficacy for seizure control in Wolf–Hirschhorn syndrome

“…Wolf-Hirschhorn syndrome (WHS; Online Mendelian Inheritance in Man (OMIM) #194190) is a rare contiguous gene deletion syndrome affecting the terminal region of chromosome human chromosome 4, petite arm (4p) [1]. Epilepsy is a serious neurologic challenge for over 90% of individuals with WHS, presenting in early childhood and potentially affecting cognitive development [2]. A previous study involving 87 individuals with WHS determined that seizure types most commonly experienced are generalized tonic-clonic, tonic or clonic, and complex partial [3].…”

Effect of Seizures on the Developing Brain and Cognition

“…Among the co-morbidities associated with epilepsy in children, cognitive abnormalities are among the most common and troublesome 2,3 . The distribution of intelligence quotient (IQ) scores of children with epilepsy is skewed toward lower values 4,5 and the number of children with epilepsy experiencing difficulties in school because of learning disabilities is greater than children without epilepsy 6–11 .…”

Interictal epileptiform discharge effects on neuropsychological assessment and epilepsy surgical planning

“…Increasingly, more researchers are coming to this conclusion [40], yet clinical lore has long suggested that any effect is trivial and likely not worth considering. In this context, we believe that our current case examples, while not definitive proof of this concept, provide impetus for further study.…”

“…This impairment appeared to be due to impairment of cell formation in the hippocampus. These findings raise the possibility that IEDs during early human development could have profound effects on later cognitive and behavioral function [40]. …”